Autonomic Neuroscience[JOURNAL]
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200 papers
White matter correlates of autonomic cardiac dysfunction in anorexia nervosa.
De La Cruz F, Makris N, Schumann A … +13 more , Legarreta JH, Chen Y, Rieger K, Di Giuliano M, Zurrin R, Billah T, Kim N, Borders O, Rathi Y, Kubicki M, O'Donnell L, Bär KJ, Kikinis Z
Auton Neurosci · 2025 Aug · PMID 40466563 · Publisher ↗
Anorexia nervosa (AN) is linked to changes in autonomic function, but the specific neuroanatomical substrates of these changes are not well understood. In this study, we used diffusion-weighted imaging to examine white m...
Anorexia nervosa (AN) is linked to changes in autonomic function, but the specific neuroanatomical substrates of these changes are not well understood. In this study, we used diffusion-weighted imaging to examine white matter structure in the ventromedial prefrontal cortex-dorsal vagal complex (vmPFC-DVC) pathway, which is essential for autonomic regulation. Compared to healthy controls, individuals with AN showed significantly higher fractional anisotropy and axial diffusivity, as well as more streamlines connecting the vmPFC and DVC-indicating altered structural organization. However, radial diffusivity, which relates to myelin integrity, did not differ between groups, suggesting that changes are not due to higher myelination in AN individuals. Region-specific analysis located the differences in white matter metrics to the region of fiber decussation at the ponto-midbrain junction. Fractional anisotropy and radial diffusivity of vmPFC-DVC were associated with autonomic function in healthy controls but not in individuals with AN, pointing to a disruption in brain-body communication in AN. No differences were found in tensor metrics in other white matter tracts in the brainstem, indicating these alterations are specific to autonomic pathways rather than reflecting widespread brainstem abnormalities. This study provides the first evidence of structural disruptions in a key autonomic circuit in AN and highlights a potential decoupling between white matter integrity and autonomic regulation.
Hypothalamic excitatory input to ATR and TH expressing neurons of the nucleus of the solitary tract in mice.
Carter DA, Guo H, Thek KR … +5 more , Connelly AA, Bassi JK, Fong AY, Allen AM, McDougall SJ
Auton Neurosci · 2025 Aug · PMID 40460601 · Publisher ↗
Autonomic reflexes are modified during development or in response to specific physiological challenges and disease. One modulating region is the hypothalamic paraventricular nucleus (PVN), whose neurons project to the nu...
Autonomic reflexes are modified during development or in response to specific physiological challenges and disease. One modulating region is the hypothalamic paraventricular nucleus (PVN), whose neurons project to the nucleus of the solitary tract (NTS) to modulate viscerosensory input. Yet the neural circuitry by which this is achieved remains ill-defined. Adeno-associated virus was injected into the hypothalamus of TH-GFP or angiotensin type 1A receptor (ATR)-GFP mice to drive channel rhodopsin 2 (ChR2) expression. Whole-cell recordings of NTS neurons in close proximity to labelled hypothalamic efferents were made in horizontal slices of the brainstem, allowing activation of both hypothalamic and viscerosensory inputs. Most neurons recorded did not exhibit ChR2-mediated responses, despite extensive hypothalamic axon/terminal labelling. In some NTS neurons, ChR2-mediated stimulation of hypothalamic efferents elicited glutamatergic, AMPA receptor mediated excitatory postsynaptic currents (ChR2-EPSCs). Responsive NTS neurons included both 2nd, and higher, order neurons and ATR and few TH expressing neurons. All ChR2-EPSCs tested were blocked by TTX. Some TTX blocked ChR2-EPSCs could be recovered with the co-application 4AP, confirming monosynaptic connection between hypothalamic and NTS neurons. Superimposition of convergent inputs from hypothalamic and viscerosensory efferents resulted in summated EPSCs that would likely increase throughput probability of the viscerosensory signals at NTS neurons. The neural link between the hypothalamus and NTS comprises discreet glutamatergic input, including to TH positive and ATR expressing NTS neurons.
Autonomic and sensory dysfunction in hypermobile Ehlers-Danlos syndrome: How do small fibers contribute?
Kersebaum D, Baron R, Gierthmühlen J … +1 more , Forstenpointner J
Auton Neurosci · 2025 Aug · PMID 40460600 · Publisher ↗
Hypermobile EDS (hEDS) is associated with joint hypermobility, early-onset osteoarthritis, chronic pain, and dysautonomia. This study explored sensory-vascular profiles, as both nociceptive and autonomic nerve fibers are...
