Prolactin: structure, function, and regulation of secretion

The regulation of prolactin secretion and its targeting function of teleost

Prolactin is involved in regulating various physiological activities of vertebrates and is one of the most momentous pituitary hormones. However, not enough attention is currently paid to prolactin, especially in teleost. This paper aims to gather, organize, and analyze recent studies on the regulation and functions of prolactin. By comparing with other animal groups, it highlights the significant role of prolactin in fish reproduction, immunity, growth, and osmotic pressure regulation, as well as the upstream and downstream factors that may be involved in the regulation of prolactin functions were introduced to provide a theoretical basis for the in-depth study and potential practical application of prolactin.

Prolactin mitigates chronic stress-induced maladaptive behaviors and physiology in ovariectomized female rats

Stress is a major risk factor for several neuropsychiatric disorders in women, including postpartum depression. During the postpartum period, diminished ovarian hormone secretion increases susceptibility to developing depressive symptoms. Pleiotropic peptide hormones, like prolactin, are markedly released during lactation and suppress hypothalamic-pituitary-adrenal axis responses in women and acute stress-induced behavioral responses in female rodents. However, the effects of prolactin on chronic stress-induced maladaptive behaviors remain unclear. Here, we used chronic variable stress to induce maladaptive physiology in ovariectomized female rats and concurrently administered prolactin to assess its effects on several depression-relevant behavioral, endocrine, and neural characteristics. We found that chronic stress increased sucrose anhedonia and passive coping in saline-treated, but not prolactin-treated rats. Prolactin treatment did not alter stress-induced thigmotaxis, corticosterone (CORT) concentrations, hippocampal cell activation or survival. However, prolactin treatment reduced basal CORT concentrations and increased dopaminergic cells in the ventral tegmental area. Further, prolactin-treated rats had reduced microglial activation in the ventral hippocampus following chronic stress exposure. Together, these data suggest prolactin mitigates chronic stress-induced maladaptive behaviors and physiology in hypogonadal females. Moreover, these findings imply neuroendocrine-immune mechanisms by which peptide hormones confer stress resilience during periods of low ovarian hormone secretion.

Excessive free fatty acid sensing in pituitary lactotrophs elicits steatotic liver disease by decreasing prolactin levels

The pituitary is the central endocrine gland with effects on metabolic dysfunction-associated steatotic liver disease (MASLD). However, it is not clear whether the pituitary responds to free fatty acid (FFA) toxicity, thus dysregulating hepatic lipid metabolism. Here, we demonstrate that decreased prolactin (PRL) levels are involved in the association between FFA and MASLD based on a liver biospecimen-based cohort. Moreover, overloaded FFAs decrease serum PRL levels, thus promoting liver steatosis in mice with both dynamic diet intervention and stereotactic pituitary FFA injection. Mechanistic studies show that excessive FFA sensing in pituitary lactotrophs inhibits the synthesis and secretion of PRL in a cell-autonomous manner. Notably, inhibiting excessive lipid uptake using pituitary stereotaxic virus injection or a specific drug delivery system effectively ameliorates hepatic lipid accumulation by improving PRL levels. Targeted inhibition of pituitary FFA sensing may be a potential therapeutic target for liver steatosis.

Diagnosis of hypoprolactinemia

Prolactin is a polypeptide hormone composed of 199 amino acids, synthesized by lactotroph cells. Its primary effects are on the mammary gland and gonadal axes, but it also influences different organs and systems, particularly metabolic functions. Current literature has mainly focused on the diagnosis, monitoring, and treatment of hyperprolactinemia. Due to the lack of a well-established effective treatment for hypoprolactinemia, it is not clinically emphasized. Therefore, data on its diagnosis is limited. Hypoprolactinemia has been associated with metabolic dysfunctions such as type 2 diabetes mellitus, fatty liver, dyslipidemia, fertility problems, sexual dysfunction, and increased cardiovascular disease. While often seen as a part of combined hormone deficiencies due to pituitary damage, isolated prolactin deficiency is rare. Hypoprolactinemia can serve as a marker for extensive pituitary gland damage and dysfunction.Low or undetectable serum prolactin levels and the absence of a sufficient prolactin peak in the thyrotropin-releasing hormone (TRH) stimulation test are considered diagnostic for hypoprolactinemia. Gender appears to influence both basal prolactin levels and TRH stimulation test responses. Basal prolactin levels of, at least, 5 ng/mL for males and 7 ng/mL for females can be used as cut-off levels for normal prolactin reserve. Minimum peak prolactin responses of 18 ng/mL for males and 41 ng/mL for females to TRH stimulation can exclude hypoprolactinemia. However, larger population studies across different age groups and sexes are needed to better define normal basal prolactin levels and prolactin responses to the TRH stimulation test.

Serum Prolactin Levels and Mortality in Adults Without Prolactinoma: A Meta-Analysis

CONTEXT

Prolactin (PRL) is a highly versatile, multifunctional hormone synthesized and secreted by lactotroph cells of the anterior pituitary. Its metabolic role has been extensively studied even in normoprolactinemic populations. Recently, a wealth of observational data have outlined the potential prognostic value of PRL in various clinical settings.

OBJECTIVE

This systematic review aims to systematically evaluate and quantitatively synthesize the association between serum PRL levels and risk of mortality in adults without prolactinoma.

METHODS

A systematic literature search was conducted up to June 10, 2023, to identify studies reporting the association of serum PRL levels with clinical outcomes of adults without prolactinoma. A random-effects meta-analysis was conducted to quantify the adjusted hazard ratios [(a)HRs] for all-cause and cardiovascular death (CVD) during follow-up.

RESULTS

Twenty-eight studies were deemed eligible reporting the outcomes of adults without prolactinoma, in whom serum PRL levels were measured for risk-stratification. Fourteen studies reported appropriate data for meta-analysis encompassing a total of 23 596 individuals. Each unit of PRL increase was independently associated with increased risk of all-cause (pooled aHR = 1.17 [1.08-1.27]; I2 = 48%) and CV mortality (pooled aHR = 1.54 [1.14-2.09]; I2 = 89%). Individuals belonging to the highest PRL category had significantly higher risk for all-cause (pooled aHR = 1.81 [1.43-2.30]; I2 = 65%) and CV (pooled aHR = 1.59 [1.04-2.42]; I2 = 82%) mortality compared to their lowest-PRL category counterparts. The association between PRL levels and in-hospital death did not reach statistical significance.

CONCLUSION

PRL levels seem to be an independent predictor for mortality. Further validation is warranted before its role as a risk-stratification tool can be delineated in clinical practice.

Neuregulin 1 mitigated prolactin deficiency through enhancing TRPM8 signaling under the influence of melatonin in senescent pituitary lactotrophs

The age-related alterations in pituitary function, including changes in prolactin (PRL) production contributes to the systemic susceptibility to age-related diseases. Our previous research has shown the involvement of Nrg1 in regulating the expression and secretion of PRL. However, the precise role of Nrg1 in mitigating the senescence of pituitary lactotrophs and the underlying mechanisms are yet to be comprehended. Here, data from the GEPIA database was used to evaluate the association between transient receptor potential cation channel subfamily M member 8 (TRPM8) and PRL in normal human pituitary tissues, followed by immunofluorescence verification using a human pituitary tissue microarray. TRPM8 levels showed a significant positive association with PRL expression in normal human pituitary tissues, and both TRPM8 and PRL levels declined during aging, suggesting that TRPM8 may regulate pituitary aging by affecting PRL production. It was also found that treatment with exogenous neuregulin 1 (Nrg1) markedly delayed the senescence of GH3 cells (rat lactotroph cell line) generated by D-galactose (D-gal). In addition, melatonin reduced the levels of senescence-related markers in senescent pituitary cells by promoting Nrg1 / ErbB4 signaling, stimulating PRL expression and secretion. Further investigation showed that Nrg1 attenuated senescence in pituitary cells by increasing TRPM8 expression. Downregulation of TRPM8 activation eliminated Nrg1-mediated amelioration of pituitary cell senescence. These findings demonstrate the critical function of Nrg1 / ErbB signaling in delaying pituitary lactotroph cell senescence and enhancing PRL production via promoting TRPM8 expression under the modulation of melatonin.

Neuropsychological complications of hypoprolactinemia

Prolactin (PRL) is primarily produced by the pituitary lactotrophic cells and while initially named for its role in lactation, PRL has several other biological roles including immunomodulation, osmotic balance, angiogenesis, calcium metabolism, and appetite regulation. Most of the PRL-related literature has traditionally focused on hyperprolactinemia, whereas hypoprolactinemia has received little attention. There is evidence to suggest that PRL receptors are widely distributed within the central nervous system including the limbic system. Furthermore, PRL has been shown to play key role in the stress regulation pathway. Recent data also suggest that hypoprolactinemia may be associated with increased sexual dysfunction, anxiety, and depression. In this paper we discuss the current understanding regarding the neuropsychological impact of hypoprolactinemia and highlight the need for adequately defining hypoprolactinemia as an entity and consideration for future replacement therapies.

