Hormones And Behavior[JOURNAL]
Sun
200 papers
Corticosterone predicts double-brooding in female savannah sparrows (Passerculus sandwichensis).
Spina HA, Norris DR, Nong L … +6 more , Dobney SL, Mueller SD, Freeman NE, Doucet SM, Mennill DJ, Newman AEM
Horm Behav · 2025 Feb · PMID 39884216 · Publisher ↗
Given that double-brooding (rearing two broods within a season) can increase annual fecundity, it is unclear why some females in multi-brooded populations rear only one brood per season. The Quality Hypothesis proposes t...
Given that double-brooding (rearing two broods within a season) can increase annual fecundity, it is unclear why some females in multi-brooded populations rear only one brood per season. The Quality Hypothesis proposes that double-brooded females are high quality and, thus, have sufficient energetic resources available to bear the costs of rearing two broods per season. Glucocorticoids - endocrine hormones that have a critical role in energy regulation - could reflect female quality, and, therefore, also have the potential to indicate whether a female will rear a second brood. Using 12 years of reproductive data on migratory Savannah sparrows (Passerculus sandwichensis) from a population in eastern Canada, we explored whether baseline corticosterone concentrations were correlated with measures of female quality (body condition and fat score) and whether a female's baseline corticosterone concentrations during her first brood would predict whether she attempted a second. We found weak evidence that baseline corticosterone was negatively correlated with female body condition and found strong evidence that baseline corticosterone was negatively correlated with fat score. There was weak evidence for a positive relationship between double-brooding and baseline corticosterone in females sampled during the first brood incubation stage. Additionally, there was moderate evidence to suggest that the probability of double-brooding was negatively related to baseline corticosterone in females sampled during the first brood nestling stage. Our results provide evidence that corticosterone can reflect female condition in the context of double-brooding and demonstrate the importance of considering breeding stage when assessing corticosterone concentrations in parents.
Effects of exercise and transient estradiol exposure in middle-aged female rats.
Felton EK, Kulesz PA, Leasure JL … +1 more , Rodgers SP
Horm Behav · 2025 Feb · PMID 39864230 · Publisher ↗
The benefits of estrogen treatment on cognition in middle-aged and older women are dependent on many factors, including the timing of treatment. Moreover, the potential interactive effects with other lifestyle factors, s...
The benefits of estrogen treatment on cognition in middle-aged and older women are dependent on many factors, including the timing of treatment. Moreover, the potential interactive effects with other lifestyle factors, such as exercise, are poorly understood. In this study, we tested for lasting benefits of independent and combined treatment with estrogen and voluntary exercise initiated in midlife, using a rat model of menopause. Twelve-month-old, retired female breeders were bilaterally ovariectomized and received six weeks of 17β-estradiol (E2) treatment via subcutaneous implant, with or without access to running wheels. After E2 treatment, animals in the exercise groups had running wheel access for seven additional weeks, including a two-week period of cognitive and affective testing. Thereafter, hippocampal neuronal and cellular plasticity were assessed. E2 and exercise independently exerted effects on behavioral and cellular outcome measures. Transient E2 treatment enduringly increased motor output, lowered body weight, and increased behavioral plasticity. Exercise decreased total hippocampal microglia number and increased brain weight. No additive effects of exercise and E2 treatment were observed. E2 treatment may provide a means by which to enduringly increase physical activity in middle age, but combined E2 and exercise do not produce additive benefits on hippocampal behavioral or cellular plasticity.
Dominance and aggressiveness are associated with vasotocin neuron numbers in a cooperatively breeding cichlid fish.
Ruberto T, Swaney WT, Reddon AR
Horm Behav · 2025 Feb · PMID 39837166 · Publisher ↗
Within dominance hierarchies, individuals must interact in a rank-appropriate manner, thus behavior and its underlying neural mechanisms must change with social status. One such potential neural mechanism is arginine vas...
Within dominance hierarchies, individuals must interact in a rank-appropriate manner, thus behavior and its underlying neural mechanisms must change with social status. One such potential neural mechanism is arginine vasotocin (AVT), a nonapeptide which has been implicated in the regulation of dominance and aggression across vertebrate taxa. We investigated the relationship between social status, dominance-related behaviors, and vasotocin neuron counts in daffodil cichlids (Neolamprologus pulcher). Daffodil cichlids live in stable, mixed-sex, cooperatively breeding social groups that are organised into linear dominance hierarchies. Group members of both sexes exhibit complex behavioral repertoires which differ depending on their current social status. We recorded agonistic behaviors within groups of daffodil cichlids and correlated these with the number of AVT cells within the three distinct neuronal populations in the preoptic area of the brain, comparing across social status and sex. We found that parvocellular AVT neurons were more abundant in dominant individuals than subordinates. We also found that numbers of both parvocellular and magnocellular AVT neurons were positively associated with aggression in dominant individuals. AVT neuron counts were unrelated to submissive behavior in subordinate fish. Our data emphasise the role of AVT in modulating status and aggression in social vertebrates.