Hypermobile EDS (hEDS) is associated with joint hypermobility, early-onset osteoarthritis, chronic pain, and dysautonomia. This study explored sensory-vascular profiles, as both nociceptive and autonomic nerve fibers are part of the small-fiber group. The aim was to examine sensory-vascular characteristics in an hEDS family, with and without dysautonomia. Five female participants (ages 12-60) underwent tilt-table testing, heart-rate-variability analysis, cutaneous vasoconstriction testing, thermal sensory- and microcirculation testing. Four reported pain; two had dysautonomia and vascular hyperelasticity. All exhibited A-delta fiber loss, while those with dysautonomia also showed C-fiber impairment. Findings indicate dysautonomia and vascular maladaptation worsens with small-fiber dysfunction in hEDS.
Menopause and its effects on autonomic regulation of blood pressure: Insights and perspectives.
Lee EJ, Keller-Ross ML
Auton Neurosci · 2025 Aug · PMID 40460599 · Full text
Cardiovascular disease (CVD) risk increases substantially around the typical age of menopause (∼51 yrs). While the mechanisms underlying this phenomenon remain to be precisely elucidated, menopause-related autonomic (dys...
Cardiovascular disease (CVD) risk increases substantially around the typical age of menopause (∼51 yrs). While the mechanisms underlying this phenomenon remain to be precisely elucidated, menopause-related autonomic (dys)function likely plays a key role in CVD development in postmenopausal females. Sympathetic activity is known to increase with age and may rise more steeply in older females, resulting in autonomic imbalance and chronic disease. The menopausal loss of estradiol, a major female sex hormone, contributes to changes in autonomic and vascular physiology and is implicated in prominent menopause symptoms such as sleep difficulty and vasomotor symptoms (hot flushes/night sweats). Estrogen replacement can mitigate some of these negative health effects, but hormone therapy may not be able to reverse all menopause-linked autonomic dysfunction. Thus, this review explores the vast and complex web connecting menopause physiology and symptomatology, including how sex-hormone loss and menopause symptoms may impact autonomic function- in particular, through altered sympathetic regulation of blood pressure and impaired vagal tone- as a gateway to adverse cardiovascular health and greater CVD risk.
Sex-related differences in temperature regulation during heat stress from childhood to older age.
Debray A, Sardar S, Deshayes TA … +4 more , Mornas A, Oubouchou K, Ouazaa Y, Gagnon D
Auton Neurosci · 2025 Aug · PMID 40460598 · Publisher ↗
Epidemiological studies have observed that female sex is associated with a greater risk of adverse health outcomes during heat extremes. It remains unclear if sex-related differences in autonomic temperature regulation c...
Epidemiological studies have observed that female sex is associated with a greater risk of adverse health outcomes during heat extremes. It remains unclear if sex-related differences in autonomic temperature regulation contribute to these observations. This narrative review article provides an overview of studies that compared autonomic temperature regulation during heat stress between males and females across the lifespan. Our literature search focused on studies that investigated components of heat loss thermoeffector loops and/or that accounted for confounding differences in body morphology and metabolic heat production between males and females. Guided by this framework, we present studies that compared autonomic temperature regulation between males and females during childhood to adolescence, adulthood, middle-age, and older age. The review highlights that few studies have specifically studied sex-related differences in autonomic temperature regulation during heat stress. Most studies have focused on thermoeffector output and core temperature. In contrast, little is known regarding thermoafferent signalling, central integration of thermoafferent feedback, thermoefferent signalling and thermoeffector organ structure and function. Additional research is needed to understand how biological sex modulates autonomic temperature regulation during heat stress and how any sex-related difference may contribute to the greater health risks observed in females during heat extremes.
The sympathetic nervous system in normotensive and hypertensive pregnancies.
Ayesha S, Davenport MH, Steinback CD
Auton Neurosci · 2025 Aug · PMID 40446456 · Publisher ↗
Pregnancy is associated with significant physiological adaptations that facilitate optimal foetal development and growth. Among the most notable changes in healthy pregnancies are increases in plasma volume, cardiac outp...
Pregnancy is associated with significant physiological adaptations that facilitate optimal foetal development and growth. Among the most notable changes in healthy pregnancies are increases in plasma volume, cardiac output, and sympathetic nervous system activity, alongside a reduction in total peripheral resistance. Normotensive pregnancies are among the few physiological states in which elevated sympathetic activity is considered normal and beneficial. However, the underlying mechanisms that reconcile this increase in SNA with the concomitant decrease in blood pressure remain incompletely understood. In contrast, excessive sympathetic activity, beyond the expected pregnancy-associated increase, has also been implicated in the pathophysiology of hypertensive disorders of pregnancy, such as gestational hypertension and preeclampsia, which are major contributors to maternal and foetal morbidity and mortality. This review aims to provide an overview of the current understanding of the physiological and pathophysiological mechanisms underlying both normotensive and hypertensive pregnancies.
Can 'noisy data' perform as well as 'clean data' in outcome modeling after aneurysmal subarachnoid haemorrhage?
