[Pharmacology of thyroliberin].

The influence of synthetic thyrotropin-releasing hormone (TRH) on locomotion, on the effects of analgetics, learning and memory, electrical activity of hypothalamic neurons, blood pressure, and cerebral circulation have been studied. TRH increases the spontaneous motility and potentiates the stimulating effect of amphetamine and apomorphine. It also antagonizes the decrease of motility induced by tetrabenazine in all these tests. TRH exhibits the similarity to antidepressants. TRH antagonizes the effects of morphine and Tyr-D-Ala-Gly-Phe-(NO2)-NH2, especially in respect of respiratory depression experiments made on rats and rabbits. TRH facilitates the learning in active avoidance paradigme, diminishes the degree of retrograde amnesia evoked by maximal electroconvulsive shock. The latter effect suggests that TRH can be considered as a substance having some signs of nootropic activity. TRH seems to interact with central M-cholinergic system. This is evidenced by the ability of atropine to diminish the excitatory effect of TRH applied microiontophoretically to single neurons of the lateral hypothalamus. TRH elevates blood pressure and volume velocity of the cerebral circulation in normotensive animals and recovers the hemodynamics during hemorrhagic hypotension. The spectrum and mechanism of TRH pharmacological activity are discussed. The data suggest that TRH may be of interest for clinical trials.