Stimulation of energy metabolism by α‐adrenergic agonists in primary cultures of astrocytes

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Abstract
Noradrenaline effects on glucose oxidation were studled in primary cultures of astrocytes. CO2 formation from labeled glucose was enhanced in the presence of; noradrenaline. The stimulatory effect by noradrenaline was exerted both on lactate formation (∼20%) I and on tricarboxylic acid activity (CO2 production from glutamate) (∼40%). The effect was, at least partly, exerted on the alpha-ketoglutarate dehydrogenase step. The EC50 value for noradrenaline on lactate formation was significantly lower (60 nM) than that on oxidative metabolism (1,900 nM). Studies with specific adrenergic agonists and antagonists showed that various receptor subtypes are involved. Thus, the effect on lactate formation wasmediated exclusively by stimulation of an alpha1 receptor whereas oxidative metabolism was enhanced by both alpha1 and alpha2 receptor stimulation. No effects were exerted by beta receptor agonists or antagonists.