Uryga A, Czosnyka M, Kasprowicz M … +4 more , Burzyńska M, Dragan B, Budohoski K, Nasr N
Auton Neurosci · 2025 Aug · PMID 40440863 · Publisher ↗
BACKGROUND: Baroreflex sensitivity (BRS) is associated with clinical outcome in patients with aneurysmal subarachnoid haemorrhage (aSAH); however few studies have investigated this in typical clinical settings. This two-...
BACKGROUND: Baroreflex sensitivity (BRS) is associated with clinical outcome in patients with aneurysmal subarachnoid haemorrhage (aSAH); however few studies have investigated this in typical clinical settings. This two-centre study evaluated how outcome models differ when excluding patients who received beta-blockers and/or noradrenaline ('clean data' set) versus including all of them ('noisy data' set). METHODS: This retrospective study included consecutive aSAH patients from Addenbrooke's Hospital (UK) and Wroclaw Medical University (Poland). Early BRS was measured using the cross-correlation method. A favorable outcome was defined as a Glasgow Outcome Scale (GOS) score of 4-5 at discharge. RESULTS: A total of 108 patients were included, with 40 receiving beta-blockers and/or noradrenaline. The median age was 56 (IQR ± 17) years old, where 73 % were women. On admission, 57 % had a Glasgow Coma Scale (GCS) score of 13-15. Univariate logistic regression showed BRS was significantly associated with outcome in both the 'clean data' set (OR 1.16, 95%CI [1.02,1.30]) and 'noisy data' set (OR 1.10, 95%CI [1.03,1.18]). In multivariate analysis, the best 'clean data' model (χ = 22.89, p < 0.001, AUC = 0.88) included heart rate (HR) (OR 0.93, 95%CI [0.87,0.99]) and GCS (OR 1.38, 95%CI [1.12,1.69]). The best 'noisy data' model (χ = 32.27; p < 0.001, AUC = 0.84) included BRS (OR 1.10, 95%CI [1.01,1.20]) and GCS (OR 1.32, 95%CI [1.16,1.51]). CONCLUSIONS: Early BRS was independently associated with short-term outcome after aSAH, regardless of beta-blockers or noradrenaline use. In the 'clean data' set, HR was significantly associated with outcome, whilst in the 'noisy data' set, BRS was significantly associated with outcome. A larger multicentre study is required to validate these findings.
Age and orthostatic hypotension are associated with baroreflex sensitivity and cerebral oxygenation after postural change.
Klop M, Claassen JAHR, Mol A … +4 more , Trappenburg MC, van Wezel RJA, Maier AB, Meskers CGM
Auton Neurosci · 2025 Aug · PMID 40440862 · Publisher ↗
Baroreflex sensitivity (BRS), maintaining blood pressure (BP), and cerebral autoregulation, maintaining cerebral blood flow (CBF), are regulatory mechanisms to counteract posture-related BP changes and their effect on CB...
Baroreflex sensitivity (BRS), maintaining blood pressure (BP), and cerebral autoregulation, maintaining cerebral blood flow (CBF), are regulatory mechanisms to counteract posture-related BP changes and their effect on CBF. These mechanisms may fail in geriatric conditions such as orthostatic hypotension (OH) and cause symptoms and falls. This study aimed to determine the association of age, sex, antihypertensive use, comorbidity, and OH with BRS and cerebral oxygenation after postural change. Thirty-four younger adults (median age 25 years), 30 older adults (median age 77 years), and 41 geriatric outpatients (median age 76 years) performed 2-3 supine-stand transitions, while heart rate (electrocardiogram), BP (volume-clamp photoplethysmography), and cerebral oxygenation (near-infrared spectroscopy) were measured continuously. BRS, cerebral oxygenation and cerebral autoregulation were determined in the time and frequency domain. Associations were investigated using linear regression and group comparisons. Higher age and presence of OH (OH in at least one supine-stand transition during a continuous BP measurement) were associated with lower BRS (1 % per year, 30 % when having OH). Higher age was associated with higher cerebral oxygenation recovery (0.1 μmol/L per year) after 30 s, while OH was associated with lower cerebral oxygenation recovery (1.3 μmol/L when having OH) at 1 min after postural change. No evidence of cerebral autoregulation impairment was found across all three groups. Reduced BRS and cerebral oxygenation recovery specifically in participants with OH are in line with their assumed susceptibility to cerebral hypoxia. The role of cerebral autoregulation as a compensatory mechanism for failing BRS could not be confirmed.
'Transient immediate orthostatic hypotension' is preferable to 'initial' orthostatic hypotension.
Benditt DG, Fedorowski A, Sutton R … +24 more , van Dijk JG, Baron-Esquivas G, Biaggioni I, Brignole M, De Jong JSY, De Lange FJ, Freeman R, Furlan R, Grubb B, Hamdan MH, Kenny RA, Lim PB, Angel MM, Olshansky B, Rafanelli M, Raj SR, Reyes J, Rivasi G, Russo V, Sheldon R, Stewart JM, Thijs R, Ungar A, Van Rossum IA
Auton Neurosci · 2025 Aug · PMID 40424818 · Publisher ↗
A drop of systemic blood pressure (BP) occurring shortly after individuals move from supine or seated position to upright posture with subsequent prompt spontaneous resolution is a common physiological occurrence in huma...