Prenatal and childhood air pollution exposure, cellular immune biomarkers, and brain connectivity in early adolescents

Introduction

Ambient air pollution is a neurotoxicant with hypothesized immune-related mechanisms. Adolescent brain structural and functional connectivity may be especially vulnerable to ambient pollution due to the refinement of large-scale brain networks during this period, which vary by sex and have important implications for cognitive, behavioral, and emotional functioning. In the current study we explored associations between air pollutants, immune markers, and structural and functional connectivity in early adolescence by leveraging cross-sectional sex-stratified data from the Adolescent Brain Cognitive Development℠ Study®.

Methods

Pollutant concentrations of fine particulate matter, nitrogen dioxide, and ozone were assigned to each child's primary residential address during the prenatal period and childhood (9-10 years-old) using an ensemble-based modeling approach. Data collected at 11-13 years-old included resting-state functional connectivity of the default mode, frontoparietal, and salience networks and limbic regions of interest, intracellular directional and isotropic diffusion of available white matter tracts, and markers of cellular immune activation. Using partial least squares correlation, a multivariate data-driven method that identifies important variables within latent dimensions, we investigated associations between 1) pollutants and structural and functional connectivity, 2) pollutants and immune markers, and 3) immune markers and structural and functional connectivity, in each sex separately.

Results

Air pollution exposure was related to white matter intracellular directional and isotropic diffusion at ages 11-13 years, but the direction of associations varied by sex. There were no associations between pollutants and resting-state functional connectivity at ages 11-13 years. Childhood exposure to nitrogen dioxide was negatively correlated with white blood cell count in males. Immune biomarkers were positively correlated with white matter intracellular directional diffusion in females and both white matter intracellular directional and isotropic diffusion in males. Lastly, there was a reliable negative correlation between lymphocyte-to-monocyte ratio and default mode network resting-state functional connectivity in females, as well as a compromised immune marker profile associated with lower resting-state functional connectivity between the salience network and the left hippocampus in males. In post-hoc exploratory analyses, we found that the PLSC-identified white matter tracts and resting-state networks related to processing speed and cognitive control performance from the NIH Toolbox.

Conclusions

We identified novel links between childhood nitrogen dioxide and cellular immune activation in males, and brain network connectivity and immune markers in both sexes. Future research should explore the potentially mediating role of immune activity in how pollutants affect neurological outcomes as well as the potential consequences of immune-related patterns of brain connectivity in service of improved brain health for all.

Lysosome dynamics during human endometrial stromal cells decidualization: effect of para-nonylphenol

During the process of decidualization, the stromal cells of the endometrium change dynamically to create a favorable environment for embryo implantation. Lysosome activity has often been associated with physiological changes in the endometrium during the preimplantation period and early pregnancy. In this study, the effect of para-nonylphenol (p-NP), an endocrine disruptor, on human immortalized endometrial stromal cells (tHESCs) was investigated. After exposure to p-NP (1 nM and 1 pM), the cells were examined for the decidualization markers connexin-43, insulin like growth factor binding protein 1 (IGFBP1), and prolactin. In addition, the effect of p-NP on lysosome biogenesis and exocytosis was investigated by examining the expression and localization of the transcription factor EB (TFEB) and that of the lysosomal-associated membrane protein 1 (LAMP-1). Finally, we evaluated the effect of p-NP on extracellular matrix (ECM) remodeling using a fibronectin assay. Our results showed that p-NP reduced the expression of prolactin protein, increased the nuclear localization of TFEB, and induced the increase and translocation of the lysosomal protein LAMP-1 to the membrane of tHESCs. The data indicate an impairment of decidualization and suggest an increase in lysosomal biogenesis and exocytosis, which is supported by the higher release of active cathepsin D by tHESCs. Given the importance of cathepsins in the processing and degradation of the ECM during trophoblast invasiveness and migration into the decidua, our results appear to be clear evidence of the negative effects of p-NP on endometrial processes that are fundamental to reproductive success and the establishment of pregnancy.NEW & NOTEWORTHY Endocrine disruptors, such as para-nonylphenol, affect the decidualization of human endometrial stromal cells with an impact on decidualization itself, lysosome biogenesis and exocytosis, and extracellular matrix remodeling. All these alterations may negatively impact embryo implantation with the success of reproduction and the establishment of pregnancy.

Prolactin: A Mammalian Stress Hormone and Its Role in Cutaneous Pathophysiology

The hormone prolactin (PRL) is best recognised for its indispensable role in mammalian biology, specifically the regulation of lactation. Bearing in mind that the mammary gland is a modified sweat gland, it is perhaps unsurprising to discover that PRL also plays a significant role in cutaneous biology and is implicated in the pathogenesis of a range of skin diseases, often those reportedly triggered and/or exacerbated by psychological stress. Given that PRL has been implicated in over 300 biological processes, spanning reproduction and hair growth and thermo- to immunoregulation, a comprehensive understanding of the relationship between PRL and the skin remains frustratingly elusive. In an historical curiosity, the first hint that PRL could affect skin biology came from the observation of seborrhoea in patients with post-encephalitic Parkinsonism as a result of another global pandemic, encephalitis lethargica, at the beginning of the last century. As PRL is now being postulated as a potential immunomodulator for COVID-19 infection, it is perhaps timeous to re-examine this pluripotent hormone with cytokine-like properties in the cutaneous context, drawing together our understanding of the role of PRL in skin disease to illustrate how targeting PRL-mediated signalling may represent a novel strategy to treat a range of skin diseases and hair disorders.

Inhibition of Prolactin Affects Epididymal Morphology by Decreasing the Secretion of Estradiol in Cashmere Bucks

Yanshan Cashmere bucks are seasonal breeding animals and an important national genetic resource. This study aimed to investigate the involvement of prolactin (PRL) in the epididymal function of bucks. Twenty eleven-month-old Cashmere bucks were randomly divided into a control (CON) group and a bromocriptine (BCR, a prolactin inhibitor, 0.06 mg/kg body weight (BW)) treatment group. The experiment was conducted from September to October 2020 in Qinhuangdao City, China, and lasted for 30 days. Blood was collected on the last day before the BCR treatment (day 0) and on the 15th and 30th days after the BCR treatment (days 15 and 30). On the 30th day, all bucks were transported to the local slaughterhouse, where epididymal samples were collected immediately after slaughter. The left epididymis was preserved in 4% paraformaldehyde for histological observation, and the right epididymis was immediately preserved in liquid nitrogen for RNA sequencing (RNA-seq). The results show that the PRL inhibitor reduced the serum PRL and estradiol (E2) concentrations (p < 0.05) and tended to decrease luteinizing hormone (LH) concentrations (p = 0.052) by the 30th day, but no differences (p > 0.05) occurred by either day 0 or 15. There were no differences (p > 0.05) observed in the follicle-stimulating hormone (FSH), testosterone (T), and dihydrotestosterone (DHT) concentrations between the two groups. The PRL receptor (PRLR) protein was mainly located in the cytoplasm and intercellular substance of the epididymal epithelial cells. The PRL inhibitor decreased (p < 0.05) the expression of the PRLR protein in the epididymis. In the BCR group, the height of the epididymal epithelium in the caput and cauda increased, as did the diameter of the epididymal duct in the caput (p < 0.05). However, the diameter of the cauda epididymal duct decreased (p < 0.05). Thereafter, a total of 358 differentially expressed genes (DEGs) were identified in the epididymal tissues, among which 191 were upregulated and 167 were downregulated. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that ESR2, MAPK10, JUN, ACTL7A, and CALML4 were mainly enriched in the estrogen signaling pathway, steroid binding, calcium ion binding, the GnRH signaling pathway, the cAMP signaling pathway, and the chemical carcinogenesis-reactive oxygen species pathway, which are related to epididymal function. In conclusion, the inhibition of PRL may affect the structure of the epididymis by reducing the expression of the PRLR protein and the secretion of E2. ESR2, MAPK10, JUN, ACTL7A, and CALML4 could be the key genes of PRL in its regulation of epididymal reproductive function.

Evidence-based definition of hypoprolactinemia in European men aged 40-86 years: the European male ageing study

Empirical evidence for a low normal or reference interval for serum prolactin (PRL) is lacking for men, while the implications of very low PRL levels for human health have never been studied. A clinical state of "PRL deficiency" has not been defined except in relation to lactation. Using data from the European Male Ageing Study (EMAS), we analyzed the distribution of PRL in 3,369 community-dwelling European men, aged 40-80 years at phase-1 and free from acute illnesses. In total, 2,948 and 2,644 PRL samples were collected during phase-1 and phase-2 (3 to 5.7 years later). All samples were analysed in the same centre with the same assay. After excluding individuals with known pituitary diseases, PRL ≥ 35 ng/ml, and PRL-altering drugs including antipsychotic agents, selective serotonin reuptake inhibitors, or dopamine agonists, 5,086 data points (2,845 in phase-1 and 2,241 in phase-2) were available for analysis. The results showed that PRL declined minimally with age (slope = -0.02) and did not correlate with BMI. The positively skewed PRL distribution was log-transformed to a symmetrical distribution (skewness reduced from 13.3 to 0.015). Using two-sigma empirical rule (2[]SD about the mean), a threshold at 2.5% of the lower end of the distribution was shown to correspond to a PRL value of 2.98ng/ml. With reference to individuals with PRL levels of 5-34.9 ng/ml (event rate = 6.3%), the adjusted risk of developing type 2 diabetes increased progressively in those with PRL levels of 3-4.9 ng/ml: event rate = 9.3%, OR (95% CI) 1.59 (0.93-2.71), and more so with PRL levels of 0.3-2.9 ng/ml: event rate = 22.7%, OR 5.45 (1.78-16.62). There was also an increasing trend in prediabetes and diabetes based on fasting blood glucose levels was observed with lower categories of PRL. However, PRL levels were not associated with cancer, cardiovascular diseases, depressive symptoms or mortality. Our findings suggest that a PRL level below 3 ng/ml (64 mlU/l) significantly identifies European men with a clinically-important outcome (of type 2 diabetes), offering a lower reference-value for research and clinical practice.

