Progesterone receptor isoforms expression pattern in the rat brain during the estrous cycle

White matter volume and treatment with selective progesterone receptor modulator in patients with premenstrual dysphoric disorder

Premenstrual dysphoric disorder (PMDD) is a mood disorder for which selective progesterone receptor modulator (SPRM) treatment has been demonstrated to be beneficial. The neural signatures of this treatment have been so far identified as greater fronto-cingulate reactivity during aggressive response to provocation, but no changes in terms of gray matter structure. White matter has recently been found to differ between patients with PMDD and healthy controls. The present study thus sought to investigate the relationship between white matter volume and SPRM treatment in patients with PMDD. A pharmaco-neuroimaging study was conducted on patients with PMDD participating in a randomized controlled trial. Participants underwent magnetic resonance imaging before and after treatment randomization to ulipristal acetate (an SPRM), or placebo, for three months. The interaction effect of treatment by time on white matter volume (WMV) was assessed. Voxel based morphometry analyses were performed on both a whole brain exploratory level and on regions of interest. No treatment effect was observed on WMV in any region, including the anterior thalamic radiations, cingulum, forceps minor, fornix, inferior fronto-occipital fasciculus, superior cerebellar peduncle, superior longitudinal fasciculus, and uncinate fasciculus. This is the first finding to indicate that no white matter volume alterations follow three-month progesterone antagonism, suggesting that white matter volume does not participate in symptom relief upon SPRM treatment for PMDD.

Progesterone Receptor Activation Regulates Sensory Sensitivity and Migraine Susceptibility

Women develop chronic pain during their reproductive years more often than men, and estrogen and progesterone regulate this susceptibility. We tested whether brain progesterone receptor (PR) signaling regulates pain susceptibility. During the estrous cycle, animals were more sensitive to mechanical stimulus during the estrus stage than in the diestrus stage, suggesting a role for reproductive hormones, estrogen, and progesterone. Progesterone treatment of ovariectomized and estrogen-primed mice caused a delayed reduction in the mechanical threshold. Segesterone, a specific agonist of PRs replicated this effect, whereas, the segesterone-induced reduction in mechanical threshold was blocked in the mice lacking PRs in the nervous system. Segesterone treatment also did not alter mechanical threshold in adult male and juvenile female mice. PR activation increased the cold sensitivity but did not affect the heat and light sensitivity. We evaluated whether PR activation altered experimental migraine. Segesterone and nitroglycerin when administered sequentially, reduced the pain threshold but not when given separately. PRs were expressed in several components of the migraine ascending pain pathway, and their deletion blocked the painful effects of nitroglycerin. PR activation also increased the number of active neurons in the components of the migraine ascending pain pathway. These studies have uncovered a pain-regulating function of PRs. Targeting PRs may provide a novel therapeutic avenue to treat chronic pain and migraine in women. PERSPECTIVE: This article provides evidence for the role of progesterone receptors in regulating pain sensitivity and migraine susceptibility in females. Progesterone receptors may be a therapeutic target to treat chronic pain conditions more prevalent in women than men.

Progesterone receptor activation regulates sensory sensitivity

Women develop chronic pain during their reproductive years more often than men, and estrogen and progesterone regulate this susceptibility. We tested whether brain progesterone receptor (PR) signaling regulates pain susceptibility. During the estrous cycle, animals were more sensitive to pain during the estrus stage than in the diestrus stage, suggesting a role for reproductive hormones, estrogen, and progesterone. We measured the pain threshold daily for four days in ovariectomized, estrogen-primed animals treated with progesterone. The pain threshold was lower 2 days later and stayed that way for the duration of the testing. A specific progesterone-receptor (PR) agonist, segesterone, promoted pain, and mice lacking PR in the brain (PRKO) did not experience lowered pain threshold when treated with progesterone or segesterone. PR activation increased the cold sensitivity but did not affect the heat sensitivity and had a small effect on light sensitivity. Finally, we evaluated whether PR activation altered experimental migraine. Segesterone and nitroglycerin (NTG) when administered sequentially, reduced pain threshold but not separately. These studies have uncovered a pain-regulating function of PRs. Targeting PRs may provide a novel therapeutic avenue to treat chronic pain in women.

Limbic progesterone receptors regulate spatial memory

Progesterone and its receptors (PRs) participate in mating and reproduction, but their role in spatial declarative memory is not understood. Male mice expressed PRs, predominately in excitatory neurons, in brain regions that support spatial memory, such as the hippocampus and entorhinal cortex (EC). Furthermore, segesterone, a specific PR agonist, activates neurons in both the EC and hippocampus. We assessed the contribution of PRs in promoting spatial and non-spatial cognitive learning in male mice by examining the performance of mice lacking this receptor (PRKO), in novel object recognition, object placement, Y-maze alternation, and Morris-Water Maze (MWM) tasks. In the recognition test, the PRKO mice preferred the familiar object over the novel object. A similar preference for the familiar object was also seen following the EC-specific deletion of PRs. PRKO mice were also unable to recognize the change in object position. We confirmed deficits in spatial memory of PRKO mice by testing them on the Y-maze forced alternation and MWM tasks; PR deletion affected animal's performance in both these tasks. In contrast to spatial tasks, PR removal did not alter the response to fear conditioning. These studies provide novel insights into the role of PRs in facilitating spatial, declarative memory in males, which may help with finding reproductive partners.

Menstrual Cycle-Related Changes in Women with Schizophrenia: A Resting-State fMRI Study

INTRODUCTION

Different influences of ovarian hormones in schizophrenia (SCZ) have been reported, but no study to date has assessed their effects on the brain dynamics at rest. The present study aimed to examine the hormonal and clinical changes related to the menstrual cycle and alterations in the resting-state functional connectivity (RS-FC) depending on cycle phase and/or hormonal fluctuations in SCZ.

METHOD

This study was conducted based on both between- and within-subject experimental designs, including 13 clinically stable female patients with SCZ (32 ± 7.7 years) and 13 healthy women (30 ± 7.3 years). RS-functional magnetic resonance imaging (fMRI) scanning, as well as hormonal and clinical assessments, was applied to each participant twice during two cycle phases: early follicular and mid-luteal.

RESULTS

A difference in mid-luteal progesterone levels was found between groups, with a large effect size (Cohen's d) of 0.8 (p < 0.05). Also, the estradiol levels negatively correlated with the negative symptom severity of the patients during their mid-luteal phase. In the patients, estrogen positively correlated with the auditory network connectivity in the left amygdala during the early follicular phase. In the controls, progesterone had positive correlations with the connectivity of the posterior default mode and the left frontoparietal networks in the bilateral precuneus during the early follicular phase and had a negative correlation with the executive control network connectivity in the mid-luteal phase.

CONCLUSION

The present study showed hormonal differences between groups and suggested that the levels of cycle-dependent hormones might be associated with the changes in clinical symptom severity and the RS-FC in the groups. Our RS-fMRI findings warrant further investigation.

Mid-luteal phase progesterone effects on vigilance tasks are modulated by women's chronotype

BACKGROUND

In this study we assessed the effects of progesterone on vigilance tasks that require sustained attention. In contrast to previous research, we differentiated two components of vigilance: the exogenous component, involved in monotonous and tedious tasks such as the Psychomotor Vigilance Task (PVT); and the endogenous component, involved in tasks that require cognitive control such as the Sustained Attention to Response Task (SART).

