Beta-adrenoreceptor activation reduces dye-coupling between immature rat neocortical neurones.

The present study examined the effect of activation of adrenergic receptors by noradrenaline and the beta-receptor selective agonist isoproterenol on dye-coupling between developing lamina II/III pyramidal neurones in rat prefrontal and sensorimotor cortex. To assess dye-coupling neurones were intracellularly injected with neurobiotin. Under control conditions injections performed in slices obtained from neonatal rats (7-10 postnatal days) resulted in clusters of more than 30 tracer-coupled neurones. Preincubation with either isoproterenol or noradrenaline reduced the number of coupled cells by 60-80%. The effect of isoproterenol 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 of noradrenergic afferents during early postnatal development of the neocortex.