Physiological Activation of Presynaptic Metabotropic Glutamate Receptors Increases Intracellular Calcium and Glutamate Release

• DOI: 10.1152/jn.2000.84.1.415
• Publication Date: 2017-12-21T13:30:56Z
• Authors: Neil E. Schwartz; Simon Alford
• Keywords: Long-term depression

Activation of metabotropic glutamate receptors (mGluRs) has diverse effects on the functioning vertebrate synapses. The cellular mechanisms that underlie these changes, however, are largely unknown. role presynaptic mGluRs in modulating Ca(2+) dynamics and regulating neurotransmitter release was investigated at vestibulospinal-reticulospinal (VS-RS) synapse lamprey brain stem. Application specific Group I antagonist 7-(hydroxyimino) cyclopropa[b]chromen-1a-carboxylate ethyl ester (CPCCOEt) reduced amplitude consecutive high-frequency evoked excitatory postsynaptic currents (EPSCs). A series experiments using techniques electrophysiology calcium imaging were carried out to determine by which this phenomenon occurs. Concentration-dependent increases pre- [Ca(2+)](i) seen with application mGluR agonists. Similarly, stimulation axons caused a mGluR-dependent enhancement transients. agonist depolarization elements, while thapsigargin decreased stimulus- agonist-induced rises [Ca(2+)](i). These data suggest both membrane from intracellular stores potentially play mGluR-induced signaling. To effect modulation spontaneous release, miniature EPSCs recorded reticulospinal neurons. potent agonist, (S)-homoquisqualic acid, large increase frequency events. results demonstrate presence VS-RS synapse. leads rise enhances glutamate. Taken together, studies highlight importance synaptic activation facilitatory autoreceptors short-term plasticity transmission.