Spatial learning, memory, and reactivity of the hypothalamic-pituitary-adrenocortical system (HPA axis) were studied in adult male rats, whose mothers during pregnancy were subjected to acute moderate normobaric hypoxia, or repeated injections of buspirone, an agonist of type 1A serotonergic receptors (5HT1A), or their combination. Prenatal treatment with buspirone in rats with prenatal hypoxia impaired learning ability during the first day of 5-day training. A decrease in the effectiveness of long-term memory in comparison with short-term memory was revealed in two groups of rats: prenatal treatment with buspirone in combination with hypoxia and injection of physiological saline without hypoxia. The effectiveness of long-term memory and the level of corticosterone in response to stress did not differ between the groups, which can indicate adaptation of the 5HT1A receptor and the HPA axis to the prenatal buspirone and normobaric hypoxia during ontogeny.

The association between sleep and the immune-endocrine system is well recognized, but the nature of that relationship is not well understood. Sleep fragmentation induces a pro-inflammatory response in peripheral tissues and brain, but it also activates the hypothalamic-pituitary-adrenal (HPA) axis, releasing glucocorticoids (GCs) (cortisol in humans and corticosterone in mice). It is unclear whether this rapid release of glucocorticoids acts to potentiate or dampen the inflammatory response in the short term. The purpose of this study was to determine whether blocking or suppressing glucocorticoid activity will affect the inflammatory response from acute sleep fragmentation (ASF). Male C57BL/6J mice were injected i.p. with either 0.9% NaCl (vehicle 1), metyrapone (a glucocorticoid synthesis inhibitor, dissolved in vehicle 1), 2% ethanol in polyethylene glycol (vehicle 2), or mifepristone (a glucocorticoid receptor antagonist, dissolved in vehicle 2) 10 min before the start of ASF or no sleep fragmentation (NSF). After 24 h, samples were collected from brain (prefrontal cortex, hypothalamus, hippocampus) and periphery (liver, spleen, heart, and epididymal white adipose tissue (EWAT)). Proinflammatory gene expression (TNF-α and IL-1β) was measured, followed by gene expression analysis. Metyrapone treatment affected pro-inflammatory cytokine gene expression during ASF in some peripheral tissues, but not in the brain. More specifically, metyrapone treatment suppressed IL-1β expression in EWAT during ASF, which implies a pro-inflammatory effect of GCs. However, in cardiac tissue, metyrapone treatment increased TNF-α expression in ASF mice, suggesting an anti-inflammatory effect of GCs. Mifepristone treatment yielded more significant results than metyrapone, reducing TNF-α expression in liver (only NSF mice) and cardiac tissue during ASF, indicating a pro-inflammatory role. Conversely, in the spleen of ASF-mice, mifepristone increased pro-inflammatory cytokines (TNF-α and IL-1β), demonstrating an anti-inflammatory role. Furthermore, irrespective of sleep fragmentation, mifepristone increased pro-inflammatory cytokine gene expression in heart (IL-1β), pre-frontal cortex (IL-1β), and hypothalamus (IL-1β). The results provide mixed evidence for pro- and anti-inflammatory functions of corticosterone to regulate inflammatory responses to acute sleep loss.

Glucocorticoid (GC) hormones have traditionally been interpreted as indicators of stress, but the extent to which they provide information on physiological state remains debated. GCs are metabolic hormones that amongst other functions ensure increasing fuel (i.e. glucose) supply on the face of fluctuating energetic demands, a role often overlooked by ecological studies investigating the consequences of GC variation. Furthermore, because energy budget is limited, in natural contexts where multiple stimuli coexist, the organismś ability to respond physiologically may be constrained when multiple triggers of metabolic responses overlap in time. Using free-living spotless starling (Sturnus unicolor) chicks, we experimentally tested whether two stimuli of different nature known to trigger a metabolic or GC response respectively cause a comparable increase in plasma GCs and glucose. We further tested whether response patterns differed when both stimuli occurred consecutively. We found that both experimental treatments caused increases in GCs and glucose of similar magnitude, suggesting that both variables fluctuate along with variation in energy expenditure, independently of the trigger. Exposure to the two stimuli occurring subsequently did not cause a difference in GC or glucose responses compared to exposure to a single stimulus, suggesting a limited capacity to respond to an additional stimulus during an ongoing acute response. Lastly, we found a positive and significant correlation between plasma GCs and glucose after the experimental treatments. Our results add-up to the increasing research on the role of energy expenditure on GC variation, by providing experimental evidence on the association between plasma GCs and energy metabolism.

