Abstract
The effect of DN-1417 (γ-butyrolactone-γ-carbonylhistidyl-prolinamide citrate), a TRH analog, on the electrical activities of hippocampal pyramidal neurons in the guinea-pig brain slice was studied with intracellular recording methods. DN-1417 caused a 2-5 mV hyperpolarization in approximately 25% of the neurons examined. The behavior of the DN-induced hyperpolarization in different ionic media suggested that it was produced by an increased potassium conductance. DN-1417 decreased the spontaneous firing of the pyramidal neurons by inhibiting the fast and slow prepotentials. The excitatory postsynaptic potentials (EPSPs) were also reduced by DN-1417, and this reduction appeared to be presynaptic in origin. The inhibitory nature of the DN -1417 actions on the hippocampal pyramidal neurons is compatible with its antiepileptic action recently reported (Inanaga et al. 1981).