METHODS

A sample of 32 female participants differing in extreme chronotypes were tested at their optimal and non-optimal time-of-day, as secretion of sex hormones follows biological rhythms. Ovulation tests that measure the presence of luteinizing hormone (LH) in urine were used to minimize methodological errors. Women of Morning-type or Evening-type chronotypes completed 4 experimental sessions of the two attentional tasks when they were in their follicular (low progesterone level) and mid-luteal (high progesterone level) phases, both in the morning (8:00 AM) and the evening (8:30 PM).

RESULTS

Compared with the follicular phase, performance in the mid-luteal phase improved in the Morning-type participants and worsened in the Evening-type participants. This pattern of results was observed only when testing occurred at the optimal time-of-day and with both the PVT and the SART tasks.

CONCLUSION

These results suggest that the simultaneous presence of both progesterone and cortisol at 8:00 AM may explain the benefit observed in Morning-type females. In contrast, the low concentration of cortisol along with the reduced benefit of mid-luteal phase progesterone in the evening may account for the worsening in performance observed in Evening-type females.

The influence of hormonal contraception on depression and female sexuality: a narrative review of the literature

OBJECTIVE

Over the past decades, an increasing number of women have been using hormonal contraception. The potential role of sex hormones in regulating vegetative, psychophysiological, and cognitive functions has been highlighted in several studies, and there is a need to further understand the impact of hormonal contraception on women's quality of life, especially as regards psychological health and sexuality.

METHODS

We conducted a narrative review aimed at clarifying the mechanisms involved in the interaction between sex hormones and the brain, also focusing on the association between hormonal contraception and mood and sexual function.

RESULTS

Our findings clarified that hormonal contraception may be associated with depressive symptoms, especially among adolescents, and with sexual dysfunction. However, the evidence included in this review was conflicting and did not support the hypothesis that hormonal contraception directly causes depressive symptoms, major depressive disorder, or sexual dysfunction.

CONCLUSIONS

The optimal hormonal contraception should be identified in the context of shared decision making, considering the preferences and needs of each woman, as well as her physical and psychosexual conditions.

Subgenual cingulate resting regional cerebral blood flow in premenstrual dysphoric disorder: differential regulation by ovarian steroids and preliminary evidence for an association with expression of ESC/E(Z) complex genes

Substantial evidence suggests that circulating ovarian steroids modulate behavior differently in women with PMDD than in those without this condition. However, hormonal state-related abnormalities of neural functioning in PMDD remain to be better characterized. In addition, while altered neural function in PMDD likely co-exists with alterations in intrinsic cellular function, such a relationship has not been explored. Here, we investigated the effects of ovarian steroids on basal, resting regional cerebral blood flow (rCBF) in PMDD, and, in an exploratory analysis, we tested whether the rCBF findings were linked to the expression of ESC/E(Z) genes, which form an essential ovarian steroid-regulated gene-silencing complex. Resting rCBF was measured with oxygen-15 water PET (189 PET sessions in 43 healthy women and 20 women with PMDD) during three self-as-own-control conditions: GnRH agonist (Lupron)-induced ovarian suppression, estradiol add-back, and progesterone add-back. ESC/E(Z) gene expression data were obtained from RNA-sequencing of lymphoblastoid cell lines performed in a previous study and were examined in relation to hormone-induced changes in rCBF. In the rCBF PET data, there was a significant diagnosis-by-hormone interaction in the subgenual cingulate (P_FDR = 0.05), an important neuroanatomical hub for regulating affective state. Whereas control women showed no hormonally-related changes in resting rCBF, those with PMDD showed decreased resting rCBF during both estradiol (P = 0.02) and progesterone (P = 0.0002) add-back conditions. In addition, in PMDD, ESC/E(Z) gene expression correlated with the change in resting rCBF between Lupron-alone and progesterone conditions (Pearson r = -0.807, P = 0.016). This work offers a formulation of PMDD that integrates behavioral, neural circuit, and cellular mechanisms, and may provide new targets for future therapeutic interventions.

Ulipristal Acetate for Treatment of Premenstrual Dysphoric Disorder: A Proof-of-Concept Randomized Controlled Trial

OBJECTIVE

Premenstrual dysphoric disorder (PMDD) is a common mood disorder, characterized by distressing affective, behavioral, and somatic symptoms in the late luteal phase of the menstrual cycle. The authors investigated continuous treatment with a selective progesterone receptor modulator, ulipristal acetate (UPA), as a potential treatment for PMDD.

METHODS

The authors conducted an investigator-initiated, multicenter, double-blind, randomized, parallel-group clinical trial in which women with PMDD (N=95) were treated with either 5 mg/day of UPA or placebo during three 28-day treatment cycles. The primary outcome was the change in premenstrual total score on the Daily Record of Severity of Problems (DRSP) from baseline to end of treatment. DRSP scores were captured by daily ratings using a smartphone application and were analyzed with linear mixed models for repeated measures.

RESULTS

The mean improvement in DRSP score after 3 months was 41% (SD=18) in the UPA group, compared with 22% (SD=27) in the placebo group (mean difference -18%; 95% CI=-29, -8). Treatment effects were also noted for the DRSP depressive symptom subscale (42% [SD=22] compared with 22% [SD=32]) and the DRSP anger/irritability subscale (47% [SD=21] compared with 23% [SD=35]), but not for the DRSP physical symptom subscale. Remission based on DRSP score was attained by 20 women in the UPA group (50.0%) and eight women in the placebo group (21.1%) (a statistically significant difference).

CONCLUSIONS

If these results are replicated, UPA could be a useful treatment for PMDD, particularly for the psychological symptoms associated with the disorder.

Progesterone modulates neuronal excitability bidirectionally

Progesterone acts on neurons directly by activating its receptor and through metabolic conversion to neurosteroids. There is emerging evidence that progesterone exerts excitatory effects by activating its cognate receptors (progesterone receptors, PRs) through enhanced expression of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs). Progesterone metabolite 5α,3α-tetrahydro-progesterone (allopregnanolone, THP) mediates its anxiolytic and sedative actions through the potentiation of synaptic and extrasynaptic γ-aminobutyric acid type-A receptors (GABAARs). Here, we review progesterone's neuromodulatory actions exerted through PRs and THP and their opposing role in regulating seizures, catamenial epilepsy, and seizure exacerbation associated with progesterone withdrawal.

Sex differences and effects of the estrous stage on hippocampal-prefrontal theta communications

Effective communication between the mammalian hippocampus and neocortex is essential to certain cognitive-behavioral tasks critical to survival in a changing environment. Notably, functional synchrony between local field potentials (LFPs) of the ventral hippocampus (vHPC) and the medial prefrontal cortex (mPFC) within the theta band (4-12 Hz) underlies innate avoidance behavior during approach-avoidance conflict tasks in male rodents. However, the physiology of vHPC-mPFC communications in females remains unestablished. Furthermore, little is known about how mPFC subdivisions functionally interact in the theta band with hippocampal subdivisions in both sexes in the absence of task demand. Given the established roles of biological sex and gonadal hormone status on innate avoidance behaviors and neuronal excitability, here, we characterize the effects of biological sex and female estrous stage on hippocampal-prefrontal (HPC-mPFC) theta signaling in freely moving female and male rats. LFPs from vHPC, dorsal hippocampus (dHPC), mPFC-prelimbic (PrL), and mPFC-infralimbic (IL) were simultaneously recorded during spontaneous exploration of a familiar arena. Data suggest that theta phase and power in vHPC preferentially synchronize with PrL; conversely, dHPC and IL preferentially synchronize. Males displayed greater vHPC-PrL theta synchrony than females, despite similar regional frequency band power and inter-regional coherence. Additionally, several significant estrous-linked changes in HPC-mPFC theta dynamics were observed. These findings support the hypothesis that HPC-mPFC theta signaling is sensitive to both biological sex and female estrous stage. These findings establish novel research avenues concerning sex as a biological variable and effects of gonadal hormone status on HPC-mPFC network activity as it pertains to threat evaluation biomarkers.

