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).