Role of the GLP2-Wnt1 axis in silicon-rich alkaline mineral water maintaining intestinal epithelium regeneration in piglets under early-life stress.

Stress-induced intestinal epithelial injury (IEI) and a delay in repair in infancy are predisposing factors for refractory gut diseases in adulthood, such as irritable bowel syndrome (IBS). Hence, it is necessary to develop appropriate mitigation methods for mammals when experiencing early-life stress (ELS). Weaning, as we all know, is a vital procedure that all mammalian newborns, including humans, must go through. Maternal separation (MS) stress in infancy (regarded as weaning stress in animal science) is a commonly used ELS paradigm. Drinking silicon-rich alkaline mineral water (AMW) has a therapeutic effect on enteric disease, but the specific mechanisms involved have not been reported. Herein, we discover the molecular mechanism by which silicon-rich AMW repairs ELS-induced IEI by maintaining intestinal stem cell (ISC) proliferation and differentiation through the glucagon-like peptide (GLP)2-Wnt1 axis. Mechanistic study showed that silicon-rich AMW activates GLP2-dependent Wnt1/ß-catenin pathway, and drives ISC proliferation and differentiation by stimulating Lgr5+ ISC cell cycle passage through the G1-S-phase checkpoint, thereby maintaining intestinal epithelial regeneration and IEI repair. Using GLP2 antagonists (GLP23-33) and small interfering RNA (SiWnt1) in vitro, we found that the GLP2-Wnt1 axis is the target of silicon-rich AMW to promote intestinal epithelium regeneration. Therefore, silicon-rich AMW maintains intestinal epithelium regeneration through the GLP2-Wnt1 axis in piglets under ELS. Our research contributes to understanding the mechanism of silicon-rich AMW promoting gut epithelial regeneration and provides a new strategy for the alleviation of ELS-induced IEI.

Distinct ACC Neural Mechanisms Underlie Authentic and Transmitted Anxiety Induced by Maternal Separation in Mice.

It is known that humans and rodents are capable of transmitting stress to their naive partners via social interaction. However, a comprehensive understanding of transmitted stress, which may differ from authentic stress, thus revealing unique neural mechanisms of social interaction resulting from transmitted stress and the associated anxiety, is missing. We used, in the present study, maternal separation (MS) as a stress model to investigate whether MS causes abnormal behavior in adolescence. A key concern in the analysis of stress transmission is whether the littermates of MS mice who only witness MS stress ("Partners") exhibit behavioral abnormalities similar to those of MS mice themselves. Of special interest is the establishment of the neural mechanisms underlying transmitted stress and authentic stress. The results show that Partners, similar to MS mice, exhibit anxiety-like behavior and hyperalgesia after witnessing littermates being subjected to early-life repetitive MS. Electrophysiological analysis revealed that mice subjected to MS demonstrate a reduction in both the excitatory and inhibitory synaptic activities of parvalbumin interneurons (PVINs) in the anterior cingulate cortex (ACC). However, Partners differed from MS mice in showing an increase in the number and excitability of GABAergic PVINs in the ACC and in the ability of chemogenetic PVIN inactivation to eliminate abnormal behavior. Furthermore, the social transfer of anxiety-like behavior required intact olfactory, but not visual, perception. This study suggests a functional involvement of ACC PVINs in mediating the distinct neural basis of transmitted anxiety.SIGNIFICANCE STATEMENT The anterior cingulate cortex (ACC) is a critical brain area in physical and social pain and contributes to the exhibition of abnormal behavior. ACC glutamatergic neurons have been shown to encode transmitted stress, but it remains unclear whether inhibitory ACC neurons also play a role. We evaluate, in this study, ACC neuronal, synaptic and network activities and uncover a critical role of parvalbumin interneurons (PVINs) in the expression of transmitted stress in adolescent mice who had witnessed MS of littermates in infancy. Furthermore, inactivation of ACC PVINs blocks transmitted stress. The results suggest that emotional contagion has a severe effect on brain function, and identify a potential target for the treatment of transmitted anxiety.

