3.3 Short-term DREADD specifically activate BLA astrocytes
induces mechanical pain but not anxiety-like behavior in naive rats.
To further investigate whether the activation of BLA astrocytes was
sufficient to cause mechanical allodynia, we activated BLA astrocytes in
naive rats with the gfaABC1D-M3-EGFP virus (Fig. 3A). We observed that
in the gfaABC1D-M3-EGFP group, mechanical allodynia was gradually
induced, peaked at 2 hours after CNO administration, and then returned
to normal 6 hours after CNO treatment. However, no significant changes
in MWT were found in the gfaABC1D-M3-EGFP group treated with normal
saline (Fig. 3B). CNO caused the MWT to significantly decrease in the
gfaABC1D-M3-EGFP group compared with the gfaABC1D-EGFP group (Fig. 3C).
Next, we observed the effects of chemical genetic activation of BLA
astrocytes on the behavioral performance of rats in open field and
elevated cross maze. The results of open field test showed that after
intraperitoneal administration of CNO (0.5 mg/kg), rats transfected with
gfaABC1D-EGFP or gfaABC1D-M3-EGFP virus had similar trajectories in the
open field (Fig. 3D), showing no significant difference in the total
distance (Fig. 3E) and the central motor distance (Fig. 3F). Results
from the elevated plus maze also showed that after CNO administration,
the activity trajectories of the rats transfected with gfaABC1D-EGFP or
gfaABC1D-M3-EGFP in the elevated cross maze were similar (Fig. 3G),
which showed that there was no significant difference in the activity
time in the open arm (Fig. 3H) and the number of explorations into the
open arm (Fig. 3I).
Then, we assessed the expression of astrocytes in the BLA to prove that
CNO specifically activated gfaABC1D-M3-EGFP-infected cells. We found
that CNO significantly enhanced astrocyte expression in the
gfaABC1D-M3-EGFP group compared with the gfaABC1D-EGFP group (Fig.
3J-3L). Based on these findings, BLA astrocytes may be an integral part
of DNP pathogenesis.