Leukemia Inhibitory Factor Contributes to Reactive Astrogliosis via Activation of Signal Transducer and Activator of Transcription 3 Signaling after Intracerebral Hemorrhage in Rats.

ABSTRACT

Reactive astrogliosis has occurred after intracerebral hemorrhage (ICH). Leukemia inhibitory factor (LIF) can act as a modulator for glial gene expression. Signal transducer and activator of transcription 3 (STAT3) is a critical regulator of reactive astrogliosis. The present study tested whether endogenous LIF acted on ICH-induced reactive astrogliosis via the STAT3 signaling pathway. Rats were divided into three experimental groups 1) Rats received either an ICH or a needle insertion (sham), 2) Rats received 100 ng LIF or an equal volume of phosphate-buffered saline (PBS) by direct infusion into the lateral ventricle (LV) after ICH, and 3) AG490 (0.25 mg/kg) was injected into the LV to block STAT3 signaling. Brains were perfused to identify proliferating cell nuclear antigen (PCNA)+/glial fibrillary acidic protein (GFAP)+nuclei. The expression of GFAP, LIF, LIF receptor (LIFR), glycoprotein 130 (gp130), and phospho-STAT3 (p-STAT3) was evaluated by immunohistochemistry and Western blot, respectively. After ICH, the number of the PCNA+/GFAP+ nuclei and the expression of GFAP, LIF, LIFR, gp130, and p-STAT3 were increased. Moreover, LIF increased the number of PCNA+/GFAP+ nuclei and the expression of GFAP, LIFR, gp130, and p-STAT3. The number of PCNA+/ GFAP+ nuclei and GFAP protein levels were attenuated markedly after inhibition of p-STAT3. Together, these data suggest that LIF contributes to ICH-related reactive astrogliosis via activation of STAT3 signaling.