Step Sequence Is a Critical Gait Parameter of Unilateral 6-OHDA Parkinson's Rat Models

Parkinson's disease is a progressive neurological disorder, marked by the loss of dopaminergic neurons in the nigrostriatal pathway that leads to abnormal gait, rigidity, slowness of movement, and tremor. The ability to recapitulate and measure the neurological sequelae in rodent models of Parkinson's disease is important for studying and evaluating potential therapeutics. Individual variability in lesion severity and injury progression are key factors in the 6-hydroxydopamine model that require normalization when evaluating therapeutic effects. The gait parameters that were found to be affected by 6-hydroxydopamine lesioning of the nigrostriatal pathway in rats may be used to study novel transgenic models of Parkinson's disease as well as to test novel therapeutics. Previously, studies have used a video-based system to analyze gait abnormalities in the 6-hydroxydopamine model of Parkinson's disease, but these studies did not account for individual variability on reported gait parameters. By analyzing the ratio of parameters from the injured to uninjured sides and correcting for speed in related parameters, hindpaw step cycle parameters, hindpaw print area, and step sequence are significantly altered in different ways for each type of lesion, when compared to saline-injected controls. These findings enable new metrics for evaluating therapeutic efficacy of drug-, gene-, or cell-based therapies in rat models of Parkinson's disease.