Anabolic-androgenic steroids affect the content of substance P and substance P1-7 in the rat brain

The effects of intramuscular (i.m.) injections of nandrolone decanoate (15 mg/kg/day), an anabolic-androgenic steroid, on the levels of substance P (SP) and on its N-terminal fragment SP1-7 were examined in the male rat brain by radioimmunoassay. The results demonstrated that the SP immunoreactivity in amygdala, hypothalamus, striatum, and periaqueductal gray was significantly enhanced, whereas the concentration of the N-terminal fragment SP1-7 was enhanced in the nucleus accumbens and in periaqueductal gray. In the striatum the steroid induced a decrease in the content of SP1-7. The relevance of these peptides in connection with anabolic-androgenic steroid-induced aggression is discussed. (C) 2000 Elsevier Science Inc. All rights reserved.