Muscarinic Receptor-Mediated Increase in Extracellular Inositol 1,4,5-Trisphosphate Levels in the Rat Hippocampus: An In Vivo Microdialysis Study
Article first published online: 23 NOV 2002
Journal of Neurochemistry
Volume 62, Issue 2, pages 557–562, February 1994
How to Cite
Minisclou, C., Rouquier, L., Benavides, J., Scatton, B. and Claustre, Y. (1994), Muscarinic Receptor-Mediated Increase in Extracellular Inositol 1,4,5-Trisphosphate Levels in the Rat Hippocampus: An In Vivo Microdialysis Study. Journal of Neurochemistry, 62: 557–562. doi: 10.1046/j.1471-4159.1994.62020557.x
- Issue published online: 23 NOV 2002
- Article first published online: 23 NOV 2002
- Received March 29, 1993; revised manuscript received June 22, 1993; accepted June 24, 1993.
- Inositol 1,4,5-trisphosphate;
- Muscarinic receptor
Abstract: The extracellular concentration of inositol 1,4,5-trisphosphate (IP3) has been monitored in the ventral hippocampus of the anesthetized rat by using a microdialysis technique coupled to a radioreceptor assay. Three hours after the implantation of the cannula, basal extracellular concentration of IP3 (corrected for a 9% recovery) was 71 nM (0.39 pmol/60-µl fraction) and remained stable for at least 5 h. Local infusion of carbachol for 60 min caused a significant concentration-related increase in extracellular IP3 levels (0, 24, and 57% at 1, 50, and 100 µM, respectively). Acetylcholine (100 µM) and muscarine (100 µM) increased IP3 outflow by 40 and 42%, respectively. The effect of carbachol was fully prevented by coinfusion of 10 µM pirenzepine and reduced by 1 µM tetrodotoxin indicating that the carbachol response is mediated by neuronal muscarinic receptors. These data demonstrate the feasibility of using microdialysis and a radioreceptor assay to measure IP3 in the extracellular space. This approach could prove useful for the study of the in vivo operation of muscarinic and, by extension, a number of receptors coupled to phosphoinositide turnover.