Abstract
Autism is a neurodevelopmental disorder with a strong genetic component and neuropathology in diverse brain regions. The cerebellum, in particular, has been directly implicated in autism by postmortem analysis at the cellular and molecular level, and by structural and functional imaging. Postmortem molecular analysis, in addition to a growing body of genetic evidence, also implicates the GABA neurotransmitter system. Given these findings, I investigated whether GABAA receptor subunits were altered in density and distribution in the cerebellar cortex of autistic cases versus controls. Immunohistochemistry of postmortem tissue allowed clear visualization and semi-quantitative analysis of α6 subunit expression, which was not significantly different in autistic cases versus controls in the small sample available, F(1, 8) = 1.065, p = .332. Nevertheless, autistic cases did tend to have a lower percent area of α6 subunit expression, and there were qualitative differences in the distribution of <l6 subunit between autistics and controls. This initial characterization of the density and distribution of the GABAA receptor Ct6 subunit in the cerebellar cortex of cases in this sample indicates that its expression is not severely affected in autism. This result is surprising considering previous reports of cerebellar and GABAergic neuropathology in autism. Thus, my results may be suggestive of the discrete nature of GABAergic neuropathology in the cerebellum of autistic individuals. Future experiments that characterize the expression profiles of all the major GABAA receptor subunits in the cerebellum will involve a larger sample size and a more quantitative measurement method, such as quantitative RT -PCR, to yield more definitive results.