Social defeat stress before pregnancy induces depressive-like behaviours and cognitive deficits in adult male offspring: correlation with neurobiological changes

Inter- and transgenerational heritability of preconception chronic stress or alcohol exposure: Translational outcomes in brain and behavior

Chronic stress and alcohol (ethanol) use are highly interrelated and can change an individual's behavior through molecular adaptations that do not change the DNA sequence, but instead change gene expression. A recent wealth of research has found that these nongenomic changes can be transmitted across generations, which could partially account for the "missing heritability" observed in genome-wide association studies of alcohol use disorder and other stress-related neuropsychiatric disorders. In this review, we summarize the molecular and behavioral outcomes of nongenomic inheritance of chronic stress and ethanol exposure and the germline mechanisms that could give rise to this heritability. In doing so, we outline the need for further research to: (1) Investigate individual germline mechanisms of paternal, maternal, and biparental nongenomic chronic stress- and ethanol-related inheritance; (2) Synthesize and dissect cross-generational chronic stress and ethanol exposure; (3) Determine cross-generational molecular outcomes of preconception ethanol exposure that contribute to alcohol-related disease risk, using cancer as an example. A detailed understanding of the cross-generational nongenomic effects of stress and/or ethanol will yield novel insight into the impact of ancestral perturbations on disease risk across generations and uncover actionable targets to improve human health.

Xiangshao Granules reduce the aggressive behavior and hippocampal injury of premenstrual irritability in rats by regulating JIK/JNK/p38 signal pathway

ETHNOPHARMACOLOGICAL RELEVANCE

As a typical prescription for soothing the liver, Xiangshao granule has a good effect on the symptoms of irritability and anxiety. Clinical evidence suggests that it has significant efficacy in the treatment of Premenstrual dysphoria disorder (PMDD). However, the underlying mechanism remains unclear.

AIM OF THE STUDY

PMDD is a common disease in women of childbearing age, seriously affecting their family, society, and daily work life. The registered herbal medicine, Xiangshao granules, is used for relieving PMDD dysphoria and irritability symptoms with excellent efficacy in China. This study was focused on the deep intervention mechanism of Xiangshao granules in treating PMDD.

MATERIALS AND METHODS

The vaginal smear and open field test were used to screen rats in nonreception phase of estrus cycle with similar macroscopic behaviors and regular estrus cycle. The rat model of PMDD irritability was established through social isolation and residential invasion, with which, the irritability symptoms of PMDD patients with menstrual cycle dependence was also well simulated. Elevated plus Maze Test and Social interaction activities were used to measure the anxiety-like behavior of rats. TUNEL Staining and Hematoxylin-Eosin staining were used to measure apoptosis of hippocampal neurons. RT-PCR, Western blot and immunofluorescence were used to measure the expression of GR, JIK, p-JIK, p38, P-P38, JNK, caspase 3, and caspase 12.

RESULTS

In this study, Xiangshao granules showed consistent therapeutic effects similar with those in clinic, significantly reducing aggressive and anxiety-like behaviors with improved social skills in PMDD rats. In mechanism, Xiangshao granules lowered the apoptosis of hippocampal neurons and weakened the morphological damage of the hippocampal brain evidenced by the decreased mRNA and protein expression of glucocorticoid receptor, caspase-3, and caspase-12. In addition, administration of Xiangshao granules led to the decreased expression of JIK in the PMDD irritability rat model which agreed well with the previous studies. The JNK/p38 mitogen-activated protein kinases (MAPKs) signaling pathway is abnormally activated in the hippocampal brain region of PMDD rats, while treated with Xiangshao granules could increase JIK expression and inhibit the abnormal activation of the JNK/p38 MAPK signaling pathway, effectively reducing the stress damage in the hippocampus.

CONCLUSIONS

Xiangshao Granules Reduce the Aggressive Behavior and Hippocampal Injury of Premenstrual Irritability in Rats by Regulating JIK/JNK/p38 Signal Pathway.