Toward understanding the neural mechanisms involved in early life stress-induced aggression: A Highlight for "Maternal separation early in life induces excessive activity of the central amygdala related to abnormal aggression".

Early life stress, such as childhood abuse and neglect, is one of the major risk factors for the development of antisocial behavior. In rat models, repeated maternal separation (MS) stress, in which the pups are separated from the dams for a few hours each day during the first 2-3 weeks of life, increases aggressive behavior in adult males. This Editorial highlights an article in the current issue of the Journal of Neurochemistry that demonstrates the involvement of the central nucleus of the amygdala (CeA) in the escalation of aggressive behavior in the MS model. The authors show that MS rats exhibit higher c-Fos expression in the CeA during an aggressive encounter compared to non-isolated control rats. Unexpectedly, other amygdala subnuclei did not show differential activation between MS and control groups. Using optogenetics, they provide direct evidence that activation of CeA neurons increases intermale aggressive behavior and that bilateral CeA activation shifts behavioral patterns toward more qualitatively intense aggressive behavior than unilateral CeA activation. These findings highlight the important role of the CeA in the development of abnormal aggression and indicate that this region may be an important therapeutic target for human aggression induced by early life stress.

Gas5 regulates early-life stress-induced anxiety and spatial memory.

Early-life stress (ES) induced by maternal separation (MS) remains a proven causality of anxiety and memory deficits at later stages of life. Emerging studies have shown that MS-induced gene expression in the hippocampus is operated at the level of transcription. However, the extent of involvement of non-coding RNAs in MS-induced behavioural deficits remains unexplored. Here, we have investigated the role of synapse-enriched long non-coding RNAs (lncRNAs) in anxiety and memory upon MS. We observed that MS led to an enhancement of expression of the lncRNA growth arrest specific 5 (Gas5) in the hippocampus; accompanied by increased levels of anxiety and deficits in spatial memory. Gas5 knockdown in early life was able to reduce anxiety and partially rescue the spatial memory deficits of maternally separated adult mice. However, the reversal of MS-induced anxiety and memory deficits is not attributed to Gas5 activity during neuronal development as Gas5 RNAi did not influence spine development. Gene Ontology analysis revealed that Gas5 exerts its function by regulating RNA metabolism and translation. Our study highlights the importance of MS-regulated lncRNA in anxiety and spatial memory.

Lateral habenula IL-10 controls GABAA receptor trafficking and modulates depression susceptibility after maternal separation.

Maternal separation (MS), a form of early life adversity, increases the risk of psychiatric disorders in adulthood by intricately linking cytokines and mood-regulating brain circuits. The Lateral Habenula (LHb) encodes aversive experiences, contributes to negative moods, and is pivotal in depression development. However, the precise impact of MS on LHb cytokine signaling and synaptic plasticity remains unclear. We reported that adolescent MS offspring mice displayed susceptibility to depression behavioral phylotypes, with neuronal hyperactivity and an imbalance in pro-inflammatory and anti-inflammatory cytokines in the LHb. Moreover, the decreased IL-10 level negatively correlated with depressive-like behaviors in susceptible mice. Functionally, LHb IL-10 overexpression restored decreased levels of PI3K, phosphorylated AKT (pAKT), gephyrin, and membrane GABAA receptor proteins while reducing abnormally elevated GSK3ß and Fos expression, rescuing the MS-induced depression. Conversely, LHb neuronal IL-10 receptor knockdown in naive mice increased Fos expression and elicited depression-like symptoms, potentially through impaired membrane GABAA receptor trafficking by suppressing the PI3K/pAKT/gephyrin cascades. Hence, this work establishes a mechanism by which MS promotes susceptibility to adolescent depression by impeding the critical role of IL-10 signaling on neuronal GABAA receptor function.

Early life adversity accelerates hypothalamic drive of pubertal timing in female rats with associated enhanced acoustic startle.

