Plasma Allopregnanolone Levels Research Articles

T171 Measurement of plasma allopregnanolone levels and the impact of solid phase extraction step on competitive immunoassay performance

T171 Measurement of plasma allopregnanolone levels and the impact of solid phase extraction step on competitive immunoassay performance

T167 Measurement of plasma allopregnanolone levels and the impact of solid phase extraction step on competitive immunoassay performance

T167 Measurement of plasma allopregnanolone levels and the impact of solid phase extraction step on competitive immunoassay performance

Serum levels of allopregnanolone in migraine patients: A case–control study

Introduction: Migraine is a very common disorder and the mechanisms contributing to headache still remain controversial. Allopregnanolone (AP) is a neurosteroid metabolite of progesterone. Previously, there were some studies of AP on the positive effects of many diseases. Objectives: The aim of this study was to evaluate AP levels in patients with migraine and compare with levels measured in healthy individuals. Materials and Methods: This case–control study included fifty patients with acute migraine headache who were previously diagnosed with migraine and fifty sex- and age-matched healthy volunteers with no headache complaints. Migraine patients who fulfilled the International Headache Classification criteria of migraine and healthy controls were included in this study. Plasma AP levels were compared in both groups. Results: Fifty patients (35 females and 15 males) and fifty healthy volunteers (38 females and 12 males) fulfilled the inclusion criteria and were enrolled in the study. AP levels of migraine patients and control group were compared; there was a statistically significant difference between the two groups (1.22 ± 1.92, 6.07 ± 4.89, respectively; P Conclusion: This study showed that low AP levels were detected in migraine patients. These markers may contribute to our understanding of the pathophysiology of migraine.

Approche GABAergique de la dépression du post-partum : une revue critique translationnelle

IntroductionPrevalence of postpartum depression (PPD) ranges from 10 to 15 % of parturients. The impact of the PPD is major on the maternal bond and the health of both mother and child. Its physiopathological mechanisms appear to differ from other types of depression. Today, pharmacotherapy is based on nonspecific treatment, and recent therapeutic advances in this field require a comprehensive approach of the implication of the GABAergic system in the development of PPD. Neurosteroid levels during pregnancy and after parturition and the GABA-A-r modulation are thought to be involved in PPD. ObjectiveTo evaluate if the GABAergic approach is relevant in postpartum depression management. MethodsWe conducted a systematic review of literature based on the MEDLINE database with the following Medical Subject Headings (MeSH): “postpartum depression”, “GABA”, “ganaxolone”, “brexanolone”, “allopregnanolone”, prior to September 2019. We selected articles in English: preclinical and clinical studies, literature review, observational and therapeutic studies. ResultsPreclinical models (mouse and rat) show changes in GABAergic inhibition in the peripartum period and correlation between allopregnanolone and GABA-A-r plasticity. This plasticity in the peripartum period maintains levels of inhibition adapted despite increased neurosteroid levels. KO models for the GABA-A-r δ subunit develop depression and anxiety symptoms in the postpartum period, and a change in the expression of the gene coding for the GABA-R alpha-4 subunit was found. Artificial inhibition of progesterone metabolism during post-partum increased depression symptoms. GABAergic fluctuation seems to be interrelated with other systems such as those of oxytocins. A synthetic neurosteroid (SGE-516) was tested on mouse models of PPD, KO for δ-GABA-A-r or KCC2, and showed decreased depressive symptoms and better mothering. Clinical studies confirm neurosteroid fluctuation and changes in the GABAergic system during the peripartum period. Allopregnanolone is the neurosteroid the most studied in PPD, and it is elevated in the brain during the pregnancy. Studies disagree on the presence of significant differences in allopregnanolone plasma levels during pregnancy or postpartum between women with PPD or not. Women with a history of PPD have greater susceptibility to neurosteroid withdrawal. Imagery and genetical data also show a link between allopregnanolone and PPD. The GABA-A-r may not recover in time following a reduced number during pregnancy, and this mismatch between neurosteroid levels and their receptor may trigger PPD. Several randomized controlled trials investigated brexanolone administrated IV, a synthetic formulation of allopregnanolone, and demonstrated a rapid and well tolerated reduction in depressive symptoms. In March 2019 brexanolone obtained FDA approval in PPD indication under the name Zulresso. However, there are differences in the time of beginning of PPD, which could constitute different subgroups of this disease, and which physiopathology could respond to different mechanisms. Prenatal depression does not respond to a GABAergic approach, but women without any risk factor or previous mood disorder developing PPD in the weeks following childbirth could be particularly responsive to this kind of treatment. ConclusionDisability to modulate GABA-A-r expression during pregnancy and restore its previous state after parturition appears to trigger PPD. The GABAergic system is a promising pharmacotherapy target. From preclinical to clinical studies for about twenty years the GABAergic system has been incriminated and targeted in this challenging mental disease.

