Effects of activation of metabotropic glutamatergic receptors (mGluR) were investigated in mouse dopaminergic olfactory bulb neurons. After blockage of ionotropic receptors, focal application of glutamate or of group I/II mGluR agonist t-ACPD resulted in a depolarization, paralleled by an inward current in voltage-clamp conditions. The Group I agonist DHPG induced a depolarization, which could be largely blocked by mGluR1 antagonists. The DHPG action i) was prevented by buffering intracellular Ca2+ with BAPTA and by a phospholipase C inhibitor; ii) was not affected by the block of Ca2+ entry, and iii) was blocked by inhibitors of the Na+/Ca2+ exchanger. These observations were interpreted as a mGluR1-mediated intracellular Ca2+ release, followed by the activation of an electrogenic Na+/Ca2+ exchanger. The mGluR5 agonist CHPG induced a hyperpolarization of membrane potential, resulting in a decrease of the spontaneous firing frequency. CHPG induced i) a decrease in membrane resistance; ii) an increase in the action potential repolarization rate, and iii) an increase in the amplitude of the afterhyperpolarization. This was interpreted as a mGluR5-mediated opening of a K+ conductance. These data suggest that mGluR1 and mGluR5 play different and non-overlapping roles in the regulation of the excitability of bulbar dopaminergic neurons. © 2010 Elsevier B.V. All rights reserved.
|Titolo:||Metabotropic glutamate receptors 1 and 5 differentially regulate bulbar dopaminergic cell function|
CIFELLI, Pierangelo [Conceptualization]
|Data di pubblicazione:||2010|
|Appare nelle tipologie:||1.1 Articolo in rivista|