Effects of desensitized nicotinic receptors on rotational behavior in a 6-hydroxydopamine model of Parkinson's disease.

The purpose of this study was to investigate the effects of desensitized nicotinic acetylcholine receptors (nAChRs) on rotational behavior in the unilateral 6-hydroxydopamine (6-OHDA) model of Parkinson's disease (PD). When rats were treated with different doses of nicotine, nAChRs were observed in activated, subacute desensitized, acute desensitized, and chronic desensitized states. The rotational behavior of the hemiparkinsonian rats was determined when nAChRs were in the activated or different desensitized states. The results showed that hemiparkinsonian rats exhibited no significant changes in apomorphine-induced rotation when brain nAChRs were in an activated state. However, hemiparkinsonian rats displayed a significant reduction in apomorphine-induced rotational behavior when brain nAChRs were in subacute, acute, or chronic desensitized states induced by repeated administration of nicotine. When nAChRs were blocked by the nAChR antagonist mecamylamine, the behavior of the hemiparkinsonian rats worsened. These results suggest that desensitized nAChRs can lead to behavioral improvement in the 6-OHDA rat model of PD.