Plasma allopregnanolone levels in drug-free, comorbidity-free obsessive-compulsive disorder

Objective: Although there are studies in the literature focusing on the relationship between neurosteroids and psychiatric disorders, the studies on patients with obsessive-compulsive disorder (OCD) are limited in number. Nevertheless, allopregnanolone, a neurosteroid, in OCD patients has not been investigated in this limited number of studies. Allopregnanolone is considered to have a role in the pathogenesis of many psychiatric disorders. Accordingly, the present study aimed to investigate the relationship between the neurosteroid allopregnanolone and OCD. Methods: The study included 40 OCD patients diagnosed based on the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) diagnostic criteria and 40 healthy control subjects. The study participants completed the Yale-Brown Obsessive Compulsive Scale. Taking the diurnal rhythm of neurosteroids into consideration, blood samples for determination of plasma allopregnanolone levels were obtained from all patients and controls between 09:00 and 10:00 in the morning after 12 hours of fasting, tobacco abstinence, and 30 minutes of resting period. Plasma allopregnanolone level was analyzed using the enzyme-linked immunosorbent assay (ELISA). Results: No significant difference was determined between the patient and control groups regarding serum allopregnanolone levels. Evaluation of the allopregnanolone levels of the patients for each obsession type according to its presence and absence revealed no significant difference in any of them. Evaluation of the allopregnanolone levels of the patients for each compulsion type according to its presence and absence revealed that the allopregnanolone level of the patients with counting-organizing compulsive behavior was lower than that of those without. Discussion: Although there was no difference between OCD patients and controls regarding plasma allopregnanolone level, it is difficult to make a conclusion that allopregnanolone level does not play a role in the etiopathogenesis of disease. Conducting further studies, which would analyze allopregnanolone level in materials other than plasma such as cerebrospinal fluid using multiple analyses and separately evaluates females and males with higher number of patients, is of importance to enlighten at least some aspects of allopregnanolone-OCD relationship. Moreover, significantly lower plasma allopregnanolone level particularly in a single type of compulsion brings in mind again the suggestion that different etiopathogenesis might have a role in the symptom subtypes of OCD, which has begun to be discussed in the recent years.

Combined effect of gestational stress and postpartum stress on maternal care in rats

Variations in maternal care in the rat influence the development of individual differences in behavioral and endocrine responses to stress. This study aimed to examine the interaction between intragastric intubation during late gestation and postpartum stress, induced by pup separation, on maternal behavior and on dams' emotional state and HPA axis function. Rats received intragastric intubation of water on days 12–20 of gestation or remained untreated in their home cage (naïve dams). Pup separation was used as a model of postpartum stress. The procedure consisted of a daily separation of the dam from its litter for 3h from PND 3 until PND 15. Pup separation was carried out in both naïve and intubated dams. The behavioral results indicate that the association of these two stressors significantly decreased arched-back nursing (ABN) and licking and grooming (LG), behaviors considered important parameters to discriminate the high quality of maternal care. Moreover, dams that received both stressors displayed less nest building and blanket nursing behaviors; no effect on the frequency of passive and total nursing was recorded. The analysis of single effects on ABN and LG, revealed that dams that underwent gestational stress induced by intragastric intubation displayed less LG, but ABN was overall unchanged. On the contrary, pup separation stress significantly increased ABN and LG upon reunion of naïve dams with their pups. Treatments per se or the association of both induced modest changes in plasma levels of allopregnanolone and corticosterone that likely did not influence maternal care. These data show that the association of a mild stress during gestation with an unfavorable experience after parturition had a significant impact on maternal care. This effect seems independent from HPA axis activation or from changes in emotional state; further studies would be necessary to ascertain the neural changes that could contribute to altered maternal behavior in stressed mothers. Moreover, these results suggest that the use of intragastric intubation during gestation would interfere with measures of drug-induced changes in maternal behavior and likely their consequences on the offspring.

