TY - JOUR T1 - Sympathetic and parasympathetic nerves regulate postsynaptic alpha-2 adrenoceptor in salivary glands. JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 488 LP - 493 VL - 239 IS - 2 AU - M D Kaniucki AU - J C Elverdin AU - M A Luchelli-Fortis AU - C J Perec AU - F J Stefano Y1 - 1986/11/01 UR - http://jpet.aspetjournals.org/content/239/2/488.abstract N2 - The effects of sympathetic denervation or parasympathetic decentralization on the inhibitory effects of postsynaptic alpha-2 adrenoceptors were studied in the submaxillary and the sublingual gland of the rat. Chronic sympathetic denervation enhanced by a factor of 10 the potency of clonidine to inhibit the secretory responses of the submaxillary gland to either norepinephrine or methacholine. In denervated glands, clonidine (1 microgram/kg), reduced markedly the response to norepinephrine, but potentiated this response in control glands. Blockade of postsynaptic alpha-2 adrenoceptors with idazoxan (3 micrograms/kg) enhanced the secretory responses of denervated glands to norepinephrine. Parasympathetic decentralization also potentiated the inhibitory effects of the alpha-2 agonists. In the submaxillary gland the potency of guanabenz to decrease the secretory response to methacholine was increased by a factor of 30. Supersensitivity to the inhibitory effects of clonidine was also observed in parasympathetically decentralized sublingual glands. Parasympathetic decentralization increased the maximum binding site of [3H]clonidine binding by about 50% in both the submaxillary and sublingual glands. No changes in KD were detected. This surgical procedure also increased the maximum binding site of [3H]prazosin binding in submaxillary glands. The present findings show clearly that interruption of either branch of the autonomic nervous system induces supersensitivity of the inhibitory response mediated through postsynaptic alpha-2 adrenoceptors. The enhanced inhibitory activity could mask alpha-1 adrenoceptor supersensitivity after postganglionic sympathetic denervation. ER -