Prolactin effects on the pathogenesis of diabetes mellitus

BACKGROUND

Prolactin (PRL) is a pituitary hormone promoting lactation in response to the suckling reflex. Beyond its well-known effects, novel tissue-specific and metabolic functions of PRL are emerging.

AIMS

To dissect PRL as a critical mediator of whole-body gluco-insulinemic sensitivity.

METHODS

PubMed-based search with the following terms 'prolactin', 'glucose metabolism', 'type 2 diabetes mellitus', 'type 1 diabetes mellitus', 'gestational diabetes mellitus' was performed.

DISCUSSION

The identification of the PRL-glucose metabolism network poses the basis for unprecedented avenues of research in the pathogenesis of diabetes mellitus type 1 or 2, as well as of gestational diabetes. In this regard, it is of timely relevance to define properly the homeostatic PRL serum levels since glucose metabolism could be influenced by the circulating amount of the hormone.

RESULTS

This review underscores the basic mechanisms of regulation of pancreatic β-cell functions by PRL and provides a revision of articles which have investigated the connection between PRL unbalancing and diabetes mellitus. Future studies are needed to elucidate the burden and the role of PRL in the regulation of glucose metabolism and determine the specific PRL threshold that may impact the management of diabetes.

CONCLUSION

A careful evaluation and context-driven interpretation of PRL levels (e.g., pregnancy, PRL-secreting pituitary adenomas, drug-related hyper- and hypoprolactinemia) could be critical for the correct screening and management of glucometabolic disorders, such as type 1 or 2 as well as gestational diabetes mellitus.

The fallacy of functional nomenclature in the kingdom of biological multifunctionality: physiological and evolutionary considerations on ion channels

Living organisms are multiscale complex systems that have evolved high degrees of multifunctionality and redundancy in the structure-function relationship. A number of factors, only in part determined genetically, affect the jobs of proteins. The overall structural organization confers unique molecular properties that provide the potential to perform a pattern of activities, some of which are co-opted by specific environments. The variety of multifunctional proteins is expanding, but most cases are handled individually and according to the still dominant 'one structure-one function' approach, which relies on the attribution of canonical names typically referring to the first task identified for a given protein. The present topical review focuses on the multifunctionality of ion channels as a paradigmatic example. Mounting evidence reports the ability of many ion channels (including members of voltage-dependent, ligand-gated and transient receptor potential families) to exert biological effects independently of their ion conductivity. 'Functionally based' nomenclature (the practice of naming a protein or family of proteins based on a single purpose) is a conceptual bias for three main reasons: (i) it increases the amount of ambiguity, deceiving our understanding of the multiple contributions of biomolecules that is the heart of the complexity; (ii) it is in stark contrast to protein evolution dynamics, largely based on multidomain arrangement; and (iii) it overlooks the crucial role played by the microenvironment in adjusting the actions of cell structures and in tuning protein isoform diversity to accomplish adaptational requirements. Biological information in protein physiology is distributed among different entwined layers working as the primary 'locus' of natural selection and of evolutionary constraints.

Sleep and local field potential effect of the D2 receptor agonist bromocriptine during the estrus cycle and postpartum period in female rats

BACKGROUND

Pituitary lactotrophs are under tonic dopaminergic inhibitory control and bromocriptine treatment blocks prolactin secretion.

METHODS

Sleep and local field potential were addressed for 72 h after bromocriptine treatments applied during the different stages of the estrus cycle and for 24 h in the early- and middle postpartum period characterized by spontaneously different dynamics of prolactin release in female rats.

RESULTS

Sleep changes showed strong dependency on the estrus cycle phase of the drug application. Strongest increase of wakefulness and reduction of slow wave sleep- and rapid eye movements sleep appeared during diestrus-proestrus and middle postpartum treatments. Stronger sleep-wake effects appeared in the dark phase in case of the estrus cycle treatments, but in the light phase in postpartum treatments. Slow wave sleep and REM sleep loss in case of estrus cycle treatments was not compensated at all and sleep loss seen in the first day post-injection was gained further later. In opposition, slow wave sleep loss in the light phase after bromocriptine injections showed compensation in the postpartum period treatments. Bromocriptine treatments resulted in a depression of local field potential delta power during slow wave sleep while an enhancement in beta and gamma power during wakefulness regardless of the treatment timing.

CONCLUSIONS

These results can be explained by the interplay of dopamine D2 receptor agonism, lack of prolactin release and the spontaneous homeostatic sleep drive being altered in the different stages of the estrus cycle and the postpartum period.

The diagnosis and prevalence of hypoprolactinemia in patients with panhypopituitarism and the effects on depression and sexual functions

PURPOSE

We aimed to investigate the prevalence and the diagnostic criteria of hypoprolactinemia in patients with panhypopituitarism and the effects of hypoprolactinemia on depression and sexual functions.

MATERIALS AND METHODS

Forty-eight patients with panhypopituitarism and 20 healthy volunteers were included. Basal hormone levels were measured and a TRH stimulation test was performed. For the evaluation of sexual functions, questionnaries of Female Sexual Functional Index (FSFI) for females and International Erectile Functional Index for males were performed to the subjects. Depressive symptoms were evaluated by Beck Depression Envontory score (BDI-II).

RESULTS

The peak PRL response to TRH stimulation test at 5th percentile in the control group was 18.6 ng/ml in males and 41.6 ng/ml in females and accepted as the cut-offs for sufficient response of PRL. Prolactin was insufficient in 42(87.5%) patients. A basal PRL level of ≤ 5.7 ng/ml in males and 7.11 ng/ml in females was 100% specific in predicting an inadequate response to TRH stimulation test with 80% and 70% sensitivity respectively. A basal PRL level of ≥ 8.5 ng/dl in males was 100% specific and 76% sensitive, and in females a level of ≥ 15.2 ng/dl was 96% specific and 66% sensitive in predicting an adequate response to TRH. PRL deficient patients with panhypopituitarism had higher depression scores compared to the controls, lower sexual function scores in males.

CONCLUSION

PRL deficiency is prevalent among individuals with panhypopituitarism, with the potential to result in elevated depression scores in both sexes and impaired sexual functions in males. A basal PRL level seems to be sufficient for the diagnosis of hypoprolactinemia in routine clinical practice.

The influence of the prolactin/vasoinhibin axis on post-stroke lesion volume, astrogliosis, and survival

Ischemic stroke is a significant global health issue, ranking fifth among all causes of death and a leading cause of serious long-term disability. Ischemic stroke leads to severe outcomes, including permanent brain damage and neuronal dysfunction. Therefore, decreasing and preventing neuronal injuries caused by stroke has been the focus of therapeutic research. In recent years, many studies have shown that fluctuations in hormonal levels influence the prognosis of ischemic stroke. Thus, it is relevant to understand the role of hormones in the pathophysiological mechanisms of ischemic stroke for preventing and treating this health issue. Here, we investigate the contribution of the prolactin/vasoinhibin axis, an endocrine system regulating blood vessel growth, immune processes, and neuronal survival, to the pathophysiology of ischemic stroke. Male mice with brain overexpression of prolactin or vasoinhibin by adeno-associated virus (AAV) intracerebroventricular injection or lacking the prolactin receptor (Prlr-/-) were exposed to transient middle cerebral artery occlusion (tMCAO) for 45 min followed by 48 h of reperfusion. Overexpression of vasoinhibin or the absence of the prolactin receptor led to an increased lesion volume and decreased survival rates in mice following tMCAO, whereas overexpression of prolactin had no effect. In addition, astrocytic distribution in the penumbra was altered, glial fibrillary acidic protein and S100b mRNA expressions were reduced, and interleukin-6 mRNA expression increased in the ischemic hemisphere of mice overexpressing vasoinhibin. Of note, prolactin receptor-null mice (Prlr-/-) showed a marked increase in serum vasoinhibin levels. Furthermore, vasoinhibin decreased astrocyte numbers in mixed hippocampal neuron-glia cultures. These observations suggest that increased vasoinhibin levels may hinder astrocytes' protective reactivity. Overall, this study suggests the involvement of the prolactin/vasoinhibin axis in the pathophysiology of ischemic stroke-induced brain injury and provides insights into the impact of its dysregulation on astrocyte reactivity and lesion size. Understanding these mechanisms could help develop therapeutic interventions in ischemic stroke and other related neurological disorders.

