Assessing the Efficacy of Specific Cerebellomodulatory Drugs for Use as Therapy for Spinocerebellar Ataxia Type 1

Nupur Nag, Volga Tarlac, Elsdon Storey

Spinocerebellar ataxias are autosomal dominant diseases, associated in some types with a CAG repeat expansion, and characterised by a progressive loss of motor function. Currently, as there is no cure for most ataxias, treatment predominantly involves physical therapy. Various symptomatic drug treatments have been tried; however, published clinical studies have provided inconsistent results, likely due to small sample sizes, mixed patient populations and insensitive or subjective assessment scales. SCA1(154Q) transgenic mice display motor function impairments and ultimately a reduced number of cerebellar Purkinje neurons-characteristics comparable to most forms of sporadic and hereditary ataxias. We monitored motor function in SCA1(154Q) mice from 5 to 20 weeks of age and assessed the efficacy of four potential cerebellar modulatory drugs in attenuating deficits in rotor-rod performance. The drugs riluzole, amantadine, zolpidem and buspirone were selected based on their different mechanisms of action and their Food and Drug Administration (FDA)/Australian Therapeutic Goods Administration approval for other indications. SCA1(154Q) and C57/Bl6 wild-type mice were administered with four ascending acute doses of each drug, over 2 days. Following each dose, mice were assesed for motor function on the accelerating rotor-rod. None of the four drugs attenuated motor deficts in SCA1(154Q) mice at any dose; at FDA equivalent and higher dose administration of zolpidem and buspirone led to sedation in both strains. Our results suggest that the aforementioned drugs are likely to be ineffective for symptomatic treatment of SCA1 and most other ataxic patients and emphasise the need for comphrehensive drug studies prior to clinical use.