Thyrotrophin-Releasing Hormone Analogues Increase Dopamine Release from Slices of Rat Brain

Abstract: Rat brain slices were incubated with a high concentration of K⁺, thyrotrophin-releasing hormone (TRH), or one of two biologically stable TRH analogues (CG 3509 or RX 77368). Basal release of endogenous dopamine, measured by electrochemical detection, was increased by K⁺ (30 m M ) from slices of hypothalamus, septum, nucleus accumbens, and striatum. CG 3509 (10⁵–10⁻³ M ) increased the release of dopamine from slices of nucleus accumbens, septum, and hypothalamus in a dose-dependent fashion, whereas RX 77368 (10⁻⁴ M ) increased the release of dopamine from the septum only. Neither analogue increased the release of striatal dopamine. The results provide further evidence for specific regional interactions between TRH and dopamine in rat brain.