Effects of Δ9-Tetrahydrocannabinol on Regional Brain Acetylcholine
In view of the fact that Δ9-tetrahydrocannabinol (Δ9-THC) is a central nervous system (CNS) depressant, it could be expected to elevate whole brain ACh levels. This hypothesis is supported by our previous findings (2). Large doses of Δ9-THC (30 min before sacrifice i.p.) significantly elevated total rat brain ACh. In addition, using intraventricular hemi-cholinium-3 (HC-3), decreased ACh utilization was found after lower doses of Δ9-THC. This effect was similar to that produced by other CNS depressants, including morphine. In contrast, Askew et al. (1) found that i. v. administration of Δ9-THC (5.0 mg/kg) decreased whole brain ACh levels at 1 h in the rat. The discrepancy between our findings and those of Askew and coworkers was thought to stem from technical variations between laboratories. It was noted that Askew and coworkers utilized commercial equipment requiring 30 s to microwave whole rats, while other investigators, including our laboratory, use 0.3–7 s for focussed microwave irradiation of the rat head. This difference in sacrifice technique might also explain the large in-group variations in the data published by Askew and coworkers. Nevertheless, the significance between control and experimental animals was borderline. We subsequently repeated their experiment, using the dosage, time and technique of i. v. administration of Δ9-THC and found only an elevation in total brain ACh (3).
KeywordsCentral Nervous System Depressant Brain Acetylcholine Central Cholinergic Function Focus Microwave Irradiation Regional Brain Level
Unable to display preview. Download preview PDF.
- 3.Domino, E. F. (1976): In: Marihuana; Chemistry, Biochemistry and Cellular Effects, (Eds.) G.G. Nahas, Springer-Verlag, New York, pp.407–413.Google Scholar
- 6.Donelson, A.C. and Domino, E.F. (1976): Fed. Proc. 35:307.Google Scholar
- 8.Karbowski, M., Jagoda, A., Dewey, W. L. and Harris, L.S. (1975): Pharmacologist 17:254.Google Scholar
- 9.Layman, J.M. and Milton, A.S. (1971): Brit. J. Pharmacol. 42: 308–310.Google Scholar