Journal September 19, 2026 7 min read

What does the research say about prolactin?

Prolactin is a peptide hormone and cytokine that acts via the prolactin receptor. This page summarises research on its measurement, regulation, and roles in endocrine, immune, and reproductive physiology, including anima

peptides-pro Editorial

Prolactin (PRL) is a peptide hormone and cytokine, also known as lactotropin or mammotropin. It is a member of the somatotropin/prolactin family and is encoded by the PRL gene. The mature hormone is a single-chain polypeptide of 199 amino acids with a molecular weight of approximately 23 kDa. It is produced primarily by lactotroph cells of the anterior pituitary, but also by extrapituitary tissues including the decidua, myometrium, mammary epithelium, and immune cells. Prolactin circulates in multiple forms, including monomeric (23 kDa), dimeric, and polymeric (big-big) variants, and its secretion is under tonic inhibitory control by dopamine acting via D2 receptors.

The work described here centres on the prolactin receptor (PRLR), a member of the cytokine receptor superfamily, which signals through JAK2/STAT5 and other pathways.

Research Studies

Prolactin and pituitary abscess in a POEMS-like syndrome

A case report described a patient with a pituitary abscess and features suggestive of POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes) [1]. The co-presentation was noted as previously unreported. Endocrine dysfunction in this context can involve multiple anterior pituitary hormones, including prolactin, though the report focused on the diagnostic challenge and multisystem manifestations. The authors highlighted that chronic cytokine overproduction in POEMS-like syndromes may contribute to endocrine abnormalities.

Prolactin and pituitary metastasis: endocrine phenotype

A retrospective case series of 14 patients with pituitary metastasis (2010–2025) characterised clinical presentation, endocrine phenotype, and outcomes [2]. Median age was 52.5 years. Presenting manifestations included diabetes insipidus, anterior pituitary dysfunction, and neuro-ophthalmic deficits. Prolactin levels were among the endocrine parameters assessed; however, the series emphasised red flags for early diagnosis rather than prolactin-specific outcomes. The authors noted that pituitary metastasis should be considered in patients with systemic cancer and new endocrine or visual symptoms.

Prolactin and performance-enhancing peptides modulating the GH-IGF1 axis

A review of performance-enhancing peptides marketed as "research compounds" described agents intended to modulate the growth hormone–insulin-like growth factor-1 (GH-IGF-1) axis, including GHRH analogues (sermorelin, tesamorelin, CJC-1295 with and without DAC), growth hormone secretagogues (GHRP-2, GHRP-6, hexarelin, ipamorelin), the GH fragment AOD9604, and IGF-1 analogues [3]. While prolactin was not a primary focus, the review noted that some of these agents can influence pituitary hormone secretion, and that self-administration protocols lack regulatory oversight. The authors stressed the gap between clinical evidence and patient self-administration.

Prolactin and the dorsal vagal complex: cross-species atlas of cagrilintide effects

A transcriptomics atlas of over 530,000 cells from rat, mouse, and macaque caudal brainstem identified 80 neuronal cell populations and mapped the rat dorsal vagal complex (DVC) [4]. The study focused on amylin receptor agonists such as cagrilintide and their effects on energy balance. While prolactin was not directly examined, the DVC is a site where multiple hormonal signals converge, and the atlas provides a resource for understanding how peptides like prolactin might act in this region. The authors showed that cagrilintide regulates two conserved Calcr-expressing DVC neuronal populations, with acute treatment altering gene expression in area postrema Calcr/Ramp3 neurons.

Prolactin and asprosin in SSRI-induced male dysfunction

In a rat model, asprosin infusion modulated central circuits to rescue selective serotonin reuptake inhibitor (SSRI)-induced male dysfunction [5]. The study showed that asprosin, a fasting-induced adipokine, acts centrally to restore erectile function, copulatory behavior, and testicular morphology in SSRI-treated rats. Prolactin was not the primary outcome, but the work highlights how central circuits controlling reproductive function can be influenced by metabolic hormones. The authors positioned asprosin as a promising therapeutic candidate, though this remains preclinical.