Maternal stress induced endoplasmic reticulum stress and impaired pancreatic islets’ insulin secretion via glucocorticoid receptor upregulation in adult male rat offspring

Exposure to perinatal (prenatal and/or postnatal) stress is considered as a risk factor for metabolic disorders in later life. Accordingly, this study aimed to investigate the perinatal stress effects on the pancreatic endoplasmic reticulum (ER) stress induction, insulin secretion impairment and WFS1 (wolframin ER transmembrane Glycoprotein, which is involved in ER homeostasis and insulin secretion) expression changes, in rat offspring. According to the dams’ period of exposure to variable stress, their male offspring were divided into, control (CTRL); pre-pregnancy, pregnancy, lactation stress (PPPLS); pre-pregnancy stress (PPS); pregnancy stress (PS); lactation stress (LS); pre-pregnancy, pregnancy stress (PPPS); pregnancy, lactation stress (PLS); pre-pregnancy, lactation stress (PPLS) groups. Offspring pancreases were removed for ER extraction and the assessment of ER stress biomarkers, WFS1 gene DNA methylation, and isolated islets’ insulin secretion. Glucose tolerance was also tested. In the stressed groups, maternal stress significantly increased plasma corticosterone levels. In PPS, PS, and PPPS groups, maternal stress increased Bip (Hsp70; heat shock protein family A member 4), Chop (Ddit3; DNA- damage inducible transcript3), and WFS1 protein levels in pancreatic extracted ER. Moreover, the islets’ insulin secretion and content along with glucose tolerance were impaired in these groups. In PPS, PS, LS and PPPS groups, the pancreatic glucocorticoid receptor (GR) expression increased. Maternal stress did not affect pancreatic WFS1 DNA methylation. Thus, maternal stress, during prenatal period, impaired the islets’ insulin secretion and glucose homeostasis in adult male offspring, possibly through the induction of ER stress and GR expression in the pancreas, in this regard the role of WFS1 protein alteration in pancreatic ER should also be considered.

Depression in Adolescence and Brain-Derived Neurotrophic Factor

The incidence of depression among adolescents has been rapidly increasing in recent years. Environmental and genetic factors have been identified as important risk factors for adolescent depression. However, the mechanisms underlying the development of adolescent depression that are triggered by these risk factors are not well understood. Clinical and preclinical studies have focused more on adult depression, and differences in depressive symptoms between adolescents and adults make it difficult to adequately diagnose and treat adolescent depression. Brain-derived neurotrophic factor (BDNF) is known to play a critical role in the pathophysiology of many psychiatric disorders, including depression. However, there are still few studies on adolescent depression. Therefore, in this review paper, the causes and treatment of adolescent depression and the function of BDNF are investigated.

Maternal stress prior to conception impairs memory and decreases right dorsal hippocampal volume and basilar spine density in the prefrontal cortex of adult male offspring

Chronic parental stress impacts offspring functioning throughout life. Chronic variable stress prior to conception impairs offspring development in terms of behavior, neuroanatomy, and neurobiology. Previously, our lab demonstrated that even a consistent stressor experienced by the sire or the dam shapes offspring development beginning in early life. Here, we show how consistent maternal stress prior to conception influences the brain and behavior of offspring in adolescence and adulthood. Female Long-Evans rats were exposed to elevated platform stress twice daily for 27 consecutive days immediately prior to mating with non-stressed males. Male and female offspring were assessed in the open field and elevated plus maze in adolescence, and open field, elevated plus maze, Whishaw tray reaching, and Morris water task in adulthood. Offspring were then euthanized, and their brains were stained with Golgi-Cox solution and then examined for dendritic spine density and hippocampal volume. Major findings include deficits in spatial memory, decreased medial prefrontal cortex spine density, and reduced right dorsal hippocampal volume in male offspring only. This work illustrates that the effects of consistent maternal stress prior to conception are lifelong and highly sexually dimorphic.