Ethanol withdrawal-induced dysregulation of neurosteroid levels in plasma, cortex, and hippocampus in genetic animal models of high and low withdrawal.

Endogenous γ-aminobutyric acidA receptor (GABAAR)-active neurosteroids (e.g., allopregnanolone) regulate central nervous system excitability and many physiological functions, so fluctuations are implicated in several neuropsychiatric disorders. Pertinently, evidence supports an inverse relationship between endogenous GABAAR-active neurosteroid levels and behavioral changes in excitability during ethanol withdrawal (WD). The present studies determined mouse genotype differences in ten neurosteroid levels in plasma, cortex, and hippocampus over the time course of ethanol WD in the WD Seizure-Prone (WSP) and WD Seizure-Resistant (WSR) selected lines and in the DBA/2J (DBA) inbred strain. Gas chromatography-mass spectrometry was utilized to simultaneously quantify neurosteroid levels from control-treated male WSP-1, WSR-1, and DBA mice and during 8 and 48h of WD. Combined with our prior work, there was a consistent decrease in plasma allopregnanolone levels at 8h WD in all three genotypes, an effect that persisted at 48h WD only in DBA mice. WSR-1 and WSP-1 mice exhibited unexpected divergent changes in cortical neurosteroids at 8h WD, with the majority of neurosteroids (including allopregnanolone) being significantly decreased in WSR-1 mice, but unaffected or significantly increased in WSP-1 mice. In DBA mice, hippocampal allopregnanolone and tetrahydrodeoxycorticosterone were significantly decreased at 8h WD. The pattern of significant correlations between allopregnanolone and other GABAAR-active neurosteroid levels differed between controls and withdrawing mice. Ethanol WD dysregulated neurosteroid synthesis. Results in WSP-1 mice suggest that diminished GABAAR function is more important for their high WD phenotype than fluctuations in neurosteroid levels.

Juvenile social isolation affects maternal care in rats: involvement of allopregnanolone.

Social isolation of rats immediately after weaning is thought to represent an animal model of anxiety-like disorders. Socially isolated virgin females showed a significant decrease in allopregnanolone levels, associated with increased anxiety-related behavior compared with group-housed rats. The present study investigates whether post-weaning social isolation affects maternal behavior and assesses neuroactive steroid levels in adult female rats during pregnancy and postpartum. Socially isolated dams displayed a reduction in the frequency of arched back nursing (ABN) behavior compared to group-housed dams. In addition, both total and active nursing were lower in socially isolated dams compared to group-housed dams. Compared to virgin females, pregnancy increases allopregnanolone levels in group-housed as well as isolated dams and such increase was greater in the latter group. Compared to pregnancy levels, allopregnanolone levels decreased after delivery and this decrease was more pronounced in isolated than group-housed dams. Moreover, the fluctuations in plasma corticosterone levels that occur in late pregnancy and during lactation follow a different pattern in socially isolated vs. group-housed rats. The present results show that social isolation in female rats decreases maternal behavior; this effect is associated with lower allopregnanolone concentrations at postpartum, which may account, at least in part, for the poor maternal care observed in socially isolated dams. In support of this conclusion is the finding that finasteride-treated dams, which display a decrease in plasma allopregnanolone levels, also showed a marked reduction in maternal care, suggesting that allopregnanolone may contribute to the quality of maternal care.

5α-Reductase Inhibition Prevents the Luteal Phase Increase in Plasma Allopregnanolone Levels and Mitigates Symptoms in Women with Premenstrual Dysphoric Disorder.