Validation of housekeeping genes as an internal control for gene expression studies in the brain of ovariectomized rats treated with tibolone

INTRODUCTION

In the central nervous system (CNS), tibolone actions are mainly modulated through its interaction with estrogen, progesterone, and androgen receptors. Several studies have reported the expression of sex hormone receptors in the CNS using the RT-PCR endpoint technique. Although some studies have validated reference genes for rat brain tissue in different experimental conditions, no suitable reference genes have been reported in brain tissue from ovariectomized rats treated with tibolone.

OBJECTIVE

The aim of this investigation was to evaluate the expression of different housekeeping genes in several brain regions in ovariectomized rats treated with tibolone to determine the stability of a single housekeeping gene and a combination of two housekeeping genes under these experimental conditions.

METHODS

Adult female Sprague-Dawley rats were ovariectomized. Seven days after the surgery, animals were administered a single dose of vehicle (water) or tibolone (10 mg/kg/weight). Twenty-four hours later, animals were sacrificed, and the hypothalamus, hippocampus, prefrontal cortex, and cerebellum were dissected. Total RNA was extracted from these tissues, and RT-qPCR was performed to amplify Ppia, Hprt1, Rpl32, and Gapdh housekeeping genes.

RESULTS

Ppia was the most stable gene in the hypothalamus and cerebellum, whereas Hprt1 was the most stable gene in the prefrontal cortex. For the analysis of the combination of two genes, the most stable combination was Ppia and Hrpt1 for the prefrontal cortex and Ppia and Rpl32 for the cerebellum.

CONCLUSION

In ovariectomized rats treated with tibolone, Hprt1 and Ppia genes showed high stability as housekeeping genes for qPCR analysis.

Progesterone - Friend or foe?

Estradiol is the "prototypic" sex hormone of women. Yet, women have another sex hormone, which is often disregarded: Progesterone. The goal of this article is to provide a comprehensive review on progesterone, and its metabolite allopregnanolone, emphasizing three key areas: biological properties, main functions, and effects on mood in women. Recent years of intensive research on progesterone and allopregnanolone have paved the way for new treatment of postpartum depression. However, treatment for premenstrual syndrome and premenstrual dysphoric disorder as well as contraception that women can use without risking mental health problems are still needed. As far as progesterone is concerned, we might be dealing with a two-edged sword: while its metabolite allopregnanolone has been proven useful for treatment of PPD, it may trigger negative symptoms in women with PMS and PMDD. Overall, our current knowledge on the beneficial and harmful effects of progesterone is limited and further research is imperative.

The Role of Sex and Sex Hormones in Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are a wide class of disorders of the central nervous system (CNS) with unknown etiology. Several factors were hypothesized to be involved in the pathogenesis of these diseases, including genetic and environmental factors. Many of these diseases show a sex prevalence and sex steroids were shown to have a role in the progression of specific forms of neurodegeneration. Estrogens were reported to be neuroprotective through their action on cognate nuclear and membrane receptors, while adverse effects of male hormones have been described on neuronal cells, although some data also suggest neuroprotective activities. The response of the CNS to sex steroids is a complex and integrated process that depends on (i) the type and amount of the cognate steroid receptor and (ii) the target cell type-either neurons, glia, or microglia. Moreover, the levels of sex steroids in the CNS fluctuate due to gonadal activities and to local metabolism and synthesis. Importantly, biochemical processes involved in the pathogenesis of NDs are increasingly being recognized as different between the two sexes and as influenced by sex steroids. The aim of this review is to present current state-of-the-art understanding on the potential role of sex steroids and their receptors on the onset and progression of major neurodegenerative disorders, namely, Alzheimer's disease, Parkinson's diseases, amyotrophic lateral sclerosis, and the peculiar motoneuron disease spinal and bulbar muscular atrophy, in which hormonal therapy is potentially useful as disease modifier.

Brain intracrinology of allopregnanolone during pregnancy and hormonal contraception

Allopregnanolone (ALLO) has a crucial role in brain development and remodeling. Reproductive transitions associated with endocrine changes affect synthesis and activity of ALLO with behavioral/affective consequences. Pregnancy is characterized by an increased synthesis of progesterone/ALLO by the placenta, maternal and fetal brains. This suggests the critical role of these steroids in maternal brain adaptation during pregnancy and the development of the fetal brain. ALLO is brain protective during complications of pregnancy, such as preterm delivery or intrauterine growth restriction (IUGR), reducing the impact of hypoxia, and excitotoxic brain damage. Negative behavioral consequences of altered progesterone/ALLO maternal brain adaptation have been also hypothesized in the post-partum and targeting ALLO is a promising treatment. Hormonal contraception may alter ALLO action, although the effects are mostly related to a specific class of progestins. Understanding the interactions between ALLO and the endocrine environment is crucial for more effective and tailored hormonal treatments.

Sex-related responses after traumatic brain injury: Considerations for preclinical modeling

Traumatic brain injury (TBI) has historically been viewed as a primarily male problem, since men are more likely to experience a TBI because of more frequent participation in activities that increase risk of head injuries. This male bias is also reflected in preclinical research where mostly male animals have been used in basic and translational science. However, with an aging population in which TBI incidence is increasingly sex-independent due to falls, and increasing female participation in high-risk activities, the attention to potential sex differences in TBI responses and outcomes will become more important. These considerations are especially relevant in designing preclinical animal models of TBI that are more predictive of human responses and outcomes. This review characterizes sex differences following TBI with a special emphasis on the contribution of the female sex hormones, progesterone and estrogen, to these differences. This information is potentially important in developing and customizing TBI treatments.

A novel therapeutic approach for treatment of catamenial epilepsy

Many women with epilepsy experience perimenstrual seizure exacerbation, referred to as catamenial epilepsy. There is no effective treatment for this condition, proposed to result from withdrawal of neurosteroid-mediated effects of progesterone. A double-blind, multicenter, phase III, clinical trial of catamenial epilepsy has failed to find a beneficial effect of progesterone. The neurosteroid-mediated effects of progesterone have been extensively studied in relation to catamenial epilepsy; however, the effects mediated by progesterone receptor activation have been overlooked. We determined whether progesterone increased excitatory transmission in the hippocampus via activation of progesterone receptors, which may play a role in regulating catamenial seizure exacerbation. In a double-blind study using a rat model of catamenial epilepsy, we found that treatment with RU-486, which blocks progesterone and glucocorticoid receptors, significantly attenuated neurosteroid withdrawal-induced seizures. Furthermore, progesterone treatment as well as endogenous rise in progesterone during estrous cycle increased the expression of GluA1 and GluA2 subunits of AMPA receptors in the hippocampi, and enhanced the AMPA receptor-mediated synaptic transmission of CA1 pyramidal neurons. The progesterone-induced plasticity of AMPA receptors was blocked by RU-486 treatment and progesterone also failed to increase AMPA receptor expression in progesterone receptor knockout mice. These studies demonstrate that progesterone receptor activation regulates AMPA receptor expression and may play a role in catamenial seizure exacerbation.

