Loading...
Please wait, while we are loading the content...
Similar Documents
Coupling of metabotropic glutamate receptor 8 to N-type Ca2+ channels in rat sympathetic neurons.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Guo, Juan Ikeda, Stephen R. |
| Copyright Year | 2005 |
| Abstract | Group III metabotropic glutamate receptors (mGluRs; mGluR4, 6, 7, and 8) couple to the Galpha(i/o)-containing G protein heterotrimers and act as autoreceptors to regulate glutamate release, probably by inhibiting voltage-gated Ca(2+) channels. Although most mGluRs have been functionally expressed in a variety of systems, few studies have demonstrated robust coupling of mGluR8 to downstream effectors. We therefore tested whether activation of mGluR8 inhibited Ca(2+) channels. Both L-glutamate (L-Glu) and l-2-amino-4-phosphonobutyric acid (L-AP4), a selective agonist for group III mGluRs, inhibited N-type Ca(2+) current in rat superior cervical ganglion neurons previously injected with a cDNA encoding mGluR8a/b. L-AP4 was approximately 100-fold more potent (IC(50) = 0.1 microM) than L-Glu ( approximately 10 microM), but it had efficacy similar to that of L-Glu ( approximately 50% maximal inhibition). The potency and efficacy of L-AP4 and L-Glu were similar for both splice variants. Agonist-induced inhibition was abolished by pretreatment with (R,S)-alpha-cyclopropyl-4-phosphonophenylglycine, a selective group III mGluR antagonist, and pertussis toxin. Deletion of either a calmodulin (CaM) binding motif in the C terminus or the entire C terminus of mGluR8 did not affect mGluR8-mediated response. Our studies indicate that both mGluR8a and 8b are capable of inhibiting N-type Ca(2+) channel, suggesting a role as presynaptic autoreceptors to regulate neuronal excitability. The studies also imply that the potential CaM binding domain is not required for the mGluR8-mediated Ca(2+) channel inhibition and the C terminus of mGluR8a is dispensable for receptor coupling to N-type Ca(2+) channels. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://molpharm.aspetjournals.org/content/molpharm/67/6/1840.full.pdf |
| Alternate Webpage(s) | http://molpharm.aspetjournals.org/content/molpharm/early/2005/03/08/mol.105.010975.full.pdf |
| PubMed reference number | 15755905v1 |
| Volume Number | 67 |
| Issue Number | 6 |
| Journal | Molecular pharmacology |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Autoreceptors Calmodulin Ganglia Hippocampus (Brain) Inhibition L-2-amino-4-phosphonobutyrate Metabotropic Glutamate Receptor 8, human Neck Pertussis Toxin Pertussis Vaccine Protein Domain Receptors, Metabotropic Glutamate Thioctic Acid Tryptophan |
| Content Type | Text |
| Resource Type | Article |