Changes in neurosteroid levels during the luteal phase of the menstrual cycle may precipitate affective symptoms. To test this hypothesis, we stabilized neurosteroid levels by administering the 5α-reductase inhibitor dutasteride to block conversion of progesterone to its neurosteroid metabolite allopregnanolone in women with premenstrual dysphoric disorder (PMDD) and in asymptomatic control women. Sixteen women with prospectively confirmed PMDD and 16 control women participated in one of two separate randomized, double-blind, placebo-controlled, cross-over trials, each lasting three menstrual cycles. After one menstrual cycle of single-blind placebo, participants were randomized to receive, for the next two menstrual cycles, either double-blind placebo or dutasteride (low-dose 0.5 mg/day in the first eight PMDD and eight control women or high-dose 2.5 mg/day in the second group of women). All women completed the daily rating form (DRF) and were evaluated in clinic during the follicular and luteal phases of each menstrual cycle. Main outcome measures were the DRF symptoms of irritability, sadness, and anxiety. Analyses were performed with SAS PROC MIXED. In the low-dose group, no significant effect of dutasteride on PMDD symptoms was observed compared with placebo (ie, symptom cyclicity maintained), and plasma allopregnanolone levels increased in women with PMDD from follicular to the luteal phases, suggesting the absence of effect of the low-dose dutasteride on 5α-reductase. In contrast, the high-dose group experienced a statistically significant reduction in several core PMDD symptoms (ie, irritability, sadness, anxiety, food cravings, and bloating) on dutasteride compared with placebo. Dutasteride had no effect on mood in controls. Stabilization of allopregnanolone levels from the follicular to the luteal phase of the menstrual cycle by blocking the conversion of progesterone to its 5α-reduced neurosteroid metabolite mitigates symptoms in PMDD. These data provide preliminary support for the pathophysiologic relevance of neurosteroids in this condition.

Effects of plasma allopregnanolone levels on drug craving in cocaine-dependent men and women

Effects of plasma allopregnanolone levels on drug craving in cocaine-dependent men and women

Circulating Levels of Allopregnanolone, a Neuroactive Steroid, and Leptin during Treatment with Valproic Acid in Children with Epilepsy

Weight gain is a well-known unwanted effect of valproic acid (VPA) therapy. Studies on VPA-associated changes of homeostatic hormones remain limited and controversial. Allopregnanolone (AP) is a circulating neuroactive steroid involved in modulation of behavioral activities whose serum levels are increased in obese children. The aim of the present study was to determine whether VPA therapy affects leptin and AP circulating levels in prepubertal girls with epilepsy. One-hundred and one patients were divided into four groups: epileptic patients with VPA-associated obesity (n = 21); lean epileptic patients under VPA therapy (n = 35); healthy obese children (n = 23), and healthy lean children (n = 22). Patients with VPA-associated obesity had significantly enhanced blood concentrations of AP (p = 0.001) and leptin (p = 0.007) than lean subjects. There were no differences in leptin and AP plasma levels between patients with VPA-associated obesity and obese controls (p = 0.45 and p = 0.10, respectively), as there were no differences between lean patients under VPA therapy and lean healthy controls (p = 0.06). In patients under VPA therapy, both plasma leptin and AP levels were significantly correlated with BMI (r = 0.074, p = 0.02, and r = 0.084, p = 0.01, respectively). Plasma leptin concentrations were not correlated with AP levels (r = 0.023, p = 0.13). In conclusion, a correlation between obesity and neuroactive steroids was shown. It remains to be established whether the increased circulating level of AP is a secondary effect of anxiolytic-sedative processes occurring in subjects with obesity-related emotional and behavioral anomalies, or plays a central role in determining abnormal eating behaviors.

P.6.b.009 Dysregulation of cell death machinery in the prefrontal cortex of human alcoholics

Progesterone has sedative and anesthetic effects but the underlying molecular mechanisms remain unclear. The two possible mechanisms by which progesterone affects the function of the brain include binding to intracellular progesterone receptors (PR) and metabolism to GABAA receptor-modulating neurosteroids. In this study, PR knockout (PRKO) mice were used as model to study the role of PRs in the anesthetic activity of progesterone. The progesterone-induced anesthetic activity was undiminished in female PRKO mice (ED50, 172 mg/kg) as compared to their wild-type littermates (ED50, 167 mg/kg). The progesterone-induced anesthetic activity was highly correlated with increased plasma allopregnanolone levels. Pretreatment of PRKO mice with the 5α-reductase inhibitor finasteride significantly reduced the progesterone-induced anesthetic activity. Allopregnanolone also evoked dose-dependent anesthetic activity in PRKO mice, which was similar to those of wild-type mice. Thus, the anesthetic activity of progesterone is not mediated by its interaction with PRs. The neurosteroid allopregnanolone partially mediates the anesthetic activity of progesterone by potentiation of GABAA receptor function.

