NGF decreases isolation-induced aggressive behavior, while increasing adrenal volume, in adult male mice.

Intravenous administration of highly purified murine nerve growth factor (NGF, either 15 or 30 micrograms/subject/day) for six consecutive days to adult male mice of the CD-1 strain markedly influenced a number of items of aggressive behavior induced by 5 weeks of individual housing. Control mice received the same doses of cytochrome c. During a 20-min fighting session on day 7, both NGF-treated groups showed longer Latency to the first Attack, while Total Attacking Time and Aggressive grooming were significantly lower when compared to control animals. Twenty-four h later, adrenals from the NGF- and cytochrome c-treated groups were dissected and analyzed by means of a Vidas Image-Analyzer. NGF administration produced a remarkable dose-dependent increase in both adrenal weight and volume (particularly in the medullary zone), supporting the hypothesis that adrenals represent a possible target for the NGF release from submaxillary salivary glands occurring upon intraspecific fighting.