Regulation of Dopamine Receptor Responsiveness by Glucocorticoids
Identification of glucocorticoid (GC) specific binding sites in the brain (McEwen et al. 1969) stimulated inquiry into a possible modulatory role of GC’s on central neuronal activity. It has been established that the highest concentration of these sites are located in the hippocampus and therefore it has been a brain region more fully investigated than any other. However, since GC specific binding sites have also been identified in the caudate putamen (DeFiore and Turner 1983), and as this area is known to contain a high concentration of dopamine (DA) receptors, we sought to determine whether GC’s regulate DA receptor responsiveness in the striatum. The present study was therefore designed to investigate the effects of adrenalectomy (ADX) and subsequent chronic corticosterone replacement therapy on the behavioural effects of apomorphine and more specifically, to examine whether any changes observed were due to an altered responsiveness at the D1, D2 or both receptor subtypes. Finally, measurements of striatal D1 and D2 receptor concentration and affinity together with studies on DA-stimulated adenylate cyclase activity were carried out to determine possible neurochemical targets which may underlie the DA-mediated behavioural changes.
KeywordsDopamine Glucocorticoid Haloperidol Corticosterone Apomorphine
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