ABCD4 is associated with mammary gland development in mammals

BACKGROUND

Mammary gland development is a critical process in mammals, crucial for their reproductive success and offspring nourishment. However, the functional roles of key candidate genes associated with teat number, including ABCD4, VRTN, PROX2, and DLST, in this developmental process remain elusive. To address this gap in knowledge, we conducted an in-depth investigation into the dynamic expression patterns, functional implications, and regulatory networks of these candidate genes during mouse mammary gland development.

RESULTS

In this study, the spatial and temporal patterns of key genes were characterized in mammary gland development. Using time-series single-cell data, we uncovered differences in the expression of A bcd4, Vrtn, Prox2, and Dlst in cell population of the mammary gland during embryonic and adult stages, while Vrtn was not detected in any cells. We found that only overexpression and knockdown of Abcd4 could inhibit proliferation and promote apoptosis of HC11 mammary epithelial cells, whereas Prox2 and Dlst had no significant effect on these cells. Using RNA-seq and qPCR, further analysis revealed that Abcd4 can induce widespread changes in the expression levels of genes involved in mammary gland development, such as Igfbp3, Ccl5, Tlr2, and Prlr, which were primarily associated with the MAPK, JAK-STAT, and PI3K-AKT pathways by functional enrichment.

CONCLUSIONS

These findings revealed ABCD4 as a candidate gene pivotal for regulating mammary gland development and lactation during pregnancy by influencing PRLR expression.

The relationship between low prolactin and type 2 diabetes

Prolactin (PRL) is secreted throughout life in men and women. At elevated levels, its physiological role in pregnancy and lactation, and pathological effects, are well known. However clinical implications of low circulating PRL are not well established. We conducted a meta-analysis to examine the relationship between low PRL levels and type 2 diabetes. Five papers included cross-sectional studies comprising 8,720 men (mean age range 51.4-60 years) and 3,429 women (49.5-61.6 years), and four papers included cohort studies comprising 2,948 men (52.1-60.0 years) and 3,203 women (49.2-60.1 years). Individuals with pregnancy, lactation and hyperprolactinemia, drugs known to alter circulating PRL levels, or pituitary diseases had been excluded. Although most studies used quartiles to categorize PRL groups for analysis, PRL cut-off values (all measured by chemiluminescence immunoassay) were variably defined between studies: the lowest PRL quartiles ranged from 3.6 ng/ml to 7.2 ng/ml in men and between 4.5 ng/ml to 8 ng/ml in women; and the highest PRL quartiles ranged from 6.9 ng/ml to 13 ng/ml in men and 9.6 ng/ml to 15.8 ng/ml in women. Type 2 diabetes was defined variably using self-reported physician's diagnosis, fasting blood glucose, oral glucose tolerance test or glycated hemoglobin (HbA1C). In cross-sectional studies, compared to individuals in the highest PRL groups (reference), those in the lowest PRL groups had greater risk of type 2 diabetes both in men: odds ratio (OR) and 95% confidence interval = 1.86 (1.56-2.22) and in women: OR = 2.15 (1.63-2.85). In cohort studies, women showed a significant association between low PRL and type 2 diabetes: OR = 1.52 (1.02-2.28) but not men: OR = 1.44 (0.46-4.57). Relatively low heterogeneity was observed (I2 = 25-38.4%) for cross-sectional studies, but higher for cohort studies (I2 = 52.8-79.7%). In conclusion, low PRL is associated with type 2 diabetes, but discrepancy between men and women in the relationship within cohort studies requires further research.

Are prolactin levels efficient in predicting a pituitary lesion in patients with hyperprolactinemia?

PURPOSE

Data regarding the presence of a prolactin (PRL) threshold above which a pituitary magnetic resonance imaging (MRI) is mandatory in patients with hyperprolactinemia (hyperPRL) are controversial and derived primarily from studies focused on female populations. Aim of our study was to evaluate in a cohort of patients of both sexes with confirmed hyperPRL, the possible correlation between PRL values and the presence of pituitary abnormalities.

METHODS

We retrospectively analyzed data from patients who underwent serial PRL sampling at our Division between January 2015 and December 2022. Patients diagnosed with monomeric hyperPRL at serial sampling and with subsequent contrast-enhanced MRI results available for the pituitary region were included in the study. Exclusion criteria were prior pituitary disease, severe renal insufficiency, liver cirrhosis, uncompensated primary hypothyroidism and ongoing therapy with hyperprolactinemic drugs. Physiological causes of hyperPRL were also ruled out.

RESULTS

Out of the 1253 patients who underwent serial PRL sampling, 139 patients (101 women and 38 men) met the inclusion criteria: 106 (76.3%) patients had some form of pituitary disease, with microlesions observed in 69.8%, macrolesions in 25.5% and other findings in 4.7% of subjects. PRL values showed a modest accuracy in predicting the presence of a pituitary abnormality and the best cut-offs identified were >25 µg/L (AUC 0.767, p = 0.003) and >44.2 µg/L (AUC 0.697, p < 0.001) in men and women, respectively; however, if only patients with PRL values > 500 µg/L were excluded from the analysis, as they were already supposed to harbor a macroprolactinoma, PRL levels were not able to predict the presence of a macrolesion neither in men nor women.

CONCLUSION

Given the high prevalence of pituitary abnormalities in patients of both sexes with hyperPRL at serial sampling, performing a pituitary imaging in all cases of hyperPRL, even if mild, appears to be a cautious choice.

Influence of energy availability on metabolic hormonal profiles in east African female and male distance runners

BACKGROUND

Energy availability (EA) and relative energy deficiency in sport (RED-S) are understudied in East African endurance athletes, both females (F) and males (M). This study assessed the metabolic hormonal profiles of such athletes relative to their EA status.

METHODS

Forty athletes (F=16, M=24) had their EA status, training, maximal oxygen uptake, and resting blood samples assessed using standard research practices. Subjects were stratified into two groups, high EA (HiEA) and low EA (LoEA) based on combined median value.

RESULTS

Cortisol (P=0.034) and insulin (P=0.044) were significantly elevated in the LoEA group, while growth hormone (P=0.045) was significantly suppressed; and, prolactin (P=0.078) trended towards suppression, respectively compared to the HiEA group. All other hormonal comparison were non-significant.

CONCLUSIONS

Metabolic hormonal profiles of female and male African distance runners are affected by their EA status. Aspects of these alterations agree in part with published findings based upon White populations, although some differences exist and need further investigation.

Neuregulin 4 (Nrg4) cooperates with melatonin to regulate the PRL expression via ErbB4/Erk signaling pathway as a potential prolactin (PRL) regulator

Neuregulin-4 (Nrg4) and melatonin play vital roles in endocrine diseases. However, there is little discussion about the function and potential mechanism of Nrg4 and melatonin in prolactin (PRL) regulation. The human normal pituitary data from Gene Expression Profiling Interactive Analysis (GEPIA) database was used to explore the correlation between NRG4 and PRL. The expression and correlation of NRG4 and PRL were determined by Immunofluorescence staining (IF) and human normal pituitary tissue microarray. Western Blot (WB) was used to detect the expression of PRL, p-ErbB2/3/4, ErbB2/3/4, p-Erk1/2, Erk1/2, p-Akt and Akt in PRL-secreting pituitary GH3 and RC-4B/C cells treated by Nrg4, Nrg4-small interfering RNA, Erk1/2 inhibitor FR180204 and melatonin. The expression of NRG4 was significantly positively correlated with that of PRL in the GEPIA database and normal human pituitary tissues. Nrg4 significantly increased the expression and secretion of PRL and p-Erk1/2 expression in GH3 cells and RC-4B/C cells. Inhibition of Nrg4 significantly inhibited PRL expression. The increased levels of p-Erk1/2 and PRL induced by Nrg4 were abolished significantly in response to FR180204 in GH3 and RC-4B/C cells. Additionally, Melatonin promotes the expression of Nrg4, p-ErbB4, p-Erk1/2, and PRL and can further promote the expression of p-Erk1/2 and PRL in combination with Nrg4. Further investigation into the function of Nrg4 and melatonin on PRL expression and secretion may provide new clues to advance the clinical control of prolactinomas and hyperprolactinemia.

Macroprolactin in mothers and their babies: what is its origin?

OBJECTIVES

Macroprolactinemia is one of the major causes of hyperprolactinemia. The aim of this study was to clarify the origin of macroprolactin (macro-PRL).

METHODS

We examined macro-PRL in the sera of 826 pregnant women and in those of their babies' umbilical cords at delivery. Macro-PRL was evaluated by precipitation with polyethylene glycol (PEG), gel filtration chromatography (GFC), and absorption with protein G (PG).

