The influence of adrenalectomy on alpha-adrenoceptor responses in rat cerebral cortex slices

Experiments were undertaken to examine the effect of depletion of adrenal steroids on neurotransmitter-stimulated cAMP accumulation in rat cerebral cortex slices. Long-term depletion due to bilateral adrenalectomy (ADX) and short term depletion due to the steroid synthesis inhibitor metopirone (MET) caused a significant increase in alpha 1-adrenoceptor-mediated potentiation of beta-adrenoceptor-stimulated cAMP accumulation. The effect of MET was prevented by corticosterone treatment. This effect of ADX was selective in that there was no change in alpha 1-adrenoceptor-mediated inositol phosphate accumulation. In addition, ADX had no effect on potentiation of isoprenaline-stimulated cAMP by either the GABAB agonist baclofen or the phorbol ester, 4 beta-phorbol dibutyrate. However, 2-chloroadenosine-stimulated cAMP accumulation was significantly reduced in ADX rats.