Early life adversity in the form of childhood maltreatment in humans or as modeled by maternal separation (MS) in rodents is often associated with an earlier emergence of puberty in females. Earlier pubertal initiation is an example of accelerated biological aging and predicts later risk for anxiety in women, especially in populations exposed to early life trauma. Here we investigated external pubertal markers as well as hypothalamic gene expression of pubertal regulators kisspeptin and gonadotropin-releasing hormone, to determine a biological substrate for MS-induced accelerated puberty. We further investigated a mechanism by which developmental stress might regulate pubertal timing. As kisspeptin and gonadotropin-releasing hormone secretion are typically inhibited by corticotropin releasing hormone at its receptor CRH-R1, we hypothesized that MS induces a downregulation of Crhr1 gene transcription in a cell-specific manner. Finally, we explored the association between pubertal timing and anxiety-like behavior in an acoustic startle paradigm, to drive future preclinical research linking accelerated puberty and anxiety. We replicated previous findings that MS leads to earlier puberty in females but not males, and found expression of kisspeptin and gonadotropin-releasing hormone mRNA to be prematurely increased in MS females. RNAscope confirmed increased expression of these genes, and further revealed that kisspeptin-expressing neurons in females were less likely to express Crhr1 after MS. Early puberty was associated with higher acoustic startle magnitude in females. Taken together, these findings indicate precocial maturation of central pubertal timing mechanisms after MS, as well as a potential role of CRH-R1 in these effects and an association with a translational measure of anxiety.

Modulation of Intestinal Motility in an Adolescent Rat Model of Irritable Bowel Syndrome.

INTRODUCTION: The pathophysiology of irritable bowel syndrome (IBS) remains unknown. This study aimed to evaluate colonic motility and serotonin system response to restraint stress (RS) among adolescent rats who underwent neonatal maternal separation (NMS) to clarify the features of pathogenesis in adolescents with IBS. METHODS: Male rats were exposed to NMS as chronic stress, and a normally handled (NH) group was used as control. Four groups were created by adding RS as acute stress treatment to the NMS and NH groups. To realize the RS treatment, the subjects were restrained for 1 h at the age of 5 weeks, and hourly fecal pellet discharge was determined. After euthanization and proximal colon intestinal tissue collection, 5-hydroxytryptamine (5-HT) and 5-hydroxytryptamine receptor 3 (5-HT3R) concentrations, enterochromaffin (EC) cell density, and the expression of mRNA-encoding slc6a4 were examined. RESULTS: The amount of fecal pellet discharge during RS increased significantly in the RS and NMS+RS groups compared with that in the NH and NMS groups, respectively. The 5-HT concentration in the intestinal tissue of rats in the RS and NMS groups increased significantly compared with that of rats in the NH group. EC cell density also increased significantly in the NMS and NMS+RS groups compared with that in the NH and RS groups. However, combined stress did not result in any significant differences in the expression of 5-HT3R and mRNA-encoding slc6a4. CONCLUSIONS: The combination of juvenile and acute stress effectively induced increased 5-HT concentration or EC cell density via the 5-HT pathway in the proximal colon of adolescent rats.

Mothers' experiences of breast milk expression during separation from their hospitalized infants: a systematic review of qualitative evidence.

