Effect of vinpocetine on noradrenergic neurons in rat locus coeruleus

Conventional extracellular single unit recordings were used to investigate the effect of vinpocetine on locus coeruleus noradrenergic neurons in chloral hydrate-anesthetized rats. Vinpocetine produced a significant and dose-dependent increase in the firing rate of locus coeruleus neurons (ED30 = 0.75 mg/kg i.v.) up to 1 mg/kg i.v., followed by a complete blockade of spiking activity at doses higher than this. The effective dose range was in very good agreement with the dose range corresponding to the memory-enhancing effects of the compound. Our results supplied direct electrophysiological evidence that vinpocetine increases the activity of ascending noradrenergic pathways. This effect can be related to the cognitive-enhancing characteristics of the compound.