A rodent model of premenstrual dysphoria: progesterone withdrawal induces depression-like behavior that is differentially sensitive to classes of antidepressants

(S)-S-adenosylmethionine in the treatment of pre-menstrual disorders in adult women: A protocol for an open-label pilot study

Pre-menstrual disorders, including pre-menstrual syndrome and pre-menstrual dysphoric disorder, are highly prevalent disorders in women of reproductive age. Pre-menstrual disorders are associated with debilitating symptoms that onset in the days prior to menses. A complex interplay between hormonal fluctuations, cellular sensitivity, and psychosocial stressors likely underly the pathophysiology of pre-menstrual disorders. Current treatment options include selective serotonin reuptake inhibitors, hormonal therapies, and psychosocial support. There is growing evidence for oestrogen, progesterone, gonadotropin Releasing Hormone analogues and Complementary and Alternative Medicines in treating Pre-menstrual disorders. (S)-S-adenosylmethionine is a complementary and alternative medicine with postulated roles in the treatment of depression, with a rather rapid onset of action and minimal side effect profile. We propose a protocol for investigating the efficacy of (S)-S-adenosylmethionine in the treatment of pre-menstrual disorders. The proposed study is an open label pilot study, that will recruit thirty women between the ages of 18-45 who experience a pre-menstrual disorder. Daily and interval questionnaires will provide a quantification of symptoms across four menstrual cycles (16 weeks). During two consecutive menstrual cycles it is proposed that participants receive oral (S)-S-adenosylmethionine Complex 400 mg three times a day (total daily dose 1200 mg), during the pre-menstrual time-period (14 days prior to menses). Changes in pre-menstrual disorder symptoms between control and treatment cycles will assist in elucidating the clinical efficacy of (S)-S-adenosylmethionine. This study has the potential to support a larger double blinded, placebo controlled randomised control trial and aims to enrich the knowledge surrounding pre-menstrual disorders.

Environmental stress during adolescence promotes depression-like behavior and endocrine abnormalities in rats

OBJECTIVE

To assess the ability of environmental stress (ES) during adolescence on depression-like behaviors and endocrinology in rats.

METHODS

Male and female Sprague-Dawley rats before or during puberty were divided into three groups: control group (CON), low-frequency ES group (LF), and high-frequency ES group (HF). ES included water/food deprivation and reversal of day and night. After 4 weeks of ES, the behavioral tests were performed. Plasma concentrations of hormones and peptides were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

ES induced a significant decrease in sucrose preference value in female adolescent rats but not males. In prepubertal rats, the reductions in sucrose preference upon ES were observed without a sex-specific effect. Compared with the CON group, female adolescent rats showed a significant increase, while male adolescent rats showed a significant decrease in plasma corticosterone (CORT) after ES. Also, ES significantly increased plasma leptin in female and male adolescent rats. Moreover, ES significantly increased plasma cholecystokinin (CCK), neuropeptide Y (NPY), and testosterone (TS) levels in adolescent female rats but not in males. No significant differences were found in plasma progesterone and E2 among adolescent rats. The prepubertal male rats showed significant plasma E2 and TS increase after ES, while there were no significant differences between groups in plasma CORT, leptin, CCK, NPY, and progesterone.

CONCLUSIONS

ES may cause depression-like behaviors in adolescent female rats. Our findings supplement the scientific basis for formulating strategies to treat and prevent adolescent depression.

Estrogen, progesterone, cortisol, brain-derived neurotrophic factor, and vascular endothelial growth factor during the luteal phase of the menstrual cycle in women with premenstrual dysphoric disorder

The interplay between ovarian hormones, stress, and inflammatory markers in developing premenstrual dysphoric disorder (PMDD) remains inadequately understood. This study investigated the associations of dynamic changes in the levels of estrogen, progesterone, cortisol, brain-derived neurotrophic factor (BDNF), and vascular endothelial growth factor (VEGF) with PMDD during the luteal phase of the menstrual cycle. A total of 58 women with PMDD and 50 healthy women were recruited in this study. These women's estrogen, progesterone, cortisol, BDNF, and VEGF levels were evaluated during the preovulation (PO), mid-luteal (ML), and late-luteal (LL) phases. Furthermore, the severity of P MDD symptoms, depressive symptoms, perceived stress, inattention, craving for sweet foods, and fatigue was assessed. The findings revealed that women with PMDD with higher levels of progesterone during the ML or LL phase or a greater increase (ML-PO) or higher sum (ML + LL) of luteal progesterone level exhibited a greater increase in PMDD symptoms during the luteal phase than did the healthy controls. Furthermore, women with PMDD exhibited higher cortisol levels during the LL phase than did the controls. The BDNF level was negatively correlated with PMDD severity. Furthermore, BDNF and VEGF levels were negatively correlated with inattention and craving for sweet foods among women with PMDD. These results suggest an association between progesterone and the exacerbation of PMDD symptoms during the LL phase. Women with PMDD have relatively high cortisol levels during the LL phase. Future investigations with experimental designs or larger sample sizes are warranted to verify the roles of progesterone and cortisol in the development of PMDD.

Paeonol ameliorates hippocampal neuronal damage by inhibiting GRM5/GABBR2/β-arrestin2 and activating the cAMP-PKA signaling pathway in premenstrual irritability rats

Premenstrual dysphoric disorder (PMDD) is a periodic psychiatric disorder with high prevalence in women of childbearing age, seriously affecting patients' work and life. Currently, the international first-line drugs for PMDD have low efficiency and increased side effects. Paeonol, a major component of the traditional Chinese medicine Cortex Moutan, has been applied in treating PMDD in China with satisfactory results, but the therapeutic mechanism is not fully understood. This study aims to evaluate the therapeutic effects and pharmacological mechanisms of paeonol on the main psychiatric symptoms and hippocampal damage in PMDD. We established a premenstrual irritability rat model by the resident-intruder paradigm and performed elevated plus maze and social interactions. And we employed the HE and Nissl staining techniques to observe the therapeutic effect of paeonol on hippocampal damage in PMDD rats. Subsequently, Elisa, qRT-PCR Array, Western Blotting, and cell models were utilized to elucidate the underlying molecular mechanisms through which paeonol intervenes in treating PMDD. In this study, we demonstrated the therapeutic effects of paeonol on irritability, anxiety, and social withdrawal behaviors in rats. In addition, we found that paeonol significantly reduced the serum corticosterone (CORT) level, improved hippocampal morphological structure and neuron number, and reduced hippocampal neuron apoptosis in PMDD rats. Paeonol reduced GRM5, GABBR2, β-arrestin2, and GRK3 expression levels in hippocampal brain regions of PMDD rats and activated the cAMP/PKA signaling pathway. Inhibitor cell experiments showed that paeonol specifically ameliorated hippocampal injury by modulating the β-arrestin2/PDE4-cAMP/PKA signaling pathway. The present study demonstrates, for the first time, that paeonol exerts a therapeutic effect on periodic psychotic symptoms and hippocampal injury in PMDD through inhibiting GRM5/GABBR2/β-arrestin2 and activating cAMP-PKA signaling pathway. These findings enhance our understanding of the pharmacological mechanism underlying paeonol and provide a solid scientific foundation for its future clinical application.

Characterization of pathogenic factors for premenstrual dysphoric disorder using machine learning algorithms in rats

We established a methodology using machine learning algorithms for determining the pathogenic factors for premenstrual dysphoric disorder (PMDD). PMDD is a disease characterized by emotional and physical symptoms that occurs before menstruation in women of childbearing age. Owing to the diverse manifestations and various pathogenic factors associated with this disease, the diagnosis of PMDD is time-consuming and challenging. In the present study, we aimed to establish a methodology for diagnosing PMDD. Using an unsupervised machine-learning algorithm, we divided pseudopregnant rats into three clusters (C1 to C3), depending on the level of anxiety- and depression-like behaviors. From the results of RNA-seq and subsequent qPCR of the hippocampus in each cluster, we identified 17 key genes for building a PMDD diagnostic model using our original two-step feature selection with supervised machine learning. By inputting the expression levels of these 17 genes into the machine learning classifier, the PMDD symptoms of another group of rats were successfully classified as C1-C3 with an accuracy of 96%, corresponding to the classification by behavior. The present methodology would be applicable for the clinical diagnosis of PMDD using blood samples instead of samples from the hippocampus in the future.

