Effects of Vitamin B6 on the Brain Glutamate Pyrovate Transaminase and Glutamate Oxaloacetate Transaminase in Young and Old Rats

Abstract

Excessive amounts of extracellular glutamate in brain are excitotoxic and lead to neuronal death. Glutamate pyrovate transamiase (GPT) and glutamate oxaloacetate transaminase (GOT) catalyze transamination of glutamate to alpha ketoglutarate. Because vitamin B6 is essential for the enzymes activities, this study was undertaken to examine the effect of vitamin B6 on age related changes of this enzyme in rat brain. Three and 30 months old male rats were injected with vitamin B6 and the animal's brains were homogenized in phosphate buffer and the enzymes activities were measured in the super- natant. The activities of the enzymes in aged rats were significantly lower as compared to that of young animals. Vitamin B6 induced activation of the brain enzymes in both ages, however, the activation was significantly pronounced in aged animals. Significant activation of GPT and GOT by vitamin B6 in aged rat brain may be resulted from either lower availability of vitamin B6 in aged animals, or lower affinity of the enzymes for pyridoxal 5-phosphate, which is likely to be related to conformational changes during aging. It is suggested that vitamin B6 may restore the activity of these enzymes during the brain aging.