title: Persistent exercise attenuates nicotine- but not clonidine-induced antinociception in female rats.
abstract: Exercise decreases the antinociceptive effects of opiate drugs. It has been hypothesized that the exercise-induced attenuation of opiate drug action is the result of the development of cross-tolerance between endogenous opioids released during exercise and exogenous opiates. The present study was designed to evaluate the role of exercise on non-opiate antinociception. Female Long-Evans rats were allowed ad lib access to running wheels. After 3 weeks, antinociceptive responses of animals were measured using the tail flick test following the administration of clonidine or nicotine. Nicotine and clonidine both produced dose-dependent increases in antinociceptive responses. Active animals were significantly less sensitive to nicotine-induced antinociception than inactive animals. There was no difference between the two groups in clonidine-induced antinociception. The results of these experiments suggest that exercise does not attenuate non-opioid, clonidine-induced antinociception. However, exercise does attenuate nicotine-induced antinociception. Therefore, the effect of persistent exercise on analgesic drugs is not specific to opiates.
authors.affiliation: Department of Psychology, Tufts University, 490 Boston Avenue, Medford, MA 02155, USA.
authors.forename: Wendy Foulds
authors.initials: WF
authors.lastname: Mathes
authors.forename: Robin B
authors.initials: RB
authors.lastname: Kanarek
mesh_terms: D000698:Analgesia; D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D004361:Drug Tolerance; D005260:Female; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D010805:Physical Conditioning, Animal / Q000523:psychology*; D051381:Rats; D020318:Rats, Long-Evans; D011978:Receptors, Nicotinic / Q000187:drug effects
chemical_list: D000700:Analgesics; D018722:Nicotinic Agonists; D011978:Receptors, Nicotinic; C403531:nicotinic receptor alpha4beta2; D009538:Nicotine; D003000:Clonidine