A drop of systemic blood pressure (BP) occurring shortly after individuals move from supine or seated position to upright posture with subsequent prompt spontaneous resolution is a common physiological occurrence in humans. If the induced hypotension is severe, lightheadedness or postural instability leading to falls and injury may occur. By consensus, a transient systolic BP drop >40 mmHg within 15 s of standing is deemed abnormal and has become termed 'initial orthostatic hypotension' (initial OH, iOH). However, the term 'initial OH' implies that another hypotensive event will follow shortly. In essence, if an OH event is deemed to be 'initial', then one might reasonably assume that a subsequent OH event is imminent. However, in the setting of abrupt movement to upright posture, the BP drop is usually solitary and brief (resolution within 15-30 s); thereafter the individual is usually OH symptom-free until they undertake another similar postural change. Currently, there is no single descriptor for a posture change driven, short-lived, spontaneously resolving OH event, without the implication that further hypotension is imminent as is implied by the term 'initial OH'. In order to foster more accurate nomenclature, we recommend that 'initial OH' be retired, and 'immediate OH' or transient 'immediate OH' be substituted. While 'immediate' OH may be imperfect, it conveys an early onset event without implying additional imminent OH. Thus immediate OH or transient immediate are more accurate descriptors of this common transient hypotensive event. The abbreviation, 'iOH', remains unchanged.
Mechanism of heat treatment on exercise pressor reflex in hindlimb ischemia-reperfusion: Does the temperature gradient matter?
Qin L, Zhang X, Li J
Auton Neurosci · 2025 Jun · PMID 40382937 · Full text
PURPOSE: To examine the effect of heat treatment (HT) with two temperature gradients in skeletal muscle: 1.5 and 3 °C, on the exercise pressor reflex (EPR) responses following limb ischemia-reperfusion (IR). Specifically...
PURPOSE: To examine the effect of heat treatment (HT) with two temperature gradients in skeletal muscle: 1.5 and 3 °C, on the exercise pressor reflex (EPR) responses following limb ischemia-reperfusion (IR). Specifically, the involvement role of the P2Xs (receptors of ATP) pathway in the muscle afferent neurons was accessed. METHODS: An experimental IR model was induced by 6 h of ischemia followed by 18 h of reperfusion in rats (IR rats). For HT groups, three HT sessions (muscle temperature increased by 1.5 or 3 °C) lasted for 30 mins each were applied. EPR responses were evoked by static muscle contraction (30s). Protein expression of P2X3 receptor in dorsal root ganglions (DRGs) was evaluated by western blot. In addition, a calcium imaging study was applied to detect calcium influx induced by activation of P2X3 in the isolated muscle DRG neurons of studied animal groups. Data are presented as mean ± standard deviation (M ± SD). RESULTS: The mean arterial pressure (MAP) response to the static muscle contraction was significantly exaggerated in rats of IR 18 h (vs. sham, p < 0.01). The exaggerated BP response was attenuated with increasing Tm by 1.5 and 3 °C (vs. IR, p < 0.05). The expression of the P2X3 receptor was significantly enhanced in the DRGs of IR 18 h rats (vs. sham, p < 0.01). The upregulated P2X3 was suppressed in the DRGs of IR 18 h rats +HT of 1.5 °C and 3 °C (vs. IR, p < 0.05). In the isolated muscle afferent neurons, the Ca entry induced by extracellular application of α,β-Me-ATP (30 μM) were significantly increased in IR rats (vs. sham, p < 0.001). Both HT protocols suppressed the enhanced IR-induced Ca entry (vs. IR, p < 0.001). There was no difference between the BP responses in HT1.5 °C and 3 °C groups, nor P2X3 expression in muscle afferent DRG, P2X-mediated Ca entry in isolated muscle afferent neurons (all p > 0.05). CONCLUSION: IR injury leads to upregulation of EPR responses, and HT attenuates this effect. The P2X3 signaling pathway was involved in the beneficial regulatory effect of HT on EPR in IR. The temperature gradient did not play a role in the extent of BP and muscle afferent P2X pathway activity attenuation in the present study.
Is cardiovascular disease risk in transgender, gender-diverse, and non-binary adults associated with autonomic imbalance?
Turino Miranda K, Schwende BK, Duval A … +5 more , Streed CG, Delage SI, Chokly K, Hodgins V, Usselman CW
Auton Neurosci · 2025 Aug · PMID 40373378 · Publisher ↗
Blood pressure is a key indicator of cardiovascular health with chronically high levels increasing the risk of cardiovascular diseases (CVD) such as heart attack and stroke. Emerging evidence shows that transgender, gend...