BACKGROUND: Mother-infant separation, which is occurring with an increasing incidence, is a barrier to direct breastfeeding. Owing to the importance of breast milk to hospitalized infants, mothers are actively encouraged to express milk during their infants' neonatal intensive care unit (NICU) stay. However, mothers are often faced with a number of challenges in this process. There is a need to understand such mothers' real-life experiences of breast milk expression to develop supportive strategies to reduce the burden on mothers and increase breastfeeding rates. METHODS: A comprehensive search of 12 databases was conducted for relevant studies published from database construction to December 2022. All qualitative and mixed-method studies published in English and Chinese that reported on mothers' experiences of human milk expression during separation from their hospitalized infants were included. Two reviewers independently conducted screening, data extraction, and quality appraisal, with disagreements resolved by a third reviewer. The process of searching followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. The JBI Qualitative Assessment and Review Instrument was used to assess study quality and the credibility of study findings. Meta-aggregation was performed to integrate the results. RESULTS: This systematic review aggregated mothers' experiences of milk expression during separation from their hospitalized infants. Database search yielded 600 records, of which 19 full-text documents were screened. Finally, 13 studies of good quality were included with data from 332 mothers across seven countries. A total of 61 primary findings with illustrations were extracted from the 13 eligible studies, the findings were generalized into 16 categories, and further were concluded as four synthesized findings: purpose and motivation, physical and emotional experiences, barrier factors, and coping styles. CONCLUSION: Mothers were driven by extrinsic motivation in their decision to express breast milk. They experienced physical exhaustion and many negative emotional feelings while expressing. This process was affected by numerous barriers. Social support was essential to the initiation and maintenance of milk expression. Medical staff and families should pay more attention to the mental health of mothers with infants in the NICU. Future research should incorporate strategies to cope with emotional responses and offer practical strategies for managing milk expression. SYSTEMATIC REVIEW REGISTRATION: [ www.crd.york.ac.uk ], identifier [PROSPERO 2022 CRD42022383080].

Early Adversity Affects Cerebellar Structure and Function-A Systematic Review of Human and Animal Studies.

Recent research has highlighted cerebellar involvement in cognition and several psychiatric conditions such as mood and anxiety disorders and schizophrenia. Attention-deficit/hyperactivity disorder and autism spectrum disorder have been linked to reduced cerebellar volume as well. Cerebellar alterations are frequently present after early adversity in humans and animals, but a systematic integration of results is lacking. To this end, a systematic literature search was conducted in PubMed, Web of Science, and EBSCO databases using the keywords "early adversity OR early life stress" AND "cerebellum OR cerebellar." A total of 45 publications met the inclusion criteria: 25 studies investigated human subjects and 20 reported results from animal models. Findings in healthy subjects show bilateral volume reduction and decreased functional connectivity within the cerebellum and between the cerebellum and frontal regions after adversity throughout life, especially when adversity was assessed with the Childhood Trauma Questionnaire. In clinical populations, adults demonstrate increased cerebellar volume and functional connectivity after adversity, whereas pediatric patients show reduced cerebellar volume. Animal findings reveal cerebellar alterations without necessarily co-occurring pathological behavior, highlighting alterations in stress hormone receptor levels, cell density, and neuroinflammation markers. Cerebellar alterations after early adversity are robust findings across human and animal studies and occur independent of clinical symptoms.

The role of epigenetic mechanisms in the long-term effects of early-life adversity and mother-infant relationship on physiology and behavior of offspring in laboratory rats and mice.

Maternal care during the early postnatal period of altricial mammals is a key factor in the survival and adaptation of offspring to environmental conditions. Natural variations in maternal care and experimental manipulations with maternal-child relationships modeling early-life adversity (ELA) in laboratory rats and mice have a strong long-term influence on the physiology and behavior of offspring in rats and mice. This literature review is devoted to the latest research on the role of epigenetic mechanisms in these effects of ELA and mother-infant relationship, with a focus on the regulation of hypothalamic-pituitary-adrenal axis and brain-derived neurotrophic factor. An important part of this review is dedicated to pharmacological interventions and epigenetic editing as tools for studying the causal role of epigenetic mechanisms in the development of physiological and behavioral profiles. A special section of the manuscript will discuss the translational potential of the discussed research.

Long-lasting adverse effects of short-term stress during the suckling-mastication transition period on masticatory function and intraoral sensation in rats.