Hormonal fluctuations in rodent models using 4-vinylcyclohexene diepoxide: A systematic review and meta-analysis.
Mashimo A, Oshida R, Oka Y … +6 more , Kawabata S, Takasu C, Nihei K, Kojima T, Kanemura N, Murata K
Horm Behav · 2025 Feb · PMID 39826372 · Publisher ↗
An animal model of 4-vinylcyclohexene diepoxide (VCD)-induced premature ovarian failure was developed to mimic menopause; this model has been used in various field studies. However, detailed reports on the rodent model u...
An animal model of 4-vinylcyclohexene diepoxide (VCD)-induced premature ovarian failure was developed to mimic menopause; this model has been used in various field studies. However, detailed reports on the rodent model using VCD are lacking, and the animal species used, administration methods, and hormonal fluctuations in the creation of the VCD model have not been comprehensively elucidated. The aim of this study was to systematically review these aspects of the rodent model using VCD and elucidate its characteristics. Thirty-two studies were extracted; rats and mice (66 %/44 %) are the most commonly used animal species. In most of the studies involving mice, a dose of 160 mg/kg was administered, whereas in most rat studies, doses of 80 mg/kg and 160 mg/kg were administered. On most mice studies (70 %), the most frequently applied dosage duration was 15 days. In most rat studies (63 %), the most frequently applied duration was 25 days, followed by 14 and 15 days in 30 % of the studies. Meta-analysis indicated that the mouse model using VCD simulates significant hormonal changes, such as estradiol (E2), anti-Müllerian hormone (AMH), and follicle stimulating hormone (FSH) changes. In conclusion, although the VCD model has demonstrated significant promise in replicating menopausal hormonal conditions, further systematic studies are required to fully understand its potential applications and refine its methodologies. This comprehensive review of existing literature highlights the need for continued research to expand the use of the VCD model in diverse medical fields.
Dietary phytoestrogens recalibrate socioemotional behavior in C57Bl/6J mice in a sex- and timing-dependent manner.
Le Roux CE, Farthing AL, Lucas EK
Horm Behav · 2025 Feb · PMID 39826371 · Full text
Estrogens are potent regulators of socioemotional behavior across species. Ubiquitous in human and animal diets, plant-derived phytoestrogens (PE) bind estrogen receptors. While prior work has examined the impact of PE e...
Estrogens are potent regulators of socioemotional behavior across species. Ubiquitous in human and animal diets, plant-derived phytoestrogens (PE) bind estrogen receptors. While prior work has examined the impact of PE exposure on socioemotional behavior, findings are inconsistent across studies. To investigate whether the timing of PE diet initiation may govern differential behavioral effects, we compared the impacts of PE-free (<20 mg/kg) versus PE-rich (810 mg/kg) diet exposure across the lifetime versus acutely in adulthood. Reproductive physiology was assessed through age at puberty onset and gonadal size. In adulthood, all mice underwent a behavioral battery consisting of the open field, elevated plus maze, and social interaction tests, followed by assessment of emotional memory dynamics with cued threat conditioning, extinction, recall, and renewal. Lifetime PE exposure delayed puberty onset and increased adult gonadal size selectively in males, whereas both lifetime and adult-only PE exposure decreased adult body weight in both sexes. In males, adult-only exposure increased open-arm avoidance in the elevated plus maze but enhanced threat memory extinction. In females, lifetime PE exposure increased open-arm avoidance, reduced sociability, and impaired threat memory extinction. Interestingly, lifetime PE exposure increased the context-dependent renewal of threat memory in both sexes. These findings demonstrate sex- and timing-dependent effects of PE exposure. Male lifetime PE exposure impacts reproductive measures with limited behavioral effects, whereas female lifetime exposure broadly impairs socioemotional behavior. Conversely, adult-only PE exposure altered behavior in males with limited impact in females. This study highlights the importance of diet composition, exposure period, and sex in rodent behavioral studies.
Different social experiences drive the development of divergent stress coping styles in female swordtails (Xiphophorus nigrensis).
