Impact of the acute administration of doxycycline on LID associated markers once dyskinesia was present
Expression of FosB: Similar to described by Padovan-Neto et al., (2009) and others, FosB protein expression increased in the cell nuclei in the lesioned striatum of parkinsonian rats receiving L-DOPA (6-OHDA+vehicle+L-DOPA; Figs. 2-A, -B, -C). The acute administration of doxycycline caused a significant decrease in the expression of FosB (40%; 6-OHDA+doxycycline+L-DOPA; p < 0.001; Fig. 2-C).
Expression of COX-2: Similar to described by Bortolanza et al., (2015b), L-DOPA increased the number of cells expressing COX-2 (6-OHDA+vehicle+L-DOPA; Figs. 2-D, -E, -F) in the dopamine-depleted striatum. Doxycycline significantly reduced the induction of LID associated COX-2 (6-OHDA+doxycycline+L-DOPA; p<0.05; Figs. 2-E and -F).
Expression of GFAP and OX42: We investigated how L-DOPA, alone or combined with acute doxycycline, would affect the number (Figs. 2-G, -H, -I, -J, -K and -L) and morphology (Supplementary Fig. 3) of the astrocytes and microglia using GFAP and OX42 immunohistochemical labeling, respectively. The number of astrocytes increased as did the number activated in the dopamine-depleted striatum. It was showed an increased GFAP-immunoreactivity (6-OHDA+vehicle+L-DOPA; Figs. 2-G and -I) and cellular hypertrophy (6-OHDA+vehicle+L-DOPA; Supplementary Figs. 3-A, -B and -C). Also, L-DOPA treatment increased the number of microglia as characterized by increased OX-42 density (6-OHDA+vehicle+L-DOPA; Figs. 2-J and -L) and hypertrophic morphology (6-OHDA+vehicle+L-DOPA; Supplementary Figs. 3-D, -E and -F). Doxycycline administered before L-DOPA reduced each of these L-DOPA treatment-induced changes in the depleted striatum (6-OHDA+doxycycline+L-DOPA; Figs. 2-H, -I, -K and -L; Supplementary Fig. 3).
The increase of the immunoreactivity of Fos-B, COX2, GFAP, OX-42 in LID, or evidence of microglia and astrocytes activation was not observed in the striatum of non-lesioned rats and lesioned rats treated with only vehicle or doxycycline (data not shown).