The role of central corticoliberin in the ether stress-induced secretion of neurohypophyseal hormones and corticosterone in the rat

Parental pre-conception stress status and risk for anxiety in rat offspring: specific and sex-dependent maternal and paternal effects

Prenatal stressful events have long-lasting consequences on behavioral responses of offspring. While the effects of gestational and maternal stress have been extensively studied on psychological alterations in the progeny, little is known about effects of each parent's pre-conception life events on emotional responses in offspring. Here, the effect of maternal and/or paternal pre-conception stress was investigated on anxiogenic responses of offspring. Male and female adult rats were subjected to predatory stress (contactless exposure to a cat for 1 + 1 h per day) for 50 (male, n: 12) and 15 (female, n: 24) consecutive days; controls were not exposed. After the stress procedure, the control and stressed rats were mated to create four types of breeding pairs: control female/control male, stressed female/control male, control female/stressed male, and stressed female/stressed male. On postnatal days 30-31, the offspring were tested on the elevated plus maze and plasma corticosterone concentration was measured. Half of the pups were exposed to acute predatory stress before the elevated plus maze test. In most subgroups, corticosterone and anxiety-like behaviors in the offspring with both or only one parent exposed to pre-gestational stress increased compared to their control counterparts. However, under acute stress conditions, a different sex-dependent pattern of anxiety responses emerged. The combined effects of maternal and paternal stress were not additive. Hence, individual offspring behaviors can be influenced by the former life stress experiences of either parent. Incorporation of genetic and epigenetic aspects in development of neurobehavioral abnormalities and reprograming of the hypothalamic-pituitary-adrenal axis may contribute to this phenomenon. Lay summary Early life stress (including during pregnancy) is known to have long-lasting effects on offspring, including emotional behaviors. Whether individual anxiety behaviors can be influenced by stress experiences of each parent even before a pregnancy is less well-understood. Our findings from this study on rats exposed to predator stress before mating suggest that maternal or paternal adult life events prior to pregnancy can lead to maladaptive behavior in their offspring later in life.

Genome-Wide Analysis of Glucocorticoid-Responsive Transcripts in the Hypothalamic Paraventricular Region of Male Rats

Glucocorticoids (GCs) are essential for stress adaptation, acting centrally and in the periphery. Corticotropin-releasing factor (CRF), a major regulator of adrenal GC synthesis, is produced in the paraventricular nucleus of the hypothalamus (PVH), which contains multiple neuroendocrine and preautonomic neurons. GCs may be involved in diverse regulatory mechanisms in the PVH, but the target genes of GCs are largely unexplored except for the CRF gene (Crh), a well-known target for GC negative feedback. Using a genome-wide RNA-sequencing analysis, we identified transcripts that changed in response to either high-dose corticosterone (Cort) exposure for 12 days (12-day high Cort), corticoid deprivation for 7 days (7-day ADX), or acute Cort administration. Among others, canonical GC target genes were upregulated prominently by 12-day high Cort. Crh was upregulated or downregulated most prominently by either 7-day ADX or 12-day high Cort, emphasizing the recognized feedback effects of GC on the hypothalamic-pituitary-adrenal (HPA) axis. Concomitant changes in vasopressin and apelin receptor gene expression are likely to contribute to HPA repression. In keeping with the pleotropic cellular actions of GCs, 7-day ADX downregulated numerous genes of a broad functional spectrum. The transcriptome response signature differed markedly between acute Cort injection and 12-day high Cort. Remarkably, six immediate early genes were upregulated 1 hour after Cort injection, which was confirmed by quantitative reverse transcription PCR and semiquantitative in situ hybridization. This study may provide a useful database for studying the regulatory mechanisms of GC-dependent gene expression and repression in the PVH.

