Postpartum depression in rats: Differences in swim test immobility, sucrose preference and nurturing behaviors

Comparison of CUMS at different pregnancy stages, maternal separation, and their effects on offspring in postpartum depression mouse models

Due to the diversity of postpartum depression (PPD) patients and the complexity of associated pathophysiological changes, most current animal models cannot accurately simulate PPD-like symptoms. In this study, we established a reliable animal model for PPD by inducing chronic unpredictable mild stress (CUMS) at different stages (pre-pregnancy, pregnancy, or postnatal) in female mice, followed by maternal separation (MS) from day 2-21 after delivery. The results for female mice subjected to pre-pregnancy stress were not statistically significant due to a lower conception rate. However, female mice exposed to CUMS during either the gestational or postnatal stage, followed by MS, successfully exhibited PPD-like symptoms. The models were deemed effective based on observed behavioral abnormalities, impaired hippocampal neuron functioning, and reduced serum concentrations of neurotransmitters (5-HT, GABA, and NE). Additionally, mice that underwent gestational CUMS followed by MS displayed a more dysfunctional hypothalamic-pituitary-adrenal (HPA) axis and more severe uterine inflammation. The study also investigated the impact of PPD on the behavior and neurodevelopment of adolescent offspring through behavioral tests, enzyme-linked immunosorbent assay (ELISA), hematoxylin-eosin (HE) staining, and western blotting (WB). The results indicated that adolescent offspring of mothers with PPD exhibited behavioral and neurodevelopmental disorders, with male offspring being more susceptible than females. Female mice exposed to both CUMS and MS during the postnatal period had more severe adverse effects on their offspring compared to the other model groups.

Cajaninstilbene acid ameliorates depression-like behaviors in mice by suppressing TLR4/NF-κB mediated neuroinflammation and promoting autophagy

Depression is a life-threatening neurodegenerative disease lacking a complete cure. Cajaninstilbene acid (CSA), a potent stilbene compound, has demonstrated neuroprotective effects, however, studies on its antidepressant mechanisms are still scarce. This study examined the effects of CSA on lipopolysaccharide (LPS)-induced and chronic unpredictable mild stress (CUMS)-induced depression in mice, investigating its mechanisms related to inflammation and autophagy. Mice were treated with CSA (7.5, 15, and 30 mg/kg) daily for 3 weeks before intraperitoneal LPS injection (0.8 mg/kg). Another cohort underwent the same doses of CSA (7.5-30 mg/kg) daily for 6 weeks in accompany with CUMS stimulation. Behavioral assessments were conducted, and cortical samples were collected for molecular analysis. Findings indicate that CSA ameliorated depressive behaviors induced by both LPS and CUMS. Notably, CSA (15 mg/kg) reversed despair behavior in mice more persistently than amitriptyline, indicating that optimal doses of CSA may effectively decelerate the procession of mood despair and yield a good compliance. CSA countered CUMS-induced activation of TLR4/NF-κB pathway and the reduction in autophagy levels. Furthermore, CSA attenuated the CUMS-induced decline in neuroplasticity. Collectively, these findings suggest that CSA mitigates depression-like behaviors in mice by inhibiting TLR4/NF-κB-mediated neuroinflammation and enhancing autophagy. This research provides further insights into CSA's mechanisms of action in ameliorating depressive behaviors, offering a scientific foundation for developing CSA-based antidepressants.

Protective role of the ginsenoside Rg1 against methimazole-induced gestational hypothyroidism on reflexive behaviors, conditioned fear and cortical antioxidant levels in mice offspring

Ginsenoside Rg1(Rg1), a monomer of a tetracyclic triterpenoid derivative, possesses diverse medicinal properties attributed to its unique chemical structure and may have beneficial effects on fetal development. This study aimed to investigate the protective effects of prenatal exposure to Rg1 against Methimazole-induced gestational hypothyroidism on reflexive behaviors, conditioned fear, and cortical antioxidant levels in mouse offspring.40 female virgin mice and 12 male NMRI mice were assigned to four groups: group 1 served as the control, group 2 received Methimazole(MMI) at a concentration of 0.02% in their drinking water, group 3 received Rg1(150 mg/kg), and group 4 received both MMI and Rg1.Groups of 2-4 were administered the substances from days 1-9 of gestation. After delivery, pups were selected, and reflexive motor behaviors and conditioned fear were assessed. Additionally, levels of brain tissue catalase(CAT), malondialdehyde(MDA), superoxide dismutase(SOD), and glutathione peroxidase(GPx) levels were measured. Furthermore, postpartum immobility time in the forced swimming test (FST), tail suspension test (TST), and the number of squares crossed in the open field test (OFT)were determined. The results demonstrated that maternal exposure to Rg1 improved ambulation score, hind-limb suspension score, grip strength, front-limb suspension, hind-limb foot angle, negative geotaxis, surface righting, and conditioned fear in hypothyroidism-induced offspring(P<0.05). Rg1 decreased immobility time in the FST, and TST, and increased the number of squares crossed in the OFT in postpartum hypothyroidism-induced mice(P<0.05). Moreover, Rg1 reduced brain tissue MDA levels and increased brain tissue CAT, SOD, and GPx levels in mice and their offspring(P<0.05). These findings indicate that Rg1 mitigated postpartum depression in mice and improved reflexive motor behaviors in their pups.

