Grant: Doctoral Award - Frederick Banting and Charles Best Canada Graduate Scholarships

When organisms face physical or emotional threats the body responds by increasing stress hormones; initiated in the brain by the hypothalamus, which signals the adrenals to secrete hormones mediating the body's protective response. Abnormal functioning of this pathway significantly impacts health, with hyperactivity linked to several neurological disorders. Little is known how testosterone acts to regulate this process, but we do know normal stress adaptation depends on circulating testosterone. When rats are repeatedly exposed to mild stress, activity in the hypothalamus declines across exposures and stress hormones decrease (cortisol in humans, corticosterone in rats). Separate studies show stress adaptation increases testosterone, increases peptide expression of vasopressin in the brain, and reduces anxiety-like behavior, but the mechanisms explaining these responses and their role during stress adaptation is unknown. Research in this area is needed as testosterone and vasopressin levels could be important risk factors determining an individual's vulnerability to stress-related diseases. We'll first examine the effects of repeated stress on hormone levels and vasopressin brain expression. Next those findings will be used to characterize potential behavioral differences between stressed and stress-naïve rats. This project will unmask the basis for how individuals either resist or succumb to homeostatic threat, and link gonadal status and behavior to mechanisms controlling stress responses. This is important for understanding individual and gender differences in stress-related disorders as sex hormones (testosterone and estrogen), are already known to be significant factors predisposing individuals to variations in cognition, mood, and risk of neurologic disease as people age. Undeniably, more studies examining testosterone's impact on preventing stress-related disorders is pivotal to extending our knowledge of effective treatments and preventative health measure