RESULTS

We detected macro-PRL in 16 out of the 826 pregnant women (1.94 %) and in 14 of their babies, which may indicate the possibility of hereditary origin of macro-PRL. However, the macro-PRL ratios of the babies correlated positively with those of their mothers (r=0.72 for GFC, p<0.001 and r=0.77 for PG, p<0.001), suggesting that the immunoglobulin (Ig)G-type anti-PRL autoantibodies might be actively transferred to babies via the placenta and form macro-PRL by binding to their babies' PRL or PRL-IgG complexes may possibly pass through the placenta. There were two cases in which only mothers had macro-PRL, indicating that the mothers had autoantibodies that did not pass through the placenta, such as IgA, PRL bound to the other proteins or PRL aggregates. No cases were found in which only the babies had macro-PRL and their mothers did not, suggesting that macro-PRL might not arise by non-hereditary congenital causes.

CONCLUSIONS

Macro-PRL in women of reproductive age might be mostly IgG-type anti-PRL autoantibody-bound PRL. The likely origin of macro-PRL in babies is the transplacental transfer of IgG-type anti-PRL autoantibodies or PRL-IgG complexes from the mothers to their babies.

Single-Cell Transcriptional Profile Construction of Rat Pituitary Glands before and after Sexual Maturation and Identification of Novel Marker Spp1 in Gonadotropes

The mammalian pituitary gland drives highly conserved physiological processes such as somatic cell growth, pubertal transformation, fertility, and metabolism by secreting a variety of hormones. Recently, single-cell transcriptomics techniques have been used in pituitary gland research. However, more studies have focused on adult pituitary gland tissues from different species or different sexes, and no research has yet resolved cellular differences in pituitary gland tissue before and after sexual maturation. Here, we identified a total of 15 cell clusters and constructed single-cell transcriptional profiles of rats before and after sexual maturation. Furthermore, focusing on the gonadotrope cluster, 106 genes were found to be differentially expressed before and after sexual maturation. It was verified that Spp1, which is specifically expressed in gonadotrope cells, could serve as a novel marker for this cell cluster and has a promotional effect on the synthesis and secretion of follicle-stimulating hormone. The results provide a new resource for further resolving the regulatory mechanism of pituitary gland development and pituitary hormone synthesis and secretion.

Very short sleep duration reveals a proteomic fingerprint that is selectively associated with incident diabetes mellitus but not with incident coronary heart disease: a cohort study

BACKGROUND

The molecular pathways linking short and long sleep duration with incident diabetes mellitus (iDM) and incident coronary heart disease (iCHD) are not known. We aimed to identify circulating protein patterns associated with sleep duration and test their impact on incident cardiometabolic disease.

METHODS

We assessed sleep duration and measured 78 plasma proteins among 3336 participants aged 46-68 years, free from DM and CHD at baseline, and identified cases of iDM and iCHD using national registers. Incident events occurring in the first 3 years of follow-up were excluded from analyses. Tenfold cross-fit partialing-out lasso logistic regression adjusted for age and sex was used to identify proteins that significantly predicted sleep duration quintiles when compared with the referent quintile 3 (Q3). Predictive proteins were weighted and combined into proteomic scores (PS) for sleep duration Q1, Q2, Q4, and Q5. Combinations of PS were included in a linear regression model to identify the best predictors of habitual sleep duration. Cox proportional hazards regression models with sleep duration quintiles and sleep-predictive PS as the main exposures were related to iDM and iCHD after adjustment for known covariates.

RESULTS

Sixteen unique proteomic markers, predominantly reflecting inflammation and apoptosis, predicted sleep duration quintiles. The combination of PSQ1 and PSQ5 best predicted sleep duration. Mean follow-up times for iDM (n = 522) and iCHD (n = 411) were 21.8 and 22.4 years, respectively. Compared with sleep duration Q3, all sleep duration quintiles were positively and significantly associated with iDM. Only sleep duration Q1 was positively and significantly associated with iCHD. Inclusion of PSQ1 and PSQ5 abrogated the association between sleep duration Q1 and iDM. Moreover, PSQ1 was significantly associated with iDM (HR = 1.27, 95% CI: 1.06-1.53). PSQ1 and PSQ5 were not associated with iCHD and did not markedly attenuate the association between sleep duration Q1 with iCHD.

CONCLUSIONS

We here identify plasma proteomic fingerprints of sleep duration and suggest that PSQ1 could explain the association between very short sleep duration and incident DM.

Canonical transient receptor potential channels and hypothalamic control of homeostatic functions

Recent molecular biological and electrophysiological studies have identified multiple transient receptor potential (TRP) channels in hypothalamic neurons as critical modulators of homeostatic functions. In particular, the canonical transient receptor potential channels (TRPCs) are expressed in hypothalamic neurons that are vital for the control of fertility and energy homeostasis. Classical neurotransmitters such as serotonin and glutamate and peptide neurotransmitters such as kisspeptin, neurokinin B and pituitary adenylyl cyclase-activating polypeptide signal through their cognate G protein-coupled receptors to activate TPRC 4, 5 channels, which are essentially ligand-gated calcium channels. In addition to neurotransmitters, circulating hormones like insulin and leptin signal through insulin receptor (InsR) and leptin receptor (LRb), respectively, to activate TRPC 5 channels in hypothalamic arcuate nucleus pro-opiomelanocortin (POMC) and kisspeptin (arcuate Kiss1 [Kiss1ARH]) neurons to have profound physiological (excitatory) effects. Besides its overt depolarizing effects, TRPC channels conduct calcium ions into the cytoplasm, which has a plethora of downstream effects. Moreover, not only the expression of Trpc5 mRNA but also the coupling of receptors to TRPC 5 channel opening are regulated in different physiological states. In particular, the mRNA expression of Trpc5 is highly regulated in kisspeptin neurons by circulating estrogens, which ultimately dictates the firing pattern of kisspeptin neurons. In obesity states, InsRs are "uncoupled" from opening TRPC 5 channels in POMC neurons, rendering them less excitable. Therefore, in this review, we will focus on the critical role of TRPC 5 channels in regulating the excitability of Kiss1ARH and POMC neurons in different physiological and pathological states.

Hormones and B-cell development in health and autoimmunity

The development of B cells into antibody-secreting plasma cells is central to the adaptive immune system as they induce protective and specific antibody responses against invading pathogens. Various studies have shown that, during this process, hormones can play important roles in the lymphopoiesis, activation, proliferation, and differentiation of B cells, and depending on the signal given by the receptor of each hormone, they can have a positive or negative effect. In autoimmune diseases, hormonal deregulation has been reported to be related to the survival, activation and/or differentiation of autoreactive clones of B cells, thus promoting the development of autoimmunity. Clinical manifestations of autoimmune diseases have been associated with estrogens, prolactin (PRL), and growth hormone (GH) levels. However, androgens, such as testosterone and progesterone (P4), could have a protective effect. The objective of this review is to highlight the links between different hormones and the immune response mediated by B cells in the etiopathogenesis of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and multiple sclerosis (MS). The data collected provide insights into the role of hormones in the cellular, molecular and/or epigenetic mechanisms that modulate the B-cell response in health and disease.

Assessment of the Impact of SARS-CoV-2 Infection on the Sexual Function of Women, Levels of Oxytocin and Prolactin: A Prospective Cohort Study

(1) Background: There is a lack of direct evidence on whether SARS-CoV-2 affects women's sexual function through a biological-organic mechanism. Existing studies on the topic are few and have produced contradictory results. This study aims to explore the possible relationship between sex hormones and sexual function in patients who have been infected with SARS-CoV-2. Moreover, we aimed to determine whether these changes are related to the clinical course of COVID-19 and whether they are temporary or long-lasting. (2) Methods: A study was conducted on 104 women, including 64 women infected with COVID-19 and a control group of 40 healthy women, between January 2021 and August 2022. Blood samples were collected to measure prolactin and oxytocin levels, and a clinical assessment was performed 3 and 6 months later. Sexual function self-assessment was captured based on the FSFI scale. (3) Results: Our study found that patients with severe COVID-19 had better sexual satisfaction scores one month after recovery but no discernible difference after six months. High levels of serum prolactin were observed in patients with active COVID-19 but became similar to a control group after one month and remained stable over time. Higher prolactin levels were significantly associated with increased arousal and hydration. Individuals with severe COVID-19 had notably low levels of plasma oxytocin, but there was no correlation between oxytocin levels and sexual satisfaction. (4) Conclusions: The gynecologic symptoms, as well as disturbances in oxytocin and prolactin levels, might be observed in a short time after infection. However, SARS-CoV-2 infection has no lasting effect on sexual function, oxytocin, and prolactin levels among women.

Clinical Impact of New Reference Intervals for the Roche Prolactin II Immunoassay

Context

The Roche prolactin immunoassay is used throughout the world. It reports higher values than the Siemens immunoassay but the manufacturer-defined reference intervals are similar. Patient results are often above the Roche upper limit but within the Siemens interval, causing diagnostic confusion.

Objective

Establish new reference intervals for the Roche and Siemens prolactin immunoassays.

Methods

We established new reference intervals for the Roche and Siemens immunoassays using 374 specimens from healthy outpatients. We performed chart review for unnecessary testing and treatment for 298 patients in a 6-month period with at least 1 Roche prolactin value above the manufacturer-defined upper limit and below our new upper limit.