Particulate matter (PM10) exacerbates on MK-801-induced schizophrenia-like behaviors through the inhibition of ERK-CREB-BDNF signaling pathway

Particulate matter (PM), released into the air by a variety of natural and human activities, is a key indicator of air pollution. Although PM is known as the extensive health hazard to affect a variety of illness, few studies have specifically investigated the effects of PM10 exposure on schizophrenic development. In the present study, we aimed to investigate the impact of PM10 on MK-801, N-methyl-D-aspartate (NMDA) receptor antagonist, induced schizophrenia-like behaviors in C57BL/6 mouse. Preadolescent mice were exposed PM10 to 3.2 mg/m3 concentration for 4 h/day for 2 weeks through a compartmentalized whole-body inhalation chamber. After PM10 exposure, we conducted behavioral tests during adolescence and adulthood to investigate longitudinal development of schizophrenia. We found that PM10 exacerbated schizophrenia-like behavior, such as psychomotor agitation, social interaction deficits and cognitive deficits at adulthood in MK-801-induced schizophrenia animal model. Furthermore, the reduced expression levels of brain-derived neurotrophic factor (BDNF) and the phosphorylation of BDNF related signaling molecules, extracellular signal-regulated kinase (ERK) and cAMP response element-binding protein (CREB), were exacerbated by PM10 exposure in the adult hippocampus of MK-801-treated mice. Thus, our present study demonstrates that exposure to PM10 in preadolescence exacerbates the cognitive impairment in animal model of schizophrenia, which are considered to be facilitated by the decreased level of BDNF through reduced ERK-CREB expression.

Animal Models of Hypertension (ISIAH Rats), Catatonia (GC Rats), and Audiogenic Epilepsy (PM Rats) Developed by Breeding

Research into genetic and physiological mechanisms of widespread disorders such as arterial hypertension as well as neuropsychiatric and other human diseases is urgently needed in academic and practical medicine and in the field of biology. Nevertheless, such studies have many limitations and pose difficulties that can be overcome by using animal models. To date, for the purposes of creating animal models of human pathologies, several approaches have been used: pharmacological/chemical intervention; surgical procedures; genetic technologies for creating transgenic animals, knockouts, or knockdowns; and breeding. Although some of these approaches are good for certain research aims, they have many drawbacks, the greatest being a strong perturbation (in a biological system) that, along with the expected effect, exerts side effects in the study. Therefore, for investigating the pathogenesis of a disease, models obtained using genetic selection for a target trait are of high value as this approach allows for the creation of a model with a "natural" manifestation of the pathology. In this review, three rat models are described: ISIAH rats (arterial hypertension), GC rats (catatonia), and PM rats (audiogenic epilepsy), which are developed by breeding in the Laboratory of Evolutionary Genetics at the Institute of Cytology and Genetics (the Siberian Branch of the Russian Academy of Sciences).

Gastrodin programs an Arg-1+ microglial phenotype in hippocampus to ameliorate depression- and anxiety-like behaviors via the Nrf2 pathway in mice

BACKGROUND

Regulating the microglial phenotype is an attractive strategy for treating diseases of the central nervous system such as depression and anxiety. Gastrodin can quickly cross the blood-brain barrier and mitigate microglia-mediated inflammation, which widely used to treat a variety of central nervous system diseases associated with microglial dysfunction. However, the molecular mechanism by which gastrodin regulates the functional phenotype of microglia remains unclear.

PURPOSE

Since the transcription factor "nuclear factor erythroid 2-related factor 2″ (Nrf2) is associated with the anti-inflammatory effects of gastrodin, we hypothesized that gastrodin induces Nrf2 expression in microglia and thereby programs an anti-inflammatory phenotype.

STUDY DESIGN

Male C57BL/6 mice, treated or not with gastrodin, were given lipopolysaccharide (LPS) at 0.25 mg/kg/d for 10 days to induce chronic neuroinflammation. The effects of gastrodin on microglial phenotypes, neuroinflammation and depression- and anxiety-like behaviors were evaluated. In another experiment, animals were treated with Nrf2 inhibitor ML385 throughout the 13-day gastrodin intervention period.

METHODS

The effects of gastrodin on depression- and anxiety-like behaviors were evaluated through the sucrose preference test, forced swimming test, open field test and elevated plus-maze test; as well as its effects on morphology and molecular and functional phenotypes of hippocampal microglia through immunohistochemistry, real-time PCR and enzyme-linked immunosorbent assays.

