NEONATAL CAPSAICIN EXPOSURE AFFECTS ISOLATION-INDUCED AGGRESSIVE-BEHAVIOR AND HYPOTHALAMIC SUBSTANCE-P LEVELS OF ADULT MALE-MICE (MUS-MUSCULUS)

Subcutaneous administration of capsaicin (50 mg/kg) at Postnatal Days 2 and 5 exerted long-term effects on isolation-induced aggressive beha vior of adult mice (Mus musculus) of the CD-1 strain. Isolated capsaic in-treated mice (scored during a 10-min session) showed the highest fr equency and the longest duration of total attacks, attacks, rattling, and offensive upright posture when compared with nonisolated capsaicin -treated subjects and both isolated and nonisolated vehicle control an imals. Hypothalamic Substance P (SP) was assessed by radioimmunoassay. Capsaicin treatment significantly lowered hypothalamic SP content in both isolated and nonisolated mice. Moreover, individual scores of iso lated capsaicin-treated subjects showed a significant correlation betw een SP depletion and expression of offensive upright posture. Isolatio n per se was revealed to play an important role in depleting SP from t he hypothalamus.