Effects of Estrogen Therapy on the Serotonergic System in an Animal Model of Perimenopause Induced by 4-Vinylcyclohexen Diepoxide (VCD)

Chronic exposure to 4-vinylcycloxene diepoxide (VCD) in rodents accelerates the natural process of ovarian follicular atresia modelling perimenopause in women. We investigated why estrogen therapy is beneficial for symptomatic women despite normal or high estrogen levels during perimenopause. Female rats (28 d) were injected daily with VCD or oil for 15 d; 55-65 d after the first injection, pellets of 17β-estradiol or oil were inserted subcutaneously. Around 20 d after, the rats were euthanized (control rats on diestrus and estradiol-treated 21 d after pellets implants). Blood was collected for hormone measurement, the brains were removed and dorsal raphe nucleus (DRN), hippocampus (HPC), and amygdala (AMY) punched out for serotonin (5-HT), estrogen receptor β (ERβ), and progesterone receptor (PR) mRNA level measurements. Another set of rats was perfused for tryptophan hydroxylase (TPH) immunohistochemistry in the DRN. Periestropausal rats exhibited estradiol levels similar to controls and a lower progesterone level, which was restored by estradiol. The DRN of periestropausal rats exhibited lower expression of PR and ERβ mRNA and a lower number of TPH cells. Estradiol restored the ERβ mRNA levels and number of serotonergic cells in the DRN caudal subregion. The 5-HT levels were lower in the AMY and HPC in peristropausal rats, and estradiol treatment increased the 5-HT levels in the HPC and also increased ERβ expression in this area. In conclusion, estradiol may improve perimenopause symptoms by increasing progesterone and boosting serotonin pathway from the caudal DRN to the dorsal HPC potentially through an increment in ERβ expression in the DRN.

The stability of the transcriptome during the estrous cycle in four regions of the mouse brain

We analyzed the transcriptome of the C57BL/6J mouse hypothalamus, hippocampus, neocortex, and cerebellum to determine estrous cycle-specific changes in these four brain regions. We found almost 16,000 genes are present in one or more of the brain areas but only 210 genes, ∼1.3%, are significantly changed as a result of the estrous cycle. The hippocampus has the largest number of differentially expressed genes (DEGs) (82), followed by the neocortex (76), hypothalamus (63), and cerebellum (26). Most of these DEGs (186/210) are differentially expressed in only one of the four brain regions. A key finding is the unique expression pattern of growth hormone (Gh) and prolactin (Prl). Gh and Prl are the only DEGs to be expressed during only one stage of the estrous cycle (metestrus). To gain insight into the function of the DEGs, we examined gene ontology and phenotype enrichment and found significant enrichment for genes associated with myelination, hormone stimulus, and abnormal hormone levels. Additionally, 61 of the 210 DEGs are known to change in response to estrogen in the brain. 50 of the 210 genes differentially expressed as a result of the estrous cycle are related to myelin and oligodendrocytes and 12 of the 63 DEGs in the hypothalamus are oligodendrocyte- and myelin-specific genes. This transcriptomic analysis reveals that gene expression in the female mouse brain is remarkably stable during the estrous cycle and demonstrates that the genes that do fluctuate are functionally related.

The fetal brain: role of progesterone and allopregnanolone

Progesterone and allopregnanolone have crucial and different roles in brain development, function and recovery after injury. Pregnancy is characterized by an increased synthesis of progesterone and its neuro-active metabolites by the placenta, maternal and fetal brain. This supports the critical role of these steroids in maternal brain adaptation during pregnancy and development of the fetal brain. Moreover, allopregnanolone may play a brain-protective role during complications of pregnancy, complications of pregnancy, such as preterm delivery or intrauterine growth restriction (IUGR), by reducing the impact of hypoxia and excitotoxic brain damage or impairment myelination. Behavioral consequences of altered progesterone/allopregnanolone fetal brain programming have also been hypothesized, although further evidence is needed. New potential applications of allopregnanolone as a treatment strategy have also been proposed, addressing unmet clinical needs in perinatal care.

Progesterone: The neglected hormone in schizophrenia? A focus on progesterone-dopamine interactions

Sex differences appear to be an important factor in schizophrenia. Women with schizophrenia tend to exhibit less disease impairment than men, typically presenting with a later age-at-onset, lower overall incidence and less severe symptoms. These observations underpin the estrogen hypothesis of schizophrenia, which postulates a protective role of estrogen against the development and severity of the disorder. While there has been significant attention placed on the impact of estrogens in schizophrenia, less consideration has been afforded to the role of progesterone, the other main female gonadal hormone. This narrative review discusses the role of progesterone as a neuroactive steroid and how it may be dysregulated in schizophrenia. Preclinical and molecular studies relevant to schizophrenia are discussed with a particular focus on the interactions between progesterone and the dopaminergic system. Notably, existing data on progesterone in relation to schizophrenia is inconsistent, with some studies suggesting a neuroprotective role for the hormone (e.g. animal models of cognitive dysfunction and positive symptoms), while other studies posit a disruptive impact of the hormone (e.g. negative correlations with symptom modulation in patients). This review aims to thoroughly address these discrepancies, concluding that altogether the data suggest that progesterone is a key modulator of central systems implicated in schizophrenia. On this basis, we argue that a more inclusive, considered effort of future studies to understand the intricacies of the interactions between progesterone and estrogen. Such an effort may enhance our understanding of the roles of sex hormones in schizophrenia, thus leading to avenues for novel therapeutic approaches.

Estradiol differentially induces progesterone receptor isoforms expression through alternative promoter regulation in a mouse embryonic hypothalamic cell line

Progesterone receptor (PR) presents two main isoforms (PR-A and PR-B) that are regulated by two specific promoters and transcribed from alternative transcriptional start sites. The molecular regulation of PR isoforms expression in embryonic hypothalamus is poorly understood. The aim of the present study was to assess estradiol regulation of PR isoforms in a mouse embryonic hypothalamic cell line (mHypoE-N42), as well as the transcriptional status of their promoters. MHypoE-N42 cells were treated with estradiol for 6 and 12 h. Then, Western blot, real-time quantitative reverse transcription polymerase chain reaction, and chromatin and DNA immunoprecipitation experiments were performed. PR-B expression was transiently induced by estradiol after 6 h of treatment in an estrogen receptor alpha (ERα)-dependent manner. This induction was associated with an increase in ERα phosphorylation (serine 118) and its recruitment to PR-B promoter. After 12 h of estradiol exposure, a downregulation of this PR isoform was associated with a decrease of specific protein 1, histone 3 lysine 4 trimethylation, and RNA polymerase II occupancy on PR-B promoter, without changes in DNA methylation and hydroxymethylation. In contrast, there were no estradiol-dependent changes in PR-A expression that could be related with the epigenetic marks or the transcription factors evaluated. We demonstrate that PR isoforms are differentially regulated by estradiol and that the induction of PR-B expression is associated to specific transcription factors interactions and epigenetic changes in its promoter in embryonic hypothalamic cells.