Results

The new upper limit for the Roche assay was 37.8 ng/mL (females) and 22.8 ng/mL (males). The manufacturer-defined limits were 23.3 ng/mL and 15.2 ng/mL, respectively. New intervals for the Siemens assay matched the manufacturer. No cases of clinically significant pathophysiologic prolactin excess were identified in patients with values between the manufacturer-defined upper reference limit and our new Roche upper limit. Unnecessary further evaluation in these patients included 459 repeat prolactin measurements, 57 macroprolactin measurements, 39 magnetic resonance imaging studies, and 28 endocrine referrals. Eleven patients received dopamine agonists. The minimum cost of excess care using Medicare reimbursement rates was $34 134, with substantially higher amounts billed to patients and their insurance providers.

Conclusion

Adoption of new upper reference limits for the Roche prolactin assay of 37.8 ng/mL (females) and 22.8 ng/mL (males) would not delay diagnosis or necessary intervention in patients with clinically significant pituitary tumors but would reduce unnecessary evaluation in patients without pathophysiologic prolactin excess.

Diagnosis of hyperprolactinemia in women: A Position Statement from the Brazilian Federation of Gynecology and Obstetrics Associations (Febrasgo) and the Brazilian Society of Endocrinology and Metabolism (SBEM)

Hyperprolactinemia is a frequent cause of menstrual irregularity, galactorrhea, hypogonadism, and infertility. The most common etiologies of hyperprolactinemia can be classified as physiological, pharmacological, and pathological. Among pathological conditions, it is essential to distinguish prolactinomas from other tumors and pituitary lesions presenting with hyperprolactinemia due to pituitary stalk disconnection. Proper investigation considering clinical data, laboratory tests, and, if necessary, imaging evaluation, is important to identify the correctcause of hyperprolactinemia and manage the patient properly. This position statement by the Brazilian Federation of Gynecology and Obstetrics Associations (Febrasgo) and Brazilian Societyof Endocrinology and Metabolism (SBEM) addresses the recommendations for measurement of serum prolactin levels and the investigations of symptomatic and asymptomatic hyperprolactinemia and medication-induced hyperprolactinemia in women.

Tolerability and safety outcomes of first-line oral second-generation antipsychotics in patients with schizophrenia

INTRODUCTION

Antipsychotics are the foundation of pharmacologic treatment for schizophrenia. There are many oral antipsychotics available and given that these medications are generally considered comparably efficacious when titrated to an adequate dose, their varied tolerability, and safety profiles become critically important for medication selection.

AREAS COVERED

This paper reviews tolerability and safety considerations for first-line second-generation oral antipsychotics currently approved for the treatment of schizophrenia in the USA. Excluded from consideration are clozapine and non-oral formulations.

EXPERT OPINION

Among antipsychotics, there are many differences in adverse reactions observed in clinical trials, such as variable likelihood to cause sedation vs insomnia, weight gain and abnormalities in glucose/lipid metabolism, hyperprolactinemia, potential for impact on the QT interval, and motoric adverse effects. Additional safety data that can help with medication selection include safety in pregnancy and lactation, and potential for drug-drug interactions. Ultimately, working with patients to personalize treatment by focusing on safety and individual tolerability considerations for various adverse effects can help in building a therapeutic alliance and improving patients' outcomes.

Gynura procumbens and selected metabolites: Amelioration of depressive-like behaviors in mice and risperidone-induced hyperprolactinemia in rats

Gynura procumbens (Lour.) Merr., utilized in traditional Chinese medicine, is known for its liver-protective, liver-soothing, and depression-alleviating properties. This research examines the antidepressant and anti-hyperprolactinemia potentials of an ethanol extract from G. procumbens stems (EEGS) and specific metabolites. To model depression and hyperprolactinemia, chronic unpredictable mild stress (CUMS) was induced in mice and risperidone was administered to rats, respectively. Treatments involved administering low (5 mg/kg), medium (25 mg/kg), and high (125 mg/kg) doses of EEGS and certain metabolites to both models. Behavioral assessments were conducted in the CUMS-induced mice, while the CA3 neuronal damage in mice and histopathological alterations in rat mammary glands were evaluated using Nissl and Hematoxylin & Eosin staining techniques, respectively. EEGS decreased immobility times in the forced swimming and tail suspension tests in mice, enhancing their exploration of the central zone. It elevated the serum levels of 5-hydroxytryptamine, norepinephrine, estradiol, luteinizing hormone (LH), and testosterone in mice. Moreover, EEGS restored the neuronal cell arrangement in the CA3 area, reduced interleukin-1beta mRNA production, and increased the expression of interleukin-10 and beta-catenin mRNA. In the context of risperidone-induced hyperprolactinemia, EEGS lowered blood prolactin levels, reduced the dimensions of rat nipples, and enhanced LH, progesterone, and dopamine levels, alongside mitigating mammary hyperplasia. Among the EEGS selected metabolites, the combined effect of chlorogenic acid and trans-p-coumaric acid was found to be more effective than the action of each compound in isolation. Collectively, the findings indicate that EEGS and its selected metabolites offer promising antidepressant benefits while counteracting hyperprolactinemia.

Mechanisms of adverse mammary effect induced by olanzapine and therapeutic interventions in rat model

BACKGROUND

Olanzapine antagonizes dopamine receptors and is prescribed to treat multiple psychiatric conditions. The main side effect of concern for olanzapine is weight gain and metabolic syndrome. Olanzapine induces hyperprolactinemia, however its effect on the mammary gland is poorly documented.

METHODS

Rats received olanzapine by gavage or in drinking water at 1, 3, and 6 mg/kg/day for 5-40 days or 100 days, with and without coadministration of bromocriptine or aripiprazole and using once daily or continuous administration strategies. Histomorphology of the mammary gland, concentrations of prolactin, estradiol, progesterone, and olanzapine in serum, mammary gland and adipose tissue, and mRNA and protein expressions of prolactin receptors were analyzed.

RESULTS

In adult and prepubescent female rats and male rats, olanzapine induced significant development of mammary glands in dose- and time-dependent manners, with histopathological hyperplasia of mammary ducts and alveoli with lumen dilation and secretion, marked increase of mammary prolactin receptor expression, a marker of breast tissue, and with mild increase of circulating prolactin. This side effect can be reversed after medication withdrawal, but long-term olanzapine treatment for 100 days implicated tumorigenic potentials indicated by usual ductal epithelial hyperplasia. Olanzapine induced mammary development was prevented with the coaddition of the dopamine agonist bromocriptine or partial agonist aripiprazole, or by continuous administration of medication instead of a once daily regimen.

CONCLUSIONS

These results shed light on the previously overlooked effect of olanzapine on mammary development and present experimental evidence to support current clinical management strategies of antipsychotic induced side effects in the breast.

Maternal nutrient metabolism in the liver during pregnancy

The liver plays pivotal roles in nutrient metabolism, and correct hepatic adaptations are required in maternal nutrient metabolism during pregnancy. In this review, hepatic nutrient metabolism, including glucose metabolism, lipid and cholesterol metabolism, and protein and amino acid metabolism, is first addressed. In addition, recent progress on maternal hepatic adaptations in nutrient metabolism during pregnancy is discussed. Finally, the factors that regulate hepatic nutrient metabolism during pregnancy are highlighted, and the factors include follicle-stimulating hormone, estrogen, progesterone, insulin-like growth factor 1, prostaglandins fibroblast growth factor 21, serotonin, growth hormone, adrenocorticotropic hormone, prolactin, thyroid stimulating hormone, melatonin, adrenal hormone, leptin, glucagon-like peptide-1, insulin glucagon and thyroid hormone. Our vision is that more attention should be paid to liver nutrient metabolism during pregnancy, which will be helpful for utilizing nutrient appropriately and efficiently, and avoiding liver diseases during pregnancy.

Quasi-spherical silver nanoparticles for human prolactin detection by surface-enhanced Raman spectroscopy

Prolactin is a polypeptide hormone made of 199 amino acids; 50% of the amino acid chain forms helices, and the rest forms loops. This hormone is typically related to initiating and maintaining lactation, although it is also elevated in various pathological conditions. Serum prolactin levels of 2 to 18 ng ml-1 in men, up to 30 ng ml-1 in women, and 10 to 210 ng ml-1 in pregnant women are considered normal. Immunoassay techniques used for detection are susceptible to error in different clinical conditions. Surface-enhanced Raman spectroscopy (SERS) is a technique that allows for obtaining the protein spectrum in a simple, fast, and reproducible manner. Nonetheless, proper characterization of human prolactin's Raman/SERS spectrum at different concentrations has so far not been deeply discussed. This study aims to characterize the Raman spectrum of human prolactin at physiological concentrations using silver nanoparticles (AgNPs) as the SERS substrate. The Raman spectrum of prolactin at 20 ng ul-1 was acquired. Quasi-spherical AgNPs were obtained using chemical synthesis. For SERS characterization, decreasing dilutions of the protein were made by adding deionized water and then a 1 : 1 volume of the AgNPs colloid. For each mixture, the Raman spectrum was determined. The spectrum of prolactin by SERS was obtained with a concentration of up to 0.1 ng ml-1. It showed characteristic bands corresponding to the side chains of aromatic amino acids in the protein's primary structure and the alpha helices of the secondary structure of prolactin. In conclusion, using quasi-spherical silver nanoparticles as the SERS substrate, the Raman spectrum of human prolactin at physiological concentration was determined.

