[Characteristics of the neuromodulating effect of peripherally administered thyroliberin on the rat brain].

The study of TRH effect on monoaminergic processes (MP) in the rat brain areas (hypothalamus, striopallidar system, cortex) was carried out upon intramuscular administration of TRH in doses of 1, 5 and 10 mg/kg 0.5, 1 and 3 h after TRH injections the animals were decapitated. TRH was shown to elicit persisting (3 h) multidirectional MP alterations in catecholaminergic system and unidirectional alterations in serotoninergic system (mainly acceleration of serotonin turnover). The most marked influence is produced by the lowest TRH dose, 1 mg/kg. It is suggested that in spite of a short half-life (2-5 min) TRH is able to act as a modulator on different target points of the rat MP pathways. That could be one of the possible explanations of previously observed prolonged TRH-induced pharmacological and clinical effects.