Jie-Yu-He-Huan Capsule Ameliorates Anxiety-Like Behaviours in Rats Exposed to Chronic Restraint Stress via the cAMP/PKA/CREB/BDNF Signalling Pathway

Chronic stress is a critical factor in the aetiology of anxiety disorders; however, in the clinic, enduring and preventive measures are not available, and therapeutic drugs are associated with inevitable side effects. Our study established an anxiety rat model using chronic restraint stress (CRS) and assessed these animals using the open-field test, elevated plus-maze test, and light-dark box test. Jie-Yu-He-Huan capsule (JYHH), a Chinese medicine formula, was used as a preventative drug. The HPA axis-mediated release of corticotropin-releasing hormone, adrenocorticotropic hormone, and corticosterone from the hypothalamus was tested. In the hippocampus and prefrontal cortex, concentrations of 5-HT and its metabolite 5-hydroxyindoleacetic acid, as well as monoamine oxidase A, glucocorticoid receptor, and 5-HT1A receptor expression levels, were measured. Furthermore, we examined protein and mRNA expression of cAMP-PKA-CREB-BDNF pathway components. The results showed that JYHH had a significant preventative effect on the anxiety-like behaviour induced by CRS and prevented abnormal changes in the HPA axis and 5-HT system. Furthermore, CRS inhibited the cAMP-PKA-CREB-BDNF pathway, which returned to normal levels following JYHH treatment. This might be the underlying molecular mechanism of the antianxiety effect of JYHH, which could provide a new clinical target for preventative anxiolytic drugs for chronic stress.

Effect of Chaihu-jia-Longgu-Muli decoction on withdrawal symptoms in rats with methamphetamine-induced conditioned place preference

Traditional Chinese medicine detoxification prescription Chaihu-jia-Longgu-Muli decoction (CLMD) relieves depressive symptoms in patients withdrawing from methamphetamine. In the present study, we assessed the effects of CLMD on methamphetamine withdrawal in rats. A methamphetamine-intoxicated rat model was established. Rats were randomly divided into the control, model, high-dosage, medium-dosage, and low-dosage groups, receiving high, medium, and low doses of CLMD, respectively. Weekly body weight measurements revealed that rats treated with methamphetamine had the lowest body weight. The conditioned place preference (CPP) experiment revealed that methamphetamine-intoxicated rats stayed significantly longer in the drug-paired chamber than the control rats. However, after administering high-dosage CLMD, the amount of time the rats spent in the drug-paired chamber was significantly less than that of the model rats. Our open-field test revealed that the model group had lower crossing and rearing scores than the control group. Additionally, rats that received CLMD treatment exhibited higher crossing and rearing scores than the model rats. Striatal dopamine (DA), 5-hydroxytryptamine (5-HT), and endorphins (β-EP) and serum interleukin (IL)-1α and IL-2 concentrations were estimated. Rats in the model group had lower striatal DA, 5-HT, and β-EP and higher serum IL-1α and IL-2 concentrations than those in the control group. High-dosage CLMD administration significantly changed the concentrations of these molecules, such that they approached normal concentrations. In general, CLMD could prevent the development of methamphetamine-induced withdrawal symptoms in rats by increasing the DA, 5-HT, and β-EP and lowering the IL-1α and IL-2 concentrations.

Antidepressant and Anxiolytic-Like Effects of the Stem Bark Extract of Fraxinus rhynchophylla Hance and Its Components in a Mouse Model of Depressive-Like Disorder Induced by Reserpine Administration

There is an urgent need to find antidepressants that can be administered for long periods without inducing severe side effects to replace conventional antidepressants that control monoamine levels, such as tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs), and selective serotonin reuptake inhibitors (SSRI). We sought to determine the antidepressant effects of Fraxinus rhynchophylla Hance (F. rhynchophylla Hance, FX) and its components on a reserpine-induced mouse model. One hour after oral administration of FX (30, 50, and 100 mg/kg), esculin (50 mg/kg), esculetin (50 mg/kg), fraxin (50 mg/kg), and fluoxetine (20 mg/kg), reserpine was delivered intraperitoneally to mice. Behavioral experiments were conducted to measure anxiety and depressive-like behaviors after 10 days of administration. FX and its components increased the number of entries into the center of an open field as well as distance traveled within it and decreased immobility duration in the forced swim and tail suspension tests. Reserpine-induced increases in plasma corticosterone concentrations were attenuated by the administration of FX and its components, which were also found to decrease the reserpine-induced enhancement of mRNA levels of interleukin (IL)-12 p40, IL-6, and tumor necrosis factor (TNF)-α, pro-inflammatory cytokines. Finally, the diminished expressions of hippocampal phosphorylated cAMP response element-binding protein (pCREB) and brain-derived neurotrophic factor (BDNF) by reserpine were increased by FX and its components. Our results suggest that FX and its components regulate anxiety and depressive-like behaviors through stress hormones, immune regulation, and the activation of neuroprotective mechanisms, further supporting the potential of FX and its components as antidepressants.

