Neurotensin Activates Tuberoinfundibular Dopamine Neurons and Increases Serum Corticosterone Concentrations in the Rat

The activity of tuberoinfundibular dopamine neurons, as estimated from the amount of dihydroxyphenylalamine (DOPA) formed in the median eminence after the inhibition of DOPA decarboxylase and the concentration of dihydroxyphenylacetic acid (DOPAC) in this brain region, was significantly increased 1-8 h following the intracerebroventricular (i.c.v.) administration of neurotensin (20 micrograms). Neurotensin (5 and 20 micrograms i.c.v.) also significantly increased DOPAC concentrations in the n. accumbens but had no effect in the striatum. Serum concentrations of corticosterone in rats treated with neurotensin (1-20 micrograms i.c.v.) were 5-7 times those in vehicle-treated animals. [D-Trp11]-neurotensin (0.5 micrograms i.v.c.) also significantly increased DOPAC concentrations in the median eminence and serum corticosterone concentrations. It is concluded that neurotensin acutely increases the activity of tuberoinfundibular and mesolimbic dopamine neurons and the secretion of ACTH.