Purine metabolite inosine is an adrenergic neurotrophic substance for cultured chicken sympathetic neurons.

AUTOR(ES)

Zurn, A D

RESUMO

Purines are ubiquitous endogenous cellular metabolites that have been postulated as neurotransmitters or neuromodulators in the nervous system. Recently, we showed that a low-molecular-mass component present in liver-conditioned medium selectively enhances the adrenergic properties of dissociated chicken sympathetic neurons in culture. We report here that this substance is inosine, a purine metabolite. Indeed, analysis of the low-molecular-mass fraction of liver-conditioned medium by HPLC shows that the neurotrophic activity coelutes with and has the same absorption spectrum as inosine. Inosine increases incorporation of [3H]leucine into neuronal protein and stimulates catecholamine, but not acetylcholine, production by the sympathetic neurons in a dose-dependent fashion (half-maximal stimulation at 10(-6) M). This effect can be blocked by 5 x 10(-6) M dipyridamole, an inhibitor of nucleoside transport. Inosine therefore appears to be capable of modulating adrenergic phenotypic expression in cultured sympathetic neurons by acting via an as-yet-unknown intracellular pathway.

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