Towards understanding the biology of premenstrual dysphoric disorder: From genes to GABA

Premenstrual dysphoric disorder (PMDD) is a severe mood disorder, with affective symptoms that rise and fall in concert with the hormonal fluctuations of the menstrual cycle. PMDD's pathophysiology is poorly understood. This review describes recent research on potential biological contributors to PMDD, with a focus on neuroactive steroids, genetics, neuroimaging and cellular studies. Studies suggest that a key contributor is abnormal central nervous system (CNS) response to fluctuations in neuroactive steroid hormones. Imaging studies are limited but support alterations in serotonergic and GABA transmission. Genetic studies suggest heritability, yet specific genetic contributors have not been characterized. Finally, recent cutting-edge cellular studies indicate an underlying vulnerability to the effect of sex hormones at a cellular level. Overall the findings across studies do not yet fit together into a complete description of the underlying biology of PMDD. It is possible that PMDD consists of biological subtypes, and future research may benefit from a subtyping approach.

Agmatine prevents the manifestation of impulsive burying and depression-like behaviour in progesterone withdrawn female rats

Premenstrual dysphoric disorder (PMDD) is characterized by various physical and affective symptoms, including anxiety, irritability, anhedonia, social withdrawal, and depression. The present study investigated the role of the agmatinergic system in animal model of progesterone withdrawal in female rats. Chronic progesterone exposure of female rats for 21 days and its abrupt withdrawal showed enhanced marble burying, increased immobility time, and reduced no. of entries in open arm as compared to control animals. The progesterone withdrawal-induced enhanced marble burying anxiety and immobility time was significantly attenuated by agmatine (5-20 mg/kg, i.p.), and its endogenous modulators like L-arginine (100 mg/kg, i.p.), amino-guanidine (25 mg/kg, i.p.) and arcaine (50 mg/kg, i.p.) by their once-daily administration from day 14-day 21 of the protocol. We have also analysed the levels of agmatine, progesterone, and inflammatory cytokines in the hippocampal region of progesterone withdrawn rats. There was a significant decline in agmatine and progesterone levels and an elevation in cytokine levels in the hippocampal region of progesterone withdrawn rats compared to the control animals. In conclusion, the present studies suggest the importance of the endogenous agmatinergic system in progesterone withdrawal-induced anxiety-like and depression-like behaviour. The data also projects agmatine as a potential therapeutic target for the premenstrual dysphoric disorder.

Profiling GABA(A) Receptor Subunit Expression in the Hippocampus of PMDD Rat Models Based on TCM Theories

γ-Aminobutyric acid type A receptors (GABAARs) play an important role in cognitive and emotional regulation and are related to the hippocampus. However, little is known regarding patterns of hippocampal GABAAR subunit expression in rat models of premenstrual dysphoric disorder (PMDD). This study investigated the above changes by establishing two PMDD rat models based on Traditional Chinese Medicine (TCM) theories, namely, PMDD liver-qi invasion syndrome (PMDD-LIS) and PMDD liver-qi depression syndrome (PMDD-LDS). Behavioral tests were used to detect depression and irritability emotion. Western blot analysis was used to investigate protein levels of GABAAR α1, α2, α4, α5, β2, β3, and δ subunits, whereas ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis was performed to determine gamma-aminobutyric acid (GABA) and glutamate (Glu) levels in the hippocampus across each group. Concurrently, behavioral data indicated that the PMDD-LDS and PMDD-LIS rat models had been successfully established. GABAAR α2, α5, β2, and δ subunit was significantly upregulated, whereas α4 was significantly downregulated (P < 0.05) in PMDD-LDS rat models relative to controls. On the other hand, GABAAR α1, α2, and β3 were significantly downregulated while α4 and β2 were significantly upregulated in PMDD-LIS rat models relative to the control group (P < 0.05). Moreover, GABA levels significantly decreased, while Glu and the ratio of glutamate to GABA increased in PMDD-LIS rat models (P < 0.05). Conversely, GABA and Glu levels significantly decreased, whereas the ratio of glutamate to GABA increased in PMDD-LIS rat models (P < 0.05). Conclusively, our results revealed differential expression of GABAAR α1, α2, α4, α5, β2, β3, and δ subunits between PMDD-LIS and PMDD-LDS rat models, suggesting that they may be biomarkers in the pathogenesis of PMDD.

The Serotonergic System and Bone Metabolism During Pregnancy and Lactation and the Implications of SSRI Use on the Maternal-Offspring Dyad

Lactation is a physiological adaptation of the class Mammalia and is a product of over 200 million years of evolution. During lactation, the mammary gland orchestrates bone metabolism via serotonin signaling in order to provide sufficient calcium for the offspring in milk. The role of serotonin in bone remodeling was first discovered over two decades ago, and the interplay between serotonin, lactation, and bone metabolism has been explored in the years following. It is estimated that postpartum depression affects 10-15% of the population, and selective serotonin reuptake inhibitors (SSRI) are often used as the first-line treatment. Studies conducted in humans, nonhuman primates, sheep, and rodents have provided evidence that there are consequences on both parent and offspring when serotonin signaling is disrupted during the peripartal period; however, the long-term consequences of disruption of serotonin signaling via SSRIs during the peripartal period on the maternal and offspring skeleton are not fully known. This review will focus on the relationship between the mammary gland, serotonin, and bone remodeling during the peripartal period and the skeletal consequences of the dysregulation of the serotonergic system in both human and animal studies.

Premenstrual disorders: Premenstrual syndrome and premenstrual dysphoric disorder

Recently, the term premenstrual disorders (PMDs), which includes premenstrual syndrome and premenstrual dysphoric disorder as a continuum, has been proposed. Although the precise etiology of PMDs remains unknown, the involvement of hormonal fluctuations is clear. The brain transmitters, serotonin and γ-amino butyric acid, also seem to be involved. Serotonin reuptake inhibitors and oral contraceptives are the current mainstay of treatment, but these are insufficient. Even the currently used prospective two-period symptom diary is not widely used in actual clinical practice, creating a major problem of discrepancy between research and clinical practice. In this review, I would like to outline the latest information and problems in the etiology, diagnosis, and treatment of PMDs, with an emphasis on promising new therapies.

Risks of major affective disorders following a diagnosis of premenstrual dysphoric disorder: A nationwide longitudinal study

Whether a history of premenstrual dysphoric disorder (PMDD) is associated with a subsequent risk of major affective disorders remains unclear. This study aimed to examine the risk of unipolar depression and bipolar disorder in women with PMDD compared with those without PMDD. This study used data from the Taiwan National Health Insurance Research Database. Women who were diagnosed with PMDD and had no history of any major affective disorder were included. The controls were women without PMDD matched for demographics and physical and psychiatric comorbidities. Cox regression was used to estimate the risk of unipolar depression and bipolar disorder. We included 8222 women with PMDD and 32,888 matched controls. After adjusting for potential confounders, we found that the women with PMDD were associated with a higher risk of unipolar depression [hazard ratio (HR) 2.58; 95 % confidence interval (CI), 2.23-2.98] and bipolar disorder (HR 2.50; 95 % CI 1.62-3.88) than the controls. The PMDD group had a younger age at the diagnosis of unipolar depression (37.11 vs 41.59 years) and bipolar disorder (35.59 vs 42.02 years, p = 0.002), and shorter duration between enrollment and onset of unipolar depression (2.97 vs 5.33 years, p < 0.001) and bipolar disorder (3.05 vs 5.57 years, p < 0.001). Our results showed a strong association between PMDD and major affective disorders. Healthcare workers should be aware of patients with PMDD and the risk of developing major affective mental disorders.

