Desensitization of the D-2 dopamine receptor and the ?(2)-adrenoceptor in the intermediate lobe of the rat pituitary gland.
A D-2 dopamine receptor and a ?(2)-adrenoceptor occur in the intermediate lobe of the rat pituitary gland (IL). Exposure of intact IL tissue to a D-2 agonist diminished the ability of dopaminergic agonists [but not 5?-guanylyl imidodiphosphate (Gpp(NH)p)] to inhibit adenylate cyclase activity. Conversely, exposure of intact IL tissue to a ?-adrenergic agonist diminished the ability of a ?-adrenergic agonist (but not forskolin) to stimulate adenylate cyclase activity. Treatment of ovariectomized rats with 17?-estradiol desensitizes the ?(2)-adrenoceptor but not the D-2 receptor. Desensitization of the IL catecholamine receptors is discussed within the framework of a previously published "working model" of these receptors.
Miyazaki
K
K
Experimental Therapeutics Branch, NINCDS, National Institutes of Health, Bethesda, MD 20205, U.S.A.
Saavedra
J M
JM
Cote
T E
TE
Kebabian
J W
JW