Measurement and Regulation of Central Noradrenergic Receptors
Annual rept. 1 Dec 1992-30 Nov 1993
NEW YORK UNIV MEDICAL CENTER NY
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In the past year we have continued our investigation of the relationship between central catecholaminergic systems and the effects of stress. We have completed or made progress in three studies of the role of the noradrenergic system in biochemical and behavioral effects of stress and one study of the role of the dopaminergic system in these behavioral effects. The first noradrenergic study concerned the mechanism of a biochemical response to stress which is believed to play a role in long term stress adaptation, the activation of the immediate early gene, c-fos, in the brain. On the basis of previous data we had hypothesized that the noradrenergic system is involved in the activation of this gene in the brain by stress. In the past year we confirmed this hypothesis by showing that the c-fos mRNA and protein responses to stresses could be reduced by treatment with the beta blocker, propranolol, and enhanced by the norepinephrine NE reuptake inhibitor, desmethylimipramine DMI. These findings have supported a role of the noradrenergic system in adaptational phenomena. The second and third studies concerned the role of noradrenergic processes in two behavioral effects of stress, increased anxiety and motor impairment. In the stud on stress-induced anxiety, we found that blockade of beta receptors with propranolol potentiates the stimulatory effect of stress on anxiety in two tests of the latter, passive avoidance and defensive withdrawal.