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Effect of Glutamate on the Control of Fatty-Acid Synthesis in White Adipose Tissue of the Rat. Inhibition of Pyruvate Dehydrogenase

1975; Wiley; Volume: 53; Issue: 2 Linguagem: Inglês

10.1111/j.1432-1033.1975.tb04081.x

1432-1033

Wayne M. Taylor, Mitchell L. Halperin,

Biochemical Acid Research Studies

Abstract Glutamate (5 mM) inhibited glucose conversion to fatty acids by approximately one-third in adipocytes from fed rats. This inhibition was significantly less in the presence of pyruvate or 2-oxoglutarate. After incubation of adipose tissue from fed rats with glucose and insulin, pyruvate dehydrogenase activity was 180 · 17 mU/g wet weight. Addition of glutamate to the incubation medium decreased this activity significantly (118 · 14 mU/g wet weight). This inhibition by glutamate was also diminished when 2-oxoglutarate or pyruvate were present. Glutamate added to homogenates of adipose tissue had no effect on the activation of pyruvate dehydrogenase by Mg2+. However, glutamate inhibited the active form of the enzyme and enhanced the rate of inactivation of the enzyme complex by ATP and Mg2+. Aminooxyacetate, a transaminase inhibitor, did not reverse the effects of glutamate on pyruvate dehydrogenase nor fatty acid synthesis. It is concluded that glutamate can inhibit lipogenesis by inhibiting the activity of pyruvate dehydrogenase. Details of the possible mechanism are discussed.