NEONATAL CAPSAICIN ADMINISTRATION - EFFECTS ON BEHAVIORAL-DEVELOPMENTOF THE RAT

The effect of a single dose of capsaicin administered neonatally on th e development of six motor behavioral patterns (scratching, rearing, g rooming, searching, remaining still, and sniffing) was examined in Wis tar rats. Treated animals exhibited a significant increment in scratch ing, rearing, grooming, and searching. Capsaicin also provoked precoci ous eye opening of one to two days and a reduction in remaining still, sniffing, and body weight. These effects were accompanied by pelage d ishevelment and presence of skin ulcers in the region of the head, nec k, and shoulders. The distribution of skin ulcers suggests that the fi fth cranial nerve and roots innervating C1-C3 spinal cord segments con tain a high proportion of capsaicin-sensitive ''C'' and A delta fibers .