Journal September 25, 2026 6 min read

Which peptides are studied in relation to the HPA axis?

A research-supply overview of the peptides and neuroendocrine signalling molecules studied in relation to hypothalamic-pituitary-adrenal (HPA) axis regulation, including CRF/CRH, ACTH, and related neuropeptide pathways.

peptides-pro Editorial

The hypothalamic-pituitary-adrenal (HPA) axis is the neuroendocrine system through which the hypothalamus, pituitary gland, and adrenal cortex coordinate the stress response. In the research literature, the peptides most directly studied in relation to this axis are corticotropin-releasing factor (CRF), also called corticotropin-releasing hormone (CRH), a 41-amino-acid hypothalamic peptide that initiates the neuroendocrine stress cascade, and adrenocorticotropic hormone (ACTH), a 39-amino-acid pituitary peptide derived from the pro-opiomelanocortin (POMC) precursor that drives adrenal glucocorticoid output. Downstream, cortisol is the principal glucocorticoid measured as the axis endpoint in human studies. The evidence block for this page does not supply sequence, formula, or molecular weight identifiers for these compounds, so none are stated here.

The work centres on the CRH receptor family and the hypothalamic-pituitary-adrenal signalling cascade, with secondary involvement of the noradrenergic locus coeruleus system and the hypothalamic-pituitary-gonadal (HPG) axis in studies of stress and sleep.

Research Studies

CRF and HPA axis activation in post-traumatic stress disorder

In a registered study of patients with post-traumatic stress disorder (PTSD), the described pathophysiology is based on complex noradrenergic dysregulation. The amygdala activates the hypothalamus to release excessive corticotropin-releasing factor (CRF), which activates the HPA axis and leads to high nocturnal cortisol levels with EEG changes and increased arousals. In parallel, the locus coeruleus releases excess norepinephrine (NE), which interferes with the transition to non-REM sleep and suppresses the stability of REM sleep [1]. This is a clinical population; the CRF and NE findings are described as the mechanistic basis of the study rather than as an intervention outcome.

Neuropeptides and HPA axis dysregulation in chronic prostatitis/chronic pelvic pain syndrome

A comprehensive review synthesised evidence from the past five years regarding neuroendocrine pathways in chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). The authors analysed literature from PubMed, Web of Science, and CNKI, focusing on neuropeptide functions, hypothalamic-pituitary-adrenal (HPA) axis dysregulation, sympathetic nervous system (SNS) signalling, and glial cell involvement [3]. The review frames traditional infection-and-inflammation models as insufficient to explain limited efficacy of conventional therapies, and positions neuroendocrine mechanisms as a deeper regulatory layer under investigation.

HPA axis activation and HPG axis deactivation under sleep restriction

Two registered studies examined how HPA axis activation occurs with sleep restriction and how hypothalamic-pituitary-gonadal (HPG) axis deactivation occurs with sleep restriction. Both protocols also examined cognitive function associated with sleep restriction, including food intake and food cravings [6][7]. One of the two was conducted specifically in older men and postmenopausal women [6]. These are protocol descriptions; the evidence block does not report results.

HPA axis regulation and polyphenol intake

A registered study hypothesised that both acute and chronic intake of muscadine wine polyphenols would improve cognitive performance and mood through regulating the HPA axis, alleviating inflammation and oxidative stress, and/or inhibiting monoamine oxidase activities [5]. The hypothesis is stated at the level of the axis and does not name a specific peptide.

Cortisol and BDNF in cervicogenic headache

A registered study of isometric neck exercises in smartphone users with cervicogenic headache examined symptoms alongside cortisol and BDNF levels. The described presentation includes decreased range of motion at the cervical spine, decreased sleep quality, increased stress, disturbed mood, and altered physiologic chemicals, with higher prevalence reported in females [4]. Cortisol is the adrenal endpoint of HPA axis activity; BDNF is not an HPA axis peptide and is included here only as a co-measured marker in the same study.

HPA axis and cytokine signalling in cancer-related psychiatric disorders

A registered study in oncological psychiatry describes the pathophysiology of cancer-related psychiatric disorders as multifactorial and related to several neuropsychological and neurobiological factors, specifically including cytokine production [2]. The evidence block does not name a peptide in this context, so no peptide-level claim is made.

CRH neurons in the hypothalamic paraventricular nucleus and α7 nicotinic receptor signalling

Dysregulation of the HPA axis is described as a central feature of stress-related affective disorders, and corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN) initiate neuroendocrine stress responses. Work in this area examined α7 nicotinic acetylcholine receptor activation and its association with anxiety- and depressive-like behaviours and CREB/CRH signalling in the PVN [11]. This is animal-model work; it is reported here as a finding of the cited paper.

Adaptogens and stress-response modulation

A narrative review of phyto adaptogens describes them as primarily plant-derived bioactive compounds that enhance resistance to physical, chemical, and biological stressors, with reported promise in stress-related disorders, neurodegenerative disease, inflammation, and ageing [8]. Adaptogens are not peptides; they are included because the review addresses stress-axis modulation as a category of research interest.

Exercise-induced ACTH and cortisol responses in Thoroughbred racehorses

Exercise is described as a physiological challenge inducing intensity-dependent HPA axis responses. A study in Thoroughbred racehorses assessed whether different exercise sessions affect equine adrenal output, testing the hypothesis that training and racing sessions induce different degrees of HPA axis activation [10]. This is an animal study and the findings apply to the horse population studied.

Schisandrin B and anxiety-like behaviour in rats

A study examined the anxiolytic effects of Schisandrin B (SchB) in rats exhibiting anxiety-like behaviours, using the elevated plus-maze test and the open field test, and investigated mechanisms involving hippocampal synaptic plasticity and restoration of the intestinal barrier. Schisandrin B was administered at a dose of 10 mg/kg in that model [9]. This is animal-only evidence and does not establish any effect in humans.

Comparison of evidence types across the cited work

Compound or pathway	Model or population	Evidence type
CRF / CRH	Patients with PTSD	Clinical study description [1]
CRH neurons, α7 nAChR	Animal model	Preclinical [11]
ACTH, cortisol	Thoroughbred racehorses	Animal [10]
Schisandrin B	Rats	Animal [9]
Neuropeptides, HPA axis	CP/CPPS literature	Review [3]
Polyphenols (muscadine wine)	Human participants	Registered protocol [5]
Cortisol, BDNF	Smartphone users with cervicogenic headache	Registered protocol [4]
HPA / HPG axes	Older men and postmenopausal women; general adults	Registered protocols [6][7]

Across the cited material, direct peptide-level HPA axis research in humans is limited to CRF/CRH as a mechanistic description in PTSD [1]. ACTH and cortisol measurements appear in animal exercise physiology [10] and in human protocols measuring cortisol as an endpoint [4]. Several of the most specific mechanistic findings, including CRH neuron signalling [11] and Schisandrin B effects [9], are animal-only. Review-level synthesis of neuropeptide involvement exists for CP/CPPS [3], and adaptogen reviews address stress-axis modulation without peptide specificity [8].

If you are reading this for personal health reasons

The materials described on this page are sold for laboratory research use only, and we do not provide dosing, administration, or medical guidance of any kind. Nothing here is a recommendation to use any compound, and no outcome is promised or implied. If you are considering a compound for yourself, speak to a licensed clinician.