Impaired reduction of enhanced levels of dehydroepiandrosterone by oral dexamethasone in anorexia nervosa

Allopregnanolone and dehydroepiendrosterone (DHEA) have been supposed to be involved in some psychiatric disorders including anorexia nervosa (AN). The secretion of DHEA and allopregnanolone occurs in both the brain and the adrenal gland, where it is under the control of the corticotrophin-releasing factor (CRF)/adrenocorticotrophin hormone (ACTH) system, and, according to the increased CRF/ACTH drive found in AN, we previously reported enhanced morning levels of both DHEA and allopregnanolone in underweight anorexic patients. To further characterize the physiology of these neurosteroids in AN, we measured plasma levels of cortisol, DHEA and allopregnanolone after the oral administration of 1 mg dexamethasone at 800h in six underweight AN women and ten age-matched healthy females. We found that, before dexamethasone administration, both cortisol and DHEA plasma concentrations were significantly increased in anorexic patients as compared to controls, whereas plasma allopregnanolone levels although increased in the former did not reach a statistical significance. Moreover, while cortisol levels after dexamethasone administration were suppressed in AN to values similar to normal controls, DHEA concentrations, although significantly decreased, remained higher than in normal controls. These data support the view that in AN, the increased production of DHEA may be linked to mechanisms other than the enhanced CRF/ACTH drive.

Anesthetic effects of progesterone are undiminished in progesterone receptor knockout mice

Progesterone has sedative and anesthetic effects but the underlying molecular mechanisms remain unclear. The two possible mechanisms by which progesterone affects the function of the brain include binding to intracellular progesterone receptors (PR) and metabolism to GABA A receptor-modulating neurosteroids. In this study, PR knockout (PRKO) mice were used as model to study the role of PRs in the anesthetic activity of progesterone. The progesterone-induced anesthetic activity was undiminished in female PRKO mice (ED 50, 172 mg/kg) as compared to their wild-type littermates (ED 50, 167 mg/kg). The progesterone-induced anesthetic activity was highly correlated with increased plasma allopregnanolone levels. Pretreatment of PRKO mice with the 5α-reductase inhibitor finasteride significantly reduced the progesterone-induced anesthetic activity. Allopregnanolone also evoked dose-dependent anesthetic activity in PRKO mice, which was similar to those of wild-type mice. Thus, the anesthetic activity of progesterone is not mediated by its interaction with PRs. The neurosteroid allopregnanolone partially mediates the anesthetic activity of progesterone by potentiation of GABA A receptor function.

Anticonvulsant Activity of Progesterone and Neurosteroids in Progesterone Receptor Knockout Mice

Many of the biological actions of progesterone are mediated through the progesterone receptor (PR), a nuclear transcription factor. Progesterone is well recognized to protect against seizures in animal models. Although this activity has been attributed to the progesterone metabolite allopregnanolone, a GABAA receptor-modulating neurosteroid with anticonvulsant properties, PRs could also play a role. Here, we used PR knockout (PRKO(-/-)) mice bearing a targeted deletion of the PR gene that eliminates both isoforms of the PR to investigate the contribution of the PR to the anticonvulsant activity of progesterone. The protective activity of progesterone was examined in female and male homozygous PRKO mice and isogenic wild-type controls in the pentylenetetrazol (PTZ), maximal electroshock, and amygdala-kindling seizure models. In all three models, the anticonvulsant potency of progesterone was undiminished in PRKO mice compared with control mice. On the contrary, there was a substantial increase in the anticonvulsant potency of progesterone in the PTZ and kindling models. The antiseizure activity of progesterone in PRKO mice was reversed by pretreatment with finasteride, a 5alpha-reductase inhibitor that blocks the metabolism of progesterone to allopregnanolone. Unlike progesterone, the neurosteroids allopregnanolone and allotetrahydrodeoxycorticosterone exhibited comparable anticonvulsant potency in PRKO and wild-type mice. The basis for the heightened progesterone responsiveness of PRKO mice is not attributable to pharmacokinetic factors, because the plasma allopregnanolone levels achieved after progesterone administration were not greater in the PRKO mice. These studies provide strong evidence that the PR is not required for the antiseizure effects of progesterone, which mainly occurs through its conversion to the neurosteroid allopregnanolone.

Alcohol intoxication increases allopregnanolone levels in male adolescent humans.

