Determination of endogenous acetylcholine release in freely moving rats by transstriatal dialysis coupled to a radioenzymatic assay: effect of drugs.
The technique of intracerebral dialysis in combination with a sensitive and specific radioenzymatic method was used for recovery and quantification of endogenous extracellular acetylcholine from the striata of freely moving rats. A thin dialysis tube was inserted transversally through the caudate nuclei, and the tube was perfused with Ringer solution, pH 6.1, at a constant rate of 2 microliter min-1. The perfusates were collected at 10-min intervals. In the presence of 1 and 10 microM physostigmine, acetylcholine release was 4.5 +/- 0.02 and 7.3 +/- 0.3 pmol/10 min, respectively (not corrected for recovery). The latter concentration of the acetylcholinesterase inhibitor was used in all experiments. Under basal conditions, acetylcholine output was stable over at least 4 h. A depolarizing K+ concentration produced a sharp, reversible 87% increase in acetylcholine output. Both the basal and K+-stimulated release were Ca2+ dependent. The choline uptake inhibitor hemicholinium-3 (20 micrograms intracerebroventricularly) reduced striatal acetylcholine output to 35% of the basal value within 90 min. Scopolamine (0.34 mg/kg s.c.) provoked a sharp enhancement of acetylcholine release of approximately 63% over basal values, whereas oxotremorine (0.53 mg/kg i.p.) transiently reduced acetylcholine release by 54%. These results indicate the physiological and pharmacological suitability of transstriatal dialysis for monitoring endogenous acetylcholine release.
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003342:Corpus Striatum / Q000378:metabolism*; D003956:Dialysis / Q000379:methods; D005260:Female; D006426:Hemicholinium 3 / Q000494:pharmacology; D009043:Motor Activity; D010095:Oxotremorine / Q000494:pharmacology; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012601:Scopolamine / Q000494:pharmacology; D013997:Time Factors; D014316:Tritium
D014316:Tritium; D006426:Hemicholinium 3; D010095:Oxotremorine; D010830:Physostigmine; D012601:Scopolamine; D000109:Acetylcholine; D002118:Calcium