3.2 Fingolimod attenuated PCP-induced contextual and tone memory
retention deficits in rats in the fear conditioning task
Next, we used a contextual fear conditioning task to evaluate the
effects of fingolimod on memory retention. A timeline of the experiment
is presented in
Figure
3A. The rats were subjected to consecutive tone-shock pairings in a
conditioning training session and tested for contextual and tone-cued
fear conditioning tests 24 and 48 h later, respectively. We found that
the percentage of freezing time for the PCP-treated (10 mg/kg, i.p.)
rats was significantly lower than that for the control rats, indicating
impairments in fear memory retention. Fingolimod treatment (0.5 mg/kg, 1
mg/kg, i.p.) significantly increased the freezing time in a
dose-dependent manner (Figure 3B). Similar effects were observed in the
auditory-cued fear conditioning test, although they were not
statistically significant. The decreased freezing time in PCP-treated
rats was partially restored by fingolimod treatment (0.5 mg/kg, 1 mg/kg,
i.p.) (Figure 3C). These results suggest that fingolimod attenuates
PCP-induced deficits in fear memory retention.