RESULTS

Chronic exposure to LPS caused hippocampal microglia to secrete inflammatory cytokines, their somata to enlarge, and their dendrites to lose branches. These changes were associated with depression- and anxiety-like behaviors. Gastrodin blocked these LPS-induced alterations and promoted an Arg-1+ microglial phenotype that protected neurons from injury. The effects of gastrodin were associated with Nrf2 activation, whereas blockade of Nrf2 antagonized gastrodin.

CONCLUSION

These results suggest that gastrodin acts via Nrf2 to promote an Arg-1+ microglial phenotype, which buffers the harmful effects of LPS-induced neuroinflammation. Gastrodin may be a promising drug against central nervous system diseases that involve microglial dysfunction.

Forkhead Box 1(FoxO1) mediates psychological stress-induced neuroinflammation

OBJECTIVES

 Neuroinflammation plays a key role in cerebrovascular disease (CVD). Neuropsychiatric disorders appear to share an epidemiological association with inflammation, but the mechanisms are unclear. Forkhead box 1 (FoxO1) regulates inflammatory signaling in diabetes and cardiovascular diseases, but its role in psychological stress-induced neuroinflammation remains unknown. Therefore, we investigated the potential involvement of FoxO1 in repeated social defeat stress (RSDS)-induced neuroinflammation.

METHODS

 6-week-old male C57BL/6 J mice were randomly divided into RSDS or control groups. In the RSDS group, mice (18-22 g) were individually subjected to social defeat by an 8-week-old CD-1 mouse (28-32 g) for 10 min daily for 10 consecutive days. At 24 h after this 10-day process, corticosterone (CORT), epinephrine (EPI), hydrogen peroxide, and inflammatory factors (TNF-α, IL-6, IL-1β, and VCAM-1) from serum and brain tissues were assayed using ELISA, real-time PCR, and Western blot. Iba-1 was determined by immunofluorescence (IF), and FoxO1 siRNA was transfected into BV2 cells to further analyze the expression of inflammatory factors.

RESULTS

RSDS significantly increased the levels of TNF-α, IL-6, IL-1β, and VCAM-1 in the serum; it also increased both mRNA and protein expression of these in the brain. FoxO1 was significantly increased after stress, while its knockdown significantly suppressed stress-induced inflammation. Immunofluorescence demonstrated the activation of microglia in the setting of RSDS.

CONCLUSION

RSDS induced a measurable inflammatory response in the blood and brain, and FoxO1 was demonstrated in vitro to aggravate stress-induced inflammation.

Postpartum scarcity-adversity disrupts maternal behavior and induces a hypodopaminergic state in the rat dam and adult female offspring

Postpartum adversity is among the strongest predictors for the emergence of postpartum depression (PPD) in humans and a translational risk factor employed in rodent models. Parental care is disturbed under conditions of environmental adversity, including low resource environments, and in PPD. Nonetheless, the neural changes associated with these adversity-induced maladaptive behavioral states remain poorly understood. Postpartum scarcity-adversity can be modeled in rats by providing the dam with limited bedding and nesting (LBN) materials, which mimics the effects of a stressful low resource environment in potentiating maltreatment/neglect in humans. Indeed, LBN exposure from postpartum days (PD) 2-9 increased adverse maternal behaviors, impaired pup retrieval, and increased passive stress coping responses. Since mesolimbic dopamine (DA) activity is an important mechanism for motivated maternal behavior and is implicated in PPD, we assessed the impact of postpartum scarcity-adversity on in vivo electrophysiological properties of ventral tegmental area (VTA) DA neurons at two timepoints. We found reduced numbers of active VTA DA neurons in LBN dams at PD 9-10 but not PD-21, suggesting a transient impact on VTA population activity in LBN dams. Finally, we assessed the impact of early life scarcity-adversity on VTA DA function by conducting VTA recordings in adult female offspring and found a long-lasting attenuation in DA activity. These findings highlight a link between adversity-induced deficits in DA function and disrupted maternal behavior, suggesting the VTA/mesolimbic DA system as a potential mechanism by which postpartum scarcity-adversity drives aberrant maternal behavior, and early postnatal programming of adult VTA function in the offspring.

A novel mouse model of postpartum depression using emotional stress as evaluated by nesting behavior

Postpartum depression is an important mental health issue not only for the mother but also for the child’s development, other family members, and the society. An appropriate animal model is desired to elucidate the pathogenesis of postpartum depression. However, methods for stress loading during pregnancy have not been established. Behavioral experiments to investigate postpartum depression-like behaviors should be conducted without stress because behavioral tests affect rearing behaviors such as lactation. Therefore, we developed a new mouse model of postpartum depression using a psychological stress method. Mating partners were made to witness their partners experiencing social defeat stress and then listen to their cries. Emotional stress loading during pregnancy significantly increased postpartum depression-like behaviors. Postpartum depression also affected nurturing behaviors and caused disturbances in pup care. Furthermore, nesting behavior was impaired in the stressed group, suggesting that the observation of nesting behavior may be useful for assessing social dysfunction in postpartum depression. These results demonstrate the utility of this new mouse model of postpartum depression.

