Figure 6: The inhibitory effects of COL-3 on TNF-α release are reproduced by either reducing glucose metabolism or lowering NADPH oxidase activity . (A) Quantification of TNF-α levels in microglial cells exposed or not to LPS (10 ng/ml, 24-h) in the presence or not of COL-3 (20 μM), APO (300 µM), or 2-DG (500 µM µM). Data are means ± SEM (n = 6), *p < 0.05 vs control.#p < 0.05 vs LPS. One-way ANOVA followed by Bonferroni post-hoc test. (B) Quantification of TNFα levels in microglial cells exposed or not to αSa (70 µg/ml, 24-h) in the presence or not of COL-3 (20 μM), APO (300 µM), or 2DG (500 µM µM). Data are means ± SEM (n = 6), *p < 0.05 vs control.#p < 0.05 vs αSa. A One-way ANOVA followed by Bonferroni post-hoc test.

Background and Purpose L-DOPA induced dyskinesia is a debilitating side effect of treating Parkinson’s disease with L-DOPA. There is a need to discover a treatment that has the same benefits as L-DOPA treatment without the associated side effects. Here, we demonstrate the anti-dyskinetic potential of doxycycline and the analog compound COL-3 (without antimicrobial activity) in hemiparkinsonian rats presenting L-DOPA-induced dyskinesia. Experimental Approach Wistar adult male rats received a unilateral medial forebrain bundle injection of 6-hydroxydopamine and were then orally administered L-DOPA once a day for 14 days. This resulted in dyskinetic-like behavior. Key Results A single injection of doxycycline (intraperitoneal) or COL-3 (intracerebroventricular) together with L-DOPA attenuated the dyskinesia. Co-treatment with doxycycline from the first day of L-DOPA suppressed the onset of dyskinesia. The improved motor responses to L-DOPA remained intact in the presence of doxycycline or COL-3, indicating the preservation of the L-DOPA benefits. Doxycycline treatment was associated with decreased expression of FosB, cyclooxygenase-2, astrocytes, and microglia, which had previously been found to be elevated in the basal ganglia of rats exhibiting dyskinesia. In addition, metalloproteinase-2/-9 activity, metalloproteinase-3 expression, and production of reactive oxygen species in the basal ganglia of dyskinetic rats showed a significant positive correlation with the intensity of dyskinesia, which was decreased with the doxycycline treatment. Conclusion and Implications Given the long-established and safe use of doxycycline and the similar effect of COL-3 (without antimicrobial activity), this study indicates that both drugs should undergo testing for their ability to reduce signs of dyskinesia induced by L-DOPA in patients with Parkinson’s disease.