Effect of prenatal restraint stress and morphine co-administration on plasma vasopressin concentration and anxiety behaviors in adult rat offspring

Stressful events and exposure to opiates during gestation have important effects on the later mental health of the offspring. Anxiety is among the most common mental disorders. The present study aimed to identify effects of prenatal restraint stress and morphine co-administration on plasma vasopressin concentration (PVC) and anxiety behaviors in rats. Pregnant rats were divided into four groups (n = 6, each): saline, morphine, stress + saline and stress + morphine treatment. The stress procedure consisted of restraint twice per day, two hours per session, for three consecutive days starting on day 15 of pregnancy. Rats in the saline and morphine groups received either 0.9% saline or morphine intraperitoneally on the same days. In the morphine/saline + stress groups, rats were exposed to restraint stress and received either morphine or saline intraperitoneally. All offspring were tested in an elevated plus maze (EPM) on postnatal day 90 (n = 6, each sex), and anxiety behaviors of each rat were recorded. Finally, blood samples were collected to determine PVC. Prenatal morphine exposure reduced anxiety-like behaviors. Co-administration of prenatal stress and morphine increased locomotor activity (LA) and PVC. PVC was significantly lower in female offspring of the morphine and morphine + stress groups compared with males in the same group, but the opposite was seen in the saline + stress group. These data emphasize the impact of prenatal stress and morphine on fetal neuroendocrine development, with long-term changes in anxiety-like behaviors and vasopressin secretion. These changes are sex specific, indicating differential impact of prenatal stress and morphine on fetal neuroendocrine system development. Lay Summary Pregnant women are sometimes exposed to stressful and painful conditions which may lead to poor outcomes for offspring. Opiates may provide pain and stress relief to these mothers. In this study, we used an experimental model of maternal exposure to stress and morphine in pregnant rats. The findings indicated that maternal stress increased anxiety in offspring while morphine decreased such effects, but had negative effects on the levels of a hormone controlling blood pressure, and activity of offspring. Hence morphine should not be used in pregnancy for pain and stress relief.

Opposite effects of dexamethasone and ACTH on the adrenal cortex response to ethane dimethanesulphonate (EDS)

Recently we have reported that ethane dimethane-sulphonate (EDS), the Leydig cell cytotoxin, caused marked atrophy of the adrenal cortex of adult male rats. The aim of this work was to examine whether a 9-day treatment with dexamethasone (0.25 mg/kg/d) or ACTH (40 IU/kg/d), which started 4 days prior to administration of a single dose of EDS (75 mg/kg), influenced the response of the inner adrenocortical zones to the toxin. On day 15 after administration of EDS, adrenal weight was significantly decreased in saline treated rats, but glandular and serum corticosterone levels were not altered. In dexamethasone-suppressed rats, the effect of EDS was augmented; an additional decrease in adrenal weight was accompanied by reduced adrenal and serum corticosterone levels. In ACTH-treated animals EDS was ineffective. These results demonstrate that the deleterious effects of EDS on rat adrenal cortex can be prevented by ACTH and potentiated by dexamethasone.

Role of the circulating renin-angiotensin system in the pathogenesis of hypertension in transgenic rats. TGR(mREN2)27

Transgenic rats, termed TGR(mREN2)27, which carry the mouse ren2d renin gene, develop fulminant hypertension. To evaluate the role of the circulating renin-angiotensin system (RAS) in hypertension of TGR(mREN2)27, we determined plasma levels of its components and their regulation by ether-stress. Plasma prorenin was elevated in prehypertensive and in adult heterozygous TGR(mREN2)27 (fourtyfold), when compared with Sprague Dawley (SD) controls, whereas plasma renin concentration (PRC) and angiotensin II were not in SD rats ether anesthesia increased PRC at day (11 a.m.; fivefold), but not at night (11 p.m.). Ether had no effect on PRC in TGR(mREN2)27. In contrast, ether increased plasma corticosterone levels at day and night in both strains to a similar degree. Our data indicate that plasma active renin is not a pathogenetic factor for hypertension in TGR(mREN2)27 and suggest a primary role of circulating prorenin. The lack of stimulation of PRC by ether in TGR(mREN2)27 probably reflects predominant extrarenal origin of renin.