EFFECT OF PLASMODIUM-YOELII INFECTION ON GABA-METABOLISM OF MOUSE-BRAIN

Plasmodium yoelii infection in albino mice decreased the activity of brain glutamic acid decarboxylase (GAD) by about 30 and 48% in crude homogenate and its synaptosomal fraction, respectively. The decrease was evident from 20% parasitemia and remained more or less constant up to 80% parasitemia. The Km values of GAD in normal and infected animals were 1.2 × 10-2 and 3.3 × 10-2 mM, respectively, indicating a decrease in enzyme substrate affinity due to infection. The lowered GAD activity rose to slightly above normal by treatment of infected animals with chloroquine. Decrease in GAD activity reflected lower γ-aminobutyric acid (GABA) levels in the infected brain; however, GABA-transaminase activity was not significantly influenced by infection. It has been proposed that impaired GABA synthesis may be due to hypoxia induced by malarial infection. © 1990.