Thakur S, Adams E, Prahl C … +3 more , Vuong A, Ramsey M, Cummings ME
Horm Behav · 2025 Feb · PMID 39824047 · Publisher ↗
Individual variation in stress coping styles is widespread and consequential to health and fitness. Proactive (bold behavior, low stress reactivity, low cognitive flexibility) and reactive (shy behavior, high stress reac...
Individual variation in stress coping styles is widespread and consequential to health and fitness. Proactive (bold behavior, low stress reactivity, low cognitive flexibility) and reactive (shy behavior, high stress reactivity, high cognitive flexibility) coping styles are found in many species, but the developmental forces shaping them remain elusive. We examined how social influences, specifically mating interactions, shape the development of adult female coping styles with a manipulative rearing experiment using El Abra swordtails, Xiphophorus nigrensis. We raised juvenile females in environments with different male reproductive phenotypes: coercive-only, courting-only, or complex (both coercive and courting males). At adulthood, we measured female stress reactivity (cortisol release following acute stress), boldness (scototaxis and open field responses), and cognitive flexibility (as inhibitory control in a detour task). Females raised in coercive and complex environments developed higher cortisol reactivity than females raised with only courtship. Stress coping trait correlations varied significantly across social environments producing different coping styles across treatments. Traditional proactive and reactive stress coping styles developed in the coercive-only environment with negative correlations between stress response and boldness, stress response and cognitive flexibility, and boldness and cognitive flexibility. Meanwhile, the courtship-only environment produced a negative correlation between stress response and boldness. We thus demonstrate that the relationship between stress response and boldness can be socially modulated. These findings suggest that developmental variation in social experiences can shape suites of traits with complex relationships; and that highly stressful social interactions, such as sexual coercion, can be a strong driver of stress coping styles.
Effect of exogenous manipulation of glucocorticoid concentrations on meerkat heart rate, behaviour and vocal production.
Driscoll I, Briefer EF, Ganswindt A … +1 more , Manser MB
Horm Behav · 2025 Feb · PMID 39824046 · Publisher ↗
Encoding of emotional arousal in vocalisations is commonly observed in the animal kingdom, and provides a rapid means of information transfer about an individual's affective responses to internal and external stimuli. As...
Encoding of emotional arousal in vocalisations is commonly observed in the animal kingdom, and provides a rapid means of information transfer about an individual's affective responses to internal and external stimuli. As a result, assessing affective arousal-related variation in the acoustic structure of vocalisations can provide insight into how animals perceive both internal and external stimuli, and how this is, in turn, communicated to con- or heterospecifics. However, the underlying physiological mechanisms driving arousal-related acoustic variation remains unclear. One potential driver of such variation in behaviour and vocal production are glucocorticoids. Through exogenous glucocorticoid manipulation, we aimed to gain insight on the relationship between arousal and physiological parameters, behaviour and vocal production in wild meerkats (Suricata suricatta). To this aim, we administered glucocorticoids to wild meerkats, and recorded their heart rate, vigilance behaviour, call rate and acoustic structure during natural behavioural contexts. The results suggest that, although the glucocorticoid treatment did increase plasma glucocorticoid levels, this did not result in observable changes in heart rate, vigilance, or vocal production. This lack of treatment effect suggests that, while glucocorticoids may be a significant component and correlate of the arousal response, they are not the direct drivers of affective arousal related changes in heart rate, behaviour, or vocal production.
Exogenous estradiol impacts anxiety-like behavior of juvenile male and female Siberian hamsters in a dose-dependent manner.
Forrester-Fronstin Z, Barrett AR, Mondschein AS … +5 more , Johnson JM, Cordes CN, Lawton-Stone TS, Schatz KC, Paul MJ
Horm Behav · 2025 Jan · PMID 39731972 · Publisher ↗
Anxiety is among the most prevalent mental health issues in children. While it is well established that gonadal steroids influence anxiety-like behavior in adulthood, a potential role in prepubertal juveniles has been ov...