Reactive astrocytes are important pathophysiologically and synthesize neurosteroids. We observed that LPS increased immunoreactive TLR4 and key steroidogenic enzymes in cortical astrocytes of rats and investigated whether corticosteroids are produced and mediate astrocytic TLR4-dependent innate immune responses. We found that LPS increased steroidogenic acute regulatory protein (StAR) and StAR-dependent aldosterone production in purified astrocytes. Both increases were blocked by the TLR4 antagonist TAK242. LPS also increased 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) and corticosterone production, and both were prevented by TAK242 and by siRNAs against 11β-HSD1, StAR, or aldosterone synthase (CYP11B2). Knockdown of 11β-HSD1, StAR, or CYP11B2 or blocking either mineralocorticoid receptors (MR) or glucocorticoid receptors (GR) prevented dephosphorylation of p-Ser9GSK-3β, activation of NF-κB, and the GSK-3β-dependent increases of C3, IL-1β, and TNF-α caused by LPS. Exogenous aldosterone mimicked the MR- and GSK-3β-dependent pro-inflammatory effects of LPS in astrocytes, but corticosterone did not. Supernatants from astrocytes treated with LPS reduced MAP2 and viability of cultured neurons except when astrocytic StAR or MR was inhibited. In adrenalectomized rats, intracerebroventricular injection of LPS increased astrocytic TLR4, StAR, CYP11B2, and 11β-HSD1, NF-κB, C3 and IL-1β, decreased astrocytic p-Ser9GSK-3β in the cortex and was neurotoxic, except when spironolactone was co-injected, consistent with the in vitro results. LPS also activated NF-κB in some NeuN+ and CD11b+ cells in the cortex, and these effects were prevented by spironolactone. We conclude that intracrine aldosterone may be involved in the TLR4-dependent innate immune responses of astrocytes and can trigger paracrine effects by activating astrocytic MR/GSK-3β/NF-κB signaling.

OBJECTIVE: Depression is associated with metabolic disorders, including non-alcoholic fatty liver disease (NAFLD). However, the mechanisms underlying the interaction between them are still poorly known.
METHODS: In this study, mice on a choline deficiency, L-amino acid-defined, high-fat diet (CDAHFD) developing steatosis were challenged with chronic restraint stress (CRS), a protocol widely used to induce depression. The development of depression and steatosis was evaluated using histopathology analysis, ELISA, q-PCR and Western Blot.
RESULTS: The contribution of the activated HPA axis to hepatic steatosis progress was fully established, which was validated using a hepatocyte model. Histopathological and biochemical analysis indicated that steatosis was exacerbated by CRS challenge, and behavioral tests indicated that the mice developed depression. Among the screened endocrinal pathways, the hypothalamic-pituitary-adrenal (HPA) axis was significantly activated and the synergistic effect of CDAHFD and CRS in activating the HPA axis was observed. In the hypothalamus, expression of corticotropin-releasing hormone (CRH) was increased by 86% and the protein levels of hypothalamic CRH were upregulated by 25% to 33% by CRS treatment. Plasma CRH levels were elevated by 45-56% and plasma adrenocorticotropic hormone (ACTH) levels were elevated by 29-58% by CRS treatment. In the liver, target genes of the HPA axis were activated, accompanied by disruption of the lipid metabolism and progression of steatohepatitis. The lipid metabolism in the Hepa1-6 cell line treated with endogenous corticosterone (CORT) was in accordance with the aforementioned in vivo responses.
CONCLUSIONS: Depression aggravated hepatic steatosis in CDAHFD-fed mice by activating the HPA axis. The risk of NAFLD development should be fully considered in depressive patients and improvement of psychotic disorders could be an etiological treatment strategy for them.