Blood pressure is a key indicator of cardiovascular health with chronically high levels increasing the risk of cardiovascular diseases (CVD) such as heart attack and stroke. Emerging evidence shows that transgender, gender-diverse, and non-binary (TGD) adults tend to have higher blood pressure than age-matched cisgender adults, corresponding to an increased CVD risk in this population. Yet, the mechanisms underlying elevated blood pressure in TGD adults remain unclear, posing challenges to TGD-affirming healthcare. Given the autonomic nervous system's role in CVD - wherein reduced parasympathetic and heightened sympathetic activity are key risk factors for CVD - this review explores the question: "Is cardiovascular disease risk in TGD adults associated with autonomic imbalance?" Limited research exists on autonomic balance within TGD populations. Accordingly, this review considers how TGD-specific factors, such as minority stress, lifestyle behaviors, sex and gender, and hormones (i.e., testosterone, estrogen, progesterone), may impact autonomic balance. Finally, this review aims to underscore the critical need for interdisciplinary research to elucidate these mechanisms and advance TGD-inclusive healthcare in the domains of autonomic control of blood pressure and overall cardiovascular health.
Acute hyperoxia elicits decreases in muscle sympathetic nerve activity and action potential activation in a sex-dependent manner.
Saboune J, Schwende BK, Debray A … +3 more , Usselman CW, Davenport MH, Steinback CD
Auton Neurosci · 2025 Aug · PMID 40344748 · Publisher ↗
Acute hyperoxia (100 % oxygen) has been shown to reduce muscle sympathetic nerve activity (MSNA), suggesting that hyperoxia could be a potential strategy for lowering blood pressure. However, the efficacy of hyperoxia to...
Acute hyperoxia (100 % oxygen) has been shown to reduce muscle sympathetic nerve activity (MSNA), suggesting that hyperoxia could be a potential strategy for lowering blood pressure. However, the efficacy of hyperoxia to reduce blood pressure (e.g., mean arterial pressure; MAP) remains unclear. Therefore, we compared MSNA and MAP responses to acute hyperoxia (1-min pokilocapnic + 3-min, PetO O + 300 Torr) between 18 females and 13 males. Baseline integrated total MSNA was not different between females and males (24 ± 7 vs 23 ± 8 bursts/min, respectively; P = 0.68) while MAP was lower in females than males (85 ± 7 vs 93 ± 7 mmHg; P < 0.01). Overall, hyperoxia evoked reductions in MSNA burst frequency (BF; P = 0.02) but not burst amplitude (BA; P = 0.82) or total MSNA (=BF ∗ BA; P = 0.26), To further probe these responses, 1-min nadir total MSNA response to hyperoxia were extracted within each participant. Total MSNA was reduced from baseline during nadir hyperoxia only in males (sex ∗ cond: P = 0.04). Females exhibited a bimodal distribution of sympatho-inhibitors (F) and non-inhibitors (F). F demonstrated limited reductions in BF (P = 0.11 vs inhibitors) coupled with increases in BA (P < 0.01 vs inhibitors), resulting in no net change in total MSNA (P < 0.01 vs inhibitors). Mechanistically, action potential (AP) detection analyses revealed that F increased AP firing during hyperoxia (baseline: 313 ± 172 vs hyperoxia: 404 ± 192 spikes/min; P = 0.02), whereas hyperoxia blunted AP firing in F (baseline: 387 ± 263 vs hyperoxia: 267 ± 199 spikes/min; P = 0.02). In sum, approximately 50 % of healthy females responded to acute hyperoxia with unexpected increases in AP firing. These data may suggest that benefit of hyperoxia as a sympatho-inhibitor may be limited in young and healthy females.
Long term effects of parity on maternal autonomic function.
Nuckols VR, Davis KG, Santillan MK … +2 more , Santillan DA, Pierce GL
Auton Neurosci · 2025 Aug · PMID 40334523 · Publisher ↗
The mechanisms by which parity and gravidity, number of pregnancies reaching twenty weeks gestational age and total number of pregnancies, respectively, contribute to cardiovascular disease risk remains unknown. Autonomi...
The mechanisms by which parity and gravidity, number of pregnancies reaching twenty weeks gestational age and total number of pregnancies, respectively, contribute to cardiovascular disease risk remains unknown. Autonomic function was assessed in 65 parous women 1-5 years after normotensive pregnancy, quantified by spontaneous cardiovagal baroreflex sensitivity (BRS) and beat-to-beat blood pressure variability (BPV). Gravidity was negatively associated with BRS independent of age and body mass index (β = -2.01, P = 0.003). A similar trend was observed with greater parity (β = -1.74, P = 0.06). Gravidity and parity were not associated with BPV. These findings suggest a persistent and cumulative adverse effect of pregnancy on cardiac autonomic function in women.