Influence of progestational stress on BDNF and NMDARs in the hippocampus of male offspring and amelioration by Chaihu Shugan San

BACKGROUND

Progestational stress has been proven to be a risk for the neural development of offspring, especially in the hippocampus. However, whether Chaihu Shugan San (CSS) can ameliorate hippocampal neural development via the regulation of brain-derived neurotrophic factor (BDNF), and N-methyl-D-aspartate receptors (NMDAR) 2A (NR2A) and 2B (NR2B), and the mechanism of such action remains unclear.

METHODS

Thirty-six female rats were randomly allocated into control, chronic immobilization stress (CIS) and CSS groups according to the random number table, respectively. The male offspring were fed for 21 days after birth then randomly divided into the same three groups (6 rats/group) as the female rats. Female rats, except for the control group, underwent 21-day CIS to established a progestational stress anxiety-like model which was evaluated by body weight, the elevated plus-maze (EPM) test and serum dopamine (DA) measured using an enzyme-linked immunosorbent assay (ELISA). The expression levels of estrogen receptors (ERα/ERβ) and progesterone receptor (PR) in female rat ovaries were quantified by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. The hippocampal tissue in the 21-day offspring was observed by hematoxylin-eosin (HE) staining. The concentration of BDNF, NR2A, and NR2B were measured by RT-qPCR and immunohistochemistry in the CA3 and dentate gyrus (DG) regions of offsprings' hippocampus.

RESULTS

Compared with the female control group, significant differences in body weight, EPM test and DA concentration were observed in the CIS group, meanwhile, the concentration of ERα (P < 0.05), PR (P < 0.05) and ERβ in the ovaries were decreased. In the offsprings' hippocampus of the CIS group, the chromatin of the nucleus was edge set and with condensed and irregular morphology nucleus, and the cytoplasm was unevenly stained with spaces around the cells, moreover, the expression levels of BDNF, NR2A, and NR2B were also declined (P < 0.05). However, Chaihu Shugan San reversed these changes, especially the BDNF in the DG region (P < 0.05), and NR2A and NR2B in the CA3 and DG region (P < 0.05).

CONCLUSIONS

CSS could ameliorate the neural development of the hippocampus in offspring damaged by anxiety-like progestational stress in female rats via regulating the expression levels of ERα, ERβ, and PR in female rat ovaries and BDNF, NR2A, and NR2B in the hippocampus of their offspring.

Isoliquiritin ameliorates depression by suppressing NLRP3-mediated pyroptosis via miRNA-27a/SYK/NF-κB axis

Background

The NLRP3-mediated pyroptosis, which could be regulated by miRNA-27a, is a key player in the development of depression. Isoliquiritin is a phenolic flavonoid compound that has been demonstrated to suppress NLRP3-mediated pyroptosis. However, it is still unknown whether isoliquiritin could confer antidepressant activity via decreasing NLRP3-mediated pyroptosis by stimulating miRNA-27a. Thus, in the current study, we explored the antidepressant activity of isoliquiritin and its underlying mechanism.

Methods

Expression of miRNA-27a in depressed patients or mice was measured using qRT-PCR. Luciferase reporter assay was performed to illustrate the link between miRNA-27a and SYK. Lipopolysaccharide (LPS) and chronic social defeat stress (CSDS) depression models were established to investigate the antidepressant actions of isoliquiritin. Changes in miRNA-27a/SYK/NF-κB axis and NLRP3-mediated pyroptosis were also examined. The role of miRNA-27a in isoliquiritin-related antidepressant effect was further investigated by using miRNA-27a inhibitors and mimics of miRNA-27a.