Role of allopregnanolone-mediated γ-aminobutyric acid A receptor sensitivity in the pathogenesis of premenstrual dysphoric disorder: Toward precise targets for translational medicine and drug development

Premenstrual dysphoric disorder (PMDD) can be conceptualized as a disorder of suboptimal sensitivity to neuroactive steroid hormones. Its core symptoms (emotional instability, irritability, depression, and anxiety) are related to the increase of stress sensitivity due to the fluctuation of hormone level in luteal phase of the menstrual cycle. In this review, we describe the emotional regulatory effect of allopregnanolone (ALLO), and summarize the relationship between ALLO and γ-aminobutyric acid A (GABA_A) receptor subunits based on rodent experiments and clinical observations. A rapid decrease in ALLO reduces the sensitivity of GABA_A receptor, and reduces the chloride influx, hindered the inhibitory effect of GABAergic neurons on pyramidal neurons, and then increased the excitability of pyramidal neurons, resulting in PMDD-like behavior. Finally, we discuss in depth the treatment of PMDD with targeted GABA_A receptors, hoping to find a precise target for drug development and subsequent clinical application. In conclusion, PMDD pathophysiology is rooted in GABA_A receptor sensitivity changes caused by rapid changes in ALLO levels. Targeting GABA_A receptors may alleviate the occurrence of PMDD.

Effects of acute estradiol and progesterone on perimenstrual exacerbation of suicidal ideation and related symptoms: a crossover randomized controlled trial

Female suicide attempts peak peri-menstrually-around the onset of menses-when the ovarian steroids estradiol (E2) and progesterone (P4) fall rapidly. Given preclinical evidence that withdrawal from either E2 or P4 can provoke behaviors consistent with elevated suicide risk, we hypothesized that withdrawal from one or both of these steroids contributes to perimenstrual exacerbation of suicidal ideation (SI) and related symptoms. In a randomized, controlled, double-blind crossover experiment (NCT03720847), a transdiagnostic sample of naturally cycling, medically healthy psychiatric outpatients reporting past-month SI completed two conditions during two different 14-day experimental intervals (days 7-20 where the luteinizing hormone surge = day 0), separated by a monthlong washout cycle. In the E2 and P4 (EP) condition, participants received transdermal E2 (0.1 mg/day) plus oral micronized P4 (200 mg/day as 100 mg twice daily) to buffer perimenstrual steroid withdrawal. A matched placebo (PBO) condition allowed natural perimenstrual steroid withdrawal. Participants reported daily SI and planning (primary outcomes) and indices of depression (low mood, hopelessness), threat sensitivity (anxiety, perceived stress), executive functioning (difficulty concentrating, impulsivity), and social cognitive bias (rejection sensitivity, perceived burdensomeness). In baseline cycles, no participant met prospective criteria for DSM-5 premenstrual dysphoric disorder, but 59% met all criteria except full follicular symptom remission, and 93% showed the highest SI in the perimenstrual phase. Of 29 randomized, 28 were analyzed (14 EP-PBO, 14 PBO-EP). Experimental administration of E2 and P4 (relative to PBO) reduced perimenstrual exacerbation of SI, suicide planning, depression, hopelessness, perceived stress, rejection sensitivity, and perceived burdensomeness, particularly in the perimenstrual (natural E2 and P4 withdrawal) days. Further, delayed withdrawal from experimental E2 and P4 (but not PBO) recapitulated SI, hopelessness, and rejection sensitivity. Acute perimenstrual withdrawal from ovarian steroids may play a causal role in perimenstrual worsening of depression and SI.

Ferulic acid inhibits catamenial epilepsy through modulation of female hormones

Approximately 40% of women with epilepsy experience perimenstrual seizure exacerbation, referred to as catamenial epilepsy. These seizures result from cyclic changes in circulating progesterone and estradiol levels and there is no effective treatment for this form of intractable epilepsy. We artificially increased progesterone levels and neurosteroid levels (pseudo-pregnancy) in adult Swiss albino female mice (19-23 g) by injecting them with pregnant mares' serum gonadotropin (5 IU s.c.), followed by human chorionic gonadotropin (5 IU s.c.) after 46 h. After this, ferulic acid (25, 50, 100 mg/kg i.p.) treatment was given for 10 days. During treatment, progesterone, estradiol, and corticosterone levels were estimated in blood on days 1, 5, and 10. Neurosteroid withdrawal was induced by finasteride (50 mg/kg, i.p.) on treatment day 9. Twenty-four hours after finasteride administration (day 10 of treatment), seizure susceptibility was evaluated with the sub-convulsant pentylenetetrazol (PTZ) dose (40 mg/kg i.p.). Four to six hours after PTZ, animals were assessed for depression like phenotypes using tail-suspension test (TST). Four to six hours following TST, animals were euthanized, and discrete brain parts (cortex and hippocampus) were separated for estimation of norepinephrine, serotonin, and dopamine as well as glutamic acid decarboxylase (GAD) enzyme activity. PMSG and HCG treatment elevated progesterone and estradiol levels, assessed on days 1, 5, and 10 causing a state of pseudo-pregnancy. Treatment with finasteride increased seizure susceptibility and depression-like characteristics possibly due to decreased progesterone and elevated estrogen levels coupled with decreased monoamine and elevated corticosterone levels. Ferulic acid treatment, on the other hand, significantly decreased seizure susceptibility and depression like behavior, possibly because of increased progesterone, restored estradiol, corticosterone, monoamines, and GAD enzyme activity. We concluded anticonvulsant effect of ferulic acid in a mouse model of catamenial epilepsy, evidenced by favourable seizure attenuation and curative effect on the circulating progesterone, estradiol, and corticosterone levels along with restorative effect on GAD enzyme activity and monoamine levels.

Resident intruder paradigm-induced PMDD rat model of premenstrual irritability: behavioral phenotypes, drug intervention, and biomarkers

BACKGROUND

Premenstrual dysphoric disorder (PMDD) is high in women of childbearing age with obvious premenstrual irritability. However, reliable animal models are still lacking.

MATERIALS AND METHODS

PMDD rat model of premenstrual irritability was induced by the resident-intruder paradigm (RIP). Behavioral characteristics were determined by the aggressive behavior test, elevated plus maze, open-field test, and breast width measurement. The estrous cycle in rats was artificially manipulated by bilateral ovariectomy and exogenous hormone injection to verify the model phenotype's dependence on the estrous cycle. Fluoxetine and Baixiangdan capsules were administered by gavage to determine the symptom improvement effect of PMDD irritability. Biomarkers in serum and brain were detected using ELISA, and GABRA4 was detected in the brain by RT-PCR and Western blot.

RESULTS

Rat models demonstrated similar clinical characteristics as PMDD, such as premenstrual irritability and anxiety, and the above symptoms were estrous cycle-dependent. In addition, the levels of progesterone (P) and ALLO hormones decreased in the serum, hippocampus, amygdala, and frontal lobe in the NR phase. The contents of 5-HT in the brain were significantly increased, while NE and GABA contents were considerably reduced. Moreover, mRNA and protein expression of GABRA4 levels in model rats' amygdala, hippocampus, and frontal lobe were significantly increased, while drug intervention downregulated its expression in these tissues.

CONCLUSION

Premenstrual irritability rat model of PMDD demonstrates a behavioral phenotype consistent with the clinical symptoms of PMDD and micro index. The increased levels of 5-HT, NE, and expression of GABRA4, as well as the decrease of GABA, P, and ALLO levels, may be critical biomarkers of the abnormal changes that occur during the pathogenesis of PMDD.

Gabrb2 knock-out mice exhibit double-directed PMDD-like symptoms: GABAAR subunits, neurotransmitter metabolism disruption, and allopregnanolone binding

Background: Premenstrual dysphoric disorder (PMDD) is a severe mood disorder with pathological changes rooted in GABRB2 copy number variation. Here, we aimed to elucidate the gene dose effect and allopregnanolone binding mechanism of Gabrb2 on possible PMDD-like and comorbid phenotypes in knockout mice.

Methods: PMDD-like behaviors of Gabrb2-knockout mice were measured through various tests. Western Blot and ELISA were used to detect changes in the GABAAR subunits and related neurotransmitter changes in mice respectively for the internal mechanism. The response of mice to allopregnanolone (ALLO) was examined through an exogenous ALLO injection, then validated by the patch-clamp technique to elaborate the potential mechanism of ALLO-mediated GABAAR.

Results: Gabrb2-knockout mice displayed changes in anxiety-like and depression-like emotions opposite to PMDD symptoms, changes in social, learning, and memory capacities similar to PMDD symptoms, and pain threshold changes opposite to PMDD symptoms. GABAAR δ subunit expression in the brains of the Gabrb2-knockout mice was significantly higher than that of Wild-type mice (P<0.05). Gabrb2-knockout mice demonstrated neurotransmitter metabolism disturbance of GABA, Glu, acetylcholine, DA, norepinephrine, and epinephrine. Moreover, Gabrb2-knockout mice did not display the expected phenotypic effect after ALLO injection. Relative to WT mice, the knockout of the β2 subunit gene enhanced the agonistic effect of ALLO on GABAA receptors in cortical neuronal cells.

