engleski

Do neurotransmitter receptor change their function?

Catecholaminergic innervation influences compensatory growth of the adrenal gland remnant after unilateral adrenalectomy. The aim of the present study was to identify the receptors involved. Mature, female Wistar rats were used in 10-day experiments. Several parameters of adrenal growth were determined - wet weight, protein content, and total RNA and DNA. Both splanchnecotomy and chemical sympathectomy (guanethidine or reserpine) prevented the compensatory adrenal growth induced by contralateral adrenalectomy. While ß-adrenergic agonist isoproterenol had a stimulatory effect and reversed the effect of guanethidine, ß-blocking agents (propranolol, sotalol, atenolol, but ß2 selective antagonist butoxamine, too) prevented the compensatory adrenal growth. In contrast, neither the cold stress-induced adrenal enlargement nor the normal adrenal growth followed throughout a 45-day period, were modified by ß-blocking agents. While isoproterenolol stimulated cAMP formation in the control adrenal gland, in the adrenal gland remnant after unilateral adrenalectomy cAMP formation was inhibited by isoproterenol. This inhibitory effect was antagonized by butoxamine but not by atenolol. These observations suggest that ß-receptors stimulate the adrenal growth induced either by adrenalectomy or by denervation of the contralateral gland, changing thereat their physiological function and intracellular signaling mechanism. If this phenomenon is not unique only for compensatory growth of adrenal gland it might represent a new form of synaptic plasticity.

receptor; signaling; compensatory growth; adrenal gland

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