Anxiety is among the most prevalent mental health issues in children. While it is well established that gonadal steroids influence anxiety-like behavior in adulthood, a potential role in prepubertal juveniles has been overlooked because it is commonly thought that the gonads are quiescent during the juvenile period. However, the juvenile gonads secrete measurable amounts of steroids, and we have recently found that prepubertal ovariectomy decreases anxiety-like behavior of juvenile Siberian hamsters in the light/dark box test. The present study tested whether an injection of estradiol benzoate (1 μg or 10 μg, SC) to gonadectomized hamsters (Exp. 1) or chronic suppression of endogenous estradiol with the aromatase inhibitor, letrozole (2 mg/kg, PO), to intact hamsters (Exp. 2) affects anxiety-like behavior in the light/dark box test during the juvenile phase. Estradiol benzoate altered anxiety-like behavior of both male and female juveniles in a dose-dependent manner, with anxiolytic actions at the low dose, but no effect at the high dose. Similar effects were seen for activity measures, albeit only in females. Letrozole suppressed uterine weights demonstrating an active role for endogenous estradiol during the juvenile phase. Anxiety-like behavior, however, was impacted by the administration procedure itself, preventing conclusions on letrozole's actions on behavior. While the role for endogenous estradiol in juvenile anxiety-like behavior remains unresolved, the present findings indicate that the neural centers regulating affective behavior are responsive to exogenous estradiol prior to puberty. These findings highlight the potential impact of exogenous estrogen exposures on juvenile affective behavior.
Oral administration of ethinyl estradiol and the brain-selective estrogen prodrug DHED in a female common marmoset model of menopause: Effects on cognition, thermoregulation, and sleep.
Rothwell ES, Viechweg SS, Prokai L … +2 more , Mong JA, Lacreuse A
Horm Behav · 2025 Jan · PMID 39721460 · Publisher ↗
Menopausal symptoms of sleep disturbances, cognitive deficits, and hot flashes are understudied, in part due to the lack of animal models in which they co-occur. Common marmosets (Callithrix jacchus) are valuable nonhuma...
Menopausal symptoms of sleep disturbances, cognitive deficits, and hot flashes are understudied, in part due to the lack of animal models in which they co-occur. Common marmosets (Callithrix jacchus) are valuable nonhuman primates for studying these symptoms, and we examined changes in cognition (reversal learning), sleep (48 h/wk of sleep recorded by telemetry), and thermoregulation (nose temperature in response to mild external warming) in middle-aged, surgically-induced menopausal marmosets studied at baseline, during 3-week phases of ethinyl estradiol (EE, 4 μg/kg/day, p.o.) treatment and after EE withdrawal. We also assessed a brain-selective hormonal therapy devoid of estrogenic effects in peripheral tissues on the same measures (cognition, sleep, thermoregulation) after treatment with the estrogen prodrug 10β,17β-dihydroxyestra-1,4-dien-3-one (DHED, 100 μg/kg/day, p.o) and DHED withdrawal. Reversal learning performance was improved with EE or DHED treatment relative to phases without hormone administration, as indicated by a faster reversal of the stimulus/reward contingencies. Both EE and DHED increased non-REM sleep and reduced nighttime awakenings relative to baseline, but to the detriment of REM sleep which was highest at baseline. Nasal temperature in response to mild external warming was highest, and overnight core body temperature lowest, in the DHED treatment phase compared to both the EE and baseline phases. These results suggest that low dose estradiol, delivered either peripherally or centrally via DHED, benefits selective aspects of cognition and sleep in a marmoset menopause model. DHED appears a promising therapeutic candidate for alleviating the cognitive and sleep disruptions associated with estrogen deficiency in primates.
The effect of ovariectomy, 17β-estradiol treatment, and progesterone treatment on dopaminergic regulation of prepulse inhibition in adult and adolescent female mice.
van den Buuse M, Sun J, Gogos A
Horm Behav · 2025 Jan · PMID 39721459 · Publisher ↗
The aim of the present study was to investigate the role of ovarian hormones on dopaminergic regulation of prepulse inhibition (PPI), a measure of sensorimotor gating deficient in schizophrenia and other psychiatric illn...
The aim of the present study was to investigate the role of ovarian hormones on dopaminergic regulation of prepulse inhibition (PPI), a measure of sensorimotor gating deficient in schizophrenia and other psychiatric illnesses. Either in adulthood (11 weeks of age) or adolescence (5 weeks of age), female mice underwent ovariectomy (OVX) and were implanted with 17β-estradiol, progesterone, or a combination of these hormones. All mice were tested in adulthood for the acute effect of the dopamine receptor agonist, apomorphine, on PPI. Apomorphine treatment reduced PPI in intact mice and this effect was blocked after OVX in adulthood. A low dose implant of 17β-estradiol prevented this OVX effect and reinstated apomorphine-induced PPI disruption. Following adolescent OVX, the effect of apomorphine was not altered and it significantly reduced PPI in adulthood. A low dose implant of 17β-estradiol following adolescent OVX effect blocked apomorphine-induced PPI disruption in adulthood. Apomorphine had no effect on PPI in any of the mice treated with the high dose of 17β-estradiol or a combination of low-dose 17β-estradiol and progesterone, irrespective of treatment age, suggesting an antipsychotic action. Apomorphine tended to disrupt PPI in mice treated with progesterone only, irrespective of age of OVX. These results suggest that in adult mice, circulating 17β-estradiol and progesterone play an important role in dopaminergic regulation of PPI. This role may develop during adolescence as similar effects of OVX and ovarian hormones were not observed following interventions in 5-week old mice. Our results also confirm and extend previous evidence that 17β-estradiol may have antipsychotic properties.