Early-life stress affects brain development, eventually resulting in adverse behavioral and physical health consequences in adulthood. The present study assessed the hypothesis that short-term early-life stress during infancy before weaning, a period for the maturation of mastication and sleep, poses long-lasting adverse effects on masticatory function and intraoral sensations later in life.Rat pups were exposed to either maternal separation (MS) or intermittent hypoxia (IH-Infancy) for 6 h/day in the light/sleep phase from postnatal day (P)17 to P20 to generate "neglect" and "pediatric obstructive sleep apnea" models, respectively. The remaining rats were exposed to IH during P45-P48 (IH-Adult). Masticatory ability was evaluated based on the rats' ability to chew pellets and bite pasta throughout the growth period (P21-P70). Intraoral chemical and mechanical sensitivities were assessed using two-bottle preference drinking tests, and hind paw pain thresholds were measured in adulthood (after P60).No differences were found in body weight, grip force, and hind paw sensitivity in MS, IH-Infancy, and IH-Adult rats compared with naïve rats. Masticatory ability was lower in MS and IH-Infancy rats from P28 to P70 than in naïve rats. MS and IH-Infancy rats exhibited intraoral hypersensitivity to capsaicin and mechanical stimulations in adulthood. The IH-Adult rats did not display inferior masticatory ability or intraoral hypersensitivity.In conclusion, short-term early-life stress during the suckling-mastication transition period potentially causes a persistent decrease in masticatory ability and intraoral hypersensitivity in adulthood. The period is a "critical window" for the maturation of oral motor and sensory functions.

Maternal separation early in life induces excessive activity of the central amygdala related to abnormal aggression.

Epidemiological studies have indicated that child maltreatment, such as neglect, is a risk factor of escalated aggression, potentially leading to delinquency and violent crime in the future. However, little is known about the mechanisms by which an early adverse environment may later cause violent behavior. In this study, we aimed to thoroughly examine the association between aggression against conspecific animals and the activity of amygdala subnuclei using the maternal separation (MS) model, which is a common model of early life stress. In the MS group, pups of Sprague-Dawley rats were separated from their dam during postnatal days 2-20 (twice a day, 3 h each). We only included 9-week-old male offspring for each analysis and compared the MS group with the mother-reared control group; both groups were raised by the same dam during postnatal days 2-20. The results revealed that the MS group exhibited higher aggression and excessive activity of only the central amygdala (CeA) among the amygdala subnuclei during the aggressive behavior test. Moreover, a significant positive correlation was observed between higher aggression and CeA activation. While CeA activity is known to be involved in hunting behavior for prey, some previous studies have also indicated a relationship between CeA and intraspecific aggression. It remains unclear, however, whether excessive CeA activity directly induces intraspecific aggression. Therefore, we stimulated the CeA using optogenetics with 8-week-old rats to clarify the relationship between intraspecific aggression and CeA activity. Notably, CeA activation resulted in higher aggression, even when the opponent was a conspecific animal. In particular, bilateral CeA activation resulted in more severe displays of aggressive behavior than necessary, such as biting a surrendered opponent. These findings suggest that an adverse environment during early development intensifies aggression through excessive CeA activation, which can increase the risk of escalating to violent behavior in the future.

Beta 3-adrenoceptor agonism ameliorates early-life stress-induced visceral hypersensitivity in male rats.

Visceral hypersensitivity, a hallmark of disorders of the gut-brain axis, is associated with exposure to early-life stress (ELS). Activation of neuronal ß3-adrenoceptors (AR) has been shown to alter central and peripheral levels of tryptophan and reduce visceral hypersensitivity. In this study, we aimed to determine the potential of a ß3-AR agonist in reducing ELS-induced visceral hypersensitivity and possible underlying mechanisms. Here, ELS was induced using the maternal separation (MS) model, where Sprague Dawley rat pups were separated from their mother in early life (postnatal day 2-12). Visceral hypersensitivity was confirmed in adult offspring using colorectal distension (CRD). CL-316243, a ß3-AR agonist, was administered to determine anti-nociceptive effects against CRD. Distension-induced enteric neuronal activation as well as colonic secretomotor function were assessed. Tryptophan metabolism was determined both centrally and peripherally. For the first time, we showed that CL-316243 significantly ameliorated MS-induced visceral hypersensitivity. Furthermore, MS altered plasma tryptophan metabolism and colonic adrenergic tone, while CL-316243 reduced both central and peripheral levels of tryptophan and affected secretomotor activity in the presence of tetrodotoxin. This study supports the beneficial role of CL-316243 in reducing ELS-induced visceral hypersensitivity, and suggests that targeting the ß3-AR can significantly influence gut-brain axis activity through modulation of enteric neuronal activation, tryptophan metabolism, and colonic secretomotor activity which may synergistically contribute to offsetting the effects of ELS.

