D1-like Dopamine Receptors Selectively Block P/Q-type Calcium Channels to Reduce Glutamate Release Onto Cholinergic Basal Forebrain Neurones of Immature Rats.
From: Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki 444-8787, Japan. tmomi@nips.ac.jp
The Journal of physiology
- Publish Date: Apr 2007
- ISSN: 0022-3751
- Volume: 580
- Issue: Pt 1
- Pages: 103-17
- Medium: Print
- Language: English
- Citation (JAMA): Momiyama Toshihiko, Fukazawa Yugo, et al. D1-like Dopamine Receptors Selectively Block P/Q-type Calcium Channels to Reduce Glutamate Release Onto Cholinergic Basal Forebrain Neurones of Immature Rats.. J. Physiol. (Lond.) Apr 2007;580:103-17
Abstract
Whole-cell patch-clamp recordings of non-NMDA glutamatergic EPSCs were made from identified cholinergic neurones in slices of basal forebrain (BF) of young rats (P13-P18), to investigate the subtypes of calcium channels involved in dopamine D(1)-like receptor-mediated presynaptic inhibition of the EPSCs. The BF cholinergic neurones were pre-labelled by intracerebroventricular injection of a fluorescent marker, Cy3-192IgG. A D(1)-like receptor agonist, SKF 81297 (30 microM) suppressed the EPSCs reversibly by about 30%, and this inhibition was reproducible. Calcium channel subtypes involved in the glutamatergic transmission were elucidated using selective Ca(2+) channel blockers. The N-type Ca(2+) channel blocker omega-conotoxin (omega-CgTX, 3 microM) suppressed the EPSCs by 57.5%, whereas the P/Q-type channel selective blocker omega-agatoxin-TK (omega-Aga-TK, 200 nM) suppressed the EPSCs by 68.9%. Simultaneous application of both blockers suppressed the EPSCs by 96.1%. The R-type Ca(2+) channel blocker SNX-482 (300 nM) suppressed the EPSCs by 18.4%, whereas nifedipine, the L-type Ca(2+) channel blocker (10 microM), had little effect. In the presence of omega-Aga-TK, SKF 81297, a dopamine D(1)-like receptor agonist, had no effect on the EPSCs. On the other hand, SKF 81297 could still inhibit the EPSCs in the presence of either omega-CgTX, SNX-482 or nifedipine. SKF 81297 had no further effect on the EPSCs when external Ca(2+) concentration was raised to 7.2 mM in the presence of omega-Aga-TK, but could still inhibit the EPSCs in high Ca(2+) solution after omega-CgTX application. Forskolin (FK, 10 microM), an activator of adenylyl cyclase pathway, suppressed the EPSCs, and the FK-induced effect was mostly blocked in the presence of omega-Aga-TK but not that of omega-CgTX. These results suggest that D(1)-like receptor activation selectively blocks P/Q-type calcium channels to reduce glutamate release onto BF cholinergic neurones.
Mesh Headings (Keywords): Animals, Benzazepines, Calcium Channel Blockers, Calcium Channels, P-Type, Calcium Channels, Q-Type, Choline O-Acetyltransferase, Data Interpretation, Statistical, Dopamine Agonists, Dopamine Antagonists, Electrophysiology, Excitatory Postsynaptic Potentials, Fluorescent Antibody Technique, Fluorescent Dyes, Forskolin, Glutamic Acid, Injections, Intraventricular, Parasympathetic Nervous System, Patch-Clamp Techniques, Prosencephalon, Rats, Receptor, Nerve Growth Factor, Receptors, Dopamine D1
Check for Full Text / PubMed Unique Identifier (PMID): 17234695
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