PubMed · 14909997
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N SUSSMAN. 1952. ACTH sensitivity.. https://pubmed.ncbi.nlm.nih.gov/14909997/
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Stress is an important contributor to cardiovascular disease and to reduced immunity and fertility. As the role of androgens in stress is uncertain, we investigated the effects of testosterone (T) on hormonal responses to stress in conscious Romney Marsh wethers. Six T-treated sheep and six control sheep were stressed by exposure to a psychological and a metabolic stimulus. Baseline glucose levels were significantly lower in the treated animals compared with controls (p=0.002). T treatment significantly attenuated ACTH (p<0.01) and cortisol (p<0.05) responses to metabolic stress. Following psychological stress, ACTH responses were significantly lower in treated sheep compared with controls (p<0.05), but differences in mean cortisol responses did not reach significance. There were no significant differences in epinephrine or norepinephrine responses following either stressor. We conclude that T replacement in wethers lowers glucose and attenuates responses to metabolic and psychological stress. While the implications of these results for human physiology require further studies, they suggest that male hypogonadism may play a role in determining the risk of cardiovascular disease and diabetes.
Early life adversity can lead to increased vulnerability to psychiatric disease including depression, with symptoms of depressed mood, impaired coping with negative events, anhedonia, reduced appetite, and elevated stress hormone activity. In rats, postnatal manipulation studies have focused on behavioural and endocrine anxiety effects, and have demonstrated that mild pup stimulation in the form of early handling (EH) is chronically anxiolytic relative to no stimulation in the form of non-handling (NH). Furthermore, apparently severe manipulations in the form of 3-4 h daily litter-dam separation (maternal separation) or pup-litter-dam separation (early deprivation, ED) are either without effect or even EH-like, relative to NH. In this Wistar rat study, we investigated the effects of ED under different circadian and thermal conditions on adulthood behavioural and endocrine responsiveness to environmental challenge, relative to NH. ED was performed on days 1-14, during either the Light or Dark phase and at either 21 degrees C (cold) or 32 degrees C (warm). Dark-cold ED adults exhibited reduced motivation to obtain sucrose in a progressive ratio schedule, tended to be less mobile in a forced swim test, but did not exhibit an escape deficit in a foot-shock pre-exposure/shuttle box test, or altered basal or stress endocrine activity. Light ED was completely without effect on adult phenotype. Even relative to stringent NH comparison, dark-cold ED leads to a long-term trait of mild gustatory anhedonia in Wistar rats.
Susceptibility to some stress-induced pathologies may be strongly related to individual differences in the responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis to stressors. However, there have been few attempts in rodents to study the reliability of the individual differences in the responsiveness of the HPA to stressors and the relationship to resting corticosterone levels. In the present work, we used a normal population of Sprague-Dawley rats, with a within-subject design. Our objectives were to study: (a) the reliability of the ACTH and corticosterone response to three different novel environments widely used in psychopharmacology and (b) the relationship between stress levels of HPA hormones and the daily pattern of corticosterone secretion (six samples over a 24-h-period). Animals were repeatedly sampled using tail-nick procedure. The novel environments were the elevated plus-maze, the hole-board and the circular corridor. Animals were sampled just after 15 min exposure to the tests and again at 15 and 30 min after the termination of exposure to them (post-tests). The hormonal levels just after the tests indicate that the hole-board seems to be more stressful than the circular corridor and the elevated plus-maze, the latter being characterized by the lowest defecation rate. Correlational analysis revealed that daily pattern of resting plasma corticosterone levels did not correlate to HPA responsiveness to the tests, suggesting no relationship between resting and stress levels of HPA hormones. In contrast, the present study demonstrates, for the first time, a good within-subject reliability of the ACTH and corticosterone responses to the three environments, suggesting that HPA responsiveness to these kind of stressors is a consistent individual trait in adult rats, despite differences in the physical characteristics of the novel environments.