Conclusions: GABAAR β 2 regulates PMDD-like behaviors. The ALLO binding site may not be located on β two subunits, abnormal δ and ε subunit expression in the mouse brain and the disturbance of neurotransmitters may result in ALLO sensitivity.

Kamishoyosan Alleviates Anxiety-like Behavior in a Premenstrual Syndrome Rat Model

Kamishoyosan (KSS) is a traditional Japanese Kampo medicine that is prescribed for hormonal change-induced mood disorders including premenstrual syndrome (PMS). In clinical studies, KSS exhibited ameliorative effects on mood symptoms of PMS, such as anxiety and irritability. However, the mechanism underlying the beneficial effects of KSS is unclear. In the present study, we investigated the involvement of serotonergic machinery in the anxiolytic effects of KSS on hormonally-induced anxiety-like behavior in progesterone withdrawal (PWD) rats, which were used as a model of PMS. Female rats were injected with progesterone daily for 21 days. At 48 h after the final progesterone injection, anxiety-like behavior was evaluated using the elevated plus maze. KSS was administered orally to PWD rats 1 h prior to the test and significantly attenuated PWD-induced anxiety-like behavior. This ameliorative effect of KSS was reversed by WAY-100635, a serotonin (5-HT)_1A receptor antagonist. The effect of KSS on serotonergic transmission in the prefrontal cortex of PWD rats was also evaluated using an in vivo microdialysis procedure. KSS significantly increased the extracellular 5-HT level in the prefrontal cortex of PWD rats. In conclusion, our results suggest that KSS alleviates PWD-induced anxiety-like behavior at least partly by activating 5-HT_1A receptors and enhancing serotonergic transmission.

Imaging the human brain on oral contraceptives: A review of structural imaging methods and implications for future research goals

Worldwide over 150 million women use oral contraceptives (OCs), which are the most prescribed form of contraception in both the United States and in European countries. Sex hormones, such as estradiol and progesterone, are important endogenous hormones known for shaping the brain across the life span. Synthetic hormones, which are present in OCs, interfere with the natural hormonal balance by reducing the endogenous hormone levels. Little is known how this affects the brain, especially during the most vulnerable times of brain maturation. Here, we review studies that investigate differences in brain gray and white matter in women using OCs in comparison to naturally cycling women. We focus on two neuroimaging methods used to quantify structural gray and white matter changes, namely structural MRI and diffusion MRI. Finally, we discuss the potential of these imaging techniques to advance knowledge about the effects of OCs on the brain and wellbeing in women.

Can animal models resemble a premenstrual dysphoric condition?

Around 80% of women worldwide suffer mild Premenstrual Disorders (PMD) during their reproductive life. Up to a quarter are affected by moderate to severe symptoms, and between 3% and 8% experience a severe form. It is classified as premenstrual syndrome (PMS) with predominantly physical symptoms and premenstrual dysphoric disorder (PMDD) with psychiatric symptoms. The present review analyzes the factors associated with PMD and the Hypothalamus-Pituitary-Ovarian or Hypothalamus-Pituitary-adrenal axis and discusses the main animal models used to study PMDD. Evidence shows that the ovarian hormones participate in PMDD symptoms, and several points of regulation of their synthesis, metabolism, and target sites could be altered. PMDD is complex and implies several factors that require consideration when this condition is modeled in animals. Of particular interest are those points related to areas that may represent opportunities to develop new approximations to understand the mechanisms involved in PMDD and possible treatments.

Melatonin for premenstrual syndrome: A potential remedy but not ready

Premenstrual syndrome (PMS), a recurrent and moderate disorder that occurs during the luteal phase of the menstrual cycle and quickly resolves after menstruation, is characterized by somatic and emotional discomfort that can be severe enough to impair daily activities. Current therapeutic drugs for PMS such as selective serotonin reuptake inhibitors are not very satisfying. As a critical pineal hormone, melatonin has increasingly been suggested to modulate PMS symptoms. In this review, we update the latest progress on PMS-induced sleep disturbance, mood changes, and cognitive impairment and provide possible pathways by which melatonin attenuates these symptoms. Moreover, we focus on the role of melatonin in PMS molecular mechanisms. Herein, we show that melatonin can regulate ovarian estrogen and progesterone, of which cyclic fluctuations contribute to PMS pathogenesis. Melatonin also modulates gamma-aminobutyric acid and the brain-derived neurotrophic factor system in PMS. Interpreting the role of melatonin in PMS is not only informative to clarify PMS etiology but also instructive to melatonin and its receptor agonist application to promote female health. As a safe interaction, melatonin treatment can be effective in alleviating symptoms of PMS. However, symptoms such as sleep disturbance, depressive mood, cognitive impairment are not specific and can be easily misdiagnosed. Connections between melatonin receptor, ovarian steroid dysfunction, and PMS are not consistent among past studies. Before final conclusions are drawn, more well-organized and rigorous studies are recommended.

Sex and estrous-phase dependent alterations in depression-like behavior following mild traumatic brain injury in adolescent rats

Following mild traumatic brain injury (TBI), high school and collegiate-aged females tend to report more emotional symptoms than males. Adolescent male and female rats (35 days old) were subjected to mild TBI and evaluated for anxiety- and depression-like behaviors using the elevated plus maze and forced swim test (FST), respectively, and cellular alterations. Injured brains did not exhibit an overt lesion, atrophy of tissue or astrocytic reactivity underneath the impact site at 6-week post-injury, suggestive of the mild nature of trauma. Neither male nor female brain-injured rats exhibited anxiety-like behavior at 2 or 6 weeks, regardless of estrous phase at the time of behavior testing. Brain-injured male rats did not exhibit any alterations in immobility, swimming and climbing times in the FST compared to sham-injured rats at either 2- or 6-week post-injury. Brain-injured female rats did, however, exhibit an increase in immobility (in the absence of changes in swimming and climbing times) in the FST at 6 weeks post-injury only during the estrus phase of the estrous cycle, suggestive of a depression-like phenotype. Combined administration of the estrogen receptor antagonist, tamoxifen, and the progesterone receptor antagonist, mifepristone, during proestrus was able to prevent the depression-like phenotype observed during estrus. Taken together, these data suggest that female rats may be more vulnerable to exhibiting behavioral deficits following mild TBI and that estrous phase may play a role in depression-like behavior.

Anticonvulsant Effect of Asparagus racemosus Willd. in a Mouse Model of Catamenial Epilepsy

Asparagus racemosus Willd. (Family Liliaceae), also known as female reproductive tonic, is traditionally used across the Sub-Himalayan region in Uttarakhand, India for treatment of epilepsy and disorders of female reproductive system. Therefore, in this study, we investigated the anticonvulsant effect of A. racemosus in a mouse model of catamenial epilepsy. We artificially increased progesterone and neurosteroid levels (a state of pseudo-pregnancy) in adult Swiss albino female mice by injecting pregnant mares' serum gonadotropin (PMSG) (5 IU s.c.), followed by human chorionic gonadotropin (HCG) (5 IU s.c.) after 46 h. In the following 10 days, A. racemosus treatment was given along with measurement of progesterone, estradiol, and corticosterone levels in the blood. Neurosteroid withdrawal was induced by finasteride (50 mg/kg, i.p.) on treatment day 9. Twenty-four hours after finasteride administration (day 10 of treatment), seizure susceptibility was evaluated with the sub-convulsant pentylenetetrazole (PTZ) dose (40 mg/kg i.p.). Four hours after PTZ, animals were assessed for depression like phenotypes followed by euthanasia and separation of brain parts (cortex and hippocampus). The results showed that PMSG and HCG treatment elevated progesterone and estradiol levels. Treatment with finasteride increased seizure susceptibility and depression due to decreased progesterone and elevated estrogen levels coupled with decreased monoamine and elevated corticosterone levels. A. racemosus treatment, on the other hand, significantly decreased seizure susceptibility and depression like behaviors, possibly because of increased progesterone, restored estradiol, corticosterone, and monoamine levels. We concluded that herbal formulations using A. racemosus root extracts may be used as monotherapy or adjuvant therapy along with available AEDs for the better and safe management of catamenial epilepsy as well as comorbid depression.

