DEVELOPMENT OF METABOTROPIC GLUTAMATE RECEPTOR-MEDIATED SYNAPTIC INHIBITION

MODULATION of hippocampal CA3-CA1 synaptic transmission during metabot ropic glutamate receptor (mGluR) activation was investigated in juveni le (post-natal day (P) 15-21) and young adult rats (P28-35). The mGluR agonist 1S,3R-aminocyclopentane-1,3-dicarboxylic acid (ACPD) depresse d the EPSP slope more in young adults than juveniles. ACPD increased p aired-pulse facilitation (PPF) at both ages. The group I mGluR antagon ist (+)-alpha-methylcarboxyphenylglycine (MCPG) inhibited the ACPD-med iated depression of the EPSP slope and completely blocked the increase in PPF only in young adults. Minimal effects of MCPG on ACPD-dependen t synaptic depression were observed in juveniles. These data suggest t hat presynaptic group I mGluR-mediated synaptic inhibition increases a cross late postnatal development. In addition, other mGluR subtypes, w ith the ability to depress presynaptic function, appear to be present in juveniles.