CRF and urocortin systems

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The Emory University Silvio O. Conte Center for the Neuroscience of Mental Disease (CCNMD) brings together a group of expert basic and clinical investigators to study several animal models and clinical models relevant to the pathophysiology of depression. Considerable research has established a possible link between major depression and central corticotropin-releasing factor (CRF) containing neural circuits. CRF is the..major physiological regulator of the ~yp0thalamic~pituitary~adrenal (HPA) axis. A burgeoning database has accumulated which clearly suggests that CRF- and urocortin-producing neuronal systems integrate not only the Organism's endocrine response to stress, but also their autonomic, immunologic, and behavioral responses to stress as well. Moreover, hyperactivity of both hypothalamic and extrahypothalamic CRF neurons appears to be involved in the pathophysiology of both mood and anxiety disorders. We propose to compare the function of central CRF/urocortin systems in rat and primate models of early life stress-related depressive- like syndrome. The rat model of neonatal maternal separation and the primate model of variable foraging demand have both been shown to alter central CRF neurocircuit activity. We postulate that early life stress during some critical period of vulnerability modifies hypothalamic and extrahypothalamic CRF neurons as well as altering inputs to these CRF neurocircuits in-such a way as to produce ne\1rochemical, endocrine, and behavioral hyper-responsivity to stressors in adults. Preliminary data in these animals sh6ws alterations in noradrenergic, serotonergic and dopaminergic systems that may modify CRF neuronal function or may be modified as a result of altered CRF neuronal function. We will test whether these models of "environmental programming" have similar neurobiological underpinnings in the Long Evans rat strain and the rhesus macaque monkey. In all of these studies, we will also evaluate whether there are gender-related differences to the consequences of early life stress. In the current pr6posal we will: (1) characterize the state of CRF and urocortin neural systems in these rat and primate models at different ages, (2) assess the responsivity of these systems to acute and chronic stressors in adult animals, (3) evaluate the ability of mechanistically distinct antidepressants to modify these systems when administered to adult animals or during the period of early life stress exposure, and (4) determine whether selective targeting of the CRF1 versus CRF2alpha receptor subtype modifies the biological and behavioral actions of early life stress,. Overall, by utilizing and being guided by findings from the other projects in this Center, these studies will seek to elucidate the neurobiological basis of how early life environmental influences lead to a vulnerability to psychiatric morbidity in adults that is already supported by clinical and epidemiological data.