Tanshinone I (TsI) is an important lipophilic
diterpene extracted from Danshen (Radix Salvia miltiorrhizae) and has been used in Asia for the treatment of
cerebrovascular diseases such as
ischemic stroke. In this study, we examined the
neuroprotective effect of TsI against ischemic damage and its neuroprotective mechanism in the gerbil hippocampal CA1 region (CA1) induced by 5 min of transient global
cerebral ischemia. Pre-treatment with TsI protected pyramidal neurons from ischemic damage in the stratum pyramidale (SP) of the CA1 after
ischemia-reperfusion. The pre-treatment with TsI increased the immunoreactivities and
protein levels of anti-inflammatory
cytokines [
interleukin (IL)-4 and
IL-13] in the TsI-treated-
sham-operated-groups compared with those in the vehicle-treated-
sham-operated-groups; however, the treatment did not increase the immunoreactivities and
protein levels of pro-inflammatory
cytokines (IL-2 and
tumor necrosis factor-α). On the other hand, in the TsI-treated-
ischemia-operated-groups, the immunoreactivities and
protein levels of all the
cytokines were maintained in the SP of the CA1 after
transient cerebral ischemia. In addition, we examined that
IL-4 injection into the lateral ventricle did not protect pyramidal neurons from ischemic damage. In conclusion, these findings indicate that the pre-treatment with TsI can protect against
ischemia-induced neuronal death in the CA1 via the increase or maintenance of endogenous inflammatory
cytokines, and exogenous
IL-4 does not protect against ischemic damage.