Pten is a key intrinsic factor regulating raphe 5-HT neuronal plasticity and depressive behaviors in mice

Serotonin (5-HT)-based antidepressants, selective serotonin reuptake inhibitors (SSRIs) aim to enhance serotonergic activity by blocking its reuptake. We propose PTEN as a target for an alternative approach for regulating 5-HT neuron activity in the brain and depressive behaviors. We show that PTEN is elevated in central 5-HT neurons in the raphe nucleus by chronic stress in mice, and selective deletion of Pten in the 5-HT neurons induces its structural plasticity shown by increases of dendritic branching and density of PSD95-positive puncta in the dendrites. 5-HT levels are elevated and electrical stimulation of raphe neurons evokes more 5-HT release in the brain of condition knockout (cKO) mice with Pten-deficient 5-HT neurons. In addition, the 5-HT neurons remain normal electrophysiological properties but have increased excitatory synaptic inputs. Single-cell RNA sequencing revealed gene transcript alterations that may underlay morphological and functional changes in Pten-deficient 5-HT neurons. Finally, Pten cKO mice and wild-type mice treated with systemic application of PTEN inhibitor display reduced depression-like behaviors. Thus, PTEN is an intrinsic regulator of 5-HT neuron activity, representing a novel therapeutic strategy for producing antidepressant action.

Benefits of animal models to understand the pathophysiology of depressive disorders

Major depressive disorder (MDD) is a potentially life-threatening mental disorder imposing severe social and economic burden worldwide. Despite the existence of effective antidepressant treatment strategies the exact pathophysiology of the disease is still unknown. Large number of animal models of MDD have been developed over the years, but all of them suffer from significant shortcomings. Despite their limitations these models have been extensively used in academic research and drug development. The aim of this review is to highlight the benefits of animal models of MDD. We focus here on recent experimental data where animal models were used to examine current theories of this complex disease. We argue, that despite their evident imperfections, these models provide invaluable help to understand cellular and molecular mechanisms contributing to the development of MDD. Furthermore, animal models are utilized in research to find clinically useful biomarkers. We discuss recent neuroimaging and microRNA studies since these investigations yielded promising candidates for biomarkers. Finally, we briefly summarize recent progresses in drug development, i.e. the FDA approval of two novel antidepressant drugs: S-ketamine and brexanolone (allopregnanolone). Deeper understanding of the exact molecular and cellular mechanisms of action responsible for the antidepressant efficacy of these rapid acting drugs could aid us to design further compounds with similar effectiveness, but less side effects. Animal studies are likely to provide valuable help in this endeavor.

Oral application of clozapine-N-oxide using the micropipette-guided drug administration (MDA) method in mouse DREADD systems

The designer receptor exclusively activated by designer drugs (DREADD) system is one of the most widely used chemogenetic techniques to modulate the activity of cell populations in the brains of behaving animals. DREADDs are activated by acute or chronic administration of their ligand, clozapine-N-oxide (CNO). There is, however, a current lack of a non-invasive CNO administration technique that can control for drug timing and dosing without inducing substantial distress for the animals. Here, we evaluated whether the recently developed micropipette-guided drug administration (MDA) method, which has been used as a non-invasive and minimally stressful alternative to oral gavages, may be applied to administer CNO orally to activate DREADDs in a dosing- and timing-controlled manner. Unlike standard intraperitoneal injections, administration of vehicle substances via MDA did not elevate plasma levels of the major stress hormone, corticosterone, and did not attenuate exploratory activity in the open field test. At the same time, however, administration of CNO via MDA or intraperitoneally was equally efficient in activating hM3D_Gq-expressing neurons in the medial prefrontal cortex, as evident by time-dependent increases in mRNA levels of neuronal immediate early genes (cFos, Arc and Zif268) and cFos-immunoreactive neurons. Compared to vehicle given via MDA, oral administration of CNO via MDA was also found to potently increase locomotor activity in mice that express hM3D_Gq in prefrontal neurons. Taken together, our study confirms the effectiveness of CNO given orally via MDA and provides a novel method for non-stressful, yet well controllable CNO treatments in mouse DREADD systems.

Polymer-based prolonged-release nanoformulation of duloxetine: fabrication, characterization and neuropharmacological assessments

OBJECTIVE

The poly D, L-Lactic-co-glycolic acid (PLGA) and Polycaprolactone (PCL) have been widely applied for developing the prolonged-release formulation. The current study explores the application of these polymers for developing prolonged-release nanosphere of Duloxetine (DLX). Developing a prolonged release parenteral nanosphere formulation of DLX would be overcoming pitfalls like acid-labile degradation, first-pass metabolism and erratic bioavailability along with long-term therapeutic benefit in the treatment of depression.

