title: Continuous and intermittent nicotine treatment reduces L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesias in a rat model of Parkinson's disease.
abstract: The development of abnormal involuntary movements (AIMs) or dyskinesias is a serious complication of L-DOPA [L-3,4-dihydroxyphenylalanine] therapy for Parkinson's disease. Our previous work had shown that intermittent nicotine dosing reduced L-DOPA-induced dyskinetic-like movements in nonhuman primates. A readily available nicotine formulation is the nicotine patch, which provides a constant source of nicotine. However, constant nicotine administration more readily desensitizes nicotinic receptors, to possibly yield alternate behavioral outcomes. Therefore, we investigated whether constant nicotine administration reduced L-DOPA-induced AIMs in a rat parkinsonian model, with results compared with those with intermittent nicotine dosing. Rats with a unilateral 6-hydroxydopamine (6-OHDA) lesion were exposed to either intermittent (drinking water) or constant (minipump) nicotine for > or = 2 weeks at doses that yielded plasma levels of the nicotine metabolite cotinine similar to those in smokers. The rats were next treated with L-DOPA/benserazide (8 or 12 mg/kg/15 mg/kg) for > or = 3 weeks to allow for the development of AIMs, with nicotine treatment continued. Both modes of nicotine administration resulted in > or = 50% decline in L-DOPA-induced AIMs. Nicotine treatment also significantly reduced AIMs in L-DOPA-primed rats using either dosing regimen, whereas nicotine removal led to an increase in AIMs. There was no effect of nicotine on various measures of motor performance in 6-OHDA-lesioned rats. In summary, nicotine provided either via the drinking water or minipump reduced L-DOPA-induced AIMs in a rat model of Parkinson's disease. These results suggest that either intermittent or constant nicotine treatment may be useful in the treatment of L-DOPA-induced dyskinesias in patients with Parkinson's disease.
authors.affiliation: The Parkinson's Institute, 675 Almanor Ave., Sunnyvale, CA 94085-2934, USA.
authors.forename: Tanuja
authors.initials: T
authors.lastname: Bordia
authors.forename: Carla
authors.initials: C
authors.lastname: Campos
authors.forename: Luping
authors.initials: L
authors.lastname: Huang
authors.forename: Maryka
authors.initials: M
authors.lastname: Quik
mesh_terms: D000818:Animals; D003342:Corpus Striatum / Q000737:chemistry; D004195:Disease Models, Animal; D050483:Dopamine Plasma Membrane Transport Proteins / Q000032:analysis; D004409:Dyskinesia, Drug-Induced / Q000188:drug therapy*; D007260:Infusion Pumps; D007980:Levodopa / Q000633:toxicity*; D008297:Male; D009538:Nicotine / Q000008:administration & dosage*; D010300:Parkinson Disease / Q000188:drug therapy*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D007980:Levodopa; D009538:Nicotine