[Tyrosine hydroxylase activation upon electric stimulation of isolated hypothalamic nerve endings in rats].

The effect of electrical stimulation on the membrane-bound tyrosine hydroxylasectivity of the rat hypothalamus synaptosomes was studied. The electrical stimulation caused an elevation of O2 consumption and the elevation of glycolysis indicating synaptosome excitation. The membrane-bound tyrosine hydroxylase activity increased under these conditions. The KM value for tyrosine decreased from 0.091 to 0.026 mM. Noradrenaline inhibition of the enzymatic activity diminished. It is assumed that the effect of depolarization on the catecholamine synthesis velocity in the nerve endings involves tyrosine hydroxylase modification.