METHODS

DLX-loaded PLGA and PCL nanospheres were prepared by using the emulsion solvent evaporation technique. The developed formulation was compared with DLX oral solution concerning brain estimation. The prepared nanospheres were subjected to the morphology of the drug particles, polydispersity Index (PDI), distribution size, zeta potential, entrapment efficiency and percentage yield to generate a proof of concept.

RESULTS

DLX-loaded polymeric nanosphere exhibited the uniform size from 89.48 nm to 100.9 nm. The entrapment efficiency was in the range of 74.93 to 77.49, respectively, of PLGA and PCL formulation. The FSEM image affirmed smooth spherical morphology. A good PDI and negative zeta potential value (-31.3 mV for F1 and -30.7 mV for F2) supported the stability of the nanosphere. The brain concentration of the drug was three times enhanced supporting the effectiveness of the nanosphere during pharmacodynamic and pharmacokinetic studies.

CONCLUSION

The intramuscular DLX-loaded nanospheres signify improved brain availability relative to DLX solution. This can be a blueprint for the effective and targeted brain delivery of CNS drugs.

Maternal Separation Model of Postpartum Depression: Potential Role for Nucleus Accumbens Dopamine D1-D2 Receptor Heteromer

Postpartum depression is a mood disorder with a distinct neurobiological and behavioural profile occurring during and after the postpartum period. Dopamine pathways in the limbic regions of the brain such as the nucleus accumbens (NAc) have been shown to be involved in the etiology of depressive disorders. Selective activation of the dopamine D1-D2 receptor heteromer has been demonsrated to cause depressive- and anxiogenic-like behaviours in rats. The maternal separation model involving three hour daily maternal separation (MS) from pups on PPD 2-15 on anxiety-, depression- and anhedonia-like behaviors in the dams was investigated, together with plasma corticosterone, oxytocin and D1-D2 heteromer expression in the NAc core and shell in non-MS and MS dams. Depression, anxiety and anhedonia-like behaviours were measured using the forced swim test, elevated plus maze and sucrose preference test, respectively. In comparison to non-MS controls, MS dams displayed slightly higher depressive and anxiety-like behaviours with no difference in anhedonia-like behaviours. The MS dams displayed significantly increased care of pups after their retrieval with higher bouts of nursing, lower latency to nurse, lower bouts of out nest behaviour and decreased self-care. There was no significant alteration in D1-D2 heteromer expression in NAc core and shell between mothers of either group (MS, non-MS) or between postpartum rats and nonpregnant female rats, remaining higher than in male rats. This data provides evidence for the maternal separation model in producing a postpartum depression-like profile, but with maternal resilience able to modify behaviours to counteract any potential deleterious consequences to the pups.

1H NMR-Based Metabolic Signatures in the Liver and Brain in a Rat Model of Hepatic Encephalopathy

Hepatic encephalopathy (HE) is a debilitating neuropsychiatric complication associated with acute and chronic liver failure. It is characterized by diverse symptoms with variable severity that includes cognitive and motor deficits. The aim of the study is to assess metabolic alterations in the brain and liver using nuclear magnetic resonance (NMR) spectroscopy and subsequent multivariate analyses to characterize metabolic signatures associated with HE. HE was developed by bile duct ligation (BDL) that resulted in hepatic dysfunctions and cirrhosis as shown by liver function tests. Metabolic profiles from control and BDL rats indicated increased levels of lactate, branched-chain amino acids (BCAAs), glutamate, and choline in the liver, whereas levels of glucose, phenylalanine, and pyridoxine were decreased. In brain, the levels of lactate, acetate, succinate, citrate, and malate were increased, while glucose, creatine, isoleucine, leucine, and proline levels were decreased. Furthermore, neurotransmitters such as glutamate and GABA were increased, whereas choline and myo-inositol were decreased. The alterations in neurotransmitter levels resulted in cognitive and motor defects in BDL rats. A significant correlation was found among alterations in NAA/choline, choline/creatine, and NAA/creatine with behavioral deficits. Thus, the data suggests impairment in metabolic pathways such as the tricarboxylic acid (TCA) cycle, glycolysis, and ketogenesis in the liver and brain of animals with HE. The study highlights that metabolic signatures could be potential markers to monitor HE progression and to assess therapeutic interventions.

Rapid action of mechanism investigation of Yixin Ningshen tablet in treating depression by combinatorial use of systems biology and bioinformatics tools

ETHNOPHARMACOLOGICAL RELEVANCE

Yixin Ningshen tablet is a CFDA-approved TCM formula for treating depression clinically. However, little is known about its active compounds and related potential target proteins, so far, no researches have been performed to investigate its mechanism of action for the treatment of depression.

AIM OF THE STUDY

Here we develop an original bioinformatics pipeline composed of text mining tools, database querying and systems biology combinatorial analysis, which is applied to rapidly explore the mechanism of action of Yixin Ningshen tablet in treating depression.