Thymic atrophy affects T cell generation and migration to the periphery, thereby affecting T cell pool diversity. However, the mechanisms underlying thymic atrophy have not been fully elucidated. Here, gonadotropin-releasing hormone (GnRH) immunization and surgical castration did not affect thymocyte proliferation, but significantly reduced the apoptosis and increased the survival rate of CD4-CD8-, CD4+CD8+, CD4+CD8-, and CD4-CD8+ thymocytes. Following testosterone supplementation in rats subjected to GnRH immunization and surgical castration, thymocyte proliferation remained unchange, but the apoptosis of CD4-CD8-, CD4+CD8+, CD4+CD8-, and CD4-CD8+ thymocytes significantly increased. Transcriptome analyses of the thymus after GnRH immunization and surgical castration showed a significant reduction in the thymus\'s response to corticosterone. Cholesterol metabolism and the synthesis and secretion of corticosterone were significantly reduced. Analysis of the enzyme levels involved in the corticosterone synthesis pathway revealed that corticosterone synthesis in thymocytes was significantly reduced after GnRH immunization and surgical castration, whereas exogenous testosterone supplementation relieved this process. Testosterone promoted thymocyte apoptosis in a concentration-dependent manner, and induced corticosterone secretion in vitro. Blocking the intracellular androgen receptor (AR) signaling pathway did not significantly affect thymocyte apoptosis, but blocking the glucocorticoid receptor (GR) signaling pathway significantly reduced it. Our findings indicate that testosterone regulates thymus remodeling by affecting corticosterone synthesis in thymocytes, which activates GR signal transduction and promotes thymocyte apoptosis.

OBJECTIVE: Anorexia nervosa (AN) is characterized by hyperactivation of the hypothalamic-pituitary-adrenal axis and cognitive deficits. However, little is known about the rapid non-genomic stress response involvement. This study investigates the molecular, structural and behavioral signatures of the anorexic phenotype induction in female rats on stress-related mechanisms in the hippocampus.
METHODS: Female adolescent rats, exposed to the combination of food restriction and wheel access, i.e., the activity-based anorexia (ABA) protocol, were sacrificed in the acute phase of the pathology (postnatal day [P]42) or following a 7-day recovery period (P49).
RESULTS: ABA rats, in addition to body weight loss and increased wheel activity, alter their pattern of activity over days, showing increased food anticipatory activity, a readout of their motivation to engage in intense physical activity. Corticosterone plasma levels were enhanced at P42 while reduced at P49 in ABA rats. In the membrane fraction of the hippocampus, we found reduced glucocorticoid receptor levels together with reduced expression of caldesmon, n-cadherin and neuroligin-1, molecular markers of cytoskeletal stability and glutamatergic homeostasis. Accordingly, structural analyses revealed reduced dendritic spine density, a reduced number of mushroom-shaped spines, together with an increased number of thin-shaped spines. These events are paralleled by impairment in spatial memory measured in the spatial order object recognition test. These effects persisted even when body weight of ABA rats was restored.
CONCLUSIONS: Our findings indicate that ABA induction orchestrates hippocampal maladaptive structural and functional plasticity, contributing to cognitive deficits, providing a putative mechanism that could be targeted in AN patients.

Despite strong evidences supporting the protective role of exercise against stress-induced repercussions, the literature remains inconclusive regarding metabolic aspects. Therefore, this study aimed to evaluate the effect of Physical Training (PT) by swimming on the metabolic parameters of rats subjected to restraint stress.
Wistar rats (n = 40) were divided into four groups: Control (C), Trained (T), Stressed (S), and Trained/Stressed (TS). The restraint stress protocol involved confining the animals in PVC pipes for 60 minutes/day for 12 weeks. Concurrently, the swimming PT protocol was performed without additional load in entailed sessions of 60 minutes conducted five days a week for the same duration. The following parameters were analyzed: fitness progression assessed by the physical capacity test, body mass, serum level of glucose, triglyceride, cholesterol and corticosterone, as well as glycemic tolerance test, evaluated after glucose administration (2 g/kg, i.p.).
Trained groups (T and TS) exhibited enhanced physical capacity (169 ± 21 and 162 ± 22% increase, respectively) compared to untrained groups (C: 9 ± 5 and S: 11 ± 13% increase). Corticosterone levels were significantly higher in the S group (335 ± 9 nmoL/L) compared to C (141 ± 3 nmoL/L), T (174 ± 3 nmoL/L) and TS (231 ± 7 nmoL/L), which did not differ from each other. There were no significant changes in serum glucose, cholesterol, and triglyceride levels among the groups. However, the glycemic curve after glucose loading revealed increased glycemia in the S group (area under curve 913 ± 30 AU) but the TS group exhibited values (673 ± 12 AU) similar to the groups C (644 ± 10 AU) and T (649 ± 9 AU).
Swimming-based training attenuated stress-induced corticosterone release and prevented glucose intolerance in rats, reinforcing the importance of exercise as a potential strategy to mitigate the pathophysiological effects of stress.

