STRYCHNINE-INSENSITIVE GLYCINE BINDING TO CEREBRAL CORTICAL MEMBRANES IN DEVELOPING AND AGING MICE

The strychnine-insensitive binding of [H-3]glycine was characterized in purified cerebral cortical membranes from mice aged from 7 days to 22 months. The binding was saturable, exhibiting only one component during the whole life-span studied. The binding constant K(D) did not change during development and ageing, whereas the maximal binding capacity B(max), calculated per protein content, increased up to the age of two weeks and then again in ageing animals (18- and 22-month-olds). The binding was similarly inhibited by the antagonists 7-chlorokynurenate, 3-amino-1-hydroxypyrrolidin-2-one (HA-966) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) in 7-day-, 3-month- and 12-month-old mice. The inhibition caused by glycine, L-serine and beta-alanine also remained unaltered during the whole life-span. Beta-Alanine was a noncompetitive inhibitor. The alterations in the maximal binding capacities during development and ageing could be of importance in the regulation of NMDA receptors, which have been implicated in synaptic potentiation, developmental processes and various pathological conditions.