Amine releasing action of nicotine from rat hypothalamus in vitro

Nicotine released 3H-radioactivity from rat hypothalamus labeled with 3H-metaraminol (3H-MA) in a concentration-related manner. The release was not blocked by hexamethonium (1.8 x 10(-5)M - 2.3 x 10(-3)m), tetrodotoxin (3 x 10(-7)M), lidocaine (6 x 10(-5)M or Ca++-free medium. Cocaine (3 x 10(-5)M) blocked the releasing action of nicotine. Nicotine failed to release 3H-MA in tissue exposed to tyramine. It is concluded that the nicotine-induced release of 3H-MA is intracellular.