The influence of thyroxin on GABA metabolism in some brain structures of rats in postnatal development

It has been revealed that thyroxin injected to 21 days rats daily for 5 days in relatively a high dose (100 mg/kg of body weight) decreased reliably the glutamine acid (GA) level in the tissues of the brain cortex and hypothalamus and at the same time increased gamma-aminobutyric acid (GABA) in these structures. Thyroxin effects on the main enzymes of GABA-glutamate decarboxylase shunt (GDC) and GABA transaminase (GABA-T) were contrary as well in the brain cortex and hypothalamus. Thyroxin promotes increasing of GDC-activity and decreasing of GABA-T activity. It is drawn a conclusion that thyroxin in the indicated dose stimulates GABA formation out of GA and delays the GABA disintegration and following its transformation into GA.