MATERIALS AND METHODS

Text mining and database query were applied to identify active compounds in Yixin Ningshen tablet for the treatment of depression. Then SwissTargetPrediction was used to predict their potential target proteins. PubMed was retrieved to summarize known depression related systems biology results. Ingenuity Pathway Analysis (IPA) tools and STRING were applied to construct a compound-target protein-gene protein-differential protein-differential metabolite network with the integration of compound-target interaction and systems biology results, as well as enrich the target proteins related pathways. ChEMBL and CDOCKER were used to validate the compound-target interactions.

RESULTS

62 active compounds and their 286 potential target proteins were identified in Yixin Ningshen tablet for the treatment of depression. The construction of compound-target protein-gene protein-differential protein-differential metabolite network shrinked the number of potential target proteins from 286 to 133. Pathway enrichment analysis of target proteins indicated that Neuroactive ligand-receptor interaction, Calcium signaling pathway, Serotonergic synapse, cAMP signaling pathway and Gap junction were the common primary pathways regulated by both Yixin Ningshen Tablet and anti-depressant drugs, and MAPK, Relaxin, AGE-RAGE, Estrogen, HIF-1, Jak-STAT signaling pathway, Endocrine resistance, Arachidonic acid metabolism and Regulation of actin cytoskeleton were the specifically main pathways regulated by Yixin Ningshen tablet for the treatment of depression. Further validations based on references and molecular docking results demonstrated that Yixin Ningshen tablet could primarily target MAPT, CHRM1 and DRD1, thus regulating serotonergic neurons, cholinergic transmission, norepinephrine and dopamine reuptake for the treatment of depression.

CONCLUSIONS

This study displays the power of extensive mining of public data and bioinformatical repositories to provide answers for a specific pharmacological question. It furthermore demonstrates how the usage of such a combinatorial approach is advantageous for the biologist in terms of experimentation time and costs.

The effect of traumatic-like stress exposure on alterations in the temporal social behavior of a rodent population

Though the relationship between traumatic stress and social behavior, which has been explored for years, is dynamic and largely estimated between dyads, little is known about the causal effects of traumatic stress exposure on the time-dependent dynamic alterations in the social behaviors on a large-group level. We thus investigated the effect of a single prolonged stress (SPS) exposure, a classical animal model that recapitulates posttraumatic stress disorder (PTSD)-like symptoms in rodents, on the spatiotemporal, social behavior changes within a large group of cohabiting rats. One-half of thirty-two Sprague-Dawley rats were assigned to the experimental group and subjected to SPS treatment administered two weeks after baseline social behavior recording; the other half served as the controls. Each group of rats (n = 16) was housed in one of two large custom-made cylinders. We used an automatic tracking system to record the behavioral indices of social behavior of the rats before SPS exposure, on the SPS exposure day, during a 7-day-long quiescent period after SPS treatment, as well as during subsequent behavioral test days. In addition to SPS-induced PTSD-like behaviors, SPS induced a time-dependent, oscillating change in active/passive social behaviors that lasted for 3 weeks. SPS treatment decreased active social behaviors (especially affiliative behaviors) but increased passive social behaviors (e.g. huddling) immediately following stress exposure. Increased active social interactions were observed during the early phase after SPS treatment; while increased passive social behaviors were observed during the late phase after SPS treatment. These dynamic changes were repeatedly observed when the rats underwent subsequent stressful behavioral tests and challenges. SPS induced a long-term, time-dependent oscillating change in indices of the social behavior. These changes may serve as an adaptive mechanism, and their manifestations critically depended on the time course following the traumatic stress exposure.

The correlation between adiponectin and FGF9 in depression disorder

Adiponectin (ADPN) and fibroblast growth factor 9 (FGF9) has been reported as anti-depressive and pro-depressive factor, respectively. However, it is unknown whether there is directly interaction between ADPN and FGF9 in depression. The present study aims to investigate the correlation between ADPN and FGF9 in depression disorder. Firstly, the decreased level of ADPN and the increased level of FGF9 in plasma of depressive patients compared with non-depressive subjects were observed. Furthermore, these is a significant negative correlation between the ratio of ADPN to FGF9 and the total score of Hamilton Depression Scale in total investigated subjects. The similar changes of ADPN and FGF9 were also observed in elder adiponectin gene knockout (Adipo^-/-) mice with an increasing trend to depressive-like behaviors. Secondly, the decreasing level of ADPN and increasing level of FGF9 in plasma and hippocampus tissues were observed in chronic unpredictable mild stress (CUMS)-induced depression in ICR mice with significant depressive-like behaviors and hippocampus damage, which attenuated by injection of recombinant ADPN or FGF9 antibody into lateral ventricle. In Adipo^-/- mice, injection of FGF9 antibody into lateral ventricle also attenuated CUMS-induced depressivelike behaviors. The protein expression of FGF receptor 3 (FGFR3), the main receptor of FGF9, was significantly down-regulated in hippocampus tissues of CUMS-treated mice, which could be attenuated by treatment with either recombinant ADPN or anti-FGF9. In summary, the present results suggest that ADPN maybe a key negative regulator of FGF9/FGFR3 in depressive disorder and the dysfunction of ADPN-FGF9 pathway plays a key role in stress-induced depression.

