An in vivo procedure for the selective inactivation of rat brain cerebral cortical alpha-adrenoceptors using N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ)

Abstract

Intraperitoneal administration of 0.8 mg/kg N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) to rats significantly reduced alpha-adrenoceptor binding in cerebral cortical membranes without affecting beta-adrenoceptor sites. A selective reduction in alpha 1-adrenoceptors was achieved by injecting yohimbine prior to EEDQ, whereas prazosin pretreatment yielded a selective reduction in alpha 2-adrenoceptor binding. Administration of EEDQ decreased norepinephrine-stimulated inositol phosphate and cyclic adenosine monophosphate (cAMP) accumulation in cerebral cortical tissue as well as the cAMP response to isoproterenol in combination with 6-fluoronorepinephrine without modifying the second messenger response to isoproterenol alone. The results suggest that, under the proper conditions, EEDQ administration can selectively diminish rat brain alpha-adrenoceptor number and function, yielding a procedure that may be useful for defining the behavioral and physiological properties of these sites.