Astrocytic group I mGluR-dependent potentiation of astrocytic glutamate and potassium uptake

摘要

Metabotropic glutamate receptor (mGluR)- and PKC-dependent long-term potentiation (LTP) of postsynaptic neuronal glutamate uptake has been demonstrated in the climbing fiber-Purkinje cell synapse following tetanic stimulation of climbing fibers (Shen and Linden 2005). The hypothesis that activation of astrocytic mGluRs, or GPCRs in general, might be involved in regulating glutamate uptake has not been reported in a slice preparation or in vivo. Synaptically evoked inward currents in astrocytes representing glutamate and potassium (K+) uptake have been reported in hippocampal slices (Bergles and Jahr 1997). Two studies in hippocampal slices aimed at deciphering the locus of neuronal LTP to the presynaptic or postsynaptic site measured astrocytic transporter currents and reported no change after a 100-Hz stimulation of Schaffer collaterals (SCs) (Diamond et al. 1998; Luscher et al. 1998). However, another study reported protein transcription and Af-methyl-D-aspartate receptor (NMDAR)-dependent late but not early LTP of astrocytic glutamate transporter GLT-1 (Pita-Almenar et al. 2006).