Abstract
Cholinergic neurons in the basal forebrain nuclei (BF) which project to various nuclei in CNS receive glutamatergic inputs from several brain regions. A whole-cell patch-clamp study using slice preparations of the rat brain was performed to elucidate the developmental change in calcium channel subtypes involved in non-NMDA glutamatergic synaptic transmission onto BF cholinergic neurons. In the present study, a novel fluorescent marker, Cy3-192IgG was stereotaxically injected into the lateral ventricle to selectively label live rat cholinergic neurons in the BF region, then 4-6 days later slices were cut. Pharmacologically isolated non-NMDA glutamatergic postsynaptic currents (EPSCs) were evoked by focal stimulation. The magnitude of inhibition of EPSCs by bath application of ω-CgTX (3 μM), an N-type calcium channel blocker, was gradually decreased from 49% to 23.9% during the postnatal stages between P18 and P34. On the other hand, application of both ω-CgTX (3 μM) and ω-Aga-TK (200 nM) inhibited the EPSCs by 96-98% throughout the postnatal stages. These results suggest that the contribution of N-type channels to the synaptic transmission declines with age, indicating any physiological implication. [Jpn J Physiol 55 Suppl:S154 (2005)]