Neuroprotective Role of Steroidal Sex Hormones: An Overview

Progesterone, estrogens, and testosterone are the well-known steroidal sex hormones, which have been reported to have "nonreproductive "effects in the brain, specifically in the neuroprotection and neurotrophy. In the last one decade, there has been a surge in the research on the role of these hormones in neuroprotection and their positive impact on different brain injuries. The said interest has been sparked by a desire to understand the action and mechanisms of these steroidal sex hormones throughout the body. The aim of this article was to highlight the potential outcome of the steroidal hormones, viz. progesterone, estrogens, and testosterone in terms of their role in neuroprotection and other brain injuries. Their possible mechanism of action at both genomic and nongenomic level will be also discussed. As far as our knowledge goes, we are for the first time reporting neuroprotective effect and possible mechanism of action of these hormones in a single article.

Induction and subcellular redistribution of progesterone receptor A and B by tamoxifen in the hypothalamic ventromedial neurons of young adult female Wistar rats

The ventrolateral division of the hypothalamic ventromedial nucleus (VMNvl) is a brain center for estrogen-dependent triggering of female sexual behavior upon progesterone receptor (PR) activation. We examined the agonistic and antagonistic actions of tamoxifen in this nucleus by analyzing its effects on the total number of PR-immunoreactive neurons, PR mRNA and protein levels, and subcellular location of PRs in ovariectomized Wistar rats. The results show that tamoxifen has no agonistic action in the number of PR-immunoreactive neurons, but increases PR expression and labeling in the nucleus and cytoplasm of VMNvl neurons that constitutively express PRs. As an antagonist, tamoxifen partially inhibited the estradiol-dependent increase in the number of PR-immunoreactive neurons and in PR mRNA and protein levels, without interfering with the subcellular location of the protein. We suggest that tamoxifen influence on PR expression in the VMNvl critically depends on the presence or absence of estradiol.

Sex Hormones Regulate Cytoskeletal Proteins Involved in Brain Plasticity

In the brain of female mammals, including humans, a number of physiological and behavioral changes occur as a result of sex hormone exposure. Estradiol and progesterone regulate several brain functions, including learning and memory. Sex hormones contribute to shape the central nervous system by modulating the formation and turnover of the interconnections between neurons as well as controlling the function of glial cells. The dynamics of neuron and glial cells morphology depends on the cytoskeleton and its associated proteins. Cytoskeletal proteins are necessary to form neuronal dendrites and dendritic spines, as well as to regulate the diverse functions in astrocytes. The expression pattern of proteins, such as actin, microtubule-associated protein 2, Tau, and glial fibrillary acidic protein, changes in a tissue-specific manner in the brain, particularly when variations in sex hormone levels occur during the estrous or menstrual cycles or pregnancy. Here, we review the changes in structure and organization of neurons and glial cells that require the participation of cytoskeletal proteins whose expression and activity are regulated by estradiol and progesterone.

Isolation and Culture of Mouse Hepatocytes: Gender-Specific Gene Expression Responses to Chemical Treatments

In this chapter, the isolation of primary mouse hepatocytes and their response to chemical treatment are described. We show that it is important to consider, in the experimental design, the sex of the animals to be used. We demonstrate this by measuring the effect of sex hormones or xenobiotics on the expression of flavin-containing monooxygenase 5 in cultures of primary hepatocytes isolated from male and female mice.

Menstrual cycle influence on cognitive function and emotion processing-from a reproductive perspective

The menstrual cycle has attracted research interest ever since the 1930s. For many researchers the menstrual cycle is an excellent model of ovarian steroid influence on emotion, behavior, and cognition. Over the past years methodological improvements in menstrual cycle studies have been noted, and this review summarizes the findings of methodologically sound menstrual cycle studies in healthy women. Whereas the predominant hypotheses of the cognitive field state that sexually dimorphic cognitive skills that favor men are improved during menstrual cycle phases with low estrogen and that cognitive skills that favor women are improved during cycle phases with increased estrogen and/or progesterone, this review has not found sufficient evidence to support any of these hypotheses. Mental rotation has gained specific interest in this aspect, but a meta-analysis yielded a standardized mean difference in error rate of 1.61 (95% CI -0.35 to 3.57), suggesting, at present, no favor of an early follicular phase improvement in mental rotation performance. Besides the sexually dimorphic cognitive skills, studies exploring menstrual cycle effects on tasks that probe prefrontal cortex function, for instance verbal or spatial working memory, have also been reviewed. While studies thus far are few, results at hand suggest improved performance at times of high estradiol levels. Menstrual cycle studies on emotional processing, on the other hand, tap into the emotional disorders of the luteal phase, and may be of relevance for women with premenstrual disorders. Although evidence at present is limited, it is suggested that emotion recognition, consolidation of emotional memories, and fear extinction is modulated by the menstrual cycle in women. With the use of functional magnetic resonance imaging, several studies report changes in brain reactivity across the menstrual cycle, most notably increased amygdala reactivity in the luteal phase. Thus, to the extent that behavioral changes have been demonstrated over the course of the menstrual cycle, the best evidence suggests that differences in sexually dimorphic tasks are small and difficult to replicate. However, emotion-related changes are more consistently found, and are better associated with progesterone than with estradiol such that high progesterone levels are associated with increased amygdala reactivity and increased emotional memory.

Epigenetic regulation of Progesterone Receptor isoforms: from classical models to the sexual brain

Progesterone Receptor is a member of the nuclear receptor superfamily, which regulates several functions in both reproductive and non-reproductive tissues. Progesterone Receptor gene encodes for two main isoforms, A and B, and contains two specific promoters with their respective transcription start sites. The mRNA expression of both isoforms is mainly regulated by estrogens and specifically via the Estrogen Receptor Alpha, in a context specific manner. Furthermore, it has been reported in extensive physiological and pathological models that Progesterone Receptor isoforms regulation is related to the epigenetic state of their respective promoters. Epigenetic regulation of Progesterone Receptor isoforms in the brain is a recent and scarcely explored field in neurosciences. This review focuses on the epigenetic mechanisms involved in Progesterone Receptor regulation, emphasizing the implications for the sexual brain. Future directions for research about this important field are also discussed.

Ovarian steroids influence cerebral glucose transporter expression in a region- and isoform-specific pattern

Cerebral glucose uptake is mediated by several members of the family of facilitated glucose transporters (protein nomenclature GLUT; gene nomenclature solute carrier family 2 Slc2a). Glucose uptake differs between the sexes and also varies with menstrual status in women and across the rodent oestrous cycle. The present study demonstrates the extent to which hormonal variation across the four stages of the rat oestrous cycle affects the mRNA abundance of four members of the GLUT family, including the most well characterised cerebral transporters Slc2a1 and Slc2a3, as well as the insulin-sensitive transporters Slc2a4 and Slc2a8 in the hypothalamus, hippocampus and prefrontal cortex. Slc2a1 varied significantly across the cycle in the hippocampus and prefrontal cortex, and Slc2a3 and Slc2a4 also showed significant fluctuation in the hippocampus. Transporter expression significantly increased during pro-oestrus in both the hippocampus and prefrontal cortex. Furthermore, ovarian hormones are critical for normal expression of GLUT mRNA, as demonstrated by reduced expression of Slc2a1, Slc2a3 and Sl2a8 in the hippocampus after ovariectomy. Collectively, the data reported in the present study demonstrate that glucose transporters are highly sensitive to hormonal variation and that this sensitivity is regionally distinct; thereby fluctuations likely have specific phenotypic implications.

