Chronic voluntary wheel running facilitates corticosterone response habituation to repeated audiogenic stress exposure in male rats

Abstract

Voluntary exercise is associated with the prevention and treatment of numerous physical and psychological illnesses, yet the mechanisms by which it confers this protection remain unclear. In contrast, stress, particularly under conditions of prolonged or repeated exposure when glucocorticoid levels are consistently elevated, can have a devastating impact on health. It has been suggested that the benefits of physical exercise may lie in an ability to reduce some of the more deleterious health effects of stress and stress hormones. The present series of experiments provides evidence that voluntary exercise facilitates habituation of corticosterone but not adrenocorticotropin hormone responses to repeated stress presentations. After 6 weeks of running wheel access or sedentary housing conditions, rats were exposed to 11 consecutive daily 30 min presentations of 98 dB noise stress. Similar corticosterone responses in exercised rats and sedentary controls were observed following the first, acute stress presentation. While both groups demonstrated habituation of corticosterone secretory responses with repeated noise stress exposures, the rate of habituation was significantly facilitated in exercised animals. These results suggest that voluntary exercise may reduce the negative impact of prolonged or repeated stress on health by enhancing habituation of hypothalamo-pituitary-adrenocortical axis responses at the level of the adrenal cortex, ultimately reducing the amount of glucocorticoids the body and brain are exposed to.

Exercise-Associated Changes in the Corticosterone Response to Acute Restraint Stress: Evidence for Increased Adrenal Sensitivity and Reduced Corticosterone Response Duration

“…Consistent with previous reports, wheel running was associated with an increase in adrenal size Droste et al, 2007;Droste et al, 2003;Droste et al, 2006;Nyhuis et al, 2010;Sasse et al, 2008). Several studies have shown that stress-induced ACTH release is similar, or reduced, in wheel-running rodents when compared with sedentary controls (Droste et al, 2007;Droste et al, 2003;Fediuc et al, 2006; but see Campeau et al, 2010).…”

“…The results of Experiment 1 demonstrated that the rise time of the CORT response to restraint stress was more rapid, which may have been mediated by increased adrenal sensitivity, and is notable given the observation that wheel running has been associated with increased adrenal size Droste et al, 2007;Droste et al, 2003;Droste et al, 2006;Nyhuis et al, 2010;Sasse et al, 2008). Experiment 3 directly assessed whether the CORT response to exogenous ACTH challenge was increased in running mice.…”

“…Wheel running also changes HPA-axis function; for example, wheel running produces elevated CORT at the onset of the diurnal active period in both rats and mice (Adlard and Cotman, 2004;Droste et al, 2003;Fediuc et al, 2006;Stranahan et al, 2006) and is consistently associated with enlarged adrenals Droste et al, 2007;Droste et al, 2003;Droste et al, 2006;Nyhuis et al, 2010;Sasse et al, 2008). The HPA-axis response to both acute (Campbell et al, 2009;Campeau et al, 2010;Droste et al, 2007;Droste et al, 2003;Droste et al, 2006) and repeated Sasse et al, 2008) stress is also altered in wheel-running rodents. Thus, the changes observed in HPA-axis outcomes following wheel running mirror those of chronic stress in some cases (adrenal enlargement, diurnal CORT), and demonstrate stress resistance in others (response to stress).…”

Avaliação comportamental de ratos treinados em natação forçada

“…O exercício físico tem sido testado para aliviar diversos tipos de estresse experimentalmente induzidos, como isolamento social [5,30], ruídos [35], imobilização, frio [31], privação de alimentos e água [14], dentre outros. Há indícios de que o tipo e a intensidade do exercício, bem como o modelo animal utilizado, podem influenciar nas respostas hormonais e comportamentais [36].…”

HPA axis changes during the initial phase of psychosocial stressor exposure in male mice

“…However, if the stress systems are activated over a prolonged period of time, chronically elevated levels of plasma GCs can promote the development of somatic and affective disorders (for a review, see Sapolsky (1996), McEwen (2000) and Vanitallie (2002)). Thus, it is adaptive for an individual to habituate as fast as possible to prolonged and not life-threatening homotypic stressors (Kudielka et al 2006, Sasse et al 2008.…”