Towards a central origin of nociceptive hypersensitivity in adult rats after a neonatal maternal separation.

Early life adversities influence a nervous system still in development with long-term consequences for later life. These include nociceptive circuit alterations critical to shape an adaptive pain response to protect the organism from potential damage. Adult rats with a history of neonatal maternal separation (NMS) display visceral and somatic nociceptive hypersensitivity and inefficient analgesic responses to stress. In this study, we have characterized the consequences of NMS on wide dynamic range neurons (WDR) in the spinal cord of anaesthetized adult rats during the nociceptive processing of hot and cold noxious information. We found that WDR neurons of NMS rats display an excessive coding of mechanical and thermal information applied at the rat's hindpaws. This nicely explains the hypernociceptive behaviours seen after noxious mechanical, cold and hot peripheral stimulation. A peripheral change in the expression of molecular transducers for these stimuli (i.e., TRPV1, TRPM8 and TRPA1) does not seem to account for this general hyperexcitability. Instead, a decreased chloride-mediated inhibitory tone on WDR neurons may play a role as indicated by the abnormal elevation of the type 1 Na-K-Cl cotransporter transcripts. Altogether, we propose that long-term consequences of NMS are associated with reduced spinal cord inhibition favouring the expression of pain hypersensitivity. We cannot exclude that this phenomenon is also present at supraspinal sites, as other NMS-associated symptoms include excessive anxiety and impaired sociability.

Early-life stress affects peripheral, blood-brain barrier, and brain responses to immune challenge in juvenile and adult rats.

Early-life stress (ELS) may affect brain maturation and neuroimmune interactions and, consequently, the inflammatory response to subsequent environmental factors later in life. Recently, the coexistence of blood-brain barrier (BBB) dysfunction and inflammation has been implicated in the etiology and progression of mental and/or neurodegenerative diseases. There are sex differences in the prevalence and outcomes of these disorders. The number of studies reporting the effects of ELS and sex on BBB functioning and neuroinflammatory processes in response to immune challenge is very limited, and the data are inconsistent. In the present study, we examined whether ELS, based on the maternal separation (MS) paradigm in rats, can condition male and female subjects to subsequent lipopolysaccharide (LPS)-induced immune challenge in juvenility or adulthood. Twenty-four hours after acute LPS injection, serum proinflammatory cytokines were measured, and BBB permeability in the medial prefrontal cortex (mPFC) and hippocampus (HP) was evaluated. Additionally, the mRNA expression of neuroinflammatory markers and BBB-related genes was also studied. We found that a single LPS challenge induced a proinflammatory response both in the periphery and in the mPFC and HP and increased BBB permeability in a sex-dependent fashion. Moreover, MS enhanced the neuroinflammatory response to LPS challenge in males (especially juveniles), whereas MS females showed no difference or a blunted central response to LPS compared with control females, mainly during adulthood. These results suggest that ELS may precondition individuals to subsequent environmental factors later in life in a sex-specific manner and potentially determine their susceptibility or resilience to mental and/or neurodegenerative diseases.

Examination of the role of adrenergic receptor stimulation in the sensitization of neuroinflammatory-based depressive-like behavior in isolated Guinea pig pups.

