ARTICLE | doi:10.20944/preprints202207.0311.v1
Subject: Life Sciences, Endocrinology & Metabolomics Keywords: glucose; cortisol; corticosterone; stress; early life adversity
Online: 21 July 2022 (07:53:13 CEST)
External stressors strongly increase cardiovascular activity and induce metabolic changes that ensure the availability of glucose and oxygen as part of a co-ordinated stress response. Exposure to stress during early life appears to have an exaggerated long-term effect on this response, leading to an increased risk or cardiometabolic disorders. Here we demonstrate that acute stress induced glucose release is impacted by the early life environment in rodent maternal deprivation and early-life infection models and this was validated in our EpiPath human early-life adversity cohort. In all three models differences in baseline blood glucose levels after ELA exposure were sex dependent. The human ELA model showed higher levels of basal glucose in females, similar to the mouse infection and rat maternal deprivation models. We anticipated that the stress induced glucose rise would be a GC dependent process. However, the kinetics of stress-induced glucose release, peaking 15-28 minutes before cortisol suggest that it is a GC-independent process. We confirmed this by administering an escalating dose of cortisol to a health human cohort, and the inability of an intravenous GC bolus induce a glucose rise in man confirms that it is a rapid, GC independent, process.In conclusion, we provide a novel perspective on the mechanisms behind stress related metabolic changes and highlights the importance of collecting early life data as a measure to understand an individual’s metabolic status in a better light.
ARTICLE | doi:10.20944/preprints201805.0295.v1
Subject: Behavioral Sciences, Behavioral Neuroscience Keywords: reelin; corticosterone; glucocorticoid receptors; NMDA receptors; parvalbumin; GAD67
Online: 22 May 2018 (09:41:40 CEST)
Reelin depletion and stress seem to affect similar pathways including GABAergic and glutamatergic signaling and both are implicated in psychiatric disorders in late adolescence/early adulthood. The interaction between reelin depletion and stress, however, remains unclear. To investigate this, male and female heterozygous reelin mice (HRM) and wildtype (WT) controls were treated with the stress hormone, corticosterone (CORT), during late adolescence to simulate chronic stress. Glucocorticoid receptors (GR), N-methyl-D-aspartate receptor (NMDAr) subunits, glutamic acid decarboxylase (GAD67) and parvalbumin (PV) were measured in the hippocampus and the prefrontal cortex (PFC) in adulthood. While no changes were seen in male mice, female HRM showed a significant reduction in GR expression in the dorsal hippocampus. In addition, CORT reduced GR levels as well as GluN2B and GluN2C subunits of NMDAr in the dorsal hippocampus in female mice only. CORT furthermore reduced GluN1 levels in the PFC of female mice. The combined effect of HRM and CORT treatment appeared to be additive in terms of GR expression in the dorsal hippocampus. Female-specific CORT-induced changes were associated with overall higher circulating CORT levels in female compared to male mice. This study shows differential effects of reelin depletion and CORT treatment on GR and NMDAr protein expression in male and female mice, suggesting that females are more susceptible to reelin haploinsufficiency as well as late-adolescent stress. These findings shed more light on female-specific vulnerability to stress and have implications for stress-associated mental illnesses with a female bias including anxiety and major depression.
ARTICLE | doi:10.20944/preprints202002.0288.v1
Subject: Medicine & Pharmacology, Pathology & Pathobiology Keywords: BXD mice; recombinant inbred strains; candidate gene; DFP; neuroinflammation; corticosterone
Online: 20 February 2020 (07:01:44 CET)
Between 25 and 30% of the nearly one million military personnel who participated in the 1991 Persian Gulf War became ill with chronic symptoms ranging from gastrointestinal to nervous system dysfunction. This disorder is now referred to as Gulf War Illness (GWI) and the underlying pathophysiology has been linked to exposure-based neuroinflammation caused by organophosphorous (OP) compounds coupled with high circulating glucocorticoids. In a mouse model of GWI we developed, corticosterone was shown to act synergistically with an OP (diisopropylflurophosphate) to dramatically increase proinflammatory cytokine gene expression in the brain. Because not all Gulf War participants became sick, the question arises as to whether differential genetic constitution might underlie individual differences in susceptibility. To address this question of genetic liability, we tested the impact of OP and glucocorticoid exposure in a genetic reference population of 30 inbred mouse strains. We also studied both sexes. The results showed wide differences among strains and overall that females were less sensitive to the combined treatment than males. Furthermore, we identified one OP-glucocorticoid locus and nominated a candidate gene—Spon1—that may underlie the marked differences in response.