Women, orthostatic tolerance, and POTS: a narrative review.
Fitzgibbon-Collins LK, Pereira TJ, Edgell H
Auton Neurosci · 2025 Jun · PMID 40311188 · Publisher ↗
Young women experience orthostatic intolerance to a greater degree than men. Numerous physiological pathways could be responsible for this intolerance in both healthy and pathophysiological conditions. This review discus...
Young women experience orthostatic intolerance to a greater degree than men. Numerous physiological pathways could be responsible for this intolerance in both healthy and pathophysiological conditions. This review discusses sex differences in hemodynamics, ventilation, autonomic control, and cerebral blood flow. Further, we discuss these phenomena and their potential exacerbations in postural orthostatic tachycardiac syndrome (POTS). After normalization for body size women have lower stroke volume and blood volume, and while upright women have reduced ventilation, reduced venous return likely from attenuated respiratory pump and skeletal muscle pump activity, augmented parasympathetic withdrawal, attenuated neurovascular transduction of sympathetic outflow, and increased vasodilatory capacity compared to age-matched men. Women have greater middle cerebral artery blood velocity, potentially impaired cerebral dynamic autoregulation (depending on the timing), yet similar cerebrovascular reactivity to carbon dioxide exists between the sexes. Thus, we suggest that the greater incidence of orthostatic intolerance in women is primarily due to hemodynamic control and autonomic function; however, the enhanced parasympathetic withdrawal while upright could theoretically influence cerebral vasodilatory capacity and is proposed as a possibility in need of further investigation. POTS physiology is described briefly due to its increasing prevalence via post-COVID infections. We summarize some potential physiological changes in POTS including hemodynamic and ventilatory control, and we highlight that cerebral blood flow control is impaired and likely plays a role in the symptomology of POTS.
A single dose of nicotine modulates heart rate variability in rats with induced-ulcerative colitis.
Miraghaee DS, Khalili A, Bayat G … +5 more , Mousavi Z, Nazari M, Hosseini M, Goudarzvand M, Mazloom R
Auton Neurosci · 2025 Aug · PMID 40306144 · Publisher ↗
BACKGROUND AND AIMS: Nicotine, a widely used toxic substance, has various receptors scattered throughout the body that have shown opposite effects on inflammatory disorders. However, the effects of nicotine on heart rate...
BACKGROUND AND AIMS: Nicotine, a widely used toxic substance, has various receptors scattered throughout the body that have shown opposite effects on inflammatory disorders. However, the effects of nicotine on heart rate variability in ulcerative colitis are unclear. Therefore, the present study aimed to determine the effect of acute nicotine injection on heart rate variability in a rat model of ulcerative colitis. METHODS: Six male Wistar rat groups, containing vehicle, UC (induction of ulcerative colitis without treatment), and nicotine (0.5, 1, 1.5, and 2 mg/kg), were assessed. First, the rats were anesthetized and the initial electrocardiogram was recorded. Twenty-four hours after the induction of ulcerative colitis with 4 % acetic acid by rectal injection, a second electrocardiogram was recorded. Finally, 15 min after nicotine injection in each group, the last electrocardiogram was recorded. Linear and nonlinear indices of heart rate variability were extracted from the recorded R-R intervals. RESULTS: A single injection of nicotine at high doses increased the standard deviation of R-R intervals, root mean square of successive differences between normal heartbeats, ratio of the short-term deviation to the long-term deviation of R-R intervals, and entropy of R-R intervals in ulcerative colitis animals (at least P < 0.05). CONCLUSIONS: Acute injection of nicotine at doses 1.5 and 2 mg/kg can improve R-R interval linear indices, balance the ratio of short-term deviation to long-term deviation, and modify the entropy in the induced ulcerative colitis rats. However, further research is needed for the clinical use of acute nicotine injection in ulcerative colitis.
Deep brain stimulation for control of refractory hypertension.
Adams ZH, Hart EC, Patel NK
Auton Neurosci · 2025 Aug · PMID 40306143 · Publisher ↗
Deep brain stimulation (DBS) is an emerging treatment for patients with severe drug-resistant hypertension, particularly for those in whom other non-pharmacological treatments (e.g., renal denervation, baroreflex activat...
Deep brain stimulation (DBS) is an emerging treatment for patients with severe drug-resistant hypertension, particularly for those in whom other non-pharmacological treatments (e.g., renal denervation, baroreflex activation therapy) have failed. Growing numbers of case studies demonstrate long-term reductions in blood pressure with DBS of the ventrolateral periaqueductal gray. This is likely achieved via modulation of autonomic blood pressure control centres, reducing sympathetic outflow to the vasculature. We discuss recent advances, including whether the ventrolateral periaqueductal gray alone is a robust enough target, and whether DBS has the potential to reinstate beneficial physiological characteristics of blood pressure, such as diurnal variation.