Influence of ovarian hormones on value-based decision-making systems: Contribution to sexual dimorphisms in mental disorders

Women and men exhibit differences in behavior when making value-based decisions. Various hypotheses have been proposed to explain these findings, stressing differences in functional lateralization of the brain, functional activation, neurotransmitter involvement and more recently, sex hormones. While a significant interaction of neurotransmitter systems and sex hormones has been shown for both sexes, decision-making in women might be particularly affected by variations of ovarian hormones. In this review we have gathered information from animal and human studies on how ovarian hormones affect decision-making processes in females by interacting with neurotransmitter systems at functionally relevant brain locations and thus modify the computation of decision aspects. We also review previous findings on impaired decision-making in animals and clinical populations with substance use disorder and depression, emphasizing how little we know about the role of ovarian hormones in aberrant decision-making.

A Japanese herbal medicine attenuates anxiety-like behavior through GABAA receptor and brain-derived neurotrophic factor expression in a rat model of premenstrual syndrome

Inochinohaha White (IHW) is a Japanese herbal medicine for treating women with anxiety associated with premenstrual syndrome (PMS). In this study, we examined the effects of IHW on anxiety-like behavior in rats undergoing progesterone withdrawal (PWD), a model for PMS. Female rats were injected daily with progesterone for 21 days. Water and ethanol extracts of IHW (WE-IHW and EE-IHW, respectively) were administered orally 15 days after the initiation of progesterone injections. Anxiety-like behavior in an elevated plus maze was evaluated 48 h after the final injection of progesterone. PWD induced anxiety-like behavior, and EE-IHW (300 mg/kg), but not WE-IHW, significantly attenuated this behavior. Administration of the GABA agonists, diazepam or muscimol, significantly attenuated PWD-induced anxiety-like behavior. To investigate the underlying mechanisms of IHW action, we analyzed GABAA receptor expression in the amygdala of these rats. EE-IHW ameliorated the PWD-induced decrease in GABAA receptor β2-subunit mRNA, although β2-subunit protein was unchanged. Brain-derived neurotrophic factor (BDNF) has been reported to have anxiolytic effects and enhance GABAergic synaptic transmission. We found that EE-IHW increased BDNF levels in a dose-dependent manner. Our results suggest that EE-IHW attenuates PWD-induced anxiety-like behavior by increasing GABAA receptor-mediated signaling via increases in β2-subunit and BDNF in the amygdala.

A forced swim-based rat model of premenstrual depression: effects of hormonal changes and drug intervention

Premenstrual dysphoric disorder (PMDD), a form of premenstrual syndrome (PMS), is a severe health disturbance that affects a patient’s emotions; it is caused by periodic psychological symptoms, and its pathogenesis remains unclear. As depression-like symptoms are found in a majority of clinical cases, a reliable animal model of premenstrual depression is indispensable to understand the pathogenesis. Herein, we describe a novel rat model of premenstrual depression, based on the forced swimming test, with a regular estrous cycle. The results showed that in the estrous cycle, the depression-like behavior of rats occurred in the non-receptive phase and disappeared in the receptive phase. Following ovariectomy, the depression-like symptoms disappeared and returned after a hormone priming regimen. Moreover, fluoxetine, an anti-depressant, could reverse the behavioral symptoms in these model rats with normal estrous cycle. Further, the model rats showed significant changes in the serum levels of estrogen and progesterone, hippocampal levels of allopregnanolone, 5-hydroxytryptamine, norepinephrine, and γ-aminobutyric acid (GABA), and in the expression of GABA_A receptor 4α subunit, all of which were reversed to physiological levels by fluoxetine. Overall, we established a reliable and standardized rat model of premenstrual depression, which may facilitate the elucidation of PMS/PMDD pathogenesis and development of related therapies.

Associations between sex hormones, sleep problems and depression: A systematic review

Sleep problems and depression are both common and have a high impact on quality of life. They are also strongly associated and commonly occur together. During the reproductive age, both sleep problems and depression are almost twice as common in women than men. Epidemiological studies show that women experience more sleep problems and depressive symptoms around times when sex hormones change, such as puberty and menopause, but it is unclear what effect sex hormones have on sleep problems and depression. This systematic review aims to summarize and evaluate studies that investigated the relationship between sex hormones, sleep and depression. Systematic search resulted in 2895 articles, of which 13 met inclusion criteria. Depressed patients showed worse sleep than controls, but no significant difference in endogenous hormone levels was found. Additionally, higher endogenous estrogen was associated with better sleep in controls, but associations between endogenous sex hormones and depressive symptoms were inconclusive. More research on the effect of sex hormones on sleep and depression is necessary.

Altered exploratory behaviour and increased food intake in the spiny mouse before menstruation: a unique pre-clinical model for examining premenstrual syndrome

STUDY QUESTION

Does the newly discovered menstruating spiny mouse exhibit behavioural and metabolic changes in correlation with premenstrual phases of the menstrual cycle?

SUMMARY ANSWER

This is the first report of cycle variability in the exploratory and interactive behaviour, and food consumption in menstruating spiny mice, and demonstrates that physiological changes are also dependent on within-subject variation.

WHAT IS KNOWN ALREADY

Premenstrual syndrome (PMS) is a prominent cyclic disorder that affects millions of women worldwide. More than 70% of women endure symptoms of impending menstruation, such as bloating, abdominal cramping and nausea to some degree. Consequently, ~8% of women experience recurrent physical and emotional symptoms which are extreme enough to disrupt daily life and seek intervention. Due to a lack of an appropriate animal model, the mechanisms underlying PMS are poorly understood, and subsequently, effective treatments are limited.

STUDY DESIGN, SIZE, DURATION

This study analyses the changes in behavioural responses to the investigator during vaginal lavage (n = 14), exploratory behaviour (n = 11) and metabolism (n = 20) across the menstrual cycle in the spiny mouse (Acomys cahirinus).

PARTICIPANTS/MATERIALS, SETTING, METHODS

We performed vaginal lavages on virgin spiny mice (6-8 months of age) and subjected each cohort of females to repeated measures for vaginal lavage, exploratory behaviour and metabolism. Stages of the menstrual cycle were designated as early follicular, late follicular, early luteal, late luteal, early menstrual and late menstrual, with the late luteal and early menstrual phases considered as premenstrual phases and analysed using generalized estimating equations. For vaginal lavage, the behavioural responses to researcher handling were scored on an increasing scale of severity during the lavage process (e.g. restraint, frequency of vocalizations, total handling time). For exploratory behaviour, exploration, memory and sociability were assessed through subjection to Open Field (OF), Novel Object Recognition (NORT), Social Novelty (SN) and Elevated Plus Maze (EPM) tests. For metabolism, physiological changes were measured over a 24-h period in metabolic cages. Results are mean ± SD with statistical significance set to P < 0.05.

MAIN RESULTS AND THE ROLE OF CHANCE

Qualitative behavioural assessment showed that compared to early follicular controls, during premenstrual phases, cycling females had significantly increased probability of: manifesting difficulties during restraint (4×, P < 0.01), vocalizing (8×, P < 0.01) and exhibiting isolation in the cage (40×, P = 0.041). We saw significant increases in handling time during the premenstrual phase in cycling females (76 ± 16 s) compared to controls (55 ± 7 s, P < 0.001). For exploratory behaviour, cycling females in their early menstrual phase travelled significantly less distance in the outer zone of the OF arena (13.3 ± 9.0 m) than females in their early luteal phase (22.3 ± 9.9 m, P = 0.038) and at significantly reduced velocities (40.2 ± 10.5 mm/s and 78.8 ± 31.0 mm/s, respectively, P = 0.006). These females also had fewer entries into the EPM open arms during the same phases (9.6 ± 6.1 and versus 20.0 ± 7.2, respectively, P = 0.030) and travelled less distance (3.2 ± 2.8 m versus 7.0 ± 5.5 m, respectively, P = 0.026). No differences were observed in NORT or SN across the cycle. In the metabolism studies, spiny mice demonstrated a significant increase in food consumption (percentage of body weight) during the early follicular and late luteal phases (3.9 ± 2.4% and 3.8 ± 2.1%, respectively) compared to the late follicular phase (2.3 ± 2.6%, P = 0.015).

