Rapid changes in monoamine levels following administration of corticotropin-releasing factor or corticosterone are localized in the dorsomedial hypothalamus

Monoaminergic systems are important modulators of the neuroendocrine, auton omic, and behavioral responses to stress-related stimuli. The male roughski n newt (Taricha granulosa) was used as a model system to investigate the ef fects of corticotropin-releasing factor (CRF) or corticosterone administrat ion on tissue concentrations of norepinephrine, epinephrine, dopamine, 3,4- dihydroxyphenylacetic acid, serotonin, and 5-hydroxyindoleacetic acid (5-HI AA) in microdissected brain areas. Intracerebroventricular infusion of 25 o r 50 ng of CRF increased locomotor activity and site-specifically increased dopamine concentrations within the dorsomedial hypothalamus 30 min after t reatment when compared to vehicle-treated controls. In further studies, mal e newts were treated as follows: (1) no injection, no handling, (2) saline injection, or (3) 10 mug corticosterone and then placed in a novel environm ent. Monoamine and monoamine metabolite concentrations were similar in the unhandled and saline-injected controls 20 min after treatment. In contrast, corticosterone-injected newts had elevated concentrations of dopamine, ser otonin, and 5-HIAA in the dorsomedial hypothalamus (a region that contains dopamine- and serotonin-accumulating neuronal cell bodies in representative s of all vertebrate classes) but not in several other regions studied. Thes e site-specific neurochemical effects parallel neurochemical changes observ ed in the dorsomedial hypothalamic nucleus of mammals following exposure to a variety of physical and psychological stress-related stimuli. Therefore, these changes may reflect highly conserved, site-specific neurochemical re sponses to stress and stress-related neurochemicals in vertebrates. Given t he important role of the dorsomedial hypothalamus in neuroendocrine, autono mic, and behavioral responses to stress, and a proposed role for this regio n in fast-feedback effects of glucocorticoids on the hypothalamopituitary-a drenal axis, these stress-related monoaminergic changes are likely to have important physiological or behavioral consequences. (C) 2001 Academic Press .