BETA-ADRENOCEPTOR ACTIVATION REDUCES DYE-COUPLING BETWEEN IMMATURE RAT NEOCORTICAL NEURONS

THE present study examined the effect of activation of adrenergic rece ptors by noradrenaline and the P-receptor selective agonist isoprotere nol on dye-coupling between developing lamina II/III pyramidal neurone s in rat prefrontal and sensorimotor cortex. To assess dye-coupling ne urones were intracellularly injected with neurobiotin. Under control c onditions injections performed in slices obtained from neonatal rats ( 7-10 postnatal days) resulted in clusters of more than 30 tracer-coupl ed neurones. Preincubation with either isoproterenol or noradrenaline reduced the number of coupled cells by 60-80%. The effect of isoproter enol was suppressed by the beta 1-adrenoreceptor antagonist atenolol. Our results indicate that modulation of gap junction coupling between differentiating neocortical neurones might be one important function o f noradrenergic afferents during early postnatal development of the ne ocortex.