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Effects of Microinjected Carbachol on the Antinociceptive Response to Noxious Heat Stimuli
- Source :
- Biological and Pharmaceutical Bulletin. 26:162-165
- Publication Year :
- 2003
- Publisher :
- Pharmaceutical Society of Japan, 2003.
-
Abstract
- Injecting muscarinic receptor agonists into a specific area of the brainstem produces an antinociceptive response. The present study investigates whether direct injections of the cholinergic agonist, carbachol, into the rat nucleus reticularis gigantocellularis (NRGC)/nucleus reticularis gigantocellularis alpha (NRGCalpha) of the rostral ventrolateral medulla evokes antinociception, and then examines the interference action of cholinergic antagonists in rats. Microinjections of carbachol (0.75, 1.5, 3 micro g/site) prolonged hot plate (HP) and tail flick (TF) responses to noxious heat stimuli in a dose-dependent manner. The level of carbachol-induced antinociception during the HP and TF tests reached a maximum at 5-15 min after carbachol administration in all groups. Thereafter, the peak level progressively decreased and reached the baseline by the end of the experiment. Antinociception induced by carbachol at 3 micro g/site was attenuated by the prior administration of the muscarinic receptor antagonist, atropine (200, 500 ng/site). On the other hand, the nicotinic autonomic ganglion blocker, mecamylamine (1, 3 micro g/site), did not affect subsequent carbachol-induced antinociception. These results suggest that the antinociceptive effects induced by a microinjection of carbachol depend on muscarinic, but not nicotinic, mechanisms within the rat NRGC/NRGCalpha.
- Subjects :
- Male
medicine.medical_specialty
Hot Temperature
Carbachol
Microinjections
Pharmaceutical Science
Internal medicine
Mecamylamine
Muscarinic acetylcholine receptor
medicine
Animals
Receptors, Cholinergic
Rats, Wistar
Pain Measurement
Pharmacology
Analgesics
Chemistry
General Medicine
Rostral ventrolateral medulla
Rats
Atropine
Nociception
Nicotinic agonist
Endocrinology
Cholinergic
medicine.drug
Subjects
Details
- ISSN :
- 13475215 and 09186158
- Volume :
- 26
- Database :
- OpenAIRE
- Journal :
- Biological and Pharmaceutical Bulletin
- Accession number :
- edsair.doi.dedup.....cc30233fa3264ee1087761a97852255d