Consequences of Perinatal Cannabis Exposure

Cannabis exposure during the perinatal period results in varied and significant consequences in affected offspring. The prevalence of detrimental outcomes of perinatal cannabis exposure is likely to increase in tandem with the broadening of legalization and acceptance of the drug. As such, it is crucial to highlight the immediate and protracted consequences of cannabis exposure on pre- and postnatal development. Here, we identify lasting changes in neurons' learning flexibility (synaptic plasticity) and epigenetic misregulation in animal models of perinatal cannabinoid exposure (using synthetic cannabinoids or active components of the cannabis plant), in addition to significant alterations in social behavior and executive functions. These findings are supported by epidemiological data indicating similar behavioral outcomes throughout life in human offspring exposed to cannabis during pregnancy. Further, we indicate important lingering questions regarding accurate modeling of perinatal cannabis exposure as well as the need for sex- and age-dependent outcome measures in future studies.

Treadmill exercise ameliorates depressive symptoms through increasing serotonin expression in postpartum depression rats

Postpartum depression (PPD) is defined as the depressive symptoms that occur from the moment of delivery until 12 months after delivery. PPD symptoms are closely associated with reduced activity of the serotonergic system. Serotonin (5-hydroxytryptamine, 5-HT) plays an important role in the pathogenesis of depression. Tryptophan hydroxylase (TPH) catalyzes the rate-limiting step of 5-HT biosynthesis in the serotonergic neurons. Exercise exerts anti-depressive effect on depression patients as well as on animal models of depression. In the present study, the effect of treadmill exercise on PPD was investigated using rats. For this study, open field test for activity and forced swimming test for depressive symptoms, and immunohistochemistry for 5-HT and TPH were conducted. The rats in the exercise groups were forced to run on a motorized treadmill for 30 min once a day for 2 weeks. Activity in the open field test was decreased in the postpartum rats, however, performing treadmill running increased activity in the postpartum rats. The climbing time was decreased and the immobility time was increased in the postpartum rats. Treadmill exercise increased climbing time and suppressed immobility time in the postpartum rats. 5-HT and TPH expressions in the dorsal raphe were suppressed in the postpartum rats, and treadmill exercise enhanced 5-HT and TPH expressions in the postpartum rats. Treadmill exercise ameliorated the PPD very effectively by enhancing serotonin level.

Elevated Thyroid Peroxidase Antibody Increases Risk of Post-partum Depression by Decreasing Prefrontal Cortex BDNF and 5-HT Levels in Mice

Post-partum depression (PPD) is a common mental disease in the perinatal period that profoundly affects mothers and their offspring. Some clinical studies have found that PPD is related to thyroid peroxidase antibodies (TPOAbs); however, the mechanism underlying this relationship is unclear. Female C57BL/6 mice immunized with adenovirus encoding the cDNA of the full-length mTPO (mTPO-Ad) were used to establish the isolated TPOAb-positive mouse model in the present study. Maternal depressive-like behaviors were assessed using the forced swimming test (FST), sucrose preference test (SPT), and tail suspension test (TST) post-partum. The serum TPOAb titer was measured by enzyme-linked immunosorbent assay (ELISA) before pregnancy and post-partum. Furthermore, in the prefrontal cortex, the mRNA and protein expression levels of brain-derived neurotrophic factor (BDNF) were measured, serotonin (5-HT) levels were measured by ultra-high-performance liquid chromatography–tandem mass-spectrometry (UHPLC–MS/MS), and total thyroxine (TT4) levels were determined by ELISA. Compared with the controls, the mice immunized with mTPO-Ad displayed depressive behaviors, with a significantly lower sucrose preference (SP) at the 12-h time point and a longer immobility time in the FST and TST, which were accompanied by a lower expression of BDNF and 5-HT but no change in the TT4 concentration in the prefrontal cortex. Together, these findings suggest that elevated TPOAb may increase the risk of subsequent PPD and decrease the concentration of BDNF and 5-HT in the prefrontal cortex.

Ceftriaxone pretreatment reduces the propensity of postpartum depression following stroke during pregnancy in rats

OBJECTIVE

Ischemic stroke increases the propensity to develop depression in humans and laboratory animals, and we hypothesized that such an incidence during pregnancy may increase the risk for the development of postpartum depression (PPD).

MATERIALS AND METHODS

To test this hypothesis, we used bilateral common carotid arteries occlusion (BCCAO) to induce transient cerebral ischemia in pregnant rats, and evaluated its effects on subsequent development of PPD in dams. Additionally, we investigated whether ceftriaxone pretreatments before the induction of brain ischemia could alter the propensity of PPD.