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This is an observational study to determine fundamental changes in behaviour and metabolism in a novel species, and as such, lacks commercially available laboratory reagents and protocols specific to the spiny mouse.

WIDER IMPLICATIONS OF THE FINDINGS

The timing of these behavioural and physiological changes suggests that spiny mice exhibit symptoms analogous to PMS in higher order primates, thus providing a pre-clinical model for testing novel interventions to alleviate premenstrual symptoms and overcoming many limitations associated with this research area.

STUDY FUNDING/COMPETING INTEREST(S)

N.B. is supported by a Research Training Program stipend through Monash University. J.E. is supported by a Fellowship awarded by the Peter Fielding Foundation. The Hudson Institute of Medical Research is supported by the Victorian Government Operational Research Infrastructure Support. The authors declare no conflicts of interest.

Progesterone, reproduction, and psychiatric illness

Mood and anxiety disorders are vastly overrepresented in women, and one important contributor to these differences is the fluctuation in sex steroids in women during the reproductive years. Considerable evidence supports a role for abnormal sensitivity to these hormonal fluctuations for some women, who develop mood symptoms associated with reproductive transitions. This chapter presents evidence of the role of endogenous progesterone and its metabolites in such mood symptoms, and then goes on to cover the evidence concerning exogenous progesterone's effects on mood. Overall, the literature does not support an association between exogenous progesterone and negative mood in the general population, but does indicate that subset of women may be vulnerable to such effects. Research is lacking on women with psychiatric illness.

Allopregnanolone in premenstrual dysphoric disorder (PMDD): Evidence for dysregulated sensitivity to GABA-A receptor modulating neuroactive steroids across the menstrual cycle

Premenstrual dysphoric disorder (PMDD) is a severe mood disorder with core symptoms (affective lability, irritability, depressed mood, anxiety) and increased sensitivity to stress occurring in the luteal phase of the menstrual cycle. PMDD can be conceptualized as a disorder of suboptimal sensitivity to neuroactive steroid hormones (NASs). In this review, we describe the role of the NAS allopregnanolone (ALLO), a positive allosteric modulator of the GABA_A receptor (GABA_A-R), in PMDD's pathophysiology. We review evidence of impaired interaction between ALLO and GABA_A-Rs in terms of affective symptom expression, with evidence from rodent and human studies. We discuss evidence of increased luteal phase stress sensitivity as a result of poor ALLO-GABA control of the HPA axis. Finally, we describe how treatments such as selective serotonin reuptake inhibitors (SSRIs) and new drugs targeting GABA_A-Rs provide evidence for impaired ALLO-GABA function in PMDD. In sum, the literature supports the hypothesis that PMDD pathophysiology is rooted in impaired GABA_A-R response to dynamic ALLO fluctuations across the menstrual cycle, manifesting in affective symptoms and poor regulation of physiologic stress response.

Paeonol at Certain Doses Alleviates Aggressive and Anxiety-Like Behaviours in Two Premenstrual Dysphoric Disorder Rat Models

Premenstrual dysphoric disorder (PMDD) is a severe form of premenstrual syndrome (PMS), a common mental health disturbance associated with several periodic psychological symptoms in women. Selective serotonin reuptake inhibitors (SSRIs) are the first-line treatment for PMS/PMDD patients; however, side effects are inevitable, especially in long-term treatment. In previous studies, the natural compound paeonol in Moutan Cortex was found to play effective roles in central nervous system disorders with its anti-inflammatory, anti-oxidant, and neuroprotective effects. Consequently, we assume that paeonol might produce positive effects in the treatment of PMS/PMDD. In this study, the open-field test (OFT) and elevated plus maze (EPM) and light dark box (LDB) tests were performed in mice to determine the optimal dose of paeonol for treating anxiety. Then, paeonol was used to treat the progesterone withdrawal (PWD) and resident intruder paradigm (RIP) rat models of PMDD. Using these two reliable models, the OFT and EPM, LDB, and composite aggressive tests were performed to evaluate the effect of the drug on behavioural symptoms of PMDD. From the dosage screening results, the optimal anti-anxiety dose of paeonol was identified as 17.5 mg/kg/d for 7 days. With regard to the effect of paeonol on PMDD rat models, a significantly improvement was found in the behavioural symptoms, but the effective dose varied in different models. For the PWD model rats, treatment with 6.05 mg/kg paeonol could significantly improve anxiety and irritability, while that with 24.23 mg/kg paeonol resulted in anxiety-like effects in behavioural tests. In RIP model rats, treatment with 12.11 mg/kg paeonol demonstrated excellent effects in improving anxiety, particularly irritable emotional behaviour. In conclusion, our study indicates that paeonol is a potential therapeutic compound for PMS/PMDD; it is a drug option that helps establish dosage guidance for treatment of this condition.

Early- and Late-Luteal-Phase Estrogen and Progesterone Levels of Women with Premenstrual Dysphoric Disorder

Objective/introduction: The dynamics of ovarian hormone fluctuations during the luteal phase of the menstruation cycle were previously suggested to contribute to the development of premenstrual dysphoric disorder (PMDD) symptoms, but adequate empirical evidence has not been obtained from hormone concentration studies. We prospectively evaluated estrogen and progesterone levels in the early luteal (EL) and late luteal (LL) phases in women with PMDD and the association of these levels with PMDD symptom severity. Methods: 63 women with PMDD and 53 controls without such severe symptoms were evaluated for the estrogen and progesterone levels, and PMDD severity in the EL and LL phases. Results: The results demonstrated that the women with PMDD had a lower EL-phase estrogen level than the controls. Covariant analysis demonstrated that the interaction term between EL-phase estrogen and EL-phase progesterone level was associated with PMDD severity. Among women with lower EL estrogen levels, higher EL-phase progesterone was observed among the women with PMDD versus controls. These results suggest that low EL-phase estrogen level could moderate the provoking effect of EL progesterone in women with PMDD. Overall, these data suggest a possible role of estrogen and progesterone in the development of PMDD symptoms.

Animal models of major depression: drawbacks and challenges

Major depression is a leading contributor to the global burden of disease. This situation is mainly related to the chronicity and/or recurrence of the disorder, and to poor response to antidepressant therapy. Progress in this area requires valid animal models. Current models are based either on manipulating the environment to which rodents are exposed (during the developmental period or adulthood) or biological underpinnings (i.e. gene deletion or overexpression of candidate genes, targeted lesions of brain areas, optogenetic control of specific neuronal populations, etc.). These manipulations can alter specific behavioural and biological outcomes that can be related to different symptomatic and pathophysiological dimensions of major depression. However, animal models of major depression display substantial shortcomings that contribute to the lack of innovative pharmacological approaches in recent decades and which hamper our capabilities to investigate treatment-resistant depression. Here, we discuss the validity of these models, review putative models of treatment-resistant depression, major depression subtypes and recurrent depression. Furthermore, we identify future challenges regarding new paradigms such as those proposing dimensional rather than categorical approaches to depression.

Lowered Plasma Steady-State Levels of Progesterone Combined With Declining Progesterone Levels During the Luteal Phase Predict Peri-Menstrual Syndrome and Its Major Subdomains

BACKGROUND

It is unknown whether lowered steady state levels of sex hormones coupled with changes in those hormones during the menstrual cycle are associated with premenstrual syndrome (PMS).

OBJECTIVE

To examine associations between levels of progesterone and oestradiol during the menstrual cycle and PMS considering different diagnostic criteria for PMS.

METHODS

Forty-one women aged 18-45 years with a regular menstrual cycle completed the Daily Record of Severity of Problems (DRSP) for all 28 consecutive days of the menstrual cycle. Blood was sampled at days 7, 14, 21, and 28 to assay oestradiol and progesterone.

RESULTS

We developed a new diagnosis of peri-menstrual syndrome, which is characterized by increased DRSP severity in pre and post-menstrual periods and increased scores on the major DRSP dimensions, i.e., depression, physio-somatic symptoms, breast tenderness and appetite, and anxiety. This new diagnosis performed better than classical diagnoses of PMS, including that of the American College of Obstetricians and Gynecologists (ACOG). Lowered steady state levels of progesterone, when averaged over the menstrual cycle, together with declining progesterone levels during the luteal phase predict severity of peri-menstrual symptoms. Steady state levels of oestradiol and declining oestradiol levels during the cycle are also related to DRSP severity although most of these effects appeared to be mediated by progesterone.