Early-life attachment disruption appears to sensitize neuroinflammatory signaling to increase later vulnerability for stress-related mental disorders, including depression. How stress initiates this process is unknown, but studies with adult rats and mice suggest sympathetic nervous system activation and/or cortisol elevations during the early stress are key. Guinea pig pups isolated from their mothers exhibit an initial active behavioral phase characterized by anxiety-like vocalizing. This is followed by inflammatory-dependent depressive-like behavior and fever that sensitize on repeated isolation. Using strategies that have been successful in adult studies, we assessed whether sympathetic nervous system activity and cortisol contributed to the sensitization process in guinea pig pups. In Experiment 1, the adrenergic agonist ephedrine (3 or 10 mg/kg), either alone or with cortisol (2.5 mg/kg), did not increase depressive-like behavior or fever during initial isolation the following day as might have been expected to if this stimulation was sufficient to account for the sensitization process. In Experiment 2, both depressive-like behavior and fever sensitized with repeated isolation, but beta-adrenergic receptor blockade with propranolol (10 or 20 mg/kg) did not affect either of these responses or their sensitization. The high dose of propranolol did, however, reduce vocalizing. These results suggest sympathetic nervous system activation is neither necessary nor sufficient to induce the presumptive neuroinflammatory signaling underlying sensitization of depressive-like behavioral or febrile responses in developing guinea pigs. Thus, processes mediating sensitization of neuroinflammatory-based depressive-like behavior following early-life attachment disruption in this model appear to differ from those previously found to underlie neuroinflammatory priming in adults.

Investigating the Effects of Maternal Separation on Hypothalamic-Pituitary-Adrenal Axis and Glucose Homeostasis under Chronic Social Defeat Stress in Young Adult Male Rat Offspring.

INTRODUCTION: Given the suggested metabolic regulatory effects of stress-responsive genes and based on the impacts of early-life stress on HPA axis development, this study aimed to characterize the maternal separation (MS) impact on the communication between glucose metabolism and HPA axis dysregulations under chronic social defeat stress (CSDS). METHODS: During the first 2 weeks of life, male Wistar rats were either exposed to MS or left undisturbed with their mothers (Std). Starting on postnatal day 50, the animals of each group were either left undisturbed in the standard group housing (Con) or underwent CSDS for 3 weeks. There were four groups (n = 10/group): Std-Con, MS-Con, Std-CSDS, and MS-CSDS. RESULTS: Early and/or adult life adversity reduced ß-cell number, muscular FK506-binding protein 51 (FKBP51) content, and BMI in adulthood. The reduction of ß-cell number and BMI in the MS-CSDS rats were more profound than MS-Con group. CSDS either alone or in combination with MS reduced locomotor activity and increased and decreased corticotropin-releasing factor type 1 receptor (CRFR1) content, respectively, in hypothalamus and pancreas. Although, under CSDS, MS intensified HPA axis overactivity and reduced isolated islets' insulin secretion, it could promote resilience to depression symptoms. No differences were observed in hypothalamic Fkbp5 gene DNA methylation and glucose tolerance among groups. CONCLUSION: MS exacerbated HPA axis overactivity and the endocrine pancreas dysfunctions under CSDS. The intensified corticosterone secretion and the diminished content of pancreatic CRFR1 protein could be involved in the reduced ß-cell number and islets' insulin secretion under CSDS. The decreased muscular FKBP51 content might be a homeostatic response to slow down insulin resistance development under chronic stress.

Double perinatal stress reduces the sexual response of adult female Wistar rats.