Prolactin and secondary colostrum components in neonatal calves

A scoping review examined the effects of secondary colostrum components—cytokines, oligosaccharides, fatty acids, enzymes, and other nutrients—on neonatal calf physiology and metabolism [6]. While prolactin was not specifically discussed, colostrum contains numerous bioactive factors that can influence endocrine and metabolic development. The review emphasised that timely colostrum feeding is critical for IgG transfer and passive immunity, and that secondary components may refine management strategies such as extended colostrum feeding.

Prolactin as a biomarker in a blackcurrant-based supplement under hypoxia

A registered clinical trial (NCT07166835) is investigating the cognitive effects of a blackcurrant-based drink (Ārepa) under normobaric hypoxia (4,500 m for ~180 minutes) [7]. The double-blind, randomised, placebo-controlled crossover design includes cognitive testing and physiological measures. Prolactin is listed among the biomarkers to be assessed, along with MAO-B, BDNF, hsCRP, S100B, C3G, and sarmentosin. The trial aims to determine whether the nootropic drink can support cognitive function under hypoxic stress; results are not yet available.

Prolactin and cytokines in migraine pathophysiology

A clinical trial (NCT06426316) is exploring the role of cytokines and regulatory T lymphocytes in migraine pathophysiology [8]. Migraine is more prevalent in women and in patients with autoimmune/inflammatory diseases such as multiple sclerosis, rheumatoid arthritis, Crohn's disease, systemic lupus erythematosus, and endometriosis. Several peptides, including calcitonin gene-related peptide (CGRP), are implicated. Prolactin is not a primary focus, but the study may provide insights into how hormonal and immune factors intersect in migraine. The trial is ongoing.

Prolactin and hormone metabolism in overweight women: a probiotic trial

A randomised, double-blind, placebo-controlled trial investigated the effects of a 12-week multi-strain probiotic intervention (Lacticaseibacillus rhamnosus LRa05, Limosilactobacillus reuteri LR08, and Lactobacillus crispatus LCr86) on hormone metabolism, body composition, and emotional regulation in overweight women [9]. The study assessed endocrine, metabolic, and psychological parameters. While prolactin was not specified in the available summary, the trial contributes to understanding how gut microbiota may influence hormonal profiles. The findings are not yet detailed in the evidence block.

Prolactin and seasonal brain plasticity in Siberian hamsters and Japanese quail

Transcriptomic analyses of limbic structures across photoperiodic phenotypes in Siberian hamsters and Japanese quail brains examined seasonal morphological brain plasticity [10]. The study focused on the hippocampus and amygdala (nucleus taeniae in birds) and their role in seasonal shifts in emotional state. Prolactin is known to be involved in seasonal reproduction and parental behavior in some species, but this study did not directly measure prolactin. It provides a comparative framework for understanding how photoperiod influences brain and behavior.

Prolactin and hypophysitis in sarcoidosis

A systematic review characterised hypophysitis in sarcoidosis, a rare manifestation of neurosarcoidosis that may cause permanent endocrine dysfunction, visual impairment, and neurological morbidity [11]. The review examined clinical presentation, diagnostic findings, treatment, and outcomes. Prolactin abnormalities can occur in hypophysitis due to pituitary stalk involvement or direct gland damage, but the review's focus was on overall management and prognosis.

Prolactin and GnRH agonists in premenopausal breast cancer

A retrospective cohort study compared goserelin and leuprolide, both GnRH agonists used for ovarian function suppression in premenopausal breast cancer patients receiving adjuvant endocrine therapy [12]. The study investigated whether different molecular structures lead to clinically meaningful differences in efficacy and safety. Prolactin is not directly targeted by GnRH agonists, but ovarian suppression can indirectly affect prolactin levels. The findings are not detailed in the evidence block.

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