Teenage drinking is a cause of growing concern in industrialized countries, where almost 35% of alcohol drinkers are under 16 years old. Increased anxiety, irritability and depression among adolescents may induce them to seek the anxiolytic and rewarding properties of alcohol. Allopregnanolone is rewarding in rodents, and therefore may contribute to the effects of alcohol. In this paper, we studied the effects of acute alcohol intoxication on the plasma levels of allopregnanolone in male adolescents. Blood samples were drawn from male adolescents who arrived at the Emergency Department of the Hospital. Two groups were studied: one study group was formed by adolescents who arrived with evident behavioral symptoms of acute alcohol intoxication (AAI) and the other by those arriving for mild trauma (contusions, sprains) after no consumption of alcohol (Controls). Our results demonstrate that AAI significantly increases serum allopregnanolone levels in male adolescents. Because alcohol and allopregnanolone positively modulate gamma-aminobutyric acid type A (GABAA) receptors, allopregnanolone may play a major role in the anxiolytic and rewarding effects of alcohol, either directly or by influencing the sensitivity of GABAA receptors to alcohol.

Neurosteroid consumption has anxiolytic effects in mice

The neurosteroids allopregnanolone (ALLOP) and pregnanolone (PREG), like ethanol, potentiate γ-aminobutyric acid A receptor function. PREG-hemisuccinate (PREG-HS) is a negative modulator of N-methyl- d-aspartate (NMDA) receptors. Because C57BL/6J (B6) and DBA/2J (D2) mice differ in ethanol preference, voluntary consumption of ALLOP and PREG-HS (50 μg/ml solution) versus tap water was measured in B6 and D2 mice for a minimum of 8 days. Mice were acclimated to a reverse light–dark cycle prior to the initiation of experiments. In the first study, both B6 and D2 mice exhibited preference for the PREG-HS solution. In the second study, neither strain exhibited significant preference for the ALLOP solution versus water. However, the ALLOP-consuming B6 and D2 mice exhibited significant anxiolysis when they were tested on the elevated plus maze following 8 days of ALLOP consumption, compared to separate animals that consumed only water. A subsequent study determined that systemic administration of PREG-HS had significant anxiolytic effects in both B6 and D2 mice, when assessed on the elevated plus maze. Plasma ALLOP levels in the steroid-consuming mice from both studies were significantly increased versus basal levels only in the D2 strain. While the pattern of steroid intake or strain differences in steroid conversion may have influenced the differential change in plasma ALLOP levels, it is noteworthy that both strains consumed doses of ALLOP, and presumably doses of PREG-HS, that were anxiolytic.

Neurosteroid withdrawal model of perimenstrual catamenial epilepsy.

Perimenstrual catamenial epilepsy, the increase in seizure frequency that some women with epilepsy experience near the time of menstruation, may in part be related to withdrawal of the progesterone metabolite allopregnanolone, an endogenous anticonvulsant neurosteroid that is a potent positive allosteric gamma-aminobutyric acidA (GABA(A)) receptor modulator. The objective of this study was to develop an animal model of perimenstrual catamenial epilepsy for use in evaluating drug-treatment strategies. A state of prolonged high serum progesterone (pseudopregnancy) was induced in 26-day-old female rats by sequential injection of pregnant mares' serum gonadotropin and human chorionic gonadotropin. Neurosteroid withdrawal was induced by treatment with finasteride (100 mg/kg, i.p.), a 5alpha-reductase inhibitor that blocks the conversion of progesterone to allopregnanolone. Plasma progesterone and allopregnanolone levels were measured by gas chromatography/electron capture negative chemical ionization mass spectrometry. Seizure susceptibility was evaluated with the convulsant pentylenetetrazol (PTZ). Plasma allopregnanolone levels were markedly increased during pseudopregnancy (peak level, 55.1 vs. control diestrous level, 9.3 ng/mL) and were reduced by 86% 24 h after finasteride treatment (6.4 ng/mL). Progesterone levels were unaffected by finasteride. After finasteride-induced withdrawal, rats showed increased susceptibility to PTZ seizures. There was a significant increase in the number of animals exhibiting clonic seizures when challenged with subcutaneous PTZ (60 mg/kg) compared with control pseudopregnant animals not undergoing withdrawal and nonpseudopregnant diestrous females. The CD50 (50% convulsant dose) was 46 mg/kg, compared with 73 mg/kg in nonwithdrawn pseudopregnant animals and 60 mg/kg in diestrous controls. The threshold doses for induction of various seizure signs, measured by constant intravenous infusion of PTZ, were reduced by 30-35% in neurosteroid-withdrawing animals compared with control diestrous females. No change in threshold was observed in pseudopregnant rats treated from days 7 to 11 with finasteride, demonstrating that high levels of progesterone alone do not alter seizure reactivity. Neurosteroid withdrawal in pseudopregnant rats results in enhanced seizure susceptibility, providing an animal model of perimenstrual catamenial epilepsy that can be used for the evaluation of new therapeutic approaches.

