[Effect of gamma-aminobutyric acid on the concentration of noradrenaline in the synaptosoma fraction of the meso-diencephalic region of rat brain].

We had previously shown [1, 2, 3, 4] that intraperitoneal administrations of 5 mg/kg amounts of gamma-aminobutyric acid (GABA) lower norepinephrine (NE) level of rat brain, this effect being most pronounced in the hypothalamic region. Subsequent studies showed that GABA increased normetanephrine level in iproniazid pretreated rats (II) and decreased NE content of crude mitochondrial fractions (12). These data implied changes in NE content of nerve endings. The results of the present study indicate that the NE content of the synaptosomal fraction of the mesodiencephalic region of GABA treated rats is significantly lower than that of untreated animals. This is a further confirmation of our previous results favouring a release of NE from nerve endings following the administration of GABA.