ARTICLE | doi:10.20944/preprints202009.0159.v1
Subject: Medicine & Pharmacology, Psychiatry & Mental Health Studies Keywords: Nicotine; Cotinine; Corticosterone; LCMS; Sex; C57BL/6J mouse; CYP2A5; Plasma Levels; Subcutaneous Injection
Online: 7 September 2020 (08:08:54 CEST)
We assessed if there were any sex-related differences in the ability of nicotine to increase plasma corticosterone secretion after single or repeated nicotine administration. For single-dose studies, male and female mice were habituated to the test room for 1 h and injected with saline or nicotine (0.25 or 1 mg/kg, s.c.). In repeated-dosing studies, mice were injected with saline or nicotine (1 mg/kg, s.c.) once daily for six days, and, on day 7, received nicotine (1 mg/kg, s.c.). The mice were euthanized 15 min later, and trunk blood was collected for the measurement of corticosterone, nicotine, and cotinine. Our results showed that saline or nicotine each significantly increased plasma corticosterone levels in both male and female mice, with a greater response in female mice. Plasma corticosterone levels were increased in male but not female mice after repeated compared to single nicotine administration. The level of cotinine, a biomarker of nicotine use, was significantly higher in female than in male mice. Taken together, these novel findings suggest that female mice responded to nicotine and stress of handling more than male mice and provide for the first-time quantitative data on the male-female differences in nicotine-induced elevations of corticosterone and of cotinine.
Subject: Medicine & Pharmacology, Allergology Keywords: predator scent; aldosterone; corticosterone; adrenal gland; dorsal raphe nucleus (DRN); serotonin (5-HT); electrophysiology
Online: 15 July 2021 (10:40:31 CEST)
Exposure to predator scent (PS) has been used as a model of stress associated with danger to life and body integrity. We tested the hypothesis that repeated PS exposure alters the excitability of serotonin (5-HT) neurons of the dorsal raphe nucleus. To study the mechanisms involved, we approached serum and adrenal corticosterone and aldosterone concentrations, as well as cortical brain-derived neurotrophic factor (BDNF) expression. Adult male Sprague-Dawley rats were exposed to PS for ten minutes daily for ten consecutive days. Two weeks after the last exposure, electrophysiological and biochemical assessments were performed. Measurements by in vivo electrophysiology showed increased spontaneous firing activity of 5-HT neurons in rats exposed to PS. PS exposure resulted in reduced serum corticosterone and aldosterone concentrations. Concentrations of both corticosteroids in the adrenal glands, as well as the relative weight of the adrenals, were unaffected. The gene expression of hippocampal BDNF of rats exposed to PS remained unaltered. In conclusion, repeated exposure of rats to PS leads to enhanced firing activity of 5-HT neurons accompanied by reduced serum, but not adrenal aldosterone and corticosterone concentrations. Reduced corticosteroid concentrations in the blood appear to be the result of increased metabolism and/or tissue uptake rather than altered steroidogenesis. The decrease in circulating corticosterone in rats experienced repeated PS may represent part of the mechanisms leading to increased excitability of 5-HT neurons. The increase in 5-HT neuronal firing activity might be an important compensatory mechanism designated to diminish the harmful effects of the repeated PS exposure on the brain.
ARTICLE | doi:10.20944/preprints202201.0433.v1
Subject: Behavioral Sciences, Behavioral Neuroscience Keywords: cohousing; stress; CD1 mouse; C57BL/6J mouse; Sprague Dawley rat; fecal corticosterone or cortisol metabolites; dyadic social interaction; conditioned place preference
Online: 28 January 2022 (11:13:58 CET)
Rats, including those of the Sprague Dawley strain, may kill mice. Because of this muridical behavior, it is standard practice in many research animal housing facilities to separate mice from rats (i.e., the predators) to minimize stress for the mice. We therefore tested the effect of cohousing on the stress levels of mice from either the C57BL/6J (BL6) or the CD1 strain and Sprague Dawley (SD rat) by determining their fecal corticosterone or cortisol metabolites (FCM) concentration and investigated how cohousing impacts a behavioral assay, i.e., conditioned place preference for intragenus (i.e., mouse-mouse or rat-rat) dyadic social interaction (DSI CPP) that had been shown be sensitive to social factors, especially to handling by humans. We found that the two delivery batches of BL6 mice or SD rats, respectively, had different stress levels at delivery that were statistically significant for the BL6 mice. Even so, the BL6 mice cohoused with rats had significantly increased FCM concentrations, indicative of higher stress levels, as compared to (1) BL6 mice housed alone or (2) BL6 mice at delivery. In contrast to their elevated stress levels, the attractiveness for contextual cues associated with mouse-mouse social interaction (DSI CPP) even increased in rat-cohoused BL6 mice, albeit nonsignificantly. Thus, cohousing BL6 mice and rats did not impair a behavioral assay in BL6 mice that had proved to be sensitive to handling stress by humans in our laboratory. SD rats cohoused with BL6- or CD1 mice and CD1 mice cohoused with SD rats showed DSI CPP that was not different from our previously published data on SD rats and BL6 mice of the Jackson- or NIH substrain obtained in the absence of cohousing. Our findings suggest that the effect of cohousing rats and mice under the conditions described above on their stress levels as opposed to their behavior might be less clearcut than generally assumed and might be overriden by conditions that cannot be controlled, i.e., different deliveries. Our findings can help to use research animal housing resources, which usually are limited, more efficiently.