A thyrotropin releasing hormone analog, DN-1417, increases endogenous dopamine release from slices of rat striatum and nucleus accumbens.

Besides its hormonal effects, thyrotro pin releasing hormone (TRH) induces se veral behavioral changes in rats. Marked increases in locomotor activity occur after administration of TRH and its analogs. This effect was hypothesized to be due to a stimulation of mesolimbic dopaminergic neurons (Miyamoto and Nagawa, 1977; Heal and Green, 1979). TRH has no effect on the reuptake of monoamines (Tuomisto and Mannist, 1973) or the concentration of dopamine (DA) sensitive adenylate cyclase (Green et al. 1976). It was proposed that TRH and its analogs release DA from presyn aptic terminals of dopaminergic neurons. Kerwin and Pycock (1979) demonstrated that TRH induced 3H-DA release from the n. accumbens which was preloaded with 3H-DA. It did not release 3H-DA from the caudate nucleus. Fukuda et al. (1979) reported that unilateral injection of TRH into the nucleus caudatus pro duced rotation in rats. In biochemical