Physiological and clinical comparison of active stand and head-up tilt tests in Postural Orthostatic Tachycardia Syndrome (POTS).
Uppal J, Baker JR, Hira R … +5 more , Karalasingham K, Ranada S, Deol P, Sheldon RS, Raj SR
Auton Neurosci · 2025 Aug · PMID 40273723 · Publisher ↗
Head-up tilt (HUT) and active stand tests (AST) are used in the diagnosis of Postural Orthostatic Tachycardia Syndrome (POTS), but their relative diagnostic accuracy is unclear. This necessitates a direct comparison unde...
Head-up tilt (HUT) and active stand tests (AST) are used in the diagnosis of Postural Orthostatic Tachycardia Syndrome (POTS), but their relative diagnostic accuracy is unclear. This necessitates a direct comparison under standardized conditions. We aimed to compare the hemodynamic responses and diagnostic accuracy of AST vs. HUT in POTS. To address this, patients with POTS (n = 60) completed a 10-min AST followed by HUT on the same day. Beat-to-beat hemodynamics were recorded during 10-min supine baselines and each test. Delta values were calculated for each test (upright 1-min averages minus baseline average). Δ[heart rate] increased significantly over time (1_Min: 28 bpm to 10_Min: 40 bpm; P < 0.001), and was greater for HUT (33 bpm vs. 37 bpm; P = 0.01), with significant Time x Condition interaction (38 bpm vs. 42 bpm at10min; P < 0.001). Δ[stroke volume] declined over time (1_Min: -18 ml to 10_Min: -32 ml); P < 0.001), with no significant test or interaction effects (P = 0.36; P = 0.21). Δ[SBP] decreased (1_Min: -0.3 mmHg to 10_Min: -5.7 mmHg); P < 0.001) over time, with no test or interaction effects. Fewer patients met POTS heart rate criteria during the AST (AST: 74 % vs. HUT: 98 %; p < 0.001). Lowering the threshold to 27 bpm for AST narrowed the gap but was still significantly higher for HUT (AST: 83 % vs HUT: 98 %; p = 0.02). Orthostatic tachycardia differs between AST and HUT in patients with POTS. The proportion of patients with POTS meeting the heart rate diagnostic criteria differs significantly between AST and HUT, a discrepancy that can be mitigated by lowering the heart rate threshold for the AST.
Cardiovascular and neuroimmune adaptations to enalapril and exercise training: A comparative study in male and ovariectomized female spontaneously hypertensive rats.
Silva GDC, Ferreira MJ, Araujo AA … +5 more , Nascimento Filho AVD, Bernardes N, do Amaral JB, Irigoyen MC, De Angelis K
Auton Neurosci · 2025 Aug · PMID 40253895 · Publisher ↗
UNLABELLED: Antihypertensive drug and exercise training are commonly prescribed to treat arterial hypertension. However, there is a considerable gap in understanding how physiological mechanisms of male and female adapt...
UNLABELLED: Antihypertensive drug and exercise training are commonly prescribed to treat arterial hypertension. However, there is a considerable gap in understanding how physiological mechanisms of male and female adapt to the combination of these approaches. Therefore, we focused to investigate sexual differences in cardiovascular, autonomic, inflammation and systemic oxidative stress adaptations in male and OVX female ovariectomized spontaneously hypertensive rats (SHR) treated with enalapril associated with moderate-intensity concurrent exercise training. Enalapril (3 mg/kg, diluted in drinking water) and exercise training (3 days/week, moderate intensity) was carried out for 8 weeks. Blood pressure (BP), heart rate (HR) and its variabilities were assessed. Serum and plasma were used for inflammatory and oxidative stress analyses. Enalapril, associated or not with exercise training, induced a reduction in diastolic and mean BP in both sexes; however, only the OVX female groups showed a reduction in systolic BP, as well as resting bradycardia. Both sexes showed improvements in BP and HR variability following the treatments; however, improvement in SD2/SD1 ratio, which indicates how much the heartbeats occur at irregular intervals, and in variance of systolic BP were observed only in trained groups. A higher spontaneous baroreflex sensitivity, as well as reduced IL-6/IL-10 were found only in the trained groups. Increased IL-10 was observed in male trained group (vs. other groups). Finally, combination enalapril and exercise training reduced systemic pro-oxidants such as NADPH oxidase and hydrogen peroxide. The findings of our study showed that OVX female SHR, after ovarian hormone deprivation, presented more pronounced effects on hemodynamics, BP variability, and anti-inflammatory profile than hypertensive males with the combination of treatments. BACKGROUND: Researchers are investigating how the body responds differently in males and females. These differences are also evident when examining how pharmacological and non-pharmacological approaches help the body control arterial hypertension. This study aimed to investigate how drug medication combined with exercise affects the heart's ability to self-regulate and how it relates to immune and oxidant defense, with a focus on differences in male and ovariectomized (OVX) female adaptations. METHODS: The study was conducted using hypertensive male and OVX female rats, allocated into: a) sedentary, b) enalapril, or c) enalapril plus exercise groups, totaling six groups (3 males and 3 OVX females, respectively). Enalapril (3 mg/kg/day) and exercise (aerobic and resistance exercises) were prescribed for eight weeks. The effects on blood pressure control, serum, and plasma were assessed. RESULTS: Although both males and OVX females showed improvements in blood pressure after medication, combined or not with exercise, OVX females had better control of blood pressure and heart rhythm regulation. Furthermore, including an exercise program during medication treatment improved immune defense in OVX females only, as well as the levels of key enzymes involved in the process of organ damage development in both sexes. CONCLUSION: OVX female rats benefited more from the combination of medication and exercise compared to male rats. This suggests that OVX females may experience additional health benefits from the combination of antihypertensive approaches, highlighting the importance of understanding how exercise impacts the body differently in males and OVX females, which could contribute to better long-term disease management.
