Opiate Agonist-Induced Changes in Behavioral Sensitivity to Clonidine AObserved in Perinatally Malnourished Rats Exposed to Chronic Stress

E. A. KELLER A. REY, A. C. GUTIÉRREZ AND L. M. CANCELA

PHARMACOLOGY BIOCHEMISTRY AND BEHAVIOR

PERGAMON-ELSEVIER SCIENCE LTD

Año: 1998 vol. 60 p. 1 - 5

0091-3057

KELLER, E. A., A. REY, A. C. GUTIERREZ AND L. M. CANCELA. Opiate agonist-induced changes in behavioral sensitivity to clonidine are observed in perinatally malnourished rats exposed to chronic stress . PHARMACOL BIOCHEM BEHAV 60 (1) 1–5, 1998.—Sensitivity of alpha 2 -adrenoceptors following repeated immobilization sessions plus morphine (MOR) or b -endorphin (BETA) was assayed by examining clonidine (CLO)-induced hypoactivity in adult malnourished rats at perinatal age. As previously described, chronic restraint did not attenuate the hypoactivity elicited by CLO in malnourished rats, although chronic restraint did have such an effect on motor activity in control animals. MOR and BETA administration prior to each restraint session induced subsensitivity of alp -adrenoceptors in malnourished rats as determined by a blunted response to clonidine challenge. An injection of naloxone (NAL) prior to BETA before each stress session fully antagonized the subsensitivity to clonidine observed in malnourished animals. A possible deficiency in the functional role of the opiate system in the process of adaptation to chronic stress in perinatal malnourished rats is suggested. © 1998 Elsevier Science Inc.