PRL-mediated STAT5B/ARRB2 pathway promotes the progression of prostate cancer through the activation of MAPK signaling

Previous study showed that higher expression of prolactin (PRL) was found in CRPC samples compared with hormone-naive prostate cancer (HNPC) and benign prostatic hyperplasia (BPH) samples. We further investigate the function of PRL in prostate cancer (PCa) and explored its downstream effects. We found heterogeneous expression of the PRLR in clinical prostate samples. The VCaP and 22Rv1 cells exhibited PRLR expression. Among the downstream proteins, STAT5B was the dominant subtype in clinical samples and cell lines. Human recombinant PRL stimulation of PCa cells with PRLR expression resulted in increased phosphorylation of STAT5B(pSTAT5B) and progression of PCa in vitro and in vivo, and STAT5B knockdown can suppress the malignant behavior of PCa. To understand the mechanism further, we performed Bioinformatic analysis, ChIP qPCR, and luciferase reporter gene assay. The results revealed that ARRB2 was the transcription target gene of STAT5B, and higher expression of ARRB2 was related to higher aggression and poorer prognosis of PCa. Additionally, Gene set enrichment analysis indicated that higher expression of ARRB2 was significantly enriched in the MAPK signaling pathway. Immunohistochemistry (IHC) demonstrated elevated pSTAT5B, ARRB2, and pERK1/2 expression levels in CRPC tissues compared to HNPC and BPH. Mechanically, ARRB2 enhanced the activation of the MAPK pathway by binding to ERK1/2, thereby promoting the phosphorylation of ERK1/2 (pERK1/2). In conclusion, our study demonstrated that PRL stimulation can promote the progression of PCa through STAT5B/ARRB2 pathway and activation of MAPK signaling, which can be suppressed by intervention targeting STAT5B. Blockade of the STAT5B can be a potential therapeutic target for PCa.

Biomarkers and Tourette syndrome: a systematic review and meta-analysis

Objective

This research aims to investigate whether peripheral biomarkers might differentiate individuals with Tourette syndrome (TS) from those without the condition.

Methods

A broad range of databases was searched through November 2022. This study employed a systematic literature review and subsequent meta-analysis of case-control studies that assessed the aberration of biomarkers of patients with TS and controls.

Results

A total of 81 studies were identified, out of which 60 met the eligibility criteria for inclusion in the meta-analysis. Following a meticulous screening procedure to determine the feasibility of incorporating case-control studies into the meta-analysis, 13 comparisons were statistically significant [CD3+ T cell, CD4+ T cell, CD4+ T cell to CD8+ T cell ratio, NK-cell, anti-streptolysin O antibodies, anti-DNase antibodies, glutamic acid (Glu), aspartic acid (Asp), ferritin (Fe), zinc (Zn), lead (Pb), vitamin D, and brain-derived neurotrophic factor (BDNF)]. Publication bias was found for anti-streptolysin O antibodies. Suggestive associations were evidenced for norsalsolinol (NSAL), neuron-specific enolase (NSE), and S100B.

Conclusion

In this study, we present empirical evidence substantiating the link between several peripheral biomarkers and the early diagnosis of TS. Larger and more standardized studies are necessary to replicate the observed results, elucidate the specificity of the biomarkers for TS, and evaluate their precision for use in clinical settings.

Current Insights in Prolactin Signaling and Ovulatory Function

Prolactin (PRL) is a pleiotropic hormone released from lactotrophic cells of the anterior pituitary gland that also originates from extrapituitary sources and plays an important role in regulating lactation in mammals, as well as other actions. Acting in an endocrine and paracrine/autocrine manner, PRL regulates the hypothalamic-pituitary-ovarian axis, thus influencing the maturation of ovarian follicles and ovulation. This review provides a detailed discussion of the current knowledge on the role of PRL in the context of ovulation and ovulatory disorders, particularly with regard to hyperprolactinemia, which is one of the most common causes of infertility in women. Much attention has been given to the PRL structure and the PRL receptor (PRLR), as well as the diverse functions of PRLR signaling under normal and pathological conditions. The hormonal regulation of the menstrual cycle in connection with folliculogenesis and ovulation, as well as the current classifications of ovulation disorders, are also described. Finally, the state of knowledge regarding the importance of TIDA (tuberoinfundibular dopamine), KNDγ (kisspeptin/neurokinin B/dynorphin), and GnRH (gonadotropin-releasing hormone) neurons in PRL- and kisspeptin (KP)-dependent regulation of the hypothalamic-pituitary-gonadal (HPG) axis in women is reviewed. Based on this review, a rationale for influencing PRL signaling pathways in therapeutic activities accompanying ovulation disorders is presented.

The relationship between plasma prolactin levels and clinical manifestations with neuromyelitis optica spectrum disorders

INTRODUCTION

Systemic prolactin levels have been found to increase in 19 patients diagnosed with neuromyelitis optica spectrum disorders (NMOSD). However, the relationship between plasma prolactin levels and clinical manifestations in NMOSD patients remains unclear.

METHODS

This cross-sectional study was conducted as part of a Registered Cohort Study of Inflammatory Demyelination Disease (NCT04386018). A total of 95 patients diagnosed with central nervous system demyelinating diseases and 43 healthy controls were recruited between May 2020 and February 2022 at the First Affiliated Hospital of Fujian Medical University. Plasma samples were collected from all participants and analyzed for prolactin levels using electrochemiluminescence immunoassay. The study aimed to investigate the correlation between plasma prolactin levels and clinical features in patients with central nervous system demyelinating diseases.

RESULTS

Plasma prolactin levels in NMOSD patients were significantly higher than those in multiple sclerosis/myelin oligodendrocyte glycoprotein antibody-associated diseases patients and controls (p<0.05, respectively), and were found to be correlated with disease activity, sensory abnormalities, thoracic spinal cord lesions, and MR lesion enhancement (p<0.05). A total of 16.28% of NMOSD patients exhibited macroprolactinemia. However, there was no correlation found between macroprolactin levels and disease activity (p>0.05).

CONCLUSION

Prolactin may play a role in the pro-inflammatory regulation mechanism of NMOSD.

Effects of long-term proton pump inhibitor use on sexual hormones and sexual and reproductive health in female patients

PURPOSE

Proton pump inhibitors (PPIs) are widely used to treat a range of gastrointestinal diseases around the world. Long-term use of PPIs has been associated to a variety of undesirable effects. Although short-term therapy has been shown to have little or no effect on endocrine hormone in women, however, its long-term safety has received little attention. We aimed at evaluating long-term use of PPIs and its effects on female reproductive hormones as well as related clinical consequences.

METHODS

A cross-sectional study was conducted in two outpatient gastroenterology clinics in the province of Khyber Pakhtunkhwa. This study included female patients who had been using PPIs on a regular basis for 3 months or more.

RESULTS

In total of 101 participants, patients with sexual complaints have significantly altered levels of prolactin (p = 0.05), estrogen (p < 0.001) and progesterone (p = 0.001) than patient without sexual complaints. The frequency of amenorrhea (p < 0.001), cyclic disturbances (p < 0.001), breast augmentation (p = 0.001) and painful breast (p = 0.004) were statistically significant in patients with raised serum prolactin values. Serum values of Sex hormone binding globulin SHBG (p < 0.001), estradiol (p = 0.002) and total testosterone (p < 0.001) were significantly altered between normal prolactin and hyperprolactinemic patients.

CONCLUSION

These findings suggest that long-term PPI use may cause endocrine hormone disturbances leading to sexual difficulties in women.

Effect of milking time on yield, composition, and antimicrobial components of milk in lactating goats

Various studies have attempted to improve the milk yield and composition in dairy animals. However, no study has examined the effects of milking at different times on milk yield and composition. Therefore, this study aimed to compare the yield, composition, and antimicrobial components of milk obtained from milking at different times in lactating goats. Eight goats were milked once daily at different times for three consecutive weeks (first week: 06:00 h; second week: 09:00 h; and third week: 12:00 h). The light ranged from 06:30 to 19:00 h. Milk and blood samples were collected once a day during milking time. Milking at 09:00 h resulted in a significantly higher milk yield than that obtained after milking at 06:00 and 12:00 h. Prolactin levels in plasma and the fat, Na+, β-defensin, and S100A7 (antimicrobial component) levels in milk were the lowest in the 09:00 h milking. These results indicate that milk yield, composition, and antimicrobial components can be affected by milking time, which may be related to the altered concentration of prolactin in the blood. These findings provide a rational basis for achieving maximal milk production with strong immunity by changing to a more effective milking time.