Reward of tactile genital stimulation is sexually equivalent, but mechanistically differentiated in mice.
Phung T, Monks DA
Horm Behav · 2025 Jan · PMID 39657388 · Publisher ↗
Gonadal steroid hormones are thought to activate sexual behavior by actions on multiple organ systems, including the nervous system and genitalia. We previously characterized ovarian hormone dependent behavioral and neur...
Gonadal steroid hormones are thought to activate sexual behavior by actions on multiple organ systems, including the nervous system and genitalia. We previously characterized ovarian hormone dependent behavioral and neural responses to clitoral stimulation in female mice. Here we investigate whether sex differences exist in the responses to tactile genital stimulation, and whether these might depend on gonadal androgens. We measured conditioned place preference (CPP) in response to manual tactile stimulation of either the prepuce or dorsum and subsequently measured neural activation. Behavioral and neural responses to genital stimulation were sexually equivalent in gonadally intact mice, with males exhibiting CPP and neural activation responses similar to those previously reported in females, with the exception of the Arcuate nucleus, which was activated to a greater extent in females. An unexpected sex difference in response to dorsal stimulation was observed, with only males developing CPP and increased FOS expression in the nucleus accumbens. Unlike females, the reward value of tactile stimulation was unaffected by gonadectomy in males. However, neural responses to tactile stimulation were disrupted by gonadectomy in both sexes. Testosterone treatment was only partially effective in restoring neural responses to genital stimulation and did so in a sexually diffentiated manner. We conclude that behavioral and neural responses of sexually-naïve mice to genital stimulation are largely similar between males and females, but that non-genital tactile stimulation is more reinforcing to males. Further, the relationship between gonadal steroid hormones and genital reward is sexually differentiated.
Kisspeptin participates in the positive reward state induced by paced mating and modulates sexual receptivity and paced mating behavior in female rats.
Bedos M, Ponce E, Corona R … +1 more , Paredes RG
Horm Behav · 2025 Jan · PMID 39637765 · Publisher ↗
Kisspeptin (Kp), a potent regulator of the hypothalamic-pituitary-gonad axis, was recently shown to be involved in partner preference and sexual receptivity in females. Interestingly, Kp and its receptor (Kiss1r) are exp...
Kisspeptin (Kp), a potent regulator of the hypothalamic-pituitary-gonad axis, was recently shown to be involved in partner preference and sexual receptivity in females. Interestingly, Kp and its receptor (Kiss1r) are expressed in brain regions involved in the reward and motivation of reinforcing behaviors. Therefore, in the present study, we designed 3 experiments to determine the participation of Kp in female sexual behavior and the positive affective (PA) reward state induced by paced mating (PM). In all experiments, we used sexually naïve ovariectomized Wistar female rats primed with estradiol benzoate (EB, 2.5 μg/rat) 48 h before behavioral tests. In experiment 1 (n = 9), we tested the effect of Kp on PM. We demonstrated that Kp-10 (14 nmol) induced similar levels of receptivity to treatment with EB + progesterone and facilitated PM by reducing the return latency after intromissions. In experiment 2 (n = 8), we evaluated the effect of p234 penetratin, a Kiss1r antagonist, on PM. The administration of p234 in doses of 7.5 nmol and 15 nmol reduced the mean lordosis intensity and increased mount and intromission return latencies. Finally, in Experiment 3, we tested the capacity of Kp to induce a PA state or the antagonist to block the reward state induced by PM. Kp-10 (7 and 14 nmol) induced a clear conditioned place preference. This reward state and that produced by PM were blocked by p234 (15 nmol). Our findings underscore the critical role of Kp in modulating female sexual behavior and the PA state associated with PM, highlighting its potential to enhance sexual motivation.
Seasonal variation in aggression and physiological stress in wild female and male redfronted lemurs (Eulemur rufifrons).