Short and long-term sound-induced stress on daily basis can affect the physiology of avian individuals because they are more susceptible to sound stress in an open environment.
OBJECTIVE: An ex-situ study was carried out to determine the impact of noise on physiology and ptilochronology of non-breeding male domesticated quail birds.
METHODS: During 60-days long trial, male quail birds, aged 5-weeks, weighing (c.100gm) were used. Out of 72 experimental birds, 18 birds were assigned to the Control Group (G1) while remaining 54 birds were divided equally into 3 treatment groups: Road Traffic noise (G2), Military activity noise (G3) and Human Activities noise (G4). Birds were housed in standard-sized separate cages (20 ×45 × 20 cm), every bird was kept apart in separate cage in open laboratory under maintained environmental conditions. Millet seeds and water were provided to all the experimental birds ad libitum. Noise originated from several sources of recorded high-intensity music (1125 Hz/ 90 dB), was administered for 5-6 hours per day. Observations were recorded in the morning and afternoon. The experiment was conducted during the non-breeding season from August to October in triplicate. Blood sampling was done after 60 days.
RESULTS: According to the current study, noise stress significantly (p<0.05) increased the concentrations of creatinine, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), bilirubin, uric acid, cholesterol, triglycerides, total protein, and glucose while a decline in the levels of albumin was seen in treatment birds of G3. While in terms of hematology, total white blood cells count (TWBC), total red blood cells count (TRBC), mean cell volume (MCV) & packed cell volume (PCV) concentrations were raised in blood of treatment birds of G3. In terms of hormones, noise stress significantly (p<0.05) increased the serum concentrations of Corticosterone in G3 while a significant (p<0.05) decline was observed in the concentrations of luteinizing hormone (LH), thyroid stimulating hormone (TSH), and follicle stimulating hormone (FSH) in the same group. Moreover, fault bar formation in G3 was more prominent than others.
CONCLUSIONS: Noise stress can significantly affect serology, hematology, hormonal physiology and ptilochronology in quail birds.

Anxiety is a common comorbidity of obesity, resulting from prescribing long-term caloric restriction diets (CRDs); patients with a reduced food intake lose weight but present anxious behaviors, poor treatment adherence, and weight regain in the subsequent 5 years. Intermittent fasting (IF) restricts feeding time to 8 h during the activity phase, reducing patients\' weight even with no caloric restriction; it is unknown whether an IF regime with ad libitum feeding avoids stress and anxiety development. We compared the corticosterone blood concentration between male Wistar rats fed ad libitum or calorie-restricted with all-day or IF food access after 4 weeks, along with their anxiety parameters when performing the elevated plus maze (EPM). As the amygdalar thyrotropin-releasing hormone (TRH) is believed to have anxiolytic properties, we evaluated its expression changes in association with anxiety levels. The groups formed were the following: a control which was offered food ad libitum (C-adlib) or 30% of C-adlib\'s energy requirements (C-CRD) all day, and IF groups provided food ad libitum (IF-adlib) or 30% of C-adlib\'s requirements (IF-CRD) with access from 9:00 to 17:00 h. On day 28, the rats performed the EPM and, after 30 min, were decapitated to analyze their amygdalar TRH mRNA expression by in situ hybridization and corticosterone serum levels. Interestingly, circadian feeding synchronization reduced the body weight, food intake, and animal anxiety levels in both IF groups, with ad libitum (IF-adlib) or restricted (IF-CRD) food access. The anxiety levels of the experimental groups resulted to be negatively associated with TRH expression, which supported its anxiolytic role. Therefore, the low anxiety levels induced by synchronizing feeding with the activity phase would help patients who are dieting to improve their diet therapy adherence.