Abstract
The effects of cholinergic agonists and antagonists were investigated on self-stimulation in rats with chronically implanted elcetrodes in the lateral posterior hypothalamus. Physostigmine (50-300 µg/kg s.c.) caused depression of self-stimulation. The magnitude, lateney and duration of this effect were dose-related. Arecoline (100-3000 µg/kg s.c.) had similar actions, but the depression was less dramatic and of shorter duration. Nicotine (25-600 µg/kg s.c.) caused biphasic effects; the initial depression was sometimes followed by facilitation, and the actions were much less consistent. The depressant effects of physostigmine and arecoline were blocked by scopolamine (0.5 mg/kg) and enhanced by mecamylamine (5.0 mg/kg). Methscopolamine (0.5 mg/kg) and trimethidinium (5.0 mg/kg) were much less effective. The results suggest that muscarinic cholinergic agonists which penetrate the blood-brain barrier depress self-stimulation on a central basis, whereas nicotinic cholinergic agonists have complex depressant and stimulant effects of both central and peripheral origin.
Footnotes
- Received July 11, 1968.
- Accepted December 6, 1968.
- © 1969 by The Williams & Wilkins Co.
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|