Interference between central dopaminergic stimulation, and adrenal secretion in normoxic or hypobaric hypoxic rats.

Previous data have established that postsynaptic stimulation of central dopaminergic receptors was mainly involved in the protective action of apomorphine against the comportmental consequences of hypobaric hypoxia in rats: disturbances in a conditioned avoidance response. We confirm this notion showing that domperidone (a peripheral dopaminergic blocking agent) does not antagonize the protective effect of apomorphine. Furthermore, we establish that the action of apomorphine is at least partially mediated by adrenal glands since it is no longer seen in adrenalectomized rats. In normal rats, apomorphine enhances the corticosterone increase which is observed during hypobaric hypoxia and decreases the hypoxia-induced elevation of the adrenaline level. It is therefore concluded that the anti-hypoxic activity of apomorphine is probably mediated by a centrally mediated dopaminergic modification of the adrenal response to hypobaric hypoxia.