Results

Our results showed the miRNA-27a expression was downregulated in the serum of depressed patients, and decreased serum and hippocampus expression of miRNA-27a were observed in rodent models of depression. SYK gene expression was significantly reduced by miRNA-27a mimic incubation. Isoliquiritin profoundly attenuated LPS or CSDS-induced depressive symptoms, as well as CSDS-induced anxiety behavior. In the hippocampus, LPS and CSDS decreased miRNA-27a mRNA expression; increased the protein levels of SYK, p-NF-κB, and NLRP3: cleaved Caspase-1, IL-1β, and GSDMD-N: and elevated the concentration of IL-1β, IL-6, and TNF-α, which were all restored by isoliquiritin administration. Meanwhile, isoliquiritin upregulated the hippocampal NeuN protein level, improved the survival and morphology of neurons, and decreased pyroptosis-related neuronal cell death. Moreover, isoliquiritin protected primary microglia against LPS and adenosine triphosphate (ATP) elicited NLRP3 inflammasome activation in vitro, evidenced by declined protein levels of p-NF-κB, NLRP3; cleaved Caspase-1, IL-1β, and GSDMD-N; upregulated miRNA-27a mRNA expression; and decreased the mRNA and protein levels of SYK. Nevertheless, miRNA-27a inhibitors significantly reversed isoliquiritin-generated therapeutic efficacy in CSDS mice and in vitro. Furthermore, the cytoprotective effect of isoliquiritin was similar to that of miRNA-27a mimics in LPS and ATP-treated primary microglia.

Taken together, these findings suggest that isoliquiritin possesses potent antidepressant property, which requires miRNA-27a/SYK/NF-κB axis controlled decrease of pyroptosis via NLRP3 cascade.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-020-02040-8.

Standardized Bacopa monnieri Extract Ameliorates Learning and Memory Impairments through Synaptic Protein, Neurogranin, Pro-and Mature BDNF Signaling, and HPA Axis in Prenatally Stressed Rat Offspring

Prenatal stress (PNS) influences offspring neurodevelopment, inducing anxiety-like behavior and memory deficits. We investigated whether pretreatment of Bacopa monnieri extract (CDRI-08/BME) ameliorates PNS-induced changes in signaling molecules, and changes in the behavior of Wistar rat offspring. Pregnant rats were randomly assigned into control (CON)/prenatal stress (PNS)/PNS and exposed to BME treatment (PNS + BME). Dams were exposed to stress by placing them in a social defeat cage, where they observed social defeat from gestational day (GD)-16–18. Pregnant rats in the PNS + BME group were given BME treatment from GD-10 to their offspring’s postnatal day (PND)-23, and to their offspring from PND-15 to -30. PNS led to anxiety-like behavior; impaired memory; increased the level of corticosterone (CORT), adrenocorticotropic hormone, glucocorticoid receptor, pro-apoptotic Casepase-3, and 5-HT_2C receptor; decreased anti-apoptotic Bcl-2, synaptic proteins (synaptophysin, synaptotagmin-1), 5-HT_1A, receptor, phosphorylation of calmodulin-dependent protein kinase II/neurogranin, N-methyl-D-aspartate receptors (2A,2B), postsynaptic density protein 95; and conversion of pro and mature brain derived neurotropic factor in their offspring. The antioxidant property of BME possibly inhibiting the PNS-induced changes in observed molecules, anxiety-like behavior, and memory deficits. The observed results suggest that pretreatment of BME could be an effective coping strategy to prevent PNS-induced behavioral impairments in their offspring.

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.