Remote-controlled vagal nerve stimulation attenuates ventricular arrhythmias and prevents heart failure progression in a rat model of acute myocardial infarction.
Hu F, Wang Y, Zang M … +6 more , Li G, Wang G, Hu D, Zheng L, Yao Y, Pu J
Auton Neurosci · 2025 Aug · PMID 40252461 · Publisher ↗
BACKGROUND: Myocardial infarction (MI) often leads to complications like ventricular arrhythmias and heart failure, driven by autonomic nervous system imbalance. This study evaluates the effectiveness of a novel remote-c...
BACKGROUND: Myocardial infarction (MI) often leads to complications like ventricular arrhythmias and heart failure, driven by autonomic nervous system imbalance. This study evaluates the effectiveness of a novel remote-controlled vagal nerve stimulation (VNS) device, featuring adjustable stimulation parameters post-implantation, specifically focusing on its potential to inhibit ventricular arrhythmias and prevent the progression of heart failure in a rat model of acute MI. METHODS: Male Sprague-Dawley rats were randomized, and MI was induced by ligation of the left anterior descending artery. Seven days post-MI, rats were divided into three groups: the MI + VNS group (n = 15), the MI + control group (n = 15), and a sham-operated group (n = 12). In the MI + VNS group, a VNS device was implanted with initial stimulation settings of 0.2 mA, 0.2 ms pulse width, and 20 Hz frequency. During follow-up, stimulation parameters were adjusted to maintain a 5-20 % reduction in heart rate from baseline. Cardiac function, arrhythmia inducibility, and myocardial fibrosis were assessed four weeks after VNS implantation. RESULTS: Remote-controlled VNS significantly improved left ventricular ejection fraction and fractional shortening compared to the MI + control group (all P < 0.001). The left ventricular end-systolic diameter was also significantly reduced (P = 0.003). Additionally, VNS-treated rats exhibited a lower incidence and duration of ventricular arrhythmias (P = 0.003) and a reduction in myocardial fibrosis (P < 0.001). Plasma levels of B-type natriuretic peptide and noradrenaline were also significantly lower in the VNS group compared to controls (all P < 0.001). CONCLUSIONS: These findings suggest that remote-controlled VNS offers a novel and dynamic approach to treating MI-related complications. By allowing for adaptive stimulation in response to real-time physiological changes, remote-controlled VNS may represent a valuable strategy for reducing the risk of heart failure and arrhythmias post-MI.
The role of cardiopulmonary baroreflex on sympathetic vasomotor outflow and blood pressure regulation during dynamic exercise.
Katayama K, Ogoh S
Auton Neurosci · 2025 Aug · PMID 40250319 · Publisher ↗
Precise cardiovascular adjustments are necessary to meet the metabolic demands of working skeletal muscle during dynamic exercise. Appropriate regulation of sympathetic vasomotor outflow is key for maintaining arterial b...
Precise cardiovascular adjustments are necessary to meet the metabolic demands of working skeletal muscle during dynamic exercise. Appropriate regulation of sympathetic vasomotor outflow is key for maintaining arterial blood pressure (ABP) and facilitating the delivery of blood flow to active skeletal muscle. Central command, the exercise pressor reflex (including mechanoreflex and metaboreflex within skeletal muscle), and the arterial baroreflex work in concert, creating complex interactions that regulate sympathetic vasomotor outflow during dynamic exercise. Although less well studied, limited evidence suggests that the cardiopulmonary baroreflex plays a significant role in modulating MSNA (muscle sympathetic nerve activity) and ABP responses during mild-intensity dynamic exercise, as well as in resetting the arterial baroreflex during dynamic exercise. This review provides an updated and comprehensive overview of the sympathetic vasomotor outflow and the ABP response during dynamic exercise via the cardiopulmonary baroreflex.
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