Classification of patients with COVID-19 by blood RNA endotype: a prospective cohort study

IMPORTANCE

In this study, whole-blood RNAs (prolactin and toll-like receptor 3) involved in the prognosis of patients with COVID-19 were identified. The RNA endotypes classified by these important RNAs highlight the possibility of stratifying the COVID-19 patient population and the need for targeted therapy based on these phenotypes.

Oxytocin Receptor-Expressing Neurons in the Medial Preoptic Area Are Essential for Lactation, whereas Those in the Lateral Septum Are Not Critical for Maternal Behavior

INTRODUCTION

In nurturing systems, the oxytocin (Oxt)-oxytocin receptor (Oxtr) system is important for parturition, and essential for lactation and parental behavior. Among the nerve nuclei that express Oxtr, the lateral septal nucleus (LS) and medial preoptic area (MPOA) are representative regions that control maternal behavior.

METHODS

We investigated the role of Oxtr- and Oxtr-expressing neurons, located in the LS and MPOA, in regulating maternal behavior by regulating Oxtr expression in a region-specific manner using recombinant mice and adeno-associated viruses. We quantified the prolactin (Prl) concentrations in the pituitary gland and plasma when Oxtr expression in the MPOA was reduced.

RESULTS

The endogenous Oxtr gene in the neurons of the LS did not seem to play an essential role in maternal behavior. Conversely, decreased Oxtr expression in the MPOA increased the frequency of pups being left outside the nest and reduced their survival rate. Deletion of Oxtr in MPOA neurons prevented elevation of Prl levels in plasma and pituitary at postpartum day 2.

DISCUSSION/CONCLUSION

Oxtr-expressing neurons in the MPOA are involved in the postpartum production of Prl. We confirmed the essential functions of Oxtr-expressing neurons and the Oxtr gene itself in the MPOA for the sustainability of maternal behavior, which involved Oxtr-dependent induction of Prl.

Revealing Sexual Dimorphism in Prolactin Regulation From Early Postnatal Development to Adulthood in Murine Models

Serum prolactin (PRL) levels exhibit a gradual rise both in male and female rats from birth to adulthood, with females consistently displaying higher levels compared to age-matched males. This pattern has traditionally been attributed to the development and maturation of endocrine and neuroendocrine networks responsible for regulating PRL synthesis and secretion. However, the effect of dopamine (DA), which acts as an inhibitory factor on lactotroph function, also increases from birth to puberty, particularly in females. Nonetheless, the secretion of PRL remains higher in females compared to males. On the other hand, the observed sex differences in serum PRL levels during early postnatal development cannot be attributed to the influence of estradiol (E2). While serum E2 levels gradually increase after birth, only after 45 days of life do the disparities in E2 levels between females and males become evident. These observations collectively suggest that neither the maturation of hypothalamic DA regulation nor the rise in E2 levels can account for the progressive and sustained elevation in serum PRL levels and the observed sexual dimorphism during postnatal development. This review highlights the importance of recent discoveries in animal models that shed light on inhibitory mechanisms in the control of PRL secretion within the pituitary gland itself, that is intrapituitary mechanisms, with a specific emphasis on the role of transforming growth factor β1 and activins in PRL secretion.

Identifying Sex-Specific Serum Patterns of Alzheimer's Mice through Deep TMT Profiling and a Concentration-Dependent Concatenation Strategy

Alzheimer's disease (AD) is the most prevalent form of dementia, disproportionately affecting women in disease prevalence and progression. Comprehensive analysis of the serum proteome in a common AD mouse model offers potential in identifying possible AD pathology- and gender-associated biomarkers. Here, we introduce a multiplexed, nondepleted mouse serum proteome profiling via tandem mass-tag (TMTpro) labeling. The labeled sample was separated into 475 fractions using basic reversed-phase liquid chromatography (RPLC), which were categorized into low-, medium-, and high-concentration fractions for concatenation. This concentration-dependent concatenation strategy resulted in 128 fractions for acidic RPLC-tandem mass spectrometry (MS/MS) analysis, collecting ∼5 million MS/MS scans and identifying 3972 unique proteins (3413 genes) that cover a dynamic range spanning at least 6 orders of magnitude. The differential expression analysis between wild type and the commonly used AD model (5xFAD) mice exhibited minimal significant protein alterations. However, we detected 60 statistically significant (FDR < 0.05), sex-specific proteins, including complement components, serpins, carboxylesterases, major urinary proteins, cysteine-rich secretory protein 1, pregnancy-associated murine protein 1, prolactin, amyloid P component, epidermal growth factor receptor, fibrinogen-like protein 1, and hepcidin. The results suggest that our platform possesses the sensitivity and reproducibility required to detect sex-specific differentially expressed proteins in mouse serum samples.

Low prolactin level identifies hypoactive sexual desire disorder women with a reduced inhibition profile

PURPOSE

Data on the role of prolactin (PRL) in the physiologic range in the female sexual response are scanty. We aimed at investigating the association between PRL and sexual function as assessed by the Female Sexual Function Index (FSFI). We explored the presence of a cut-off level of PRL able to identify Hypoactive Sexual Desire Disorder (HSDD).

METHODS

277 pre- and post-menopausal women consulting for Female Sexual Dysfunction (FSD) and sexually active were enrolled in an observational, retrospective study. 42 women were used as no-FSD controls. A clinical, biochemical and psychosexual evaluation was performed. The main outcome measures were: FSFI, Female Sexual Distress Scale-Revised, Middlesex Hospital Questionnaire and Sexual excitation/sexual inhibition scale (SIS/SES).

RESULTS

Normo-PRL FSD women (n = 264) showed lower FSFI Desire score than controls (n = 42), and higher than hyper-PRL FSD women (n = 13). These differences emerged both in pre-menopausal and post-menopausal subjects. In the normo-PRL FSD group, those with PRL in the higher quintile reported higher FSFI Desire scores than those with PRL in the lowest quintile. Women with HSDD presented a lower PRL level than those without (p = 0.032). A ROC curve analysis for PRL showed an accuracy of 0.610 ± 0.044 (p = 0.014) in predicting HSDD. With a threshold of < 9.83 μg/L, sensitivity and specificity for HSDD were 63% and 56%, respectively. Subjects with PRL < 9.83 μg/L also reported lower sexual inhibition (p = 0.006) and lower cortisol levels (p = 0.003) than those with PRL >  = 9.83 μg/L.

CONCLUSIONS

Hyper-PRL is associated with low desire; however, among normo-PRL FSD women, those with the lowest levels demonstrated a poorer desire than those with the highest levels. PRL < 9.83 μg/L predicted HSDD and a lower sexual inhibitory trait.

The association between serum prolactin levels and live birth rates in non-PCOS patients: A retrospective cohort study

BACKGROUND AND OBJECTIVES

This paper aimed to analyze the relationship between baseline prolactin (PRL) levels and live birth rates (LBRs) in patients undergoing embryo transfer who did not have polycystic ovarian syndrome (PCOS) using a retrospective design. Patient(s): A total of 20,877 patients who had undergone IVF/intracytoplasmic sperm injection (ICSI) between December 2014 and December 2019.

MATERIALS AND METHODS

We examined the association between PRL concentrations and LBRs using multivariate regression analysis. In addition, a model for nonlinear relationships based on a two-part linear regression was developed.

RESULTS

Following adjustment for confounding factors, multivariate regression analysis confirmed a statistically significant correlation between serum PRL and LBR. Particularly, when blood PRL content was less than 14.8 ng/mL, there exists a positive relation between serum PRL and LBRs. In contrast, once PRL concentrations surpassed the inflection point at 14.8 ng/mL, a meaningful relationship could no longer be inferred between serum PRL and LBR.

CONCLUSIONS

Basal serum PRL levels were segmentally connected with LBRs.

Temperature modulates the osmosensitivity of tilapia prolactin cells

In euryhaline fish, prolactin (Prl) plays an essential role in freshwater (FW) acclimation. In the euryhaline and eurythermal Mozambique tilapia, Oreochromis mossambicus, Prl cells are model osmoreceptors, recently described to be thermosensitive. To investigate the effects of temperature on osmoreception, we incubated Prl cells of tilapia acclimated to either FW or seawater (SW) in different combinations of temperatures (20, 26 and 32 °C) and osmolalities (280, 330 and 420 mOsm/kg) for 6 h. Release of both Prl isoforms, Prl188 and Prl177, increased in hyposmotic media and were further augmented with a rise in temperature. Hyposmotically-induced release of Prl188, but not Prl177, was suppressed at 20 °C. In SW fish, mRNA expression of prl188 increased with rising temperatures at lower osmolalities, while and prl177 decreased at 32 °C and higher osmolalities. In Prl cells of SW-acclimated tilapia incubated in hyperosmotic media, the expressions of Prl receptors, prlr1 and prlr2, and the stretch-activated Ca2+ channel, trpv4,decreased at 32 °C, suggesting the presence of a cellular mechanism to compensate for elevated Prl release. Transcription factors, pou1f1, pou2f1b, creb3l1, cebpb, stat3, stat1a and nfat1c, known to regulate prl188 and prl177, were also downregulated at 32 °C. Our findings provide evidence that osmoreception is modulated by temperature, and that both thermal and osmotic responses vary with acclimation salinity.