DISTINCT GROOMING PATTERNS INDUCED BY INTRACEREBROVENTRICULAR INJECTION OF CRH, TRH AND LHRH IN MALE-RATS

This paper reports the effects on grooming, related behaviors and leve ls of anxiety induced by the hypophysiotropic peptides corticotropin-r eleasing hormone (CRH, 1 mu g, 0.2 nmol, icv), thyrotropin-releasing h ormone (TRH, 100 mu g, 275 nmol, icv) and luteinizing hormone-releasin g hormone (LHRH, 1.5 mu g, 1.3 nmol, icv) administered into the latera l ventricle of the brain (icy) of adult male rats of a Holtzman-derive d colony (N = 15, each group). CRH induced an increase in total groomi ng scores, whereas LHRH, TRH and vehicle had no effect. CRH strongly i ncreased face and head grooming and induced head shakes. The time spen t in rearing and gnawing was significantly decreased. In the plus-maze , CRH reduced the time of exploration in the open arm. TRH increased f ace grooming and induced body shakes. LHRH had no effect on grooming o r rearing behavior. No body or head shakes were observed after LHRH ad ministration. Scoring of individual grooming elements demonstrated dif ferences in action of the three peptides. Although both CRH and TRH in creased face grooming, only CRH induced head grooming. Furthermore, CR H induced predominantly head shakes while TRH increased body shake act ivity. In contrast, CRH was anxiogenic and TRH appeared to induce ster eotyped behavior. From the characterization of grooming elements and r elated responses, we conclude that each hypophysiotropic peptide induc es a specific behavioral pattern.