Gestational Factors throughout Fetal Neurodevelopment: The Serotonin Link

Serotonin (5-HT) is a critical player in brain development and neuropsychiatric disorders. Fetal 5-HT levels can be influenced by several gestational factors, such as maternal genotype, diet, stress, medication, and immune activation. In this review, addressing both human and animal studies, we discuss how these gestational factors affect placental and fetal brain 5-HT levels, leading to changes in brain structure and function and behavior. We conclude that gestational factors are able to interact and thereby amplify or counteract each other's impact on the fetal 5-HT-ergic system. We, therefore, argue that beyond the understanding of how single gestational factors affect 5-HT-ergic brain development and behavior in offspring, it is critical to elucidate the consequences of interacting factors. Moreover, we describe how each gestational factor is able to alter the 5-HT-ergic influence on the thalamocortical- and prefrontal-limbic circuitry and the hypothalamo-pituitary-adrenocortical-axis. These alterations have been associated with risks to develop attention deficit hyperactivity disorder, autism spectrum disorders, depression, and/or anxiety. Consequently, the manipulation of gestational factors may be used to combat pregnancy-related risks for neuropsychiatric disorders.

Prenatal maternal stress alters depression-related symptoms in a strain - and sex-dependent manner in rodent offspring

Stress during pregnancy adversely affects foetal development and leads to later behavioural outcomes in offspring. Preclinical studies have reported conflicting effects of prenatal stress on depression-related symptoms in rodent offspring. This study aimed to study the combined effect of strain and sex on prenatal stress outcomes in a single study. To this end, male and female offspring from outbred Wistar and inbred Lewis rats, and outbred NMRI and inbred C57BL6 mice were compared. As outcomes we focussed on depression-related behaviour and related molecular and neurochemical parameters. Prenatally stressed and non-stressed offspring were subjected to the sucrose preference, novelty-suppressed feeding, tail suspension, and forced swim tests. We measured basal and stress-induced corticosterone levels in the serum, and brain-derived-neurotrophic-factor (BDNF), interleukin-1β, tumor necrosis factor-α, glutamate and serotonin in the brain to determine changes in hypothalamic-pituitary-adrenal-(HPA)-axis function, neuroplasticity, neuroinflammation, and neurotransmission. Our findings revealed that prenatal stress increases depression-like behaviour, HPA-axis (re) activity, pro-inflammatory cytokines and glutamate levels, and decreases BDNF and serotonin levels in a strain and sex-dependent manner in rodent offspring. Overall, male and female Lewis rats, female Wistar rats, male NMRI mice and female C57BL6 mice were found to be most responsive to prenatal stress. Based on these results, we conclude that genetic background and sex contribute to the great diversity in the effects of prenatal maternal stress in rodents.

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.

The serotonin system in the hippocampus CA3 involves in effects of CSDS on social recognition in adult female mandarin voles (Microtus mandarinus)

Chronic social defeat stress (CSDS) exacerbated the development of stress-related psychiatric disorders, and the social recognition dysfunction is the core feature of many psychiatric disorders. However, the effects of CSDS on female social recognition and the underlying neural mechanisms remain unclear. Using highly aggressive adult female mandarin voles (Microtus mandarinus) as animal model, the aim of this work is to investigate the effects of CSDS on social recognition in adult female rodents and the neurobiological mechanisms underlying these effects. Our results indicate the CSDS disrupted the normal social recognition in adult female voles. Meanwhile, defeated voles exhibited increased neural activity in the DG, CA1 and CA3 of the hippocampus. Furthermore, CSDS reduced levels of serotonin (5-HT) and serotonin 1A receptors (5-HT_1AR) in the CA3. We also discovered that microinjection of 8-OH-DPAT into the CA3 effectively reversed the social recognition deficits induced by CSDS, and an infusion of WAY-100635 into the CA3 of control female voles impaired social recognition. Moreover, targeted activation of the 5-HT neuron projection from the DRN to CA3 by long-term administration of CNO significantly prevented the CSDS induced social recognition deficits. Taken together, our study demonstrated that CSDS induced social recognition deficits in adult female voles, and these effects were mediated by the action of 5-HT on the 5-HT_1AR in the hippocampus CA3. The projection from the DRN to CA3 may be involved in social recognition deficits induced by CSDS.