Physiological Correlates of Premenstrual Dysphoric Disorder (PMDD)

Premenstrual dysphoric disorder (PMDD) is a mood disorder with onset of functionally impairing or distressing mood symptoms in the late luteal phase of the menstrual cycle. Psychophysiologic findings in PMDD broadly fall into two categories: vulnerability trait findings, thus categorized because they are present in the asymptomatic phases of the menstrual cycle, and state findings, which are only present in the symptomatic late luteal phase and which are potentially representative of the hormonal events and biological mechanisms that lead to PMDD. Trait vulnerability markers in PMDD include diminished cardiovascular stress responses, lower heart rate variability (reflecting increased vagal tone), and lower P300 amplitude, eventually suggesting that women with PMDD share a number of physiological correlates with related anxiety and mood disorders. State findings in PMDD include lower luteal phase prepulse inhibition and altered luteal phase emotion processing. Lower prepulse inhibition in the late luteal phase may be an important ovarian steroid-influenced indicative of altered serotonergic neurotransmission, of relevance for women with PMDD. Attempts to determine the neural correlates of emotion processing in the late luteal phase are thus far inconsistent, but promising.

Prefrontal activity during response inhibition decreases over time in the postpartum period

The postpartum period is characterized by complex hormonal changes, but human imaging studies in the postpartum period have thus far predominantly focused on the neural correlates of maternal behavior or postpartum depression, whereas longitudinal studies on neural correlates of cognitive function across the postpartum period in healthy women are lacking. The aim of this study was to longitudinally examine response inhibition, as a measure of executive function, during the postpartum period and its neural correlates in healthy postpartum women and non-postpartum controls. Thirteen healthy postpartum women underwent event-related functional magnetic resonance imaging while performing a Go/NoGo task. The first assessment was made within 48 h of delivery, and the second at 4-7 weeks postpartum. In addition, 13 healthy women examined twice during the menstrual cycle were included as non-postpartum controls. In postpartum women region of interest analyses revealed task-related decreased activations in the right inferior frontal gyrus, right anterior cingulate, and bilateral precentral gyri at the late postpartum assessment. Generally, postpartum women displayed lower activity during response inhibition in the bilateral inferior frontal gyri and precentral gyri compared to non-postpartum controls. No differences in performance on the Go/NoGo task were found between time-points or between groups. In conclusion, this study has discovered that brain activity in prefrontal areas during a response inhibition task decreases throughout the course of the first postpartum weeks and is lower than in non-postpartum controls. Further studies on the normal adaptive brain activity changes that occur during the postpartum period are warranted.

Neural progestin receptors and female sexual behavior

The steroid hormone, progesterone (P), modulates neuroendocrine functions in the central nervous system resulting in integration of reproduction and reproductive behaviors in female mammals. Although it is widely recognized that P's effects on female sex behavior are mediated by the classical neural progestin receptors (PRs) functioning as 'ligand-dependent' transcription factors to regulate genes and genomic networks, additional mechanisms of PR activation also contribute to the behavioral response. Cellular and molecular evidence indicates that PRs can be activated in a ligand-independent manner by neurotransmitters, growth factors, cyclic nucleotides, progestin metabolites and mating stimuli. The rapid responses of P may be mediated by a variety of PR types, including membrane-associated PRs or extranuclear PRs. Furthermore, these rapid nonclassical P actions involving cytoplasmic kinase signaling and/or extranuclear PRs also converge with classical PR-mediated transcription-dependent pathways to regulate reproductive behaviors. In this review, we summarize some of the history of the study of the role of PRs in reproductive behaviors and update the status of PR-mediated mechanisms involved in the facilitation of female sex behavior. We present an integrative model of PR activation via crosstalk and convergence of multiple signaling pathways.

Novel substrates for, and sources of, progestogens for reproduction

Steroid hormones, such as progesterone, are typically considered to be primarily secreted by the gonads (albeit adrenals can also be a source) and to exert their actions through cognate intracellular progestin receptors (PRs). Through its actions in the midbrain ventral tegmental Area (VTA), progesterone mediates appetitive (exploratory, anxiety, social approach) and consummatory (social, sexual) aspects of rodents' mating behaviour. However, progesterone and its natural metabolites ('progestogens') are produced in the midbrain VTA independent of peripheral sources and midbrain VTA of adult rodents is devoid of intracellular PRs. One approach that we have used to understand the effects of progesterone and mechanisms in the VTA for mating is to manipulate the actions of progesterone in the VTA and to examine effects on lordosis (the posture female rodents assume for mating to occur). This review focuses on the effects and mechanisms of progestogens to influence reproduction and related processes. The actions of progesterone and its 5α-reduced metabolite and neurosteroid, 5α-pregnan-3α-ol-20-one (3α,5α-THP; allopregnanolone) in the midbrain VTA to facilitate mating are described. The findings that 3α,5α-THP biosynthesis in the midbrain occurs with mating are discussed. Evidence for the actions of 3α,5α-THP in the midbrain VTA via nontraditional steroid targets is summarised. The broader relevance of these actions of 3α,5α-THP for aspects of reproduction, beyond lordosis, is summarised. Finally, the potential role of the pregnane xenobiotic receptor in mediating 3α,5α-THP biosynthesis in the midbrain is introduced.

A helminth cestode parasite express an estrogen-binding protein resembling a classic nuclear estrogen receptor

The role of an estrogen-binding protein similar to a known mammalian estrogen receptor (ER) is described in the estradiol-dependent reproduction of the helminth parasite Taenia crassiceps. Previous results have shown that 17-β-estradiol induces a concentration-dependent increase in bud number of in vitro cultured cysticerci. This effect is inhibited when parasites are also incubated in the presence of an ER binding-inhibitor (tamoxifen). RT-PCR assays using specific oligonucleotides of the most conserved ER sequences, showed expression by the parasite of a mRNA band of molecular weight and sequence corresponding to an ER. Western blot assays revealed reactivity with a 66 kDa protein corresponding to the parasite ER protein. Tamoxifen treatment strongly reduced the production of the T. crassiceps ER-like protein. Antibody specificity was demonstrated by immunoprecipitating the total parasite protein extract with anti-ER-antibodies. Cross-contamination by host cells was discarded by flow cytometry analysis. ER was specifically detected on cells expressing paramyosin, a specific helminth cell marker. Parasite cells expressing the ER-like protein were located by confocal microscopy in the subtegumental tissue exclusively. Analysis of the ER-like protein by bidimensional electrophoresis and immunoblot identified a specific protein of molecular weight and isoelectric point similar to a vertebrates ER. Sequencing of the spot produced a small fragment of protein similar to the mammalian nuclear ER. Together these results show that T. crassiceps expresses an ER-like protein which activates the budding of T. crassiceps cysticerci in vitro. To the best of our knowledge, this is the first report of an ER-like protein in parasites. This finding may have strong implications in the fields of host-parasite co-evolution as well as in sex-associated susceptibility to this infection, and could be an important target for the design of new drugs.

Sexual dimorphism in the effect of concomitant progesterone administration on changes caused by long-term estrogen treatment in pituitary hormone immunoreactivities of rats

BACKGROUND

Since in clinical practice long-term estrogen (E) treatment is frequently applied, our aim was to study the effect of concomitant progesterone (P) administration on changes caused by long-term estrogen treatment in the secretion of LH, FSH, PRL and GH.

