L-SERINE AND GABA UPTAKE BY SYNAPTOSOMES DURING POSTNATAL DEVELOPMENT OF RAT

MG CHELUJA; MJ SCOLARI; TM COELHO; MM BLAKE; MM BOCCIA; CM BARATTI; GB ACOSTA

COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR AND INTEGRATIVE PHYSIOLOGY

Elsevier Science

Lugar: United States; Año: 2007 vol. 146 p. 499 - 505

1095-6433

Postnatal development changes in mechanisms of synaptosomal amino acid transport have been studied in rat cerebral cortex. Specific uptake of radiolabeled L-serine was examined and compared with that of radiolabeled GABA using synaptosomes-enriched fractions freshly prepared from cerebral cortex at different postnatal days from the birth to young adulthood. The preparations were incubated with 10 nM of [3H]L-serine and 10 nM of [3H]-GABA in either the presence or absence of NaCl, KCl or choline chloride , at 2°C and 30°C, for different periods up to 30 min. The uptake of [3H]L-serine was temperature dependent in synaptosomal fractions prepared from cerebral cortex of rats in postnatal days 5, 7, 13 and 21,  but  stronger dependence was observed in adult brain, irrespective of the presence of Na+,  K+  or choline ions. At all postnatal ages studied, [3H]-GABA uptake showed a high activity in the presence of Na+ ions and at 30 ºC. The values of Km were 90-489 mM in L-serine uptake. However in the uptake of GABA the values of Km were 80-150 mM. The highest values of V max were obtained at 5 and 21postnatal days for both transport systems. These results, indicate that the uptake of L-serine and GABA are regulated differentially during postnatal development.