The effects of fludarabine on rat cerebral ischemia.

Cerebral ischemic injury involves a variety of cellular and molecular events. Signal transducers and activators of transcription-1 (STAT-1) activation is associated with neuronal cell death and contributes to ischemic injury. The effects of fludarabine, a specific inhibitor of STAT1 protein, on cerebral ischemic/reperfusion (I/R) injury were studied in a rat model. Rats subjected to I/R injury were either treated with intra-cerebroventricular injection of fludarabine (5,000 μM, 10 μl) or saline 20 min before middle cerebral artery occlusion (MCAO). MR examinations including T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and perfusion-weighted imaging (PWI) were performed after I/R period. Then rat brains were sectioned for triphenyltetrazolium chloride (TTC) stains, analyzed by Western blot and TUNEL staining of apoptosis. It was found that fludarabine treatment decreased the infarct volume of the cerebrum and the number of apoptotic neural cells in the ischemic brain. Compared to saline-treated group, the apparent diffusion coefficient (ADC) and cerebral blood volume (CBV) in the ischemic region were greater, and the mean transit time (MTT) was shortened in the fludarabine-treated group. Moreover, fludarabine inhibited the expression level of phosphorylated STAT1 (P-STAT1) in neural cells after I/R injury, whereas the expression of phosphorylated STAT3 (P-STAT3) was increased. Therefore, we concluded that fludarabine administrated in early stage of cerebral ischemia had neuroprotective effects, and the underlying mechanism could be mediated through inhibiting STAT1 phosphorylation and activating the cross regulation between STAT1 and STAT3 in neural cells.