MATERIAL/METHODS

Diethylstilbestrol (DES), P or both in silastic capsules were implanted under the skin of prepubertal Sprague-Dawley male and female rats. Animals survived for two or five months. We have also studied whether the changed hormone secretion caused by DES can return to normal level 1 or 2 months after removing DES capsule.

RESULTS

1.) The males more rapidly responded than females with decreasing basal LH release upon treatments. The basal FSH release was decreased only in males. The effect of DES persisted in males; however, in females basal LH and FSH levels were upregulated after removal of DES capsule. 2.) The basal GH levels were low in each group. The body weight and length were depressed by DES in both genders and P little blunted this effect. The body weight and length in males remained low after removal of DES capsule, in females it was nearly similar to intact rats. 3.) There was no sexual dimorphism in the effect of steroids on PRL secretion. In both genders DES extremely enhanced the PRL levels, P prevented the effect of DES. PRL levels returned to intact value after removal of DES influence. 4.) Removal of DES capsule reversed the changes in the immunohistochemical appearance of hormone immunoreactivities.

CONCLUSIONS

There was sexual dimorphism in the change of basal gonadotropic hormone and GH secretion but not of PRL upon DES and DES+P treatments. P was basically protective and this role may be mediated by P receptors locally in the pituitary gland.

Effects of mating on progesterone receptor isoforms in rat hypothalamus

In rodents, the display of sexual behavior during proestrus-estrus transition depends on the effect of estradiol and progesterone. Progesterone exerts its effects through intracellular receptor (PR) of which two isoforms (PR-A and PR-B) are found, with different regulation and function. In this study the effects of mating on the expression pattern of PR isoforms in the hypothalamus were investigated during proestrus-estrus transition by using western blot. PR-B isoform content significantly diminished during proestrus-estrus transition both in mated and nonmated female rats. In contrast, PR-A isoform content significantly increases during this period in nonmated rats, whereas it does not change in mated animals. These data show that PR isoforms are differentially expressed throughout proestrus-estrus transition and that mating modifies PR isoforms expression in the hypothalamus of the rat.

Effect of concomitant progesterone administration or the effect of removal of estrogen capsule on changes caused by long-term estrogen treatment in pituitary VIP immunoreactivities

In the anterior pituitary besides the classical tropic hormones, peptides of a small molecular weight are also synthesized. One of them is the vasoactive intestinal polypeptide (VIP). VIP immunoreactivity is readily detected in human and monkey pituitaries; however, in the rat VIP immunoreactive cells were observed in about 50% of intact rats. In estrogen treated rats VIP immunoreactive cells were observed in the anterior pituitary of all animals. In this work, we have examined the effect of long-term sexual steroid treatments on the VIP immunoreactivity of the anterior pituitary using diethylstilbestrol (DES) or progesterone (P) filled capsules. The effectiveness of steroid treatments was tested by the measurement of plasma prolactin (PRL) level and by the appearance of prolactinoma. DES enhanced the plasma PRL level and 5 months later it induced prolactinomas, the concomitant P treatment prevented both the elevation of plasma PRL level and the formation of prolactinomas. These results indicated that there was enough steroid in the capsules. There was a positive correlation between the duration of DES influence and the number of VIP immunoreactive cells. Two months after the implantation of DES there was a considerable number of VIP cells in the anterior pituitary, and 5 months after implantation the number of VIP cells was greatly increased so as to form a VIP-oma. Concomitant implantation of P prevented the formation of VIP-oma. Two months after the implantation, the DES capsule was removed. Already 2 months after removal the number of VIP cells approximated to the control level. It has been concluded that P can prevent the undesired effect of DES not only on the PRL, but on the VIP immunoreactivity as well.

The role of progestins in the behavioral effects of cocaine and other drugs of abuse: human and animal research

This review summarizes findings from human and animal research investigating the influence of progesterone and its metabolites allopreganolone and pregnanolone (progestins) on the effects of cocaine and other drugs of abuse. Since a majority of these studies have used cocaine, this will be the primary focus; however, the influence of progestins on other drugs of abuse will also be discussed. Collectively, findings from these studies support a role for progestins in (1) attenuating the subjective and physiological effects of cocaine in humans, (2) blocking the reinforcing and other behavioral effects of cocaine in animal models of drug abuse, and (3) influencing behavioral responses to other drugs of abuse such as alcohol and nicotine in animals. Administration of several drugs of abuse in both human and nonhuman animals significantly increased progestin levels, and this is explained in terms of progestins acting as homeostatic regulators that decrease and normalize heightened stress and reward responses which lead to increased drug craving and relapse. The findings discussed here highlight the complexity of progestin-drug interactions, and they suggest a possible use for these agents in understanding the etiology of and developing treatments for drug abuse.

Activation of progestin receptors in female reproductive behavior: Interactions with neurotransmitters

The steroid hormone, progesterone (P), modulates neuroendocrine functions in the central nervous system resulting in alterations in physiology and reproductive behavior in female mammals. A wide body of evidence indicates that these neural effects of P are predominantly mediated via their intracellular progestin receptors (PRs) functioning as "ligand-dependent" transcription factors in the steroid-sensitive neurons regulating genes and genomic networks. In addition to P, intracellular PRs can be activated by neurotransmitters, growth factors and cyclic nucleotides in a ligand-independent manner via crosstalk and convergence of pathways. Furthermore, recent studies indicate that rapid signaling events associated with membrane PRs and/or extra-nuclear, cytoplasmic PRs converge with classical PR activated pathways in neuroendocrine regulation of female reproductive behavior. The molecular mechanisms, by which multiple signaling pathways converge on PRs to modulate PR-dependent female reproductive behavior, are discussed in this review.

Gene expression profiles of intracellular and membrane progesterone receptor isoforms in the mediobasal hypothalamus during pro-oestrus

Progesterone action is mediated by its binding to specific receptors. Two progesterone receptor (PR) isoforms (PRA and PRB), three membrane progesterone receptor (mPR) subtypes (mPRalpha, mPRbeta and mPRgamma) and at least one progesterone membrane-binding protein [PR membrane component 1 (PRmc1)] have been identified in reproductive tissues and brain of various species. In the present study, we examined gene expression patterns for PR isoforms, mPR subtypes and PRmc1 in the rat mediobasal hypothalamus (MBH) during pro-oestrus. The mRNA level for each receptor subtype was quantified by a real-time reverse transcriptase-polymerase chain reaction (RT-PCR) at the time points: 13.00 h on dioestrous day 2; 09.00, 13.00, 17.00 and 22.00 h on pro-oestrus; and 13.00 h on oestrus. For PR, one primer set amplified PRA+PRB, whereas a second primer set amplified PRB. As expected, PRA+PRB mRNA expression was greater than PRB in MBH tissue. PRB mRNA levels increased throughout the day on pro-oestrus, with the highest levels being observed at 17.00 h. PRB mRNA levels in the MBH were increased by 2.4- and 3.0-fold at 13.00 and 17.00 h, respectively, on pro-oestrus compared to 13.00 h on dioestrous day 2. There were differential mRNA expression levels for mPRs and PRmc1 in the MBH, with the highest expression for PRmc1 and the lowest for mPRgamma. The mPRalpha mRNA contents at 13.00 and 17.00 h on pro-oestrus were increased by 1.5-fold compared to that at 13.00 h on dioestrous day 2. The mPRbeta mRNA levels at 13.00 and 17.00 h on pro-oestrus were 2.5- and 2.4-fold higher compared to that at 13.00 h on dioestrous day 2, respectively. PRA+PRB, mPRgamma and PRmc1 mRNA levels did not vary on pro-oestrus. These findings suggest that the higher expression of PRB, mPRalpha and mPRbeta in the MBH on pro-oestrous afternoon may influence both genomic and nongenomic mechanisms of progesterone action during the critical pre-ovulatory period.