Circulating Levels of Allopregnanolone in Humans: Gender, Age, and Endocrine Influences

Allopregnanolone is a neuroactive steroid involved in modulating behavioral functions, stress, and neuroendocrine axes in rats. Changes in plasma allopregnanolone levels throughout the menstrual cycle have been reported in healthy women, but there exists no information on the possible gender or age-related changes or on the source(s) of circulating allopregnanolone. The aim of the present study was to assess serum allopregnanolone concentrations according to gender, menstrual cycle, age, and menopause in normal men and women; serum progesterone (P) and dehydroepiandrosterone (DHEA) levels were evaluated in the same specimens. In addition, the possible source of circulating allopregnanolone in fertile women was investigated by using stimulatory and inhibitory endocrine tests acting on the ovary and/or adrenal cortex. The present study included 189 fertile women, 112 postmenopausal women, and 46 men. Serum steroid levels were determined after extraction, using specific RIAs. Allopregnanolone levels in fertile women in the follicular phase were similar to those in age-matched men; no significant difference was found between fertile women in the follicular phase and postmenopausal women. The highest levels were found in fertile women during the luteal phase (P< 0.01). An age-related decrease was observed in men (P < 0.01), but not in women. P and DHEA levels were significantly higher in women than in men and were higher in fertile women than in postmenopausal women (P < 0.01). Both P and DHEA showed an age-related decrease in men and women (P < 0.01). Serum allopregnanolone and P, but not DHEA, significantly increased in response to a GnRH test, whereas corticotropin-releasing factor and ACTH tests elicited a significant increase in allopregnanolone, P, and DHEA levels (P < 0.01). The suppression of adrenal steroidogenesis by dexamethasone markedly reduced both allopregnanolone and DHEA serum levels (P < 0.01). In conclusion, the present study demonstrated that although men show an age-related decrease, serum allopregnanolone levels in women do not change with age and correlate with P levels during the menstrual cycle and in response to endocrine tests. Ovary and adrenal cortex may be major sources of circulating allopregnanolone in fertile women.

Circulating levels of allopregnanolone in humans: gender, age, and endocrine influences.

Allopregnanolone is a neuroactive steroid involved in modulating behavioral functions, stress, and neuroendocrine axes in rats. Changes in plasma allopregnanolone levels throughout the menstrual cycle have been reported in healthy women, but there exists no information on the possible gender or age-related changes or on the source(s) of circulating allopregnanolone. The aim of the present study was to assess serum allopregnanolone concentrations according to gender, menstrual cycle, age, and menopause in normal men and women; serum progesterone (P) and dehydroepiandrosterone (DHEA) levels were evaluated in the same specimens. In addition, the possible source of circulating allopregnanolone in fertile women was investigated by using stimulatory and inhibitory endocrine tests acting on the ovary and/or adrenal cortex. The present study included 189 fertile women, 112 postmenopausal women, and 46 men. Serum steroid levels were determined after extraction, using specific RIAs. Allopregnanolone levels in fertile women in the follicular phase were similar to those in age-matched men; no significant difference was found between fertile women in the follicular phase and postmenopausal women. The highest levels were found in fertile women during the luteal phase (P < 0.01). An age-related decrease was observed in men (P < 0.01), but not in women. P and DHEA levels were significantly higher in women than in men and were higher in fertile women than in postmenopausal women (P < 0.01). Both P and DHEA showed an age-related decrease in men and women (P < 0.01). Serum allopregnanolone and P, but not DHEA, significantly increased in response to a GnRH test, whereas corticotropin-releasing factor and ACTH tests elicited a significant increase in allopregnanolone, P, and DHEA levels (P < 0.01). The suppression of adrenal steroidogenesis by dexamethasone markedly reduced both allopregnanolone and DHEA serum levels (P < 0.01). In conclusion, the present study demonstrated that although men show an age-related decrease, serum allopregnanolone levels in women do not change with age and correlate with P levels during the menstrual cycle and in response to endocrine tests. Ovary and adrenal cortex may be major sources of circulating allopregnanolone in fertile women.