Prox L, Heistermann M, Rakotomala Z … +2 more , Fichtel C, Kappeler PM
Horm Behav · 2025 Jan · PMID 39637764 · Publisher ↗
Intraspecific competition with fellow group members represents an unavoidable cost of group living. However, the causes of competition can vary among group members, and ecological and reproductive challenges faced by ind...
Intraspecific competition with fellow group members represents an unavoidable cost of group living. However, the causes of competition can vary among group members, and ecological and reproductive challenges faced by individuals throughout the year can trigger physical conflicts and or physiological responses. To date, few studies in mammals have described both physiological and behavioral responses to competition simultaneously across the year in both males and females. However, such an approach may shed light on ultimate drivers of sex-specific competitive strategies. In this six-year study on multiple groups of wild redfronted lemurs (Eulemur rufifrons), a primate species from Madagascar, we intended to identify the relative importance of feeding vs. reproductive competition for both sexes. We combined data on fecal glucocorticoid metabolite (FGCM) levels, a proxy for the physiological stress response, with behavioral observations on agonistic interactions during ecologically and socially challenging phases across the year. We found that while FGCM levels increased in both sexes with decreasing fruit consumption, this increase was not accompanied by concomitant changes in agonistic behavior. Female aggression and FGCM levels instead peaked during the birth season, while for males, aggression remained fairly constant across the year. Our results suggest that redfronted lemurs have mechanisms to avoid direct competition through aggression at times when individuals may need to conserve energy.
Parenthood and gene expression of oxytocin receptors and vasopressin receptors in sensory cortices of the male California mouse (Peromyscus californicus).
Wilson KM, Dwyer T, Ramirez AV … +4 more , Arquilla AM, Seelke AMH, Trainor BC, Saltzman W
Horm Behav · 2025 Jan · PMID 39549482 · Publisher ↗
The onset of parental care is associated with shifts in parents' perception of sensory stimuli from infants, mediated by neural plasticity in sensory systems. In new mothers, changes in auditory and olfactory processing...
The onset of parental care is associated with shifts in parents' perception of sensory stimuli from infants, mediated by neural plasticity in sensory systems. In new mothers, changes in auditory and olfactory processing have been linked to plasticity at several points along both sensory pathways, including cortical changes that are modulated, at least in part, by oxytocin. In males of biparental species, vasopressin, in addition to oxytocin, is important for modulating parental behavior; however, little is known about sensory plasticity in new fathers. We examined variation in the mRNA expression of oxytocin and vasopressin receptors (Oxtr and Avpr1a) in sensory cortices of virgin males, paired nonbreeding males, and new fathers in the biparental California mouse (Peromyscus californicus), and variation among cortices using the visual cortex for comparison. Reproductive status did not affect gene expression for either receptor, but compared to the visual cortex, expression of both receptors was higher in the left auditory cortex and lower in the anterior olfactory nucleus. Additionally, expression for both receptors was higher in the left auditory cortex compared to the right auditory cortex. While oxytocin and vasopressin receptor expression may remain stable across reproductive stages in male California mice, our findings provide support for auditory cortex lateralization, with the left auditory cortex possibly displaying higher sensitivity to both oxytocin and vasopressin compared to the right.
Does a single dose of testosterone increase willingness to compete, confidence, and risk-taking in men? Evidence from two randomised placebo-controlled experiments.
Nadler A, Wibral M, Dohmen T … +6 more , Falk A, Previtero A, Weber B, Camerer C, Dreber A, Nave G
Horm Behav · 2024 Nov · PMID 39531812 · Publisher ↗
The sex steroid hormone testosterone regulates aggression and display of dominance in non-human animals. According to the Challenge Hypothesis, these effects arise from context-sensitive testosterone increases that facil...
The sex steroid hormone testosterone regulates aggression and display of dominance in non-human animals. According to the Challenge Hypothesis, these effects arise from context-sensitive testosterone increases that facilitate inter-male competitions over resources, status, and mates. A growing body of literature documents similar testosterone effects on behaviors related to competition and risk-taking in humans, though the findings have been mixed. Here, we report two randomised double-blind placebo-controlled testosterone administration experiments (N = 91, N = 242) designed independently by researchers in Europe and the US. Both experiments investigated the effect of a single dose of testosterone (at 4 h and 21-24 h post administration) on men's willingness to compete, confidence, and risk-taking in economic tasks. We estimate weak treatment effects that are statistically indistinguishable from zero for all behavioral outcomes across the two experiments. Our findings cast doubt on the proposition that there is an overall effect of a single dose of testosterone administration on the dimensions of economic behavior studied. If such effects existed, detecting them experimentally via pharmacological studies would require very large samples. We discuss different explanations for our results, including the possibility that context and individual difference factors moderate the effects.