CONCLUSION

A significant increase in menstrual-cycle related symptoms can best be conceptualized as "peri-menstrual syndrome" and may result from insufficient progesterone production (relative corpus luteum insufficiency), which, in part may result from lowered oestradiol production indicating suboptimal pre-ovulatory follicular development.

Short-term, low-dose fluoxetine prevents oestrous cycle-linked increase in anxiety-like behaviour in female rats

BACKGROUND AND AIMS

We sought a robust behavioural test that evoked increased anxiety-like behaviour during the late dioestrus phase of the oestrous cycle (similar to the premenstrual period in women) and tested whether this could be prevented by acute low-dose fluoxetine (FLX).

METHODS

Female Wistar rats in different stages of their cycle were exposed to four different tests of anxiety-like behaviour.

RESULTS

No oestrous cycle differences were detected in fear potentiated startle or conditioned freezing to an aversive context. In a light switch-off test where rats move from one compartment of a shuttle-box to the other to turn off an aversive light, females displayed enhanced responding in late dioestrus. During isolation restraint stress females in late dioestrus emitted three times more 22 kHz ultrasound vocalisations (USV) than at other cycle stages. Using the USV test, short-term administration of low-dose FLX (1.75 mg kg^-1, i.p.) designed to blunt the sharp fall in brain allopregnanolone concentration during late dioestrus but without affecting 5-HT systems, prevented the increase in isolation stress-evoked USVs.

CONCLUSIONS

The light switch-off and isolation restraint-induced USV tests evoke unconditioned adverse emotional responses that are ethologically relevant and sensitive to oestrous cycle stage. The USV test fulfils many criteria required of a model for premenstrual syndrome in women. Using the USV test, short-term administration of FLX to increase brain allopregnanolone concentration without affecting 5-HT systems prevented the increased USV responding in late dioestrus. Short-term low-dose FLX treatment may have potential to alleviate development of adverse premenstrual symptoms in women.

What do we know about sex differences in depression: A review of animal models and potential mechanisms

Clinical studies have shown that women are more susceptible to depression than men. Sex differences in depression have been associated with social, cultural, as well as biological factors. In spite of extensive preclinical studies in animal models for depression that have been used for understanding the mechanisms of the disease as well as for new drug development, a substantive lack of attention on sex-specific phenotypes in depression might mask the effect of sex on the outcome. In this review article, we summarize findings on the influence of sex on behavior in the most commonly used animal models for depression. We also discuss the potential underlying mechanisms of such sex-dependent variation in the phenotype, particularly in the neuroendocrine system.

Paeoniflorin, the Main Active Ingredient of Shuyu Capsule, Inhibits Cav1.2 and Regulates Calmodulin/Calmodulin-Dependent Protein Kinase II Signalling

The aim of this study was to explore the mechanism underlying the antidepression activity of paeoniflorin, the main active ingredient of paeony extract and Shuyu capsules, and determine its effect on the calmodulin/calmodulin-dependent protein kinase II (CaM/CaMKII) signalling pathway and on the possible target, the voltage-gated calcium channel (Ca_v). Rats at the nonacceptance stage were selected for premenstrual syndrome (PMS) depression modelling. Behavioural assays were used for model testing. Rats were given Shuyu capsules, paeony extract, and bupleurum. Western blot analysis was used to assess the expression levels of calcium voltage-gated channel subunit alpha 1 C (CACNA1C), brain-derived neurotrophic factor, and CaM/CaMKII signalling pathway proteins. Intracellular Ca²⁺ concentration in CHO cell line was measured using Fluo-4-AM and whole-cell patch clamps. The PMS depression model was successfully established and demonstrated that Shuyu can mitigate depressive behaviour in a rat PMS model. Paeony extract did not affect CACNA1C protein expression in rat hippocampi but did affect Ca_v1.2-mediated CaM/CaMKII signalling pathways. Paeoniflorin significantly inhibited KCl-induced increases in intracellular Ca²⁺ concentration and Ca_v1.2 current density. Further, it may function via the CaM/CaMKII pathway and its downstream signalling molecules by regulating Ca_v1.2, thus playing an important role in the treatment and alleviation of affective disorders.

Epidemiological Distribution and Subtype Analysis of Premenstrual Dysphoric Disorder Syndromes and Symptoms Based on TCM Theories

We performed an epidemiological investigation of subjects with premenstrual dysphoric disorder (PMDD) to identify the clinical distribution of the major syndromes and symptoms. The pathogenesis of PMDD mainly involves the dysfunction of liver conveyance and dispersion. Excessive liver conveyance and dispersion are associated with liver-qi invasion syndrome, while insufficient liver conveyance and dispersion are expressed as liver-qi depression syndrome. Additionally, a nonconditional logistic regression was performed to analyze the symptomatic features of liver-qi invasion and liver-qi depression. As a result of this analysis, two subtypes of PMDD are proposed, namely, excessive liver conveyance and dispersion (liver-qi invasion syndrome) and insufficient liver conveyance and dispersion (liver-qi depression syndrome). Our findings provide an epidemiological foundation for the clinical diagnosis and treatment of PMDD based on the identification of different types.

Maternal care and affective behavior in female offspring: Implication of the neurosteroid/GABAergic system

In female rats, the proestrus phase of the estrous cycle is associated with decreased levels of anxiety-like and depressive-like behavior relative to the metestrus phase. Progesterone likely modulate these behaviors, in part through the influence of its metabolite, allopregnanolone (THP) on hippocampal GABA_AR subunit expression. As natural variations in maternal care have been found to influence both progesterone levels at proestrus and anxiety-like behavior in female offspring, we sought to investigate the importance of maternal care and the estrous cycle on affective behavior in female rats that had received Low or High levels of licking/grooming (LG) during early life. Subjects were tested for anxiety-like behavior in the elevated plus maze at proestrus or metestrus or for estrous cycle-dependent changes in depressive-like anhedonic behavior with a saccharin preference test. GABA_AR subunit expression, and THP levels in the dorsal hippocampus and in plasma were also evaluated. Estrous cycle phase influenced saccharine preference and hippocampal THP level in both phenotypes. Low LG animals showed higher levels of hedonic behavior and anxiety-like behavior, irrespective of estrous cycle phase, as well as lower THP levels within the dorsal hippocampus when compared to High LG animals. Only High LG animals showed positive correlations between hippocampal THP levels and GABA_AR subunit expression, suggesting a relative insensitivity to THP's modulation of these receptor subunits in Low LG offspring. These findings suggest that natural variations in maternal care influence anxiety-like and hedonic behavior through the modulation of the neurosteroid/GABAergic system.

Shuyu Capsules Relieve Premenstrual Syndrome Depression by Reducing 5-HT3AR and 5-HT3BR Expression in the Rat Brain

The effects of the Shuyu capsule on 5-HT_3AR and 5-HT_3BR expression in a rat model of premenstrual syndrome (PMS) depression and on 5-HT_3AR and 5-HT_3BR expression and hippocampal neuron 5-HT₃ channel current were investigated, to elucidate its mechanism of action against PMS depression. PMS depression model rats were divided into depression and Shuyu- and fluoxetine-treated groups, which were compared to control rats for frontal lobe and hippocampal 5-HT_3AR and 5-HT_3BR expression and behavior. The depressed model rats displayed symptoms of depression, which were reduced in treated and normal control rats. Frontal lobe and hippocampal 5-HT_3AR and 5-HT_3BR levels were significantly higher in the model versus the control group and were significantly lower in the Shuyu group. As compared to control rats, the 5-HT₃R channel current in the model group was significantly higher; the 5-HT₃R channel current in hippocampal neurons treated with serum from Shuyu group rats was significantly lower than that in those treated with model group serum. Thus, PMS depression may be related to 5-HT_3AR and 5-HT_3BR expression and increased 5-HT₃ channel current. Shuyu capsules rectified abnormal 5-HT_3AR and 5-HT_3BR expression and 5-HT₃ channel current changes in a rat model; this finding may provide insight into treating PMS depression.

