Time-course of striatal Toll-like receptor expression in neurotoxic, environmental and inflammatory rat models of Parkinson's disease.

Because Toll-like receptors (TLRs) are emerging as potential targets for anti-inflammatory intervention in neurodegenerative diseases, the aim of this study was to characterise the time-course of TLR expression in neurotoxic, environmental and inflammatory Parkinson's disease models. Male Sprague Dawley rats were given intra-striatal injections of 6-hydroxydopamine (10μg), rotenone (1.25μg), LPS (10μg) or Poly I:C (20μg) and were sacrificed on Days 1, 4, 14 and 28 post surgery. Changes in the expression of several inflammatory markers, including TLR3, TLR4 and selected cytokines, were examined using qRT-PCR. We found pronounced changes in the bacterial responsive TLR4 and the viral responsive TLR3 receptors in the inflamed striatum in all models, regardless of whether the challenge was neurotoxic, environmental or inflammatory in nature. However, the magnitude and time-course of changes in expression was different between the different models. This study highlights the pattern of changes in TLR expression in models of Parkinson's disease, and further strengthens the rationale for targeting TLRs for anti-inflammatory intervention in this neurodegenerative disease.