The aged female rhesus macaque as a translational model for human menopause and hormone therapy.
Kohama SG, Urbanski HF
Horm Behav · 2024 Nov · PMID 39531811 · Full text
Progress in understanding the causes of physiological and behavioral changes in post-menopausal women is hampered by the paucity of animal models that accurately recapitulate these age-associated changes. Here we evaluat...
Progress in understanding the causes of physiological and behavioral changes in post-menopausal women is hampered by the paucity of animal models that accurately recapitulate these age-associated changes. Here we evaluate the translational potential of female rhesus macaques (Macaca mulatta). Like women, these long-lived diurnal primates show marked neuroendocrine changes during aging, as well as perturbed sleep-wake cycles and cognitive decline. Furthermore, the brains of old rhesus macaques show some of the same pathological hallmarks of Alzheimer's disease as do humans, including amyloidosis and tauopathology. Importantly, unlike humans, rhesus macaques can be maintained under tightly controlled environmental conditions, such as photoperiod, temperature and diet, and tissues can be collected with zero postmortem interval; this makes them especially suitable for studies aimed at elucidating underlying molecular mechanisms. Recent findings from female macaques are helping to elucidate how sex-steroids influence gene expression within the brain and contribute to the maintenance of cognitive function and amelioration of age-associated pathologies. Taken together, these findings emphasize the translational value of female rhesus macaques as a model for elucidating causal mechanisms that underlie normative and pathological changes in post-menopausal women. They also provide a pragmatic platform upon which to develop safe and effective therapies.
Glucocorticoids and behavior in non-human primates: A meta-analytic approach to unveil potential coping mechanisms.
Fiorini-Torrico R, De Vleeschouwer KM, Fuzessy L … +1 more , Oliveira LC
Horm Behav · 2024 Nov · PMID 39522450 · Publisher ↗
Glucocorticoids (GCs) mediate responses to energetic and psychosocial challenges and are associated with behavioral adjustments that form part of an adaptive vertebrate stress response. GCs and behavior can indirectly in...
Glucocorticoids (GCs) mediate responses to energetic and psychosocial challenges and are associated with behavioral adjustments that form part of an adaptive vertebrate stress response. GCs and behavior can indirectly influence each other, leading to either an intensification or attenuation of stress responses. Exploring these GC-behavior relationships may offer insights into the beneficial aspects of behavior and help identify coping mechanisms that potentially enhance individual fitness. We conducted a systematic review of the relationship between GCs and several behavioral traits, as described in the literature on captive and wild primates, and evaluated the effect of different categorical factors on these relationships using a meta-analytic approach. According to the type of behavior, we grouped statistical measures into affiliative, agonistic, anxiety-like, and foraging domains which were further differentiated into behavioral subgroups. We also categorized measures based on setting, method, sex and age of individuals, and sample matrix involved in each primary study. Overall, we found that some affiliative and foraging behaviors are associated with lower GC levels, while agonistic and anxiety-like behaviors are linked to higher GC levels. Specifically, non-sexual affiliation and energetically inexpensive activities were negatively related to GCs. In contrast, inter- and intragroup aggression, noncommunicative and self-directed behaviors, and energetically expensive activities were positively related to GCs. By demonstrating how certain social, ecological and intrinsic factors affect the GC-behavior relationships, our study helps elucidate the contexts that may alleviate or intensify the stress responses in non-human primates.
Melatonin treatment during the breeding season increases testosterone in male green anole lizards (Anolis carolinensis).
Shankey NT, Igo BL, Grossen TL … +1 more , Cohen RE
Horm Behav · 2024 Nov · PMID 39522144 · Publisher ↗
Melatonin is a natural hormone that regulates seasonal behaviors in vertebrates by binding to its receptors (MT1 and MT2). Specifically, high levels of melatonin are associated with short photoperiods, often coinciding w...