Environmental enrichment prevents anxiety-like behavior induced by progesterone withdrawal in two strains of rats

Stress vulnerability could influence the treatment response to anxiety associated with abrupt hormonal suppression. The present study explored the effects of different treatments on experimental anxiety induced by progesterone withdrawal (PW) in a stress-sensitive rat strain, Wistar Kyoto (WKY), in the burying behavior test (BBT). The following experimental series was conducted using independent groups of Wistar (control strain) and WKY ovariectomized rats: Experiment 1: Rats were treated for 5days with oil, a constant dose of progesterone (0.5mg/rat, s.c) or a combination of progesterone (0.5mg/rat, s.c) plus fluoxetine (10 mg/kg, i.p); on day 6, all rats were subjected to BBT. Experiment 2: Rats received corn oil or decreasing doses of progesterone (0.84, 0.67, 0.5, 0.33 and 0.17mg/rat; one dose daily); on day 6, the rats were subjected to BBT. Experiment 3: Rats were divided into two groups that were subjected to 30days of standard conditions or environmental enrichment (EE); from days 25 to 30, all rats received a fixed dose of progesterone (0.5mg/rat, s.c.) or vehicle. On day 31, the rats were tested with BBT. Results showed that PW increased anxiety in both strains, and fluoxetine prevented anxiety in WKY rats. In contrast, a gradual reduction of progesterone prevents the anxiety in Wistar but not in WKY. EE was preventive against the anxiety induced by PW in both strains of rats. Thus, the results suggest that anxiety induced by PW is prevented by EE while the anxiolytic effect of pharmacological treatments depends on stress vulnerability.

Premenstrual Dysphoric Disorder: Epidemiology and Treatment

Recently designated as a disorder in the DSM-5, premenstrual dysphoric disorder (PMDD) presents an array of avenues for further research. PMDD's profile, characterized by cognitive-affective symptoms during the premenstruum, is unique from that of other affective disorders in its symptoms and cyclicity. Neurosteroids may be a key contributor to PMDD's clinical presentation and etiology, and represent a potential avenue for drug development. This review will present recent literature on potential contributors to PMDD's pathophysiology, including neurosteroids and stress, and explore potential treatment targets.

Multimodal antidepressant vortioxetine increases frontal cortical oscillations unlike escitalopram and duloxetine--a quantitative EEG study in rats

Background and Purpose

EEG studies show that 5-HT is involved in regulation of sleep–wake state and modulates cortical oscillations. Vortioxetine is a 5-HT₃, 5-HT₇, and 5-HT_1D receptor antagonist, 5-HT_1B partial agonist, 5-HT_1A agonist, and 5-HT transporter inhibitor. Preclinical (animal) and clinical studies with vortioxetine show positive impact on cognitive metrics involving cortical function. Here we assess vortioxetine's effect on cortical neuronal oscillations in actively awake rats.

Experimental Approach

Telemetric EEG recordings were obtained with the following treatments (mg·kg⁻¹, s.c.): vehicle, vortioxetine (0.1, 1.0, 3.0, 10), 5-HT_1A agonist flesinoxan (2.5), 5-HT₃ antagonist ondansetron (0.30), 5-HT₇ antagonist SB-269970-A (10), escitalopram (2.0), duloxetine (10) and vortioxetine plus flesinoxan. Target occupancies were determined by ex vivo autoradiography.

Key Results

Vortioxetine dose-dependently increased wakefulness. Flesinoxan, duloxetine, ondansetron, but not escitalopram or SB-269970-A increased wakefulness. Quantitative spectral analyses showed vortioxetine alone and with flesinoxan increased θ (4–8 Hz), α (8–12 Hz) and γ (30–50 Hz) power. Duloxetine had no effect on θ and γ, but decreased α power, while escitalopram produced no changes. Ondansetron and SB-269970 (≈31–35% occupancy) increased θ power. Flesinoxan (≈41% occupancy) increased θ and γ power.

Conclusions and Implications

Vortioxetine increased wakefulness and increased frontal cortical activity, most likely because of its 5-HT₇ and 5-HT₃ antagonism and 5-HT_1A agonism. Vortioxetine differs from escitalopram and duloxetine by increasing cortical θ, α and γ oscillations. These preclinical findings suggest a role of vortioxetine in modulating cortical circuits known to be recruited during cognitive behaviours and warrant further investigation as to their clinical impact.

Elevation of brain allopregnanolone rather than 5-HT release by short term, low dose fluoxetine treatment prevents the estrous cycle-linked increase in stress sensitivity in female rats

Withdrawal from long-term dosing with exogenous progesterone precipitates increased anxiety-linked changes in behavior in animal models due to the abrupt decrease in brain concentration of allopregnanolone (ALLO), a neuroactive metabolite of progesterone. We show that a withdrawal-like effect also occurs during the late diestrus phase (LD) of the natural ovarian cycle in rats, when plasma progesterone and ALLO are declining but estrogen secretion maintains a stable low level. This effect at LD was prevented by short-term treatment with low dose fluoxetine. During LD, but not at other stages of the estrous cycle, exposure to anxiogenic stress induced by whole body vibration at 4 Hz for 5 min evoked a significant decrease in tail flick latency (stress-induced hyperalgesia) and a decrease in the number of Fos-positive neurons present in the periaqueductal gray (PAG). The threshold to evoke fear-like behaviors in response to electrical stimulation of the dorsal PAG was lower in the LD phase, indicating an increase in the intrinsic excitability of the PAG circuitry. All these effects were blocked by short-term administration of fluoxetine (2 × 1.75 mg kg(-1) i.p.) during LD. This dosage increased the whole brain concentration of ALLO, as determined using gas chromatography-mass spectrometry, but was without effect on the extracellular concentration of 5-HT in the dorsal PAG, as measured by microdialysis. We suggest that fluoxetine-induced rise in brain ALLO concentration during LD offsets the sharp physiological decline, thus removing the trigger for the development of anxiogenic withdrawal effects.

Vortioxetine: a review of its use in major depressive disorder

Vortioxetine (Brintellix(®)) is a serotonin (5-HT) transporter inhibitor that also acts on several 5-HT receptors, such as the 5-HT3 and 5-HT1A receptors. It is approved in the US and the EU for the treatment of adult patients with major depressive disorder (MDD); this article reviews the pharmacological properties of oral vortioxetine and its clinical efficacy and tolerability in these patients. Vortioxetine is generally efficacious in patients with MDD in acute treatment trials (including elderly patients), in a relapse-prevention trial, and in open-label extension trials. It is associated with improved cognitive function in patients with MDD; this does not occur solely via improvement in depressive symptom severity. It is well tolerated, but is associated with significantly increased sexual dysfunction at the highest dosage; however, vortioxetine was shown to improve previous-treatment-emergent sexual dysfunction in patients with well-treated MDD to a greater degree than escitalopram. Vortioxetine extends the available treatment options for patients with MDD, and further investigation into its comparative efficacy versus other antidepressants will allow for more accurate placement among these treatment options.

Assessing gonadal hormone contributions to affective psychopathologies across humans and animal models

Despite increasing acknowledgement of hormonal contributions to mood and anxiety disorders, the underlying mechanisms by which gonadal hormones influence psychopathology-related behaviours remain unknown. This review focuses on recent research that examines the influence of gonadal steroid hormones, including androgens, oestrogens, and progesterone, on mood and anxiety-related behaviours in human health and disease. To this aim, the literature was surveyed for studies that assess conditions with suspected underlying hormonal imbalances in otherwise healthy participants (e.g., premenstrual dysphoric disorder, postmenopausal depression) as well as conditions linked to congenital endocrine abnormalities (e.g., Turner Syndrome, Klinefelter Syndrome, polycystic ovary syndrome, congenital adrenal hyperplasia, familial male precocious puberty, androgen insensitivity syndrome). Furthermore, to better inform clinical work and to create a translational bridge, a second goal was to set human psychopathologies and animal models of these conditions side-by-side. In the second part of the review, based on consistencies revealed in the existing literature across conditions, a new model for the impact of gonadal hormones on anxious and depressed behavioural states is proposed. Finally, we conclude by proposing directions for future research, including the development of specific tasks suitable for cross-species comparisons to increase our knowledge of the role of gonadal hormones in mood and anxiety.