The possible role of progranulin on anti-inflammatory effects of metformin in temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is the most prevalent and drug-resistant form of parietal epilepsy. TLE is accompanied by neuroinflammation in the brain, which involves reactive glial cells. Metformin is an old antidiabetic drug with anti-inflammatory and neuroprotective effects. Considering the importance of inflammation in epilepsy, we have investigated the effect of metformin on astrogliosis markers as well as pro and anti-inflammatory cytokines and its effect on progranulin expression (an important neuroprotective protein in epilepsy) in a rat TLE model. TLE was induced by intracerebroventricular microinjection of kainic acid. Metformin was orally administered for two weeks before the induction of epilepsy. Astrogliosis markers (GFAP and S100B), as well as IL-1β and IL- 10 levels, were detected by ELISA. The progranulin level was measured by Western blotting and immunohistochemistry in the hippocampus. Our results showed basal levels of GFAP, S100B, and pro-inflammatory cytokine increased in the epileptic rats but were significantly ameliorated after pretreatment with metformin. However, anti-inflammatory cytokine and progranulin also increased in the pre-treated rats and metformin alone group. An increment in the progranulin level emphasizes the importance of this protein in epilepsy. Hence, metformin may exert at least some of its anti-inflammatory effects by increasing progranulin level. In sum, we have concluded that progranulin can be a key mediator in epilepsy, and the anti-inflammatory action of metformin in status epilepticus is through increasing the secretion of IL-10 and inhibiting IL-1 β and astrogliosis.