title: Acetylcholine content and distribution in rat cortical synaptosomes after in vivo exposure to quinolinic acid.
abstract: In this study, changes in the concentration and subcellular distribution of rat cortical synaptosomal acetylcholine (ACh) was investigated after a single injection of quinolinic acid (QUIN) into the nucleus basalis magnocellularis (nbM). In the P2 fraction of normal animals the ACh concentration was 235 +/- 18 pmol/mg protein. Of this, 64 +/- 10% was recovered in the particulate (P3) fraction and 24 +/- 1% in the soluble (S3) fraction. Cortical synaptosomes (P2) prepared 0.5 h after injecting either 600 or 1000 nmol of QUIN contained significantly higher concentrations of ACh (372 +/- 127 and 496 +/- 77 pmol/mg protein, respectively) when compared to the amount of ACh in control animals. The ACh concentration in the P2 fraction was still elevated 3 h after injecting 600 nmol QUIN, however, synaptosomal ACh decreased significantly 3 h after rats were treated with 1000 nmol QUIN. Determination of subcellular ACh 0.5 h after injecting QUIN revealed that neither dose of QUIN produced a change in the distribution of ACh between P3 and S3. However, 3 h after injecting QUIN, a shift in the subcellular distribution of ACh to the cytoplasmic fraction (S3) was observed with 1000 nmol QUIN. These results show that QUIN-induced depolarization of nbM neurons which project to the cortex produce both dose-dependent and time-dependent changes in synaptosomal ACh concentration and subcellular distribution.
authors: Department of Pharmacology and Toxicology, Queen's University, Kingston, Ont. Canada.
authors: R H
authors: RH
authors: Metcalf
authors: D L
authors: DL
authors: Riddell
authors: R J
authors: RJ
authors: Boegman
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001479:Basal Ganglia / Q000166:cytology* / Q000187:drug effects; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D002799:Cholinergic Fibers / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008845:Microinjections; D011725:Pyridines / Q000494:pharmacology*; D017378:Quinolinic Acid; D011805:Quinolinic Acids / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*
chemical_list: D011725:Pyridines; D011805:Quinolinic Acids; D017378:Quinolinic Acid; D000109:Acetylcholine