RESULTS

We found that 15min BCCAO during pregnancy enhanced immobility time and reduced the frequency of swimming or climbing behaviors in the forced swim test, and decreased the sucrose preference in dams at postpartum day 21. Such behavioral alterations were associated with lower level of GLT-1 expression in the medial prefrontal cortical regions (mPFC) of PPD dams. Specifically, mPFC GLT-1 expression levels in dams with ischemia history were correlated with sucrose preference levels at postpartum day 21. Finally, ceftriaxone pretreatment (200mg/kg/day, 5days) before the 15min BCCAO prevented the development of PPD, and prevented the reduction of GLT-1 expression in the mPFC.

CONCLUSIONS

Taken together, our results suggested that ceftriaxone pretreatment before brain ischemia during pregnancy may reduce the propensity for the development of PPD by preventing the loss of GLT-1 expression in the mPFC.

Maternal alterations in the proteome of the medial prefrontal cortex in rat

Proteomic differences between rat dams and control mothers deprived of their pups immediately after delivery were investigated in the medial prefrontal cortex (mPFC). A 2-D DIGE minimal dye technique combined with LC-MS/MS identified 32 different proteins that showed significant changes in expression in the mPFC, of which, 25 were upregulated and 7 were downregulated in dams. The identity of one significantly increased protein, the small heat-shock protein alpha-crystallin B chain (Cryab), was confirmed via Western blot analysis. Alpha-crystallin B chain was distributed in scattered cells in the mPFC, as demonstrated by immunohistochemistry. Furthermore, it was found to be localized in parvalbumin-containing neurons using double labeling. The elevation of its mRNA level in rat dams was also demonstrated via RT-PCR. The functional classification of the altered proteins was conducted using the UniProt and Gene Ontology protein databases. The identified proteins predominantly participate in synaptic transport and plasticity, neuron development, oxidative stress and apoptosis, and cytoskeleton organization. A common regulator and target analysis of these proteins determined using the Elsevier Pathway Studio Platform suggests that protein level changes associated with pup nursing are driven by growth factors and cytokines, while the MAP kinase pathway was identified as a common target. A high proportion of the proteins that were found to be altered in the mPFC are associated with depression.

BIOLOGICAL SIGNIFICANCE

The behavior and emotional state of females change robustly when they become mothers. The brain, which governs these changes, may also undergo molecular alterations in mothers. As no proteomics approaches have been applied regarding maternal changes in the brain, we addressed this issue in the mPFC as this brain area is the uppermost cortical center of maternal control and the associated mood changes. The high number of protein-level alterations found between mothers taking care of their litter and those without pups indicates that pup nursing is associated with cortical protein-level changes. Alterations in proteins participating in synaptic transport, plasticity and neuron development suggest neuroplastic changes in the maternal brain. In turn, the relatively high number of altered proteins in the mPFC associated with depression suggests that the physiological effects of the protein-level alterations in the maternal mPFC could promote the incidence of postpartum depression. Cryab, a protein confirmed to be increased during maternal behaviors, was selectively found in parvalbumin cells, which, as fast-spiking interneurons, are associated with depression. The function of Cryab should be further investigated to establish whether it can be used to identify drug targets for future drug development.

Gender-linked stem cell alterations in stroke and postpartum depression

Stroke is a significant unmet clinical need. The current stroke treatment of tissue plasminogen activator is limited to the very acute 4.5 h after disease onset which benefits only less than 3% of ischemic stroke patients. Our overarching hypothesis advances the notion that gender, which has been established as a comorbidity factor of stroke, plays a key role in regenerative medicine, in particular stem cell therapy. We hypothesize that gender is a key factor in culture-induced stemness of adult stem cells. Our goal is to provide new evidence supporting gender effects on stroke and stem cells for the purpose of enhancing our understanding of the pathophysiology of the disease and developing novel stem cell-based therapeutics targeting gender-relevant stress hormones as manifested in a stroke-postpartum depression paradigm.

Behavioural changes in mothers and maternally sensitised female mice

The maternal motivation and depression-like behaviour of primiparous mother and maternally sensitised virgin female mice were investigated. During a 1-h test period, dams and sensitised female mice spent significantly more time in pup-associated than in control cages when they could freely choose between them, while virgin control and ovariectomised females had no such preference. In the forced swim test, the time spent in active (swimming and struggling) and passive (floating) behaviours was measured for 6 min. Mother mice spent more time engaged in active behaviours than virgin and sensitised female mice, while the latter two groups did not differ from each other in the forced swim test. The results suggest that maternal motivation is increased in postpartum mothers and maternally sensitised female mice. We also provide the first demonstration that postpartum mother mice display anti-depression-like behaviours in the forced swim test, while maternally sensitised females do not show such emotional changes.