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...ormonal stress response of male rats before and after puberty. Prior to puberty,whenT levels are low, theCORT response to acute and chronic stress is high relative to the response seen after puberty (=-=Viau et al., 2005-=-; Romeo and McEwen, 2006; Follib et al., 2011). This correlates with the increases in T that occur during the pubertal transition of males. However, given that Romeo et al. (2004) have shown that T ad...

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... et al., 1973), which may account for the slower return to baseline hormone levels following the termination of the stressor. Despite these potential differences in negative feedback, little or no change in the level of glucocorticoid receptors in the neuralpituitary network responsible for negative feedback has been found in either rats or mice before and after puberty (Romeo et al., 2008, in press; Vazquez, 1998). Others have observed higher levels of neural activation, as indexed by FOS expression, in the PVNof prepubertal compared to adult male rats (Lui et al., 2012; Romeo et al., 2006a; Viau et al., 2005), suggesting greater hypothalamic drive to the pituitary prior to puberty. Moreover, basal expression of CRH in the PVN appears to be higher in male rats prior to puberty (Romeo et al., 2007b), though the opposite trend has been noted in females (Viau et al., 2005). Thus, the protracted stress-induced hormonal response in prepubertal males may be due to a combination of less negative feedback on, and more positive activation of, the HPA axis. It is also possible that there are age-dependent shifts in the sensitivity of the pituitary and/or adrenal glands to CRH, AVP, and ACTH, as well as chang...

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... and testosterone levels, and altered metabolic responsiveness to stressors occur, all of which could influence hippocampal neurogenesis (Akana et al. 1999; Gomez and Dallman 2001; Gomez et al. 2002; =-=Viau et al. 2005-=-). Similarly, species differences between mice and rats in physiological and metabolic function could also influence blood alcohol concentrations and/or impact of alcohol on the brain, and hence influ...

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...neuroendocrine system essential for survival (55). Moreover, individual and gender based differences in normal and abnormal HPA function can be attributed to variations in sex steroid hormone release =-=(46, 51)-=-. Threats to homeostasis activate the HPA axis by triggering the sequential release of a chain of hormones. This is initiated by the recruitment of neurosecretory neurons in the paraventricular nucleu...

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...entsexperiment are in keeping with some previous research using 30 minutes of restraintsstress as the stressor (Romeo, Lee, Chhua, McPherson, & McEwen, 2004; Romeo et al.,s2006a; Romeo et al., 2006b; =-=Viau et al., 2005-=-; Lui et al., 2012). In contrast, other studiesshave reported higher corticosterone in adolescent than adult rats 30 minutes after restraintsstress (Foilb et al., 2011) and higher corticosterone in ad...

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...ne levels if CRH mRNA are higher in juvenile animals, social stressors orsrestraint lead to increases in CRH expression in both the pubertal and adult PVNs(McCormick et al., 2006; Romeo et al., 2007; =-=Viau et al., 2005-=-).sTogether, it appearssthe basal and stress-induced regulation of CRH cells in the PVN may contribute to thesdifferential HPA reactivity exhibited by adolescent and adult animals.sHowever, it will be...

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...ers [75], increased ectoparasite load andsmortality [74,76], and the weakening of some components of the immune system [74,77]. Moreover, Tshas inhibitory effects on the stress-induced HPA activation =-=[36,37]-=-. For example, ACTH andscorticosterone responses to acute stressors are increased with gonadectomy in rodents [77,78].sCastration also increases the ACTH and corticosterone response to various stresso...