The grasping response in rats: interaction between gamma-type endorphins and haloperidol.

gamma-Type endorphins mimic neuroleptics in inducing a grasping response in rats. It was studied whether the haloperidol-induced grasping response was altered after blockade of gamma-type endorphin activity in the rat brain. To achieve this blockade rats were injected i.c.v. with gamma-endorphin antiserum or with a monoclonal anti-idiotype desenkephalin-gamma-endorphin antibody, which may bio-inactivate the gamma-type endorphins or block the putative receptors for gamma-type endorphins, respectively. The results showed that both treatments attenuated the haloperidol-induced grasping response, particularly 3 h after haloperidol treatment. The influence of these antibodies appeared to be specific, since other sera were without effect. Thus there may be an interaction between the endogenous gamma-type endorphin activity and the haloperidol-induced grasping response.