Melatonin is a natural hormone that regulates seasonal behaviors in vertebrates by binding to its receptors (MT1 and MT2). Specifically, high levels of melatonin are associated with short photoperiods, often coinciding with the non-breeding season, meaning that melatonin may inhibit seasonal reproduction. Green anole lizards (Anolis carolinensis), have large, active gonads, increased levels of testosterone and estradiol, and increased reproductive behaviors during the breeding season. Previous studies have examined the role of melatonin in seasonal reproduction in this species, but it is unclear how melatonin receptors change seasonally or if melatonin treatment during the early breeding season influences reproduction. In Experiment 1, we measured MT1 and MT2 mRNA expression in the brains and gonads of unmanipulated anoles between breeding and non-breeding seasons. MT1 mRNA expression was significantly higher in the male brain during the breeding season compared to the non-breeding season, and MT1 mRNA levels were generally higher compared to MT2. This suggests that melatonin may regulate seasonal reproduction through MT1 in the brain, and higher levels during the breeding season may compensate for low seasonal levels of melatonin. In Experiment 2, anoles were treated with melatonin or a blank control for 10 weeks during the breeding season. In males, melatonin treatment increased testosterone levels. This suggests that rather than inhibiting reproduction, continuous high doses of melatonin may increase reproductive hormones during the breeding season. Our findings support the role of melatonin in modulating seasonal reproduction, but the exact mechanisms behind melatonin's stimulatory effect is unclear.
Infanticide is driven by unfamiliarity with offspring location and associated with androgenic shifts in mimic poison frogs.
Lewis AR, Goolsby BC, Juarez BH … +2 more , Lacey MP, O'Connell LA
Horm Behav · 2024 Nov · PMID 39514924 · Full text
Infanticide is widespread across the animal kingdom, but the physiological drivers of infanticide versus care or neglect are relatively unexplored. Here, we identified salient environmental and physiological antecedents...
Infanticide is widespread across the animal kingdom, but the physiological drivers of infanticide versus care or neglect are relatively unexplored. Here, we identified salient environmental and physiological antecedents of infanticide in the mimic poison frog (Ranitomeya imitator), a biparental amphibian. We explored potential environmental cues influencing infant-directed behavior by evaluating changes in the frequency of food provisioning and tadpole mortality after either cross-fostering tadpoles between family units or displacing tadpoles within the terraria of their parents. We found that changes in offspring location reduce care and increase infanticide. Specifically, parents fed their displaced offspring less and, in some instances, tadpole mortality increased. We also investigated whether care and infanticide were related to changes in steroid hormone concentrations in an unfamiliar setting. Infanticide of fertilized eggs and hatchlings in the new territory included cannibalism and was associated with lower testosterone concentrations, but not with changes in corticosterone. Overall, our results support earlier findings that familiarity with offspring location drives parental investment in poison frogs, while indicating an association between low androgen levels and infanticidal behavior in an amphibian.
Chronic high-dose testosterone disrupts social cognition and enhances social dominance in male long-Evans rats.
Wenner J, Wood RI
Horm Behav · 2024 Nov · PMID 39509806 · Full text
While increased aggression is the most consistent behavioral effect of anabolic androgenic steroid (AAS) abuse, its cause remains unclear. AAS may promote aggression by disrupting social behaviors which maintain dominanc...
While increased aggression is the most consistent behavioral effect of anabolic androgenic steroid (AAS) abuse, its cause remains unclear. AAS may promote aggression by disrupting social behaviors which maintain dominance hierarchies. To model AAS abuse, we treated male rats with chronic high-dose testosterone and tested social recognition, social learning, and competitive and aggressive dominance. Rats received daily injections s.c. of testosterone (7.5 mg/kg) or vehicle (n = 8/group). We tested social recognition by measuring investigation of a novel or familiar stimulus animal, social learning with the social transmission of food preference (STFP) test, aggressive dominance with the tube test, and competitive dominance with a food competition task. For social recognition, testosterone-treated rats did not prefer the novel stimulus rat (72.8 ± 9.3 s) over the familiar rat (68.8 ± 8.0 s, N.S.) rat. In the STFP test, testosterone-treated rats did not show a significant preference for the demonstrated flavor (59.9 ± 9.4 %, N.S.) compared with controls (70.1 ± 5.4 %, p < 0.05). In the tube test, testosterone did not increase the number of rounds won. However, when the testosterone-treated rat won, they were more likely to be lighter than their vehicle-treated opponent, χ(1,N = 63) = 6.56, p < 0.05, Φ = 0.32. In the food competition task, testosterone-treated subjects won more often (48 rounds) than their vehicle-treated partners (15 rounds; p < 0.05). These results suggest that AAS disrupt recognizing and learning from the social hierarchy and increase the likelihood of challenging it. Collectively, these behavioral changes may contribute to AAS-induced aggression.
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