DEVELOPMENTAL-CHANGE IN VOLTAGE DEPENDENCY OF NMDA RECEPTOR-MEDIATED RESPONSE IN NUCLEUS-TRACTUS-SOLITARII NEURONS

The developmental change of Mg2+ block of NMDA-induced response (I-NMD A) was investigated in the freshly dissociated nucleus tractus solitar ii (NTS) neurons of the rats by the use of a nystatin-perforated patch -recording configuration. Mg2+ block was less obvious in a number of f etal NTS neurons than in the neurons of > 9 days after birth (P9) and became rapidly apparent by P3. Protein kinase C (PKC) modulators, such as staurosporine, H-7 and phorbol ester, did not clearly affect the g eneration of the voltage dependency of I-NMDA in immature rats. In add ition, the facilitatory effect of glycine on the I-NMDA did not change in development. These evidences suggest that an appearance of the vol tage dependency of I-NMDA in NTS neurons might be due to a development al change in combinations of subunits composing the NMDA receptor and/ or in the intracellular modulators of the I-NMDA other than PKC.