BACKGROUND: Early-life stress affects physiological development and produces changes in various aspects of emotional behavior. AIM: We sought to examine the effects of double perinatal stress (DPS)-a combination of prenatal systemic hypoxic-ischemic (HI) insults and repeated early maternal separation-on the estrus cycle and sexual behavior of adult rats. METHODS: HI was induced by clamping the uterine arteries of pregnant rats for 45 minutes on the 18th day of gestation (HI group). Sham control animals received laparotomy and anesthesia only. Pups were born at term. Maternal separation was performed from postnatal day 1 (P1) (P0 = day of birth) to P15. At P90, the sexual response of females in estrus was evaluated. Statistical analysis was performed using 2-way analysis of variance followed by Tukey's test. OUTCOMES: We considered the estrous cycle and sexual behavior of female rats submitted to DPS, as well as the influence of female behavior on the sexual response of male rats. RESULTS: Rats submitted to DPS showed a reduction in the lordosis quotient and in the lordosis rate, suggesting a reduction in female sexual receptivity. DPS female rats showed a reduction in the number of hops and darts and in the genital exploration time rate, suggesting a reduction in sexual proceptivity. In addition, males that interacted with DPS females showed a reduction in the number of ejaculations and in copulatory efficiency. CLINICAL IMPLICATIONS: Developing a deeper understanding of perinatal factors that affect adult female sexual response will allow for more effective interventions to prevent and treat such changes. On the other hand, the analysis of the sexual response allows assessing the quality of life and the general state of health. STRENGTHS AND LIMITATIONS: The development of animal models to investigate the environmental factors that interfere in the female sexual response may allow researchers to propose and test new therapeutic strategies. On the other hand, care must be exercised when interpreting animal data and extrapolating these results to estimate the possible effects of perinatal stressors on the human sexual response. CONCLUSION: Our results revealed that females subjected to DPS showed long-term effects on sexual behavior. In conclusion, managing stressors in prenatal life and early postnatal life can prevent problems in adult sexual life and improve overall health.

Spinal P2X4 Receptors Involved in Visceral Hypersensitivity of Neonatal Maternal Separation Rats.

Recent studies have demonstrated the vital role of P2X4 receptors (a family of ATP-gated non-selective cation channels) in the transmission of neuropathic and inflammatory pain. In this study, we investigated the role of spinal P2X4 receptors in chronic functional visceral hypersensitivity of neonatal maternal separation (NMS) rats. A rat model of irritable bowel syndrome was established by neonatal maternal separation. Visceral sensitivity was assessed by recording the response of the external oblique abdominal muscle to colorectal distension. P2X4 receptor antagonist and agonist were administrated intrathecally. The expression of P2X4 receptor was examined by Western Blot and immunofluorescence. The effect of P2X4 receptor antagonist on expression of brain-derived neurotrophic factor (BDNF) was assessed by Western Blot. We found neonatal maternal separation enhanced visceral hypersensitivity and increased the expression of P2X4 receptor in spinal thoracolumbar and lumbosacral segments of rats. Pharmacological results showed that visceral sensitivity was attenuated after intrathecal injection of P2X4 receptor antagonist, 5-BDBD, at doses of 10 nM or 100 nM, while visceral sensitivity was enhanced after intrathecal injection of P2X4 receptor agonist C5-TDS at doses of 10 µM or 15 µM. In addition, the spinal expression of BDNF significantly increased in NMS rats and intrathecal injection of 5-BDBD significantly decreased the expression of BDNF especially in NMS rats. C5-TDS failed to increase EMG amplitude in the presence of ANA-12 in control rats. Our results suggested the spinal P2X4 receptors played an important role in visceral hypersensitivity of NMS rats through BDNF.

Connexin 43 regulates astrocyte dysfunction and cognitive deficits in early life stress-treated mice.

Early life stress such as maternal separation (MS), is a major risk factor for developing psychiatric disorders in adulthood. Connexin 43 (CX43), the main type of connexins expressed in astrocytes, has been indicated to participate in depression disorders. Nevertheless, the role of CX43 in MS-induced cognitive impairment and astrocyte dysfunction is unclear. Neonatal C57BL/6 mice were exposed to MS to mimic early life stress. Adeno-associated virus carrying CX43 was inoculated into mice for CX43 overexpression. Sucrose preference test, forced swim test and Morris water maze were performed for evaluating depression-like behaviors and spatial learning and memory of mice in adulthood. Real time quantitative polymerase chain reaction was conducted to detect CX43 mRNA expression in mouse brain. Immunofluorescence staining and western blotting were used for measuring expression levels of astrocytic markers in murine hippocampal dentate gyrus. The results showed that overexpressing CX43 attenuated MS exposure-induced depression-like behaviors and decrease in spatial learning and memory in mice. Upregulating CX43 alleviated MS exposure-induced downregulation of astrocytic markers. Collectively, CX43 overexpression attenuates cognitive deficits and astrocyte dysfunction in mice exposed to MS.