Postnatal development of calretinin- and parvalbumin-positive interneurons in the rat neostriatum: an immunohistochemical study.

On the basis of cytochemical and morphologic differences, two classes of gamma-aminobutyric acidergic (GABAergic) interneurons expressing calcium-binding proteins have been identified in the striatum of adult animals: neurons expressing either parvalbumin (PV) or calretinin (CR). The function of these calcium-binding proteins is not clear, however, they are associated with distinct classes of inhibitory interneurons within the adult neostriatum. By using immunocytochemical techniques, we analyzed the postnatal maturation and the spatiotemporal distribution of PV- and CR-positive neurons in the rat neostriatum compared with a third class of interneurons characterized by the expression of the acetylcholine-synthesizing enzyme, choline acetyltransferase (ChAT).

Intracellular acidification reduced gap junction coupling between immature rat neocortical pyramidal neurones.

1. Developmental changes in electrophysiological properties of pyramidal neurones correlated with the developmental decline in gap junction-dependent dye coupling were investigated in coronal slices of rat prefrontal and sensorimotor cortex. Effects of intracellular acidification induced by application of weak organic acids on neuronal dye coupling, electrotonic parameters as well as synaptic potentials were examined using the patch clamp technique.

Dye coupling between pyramidal neurons in developing rat prefrontal and frontal cortex is reduced by protein kinase A activation and dopamine.

During early postnatal development, lamina II/III pyramidal cells in rat neocortex are extensively coupled via gap junctions. The factors regulating gap junction permeability, as well as the mechanisms underlying the developmental uncoupling process are not understood. To investigate the influence of protein kinase A-mediated phosphorylation on dye coupling in the developing neocortex, pyramidal cells in slices of rat frontal and prefrontal cortex were injected intracellularly with the tracer neurobiotin.

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.