Neonatal exposure to estradiol induces resistance to helminth infection and changes in the expression of sex steroid hormone receptors in the brain and spleen in adult mice of both sexes

A single injection of 17beta-estradiol administered to 4-day-old male and female mice increased the cellular immune response, and induced resistance to Taenia crassiceps cysticercosis as well as changes in the expression pattern of progesterone (PR) and estrogen receptor (ER) isoforms in the brain and splenocytes. Regardless of gender, when treated mice reached adulthood, they were highly resistant to infection. Female mice presented early vaginal opening and altered estrous cycles. In male and female mice, the expression of the PR and ER isoforms in the brain was differentially regulated after neonatal exposure to estradiol. Moreover, an increase in the expression of IL-4 and IFN-gamma was found in the serum of experimentally infected neonatally estrogenized animals, which correlated with the observed protection against T. crassiceps infection. In conclusion, early exposure to estradiol permanently modifies immune system activity and sex steroid hormone receptors in the brain, and causes profound changes in sex-associated susceptibility, leading to resistance to helminth parasite infection.

Progestogens and brain: an update

Each synthetic progestins has its own specific activities on different tissues, which can vary significantly between progestins of different classes and even within the same class. Indeed, different progestins may support or oppose the effects of estrogen depending on the tissue, thereby supporting the concept that the clinical selection of progestins for HRT is critical in determining potential positive or detrimental effects. These actions might be particularly relevant in the central nervous system (CNS) where progesterone (P) has pivotal roles besides reproduction and sexual behavior, going from neuropsychological effects to neuroprotective functions. Growing evidence supports the idea that synthetic progestins differ significantly in their brain effects, and clinical studies indicate that these differences also occur in women. Molecular and cellular characterization of the signaling properties of synthetic progestins in brain cells is therefore required and is hoped will lead to a better clinical utilization of the available compounds, as well as to new concepts in the engineering of new molecules. The aim of the present paper is to briefly review and compare neuroendocrine effects of progestogens with special reference to P metabolism into neuroactive steroids and the opioids system.

Progesterone receptor in the forebrain of female gray short-tailed opossums: effects of exposure to male stimuli

Progesterone receptor immunoreactivity (PRir) in brain areas involved in reproductive behavior in eutherian species was examined for the first time in a female marsupial, the gray short-tailed opossum (Monodelphis domestica, hereinafter, opossum). PRir in nuclei of neurons, measured as area covered by stained nuclei, was seen in the arcuate nucleus (Arc); anteroventral periventricular nucleus (AVPv); bed nucleus of the stria terminalis (BST); medial preoptic area (MPOA), and ventromedial hypothalamus (VMH), but not in control areas adjacent to the hypothalamus or cortex. Female opossums are induced into cytological, urogenital sinus (UGS), estrus by male pheromones and into behavioral estrus, i.e., receptivity, by pairing with a male, and both estradiol (E) and progesterone (P) are involved in induction of receptivity in intact and ovariectomized females. PRir in the AVPv, MPOA, and VMH was very low in females that had never been exposed to males or their scent marks, i.e., naïve anestrous (NVA) females, and either previous or current exposure to males or their scent marks was associated with elevated PRir. PRir was significantly higher in the AVPv and MPOA of anestrous females with previous but no current exposure to males and their scent marks, i.e., experienced anestrous (EXPA) females, than in NVA females, but PRir was significantly lower in the MPOA and VMH of EXPA females than in females that were behaviorally receptive and had recently copulated, i.e., behavioral receptive estrous (BRE) females. PRir was higher in the VMH of both UGS estrous (UGSE) and BRE females compared to that in EXPA animals, but PRir did not differ between UGSE and BRE females in any of the 3 brain areas examined, including the MPOA These results provide evidence that pheromonal induction of estrus and sexual receptivity in opossums is associated with elevation of PRir in the VMH and MPOA and that prior exposure to males or their pheromones, even in the absence of current male stimuli, is associated with persistent elevation of PRir in the AVPv and MPOA.

Ultrastructural localization of extranuclear progestin receptors in the rat hippocampal formation

Progesterone's effects on hippocampus-dependent behavior and synaptic connectivity maybe mediated through the progestin receptor (PR). Although estrogen induces PR mRNA and cytosolic PR in the hippocampus, nuclear PR immunoreactivity is undetectable by light microscopy, suggesting that PR is present at extranuclear sites. To determine whether this is the case, we used immunoelectron microscopy to examine PR distribution in the hippocampal formation of proestrus rats. Ultrastructural analysis revealed that PR labeling is present in extranuclear profiles throughout the CA1 and CA3 regions and dentate gyrus, and, in contrast to light microscopic findings, in nuclei of a few pyramidal and subgranular zone cells. Most neuronal PR labeling is extranuclear and is divided between pre- and postsynaptic compartments; approximately 30% of labeled profiles were axon terminals and 30% were dendrites and dendritic spines. In most laminae, except in CA3 stratum lucidum, about 15% of PR-immunoreactive profiles were unmyelinated axons. In stratum lucidum, where the mossy fiber axons course, more than 50% of PR-labeled profiles were axonal. The remaining 25% of PR-labeled profiles were glia, some resembling astrocytes. PR labeling is strongly dependent on estrogen priming, insofar as few PR-labeled profiles were detected in ovariectomized, oil-replaced females. Synapses formed by PR-labeled terminals were predominantly asymmetric, consistent with a role for progesterone in directly regulating excitatory transmission. These findings suggest that some of progesterone's actions in the hippocampal formation may be mediated by direct and rapid actions on extranuclear PRs and that PRs are well positioned to regulate progesterone-induced changes at synapses.

Estrogen and progesterone receptor isoforms expression in the stomach of Mongolian gerbils

AIM: We studied the estrogen receptor (ER) and progesterone receptor (PR) isoforms expression in gastric antrum and corpus of female gerbils and their regulation by estradiol (E2) and progesterone (P4).

METHODS: Ovariectomized adult female gerbils were subcutaneously treated with E2, and E2 + P4. Uteri and stomachs were removed, the latter were cut along the greater curvature, and antrum and corpus were excised. Proteins were immunoblotted using antibodies that recognize ER-alpha, ER-beta, and PR-A and PR-B receptor isoforms. Tissues from rats treated in the same way were used as controls.

RESULTS: Specific bands were detected for ER-alpha (68 KDa), and PR isoforms (85 and 120 KDa for PR-A and PR-B isoforms, respectively) in uteri, gastric antrum and corpus. We could not detect ER-beta isoform. PR isoforms were not regulated by E2 or P4 in uterus and gastric tissues of gerbils. ER-alpha isoform content was significantly down-regulated by E2 in the corpus, but not affected by hormones in uterus and gastric antrum.

CONCLUSION: The presence of ER-alpha and PR isoforms in gerbils stomach suggests that E2 and P4 actions in this organ are in part mediated by their nuclear receptors.