Abstract:

Objective

To investigate the effect of butorphanol（ BT） on neuroinflammation and Janus kinase 2（ JAK2）/signal transduction and activator of transcription 3（ STAT3） signaling pathwayin rats with cerebral ischemia reperfusion injury（ CIRI）.

Methods

A CIRI rat model was established by middle cerebral artery occlusion method. After modeling， the rats were randomly divided into sham operation group（ Sham group）， Model group， low dose BT group（ L- BT group，50 mg/kg）， medium dose BT group（ M-BT group， 100 mg/kg）， and high dose BT group（ H-BT group， 200 mg/kg）. Longa 5-point method was applied to assess the neurological deficits in rats；HE staining was applied to observe the pathological changes of brain tissue； the volume of cerebral infarction was measured by TTC staining； TUNEL staining was applied to detect the apoptosis rate； the levels of tumor necrosis factor-α （TNF-α）， interleukin （IL）-1β， IL-6， inducible nitric oxide synthase （iNOS）， IL-4， and IL-10 were measured by ELISA method； and Western blot was applied to detect the expression of inhibiting G protein （Gi）， stimulating G protein （Gs）， p-JAK2，JAK2， p-STAT3， and STAT3 proteins. The data were tested for normality and homogeneity of variance. If they met the requirements， one-way ANOVA was used for comparison among multiple groups， and LSD-t test was used for comparison between two groups. If not， the rank sum test was used for comparison between multiple groups， and the Bonferroni test was pairwise compared.

Results

Compared with Sham group， pathological damage of brain tissue in Model group was more serious， and the neurological function defect score， apoptosis rate， cerebral infarction volume， TNF-α[（352.47 ± 21.46） pg/mL vs （179.34 ± 10.21） pg/mL］， IL-1β[（42.27 ± 3.67） pg/ mL vs（20.31 ±1.54） pg/mL］， IL-6， iNOS， Gs， p-JAK2/JAK2 （0.82 ± 0.10 vs 0.25 ± 0.05）， p-STAT3/ STAT3（0.91 ± 0.06 vs 0.37 ± 0.06） were increased， while Gi， IL-4 and IL-10 were decreased （all P ＜0.05）. Compared with Model group， the pathological damage of brain tissue in L-BT， M-BT and H-BT groups was alleviated， the neurological function defect score， apoptosis rate， cerebral infarction volume， TNF-α [（294.53 ± 20.17） pg/mL， （257.29 ± 17.13） pg/mL， （210.14 ± 15.46） pg/ mL vs（352.47 ± 21.46） pg/mL］， IL-1β [（37.14 ± 2.11） pg/mL， （30.18 ± 2.04） pg/mL， （25.49 ± 1.73）pg/mL vs （42.27 ± 3.67） pg/mL］， IL-6， iNOS， Gs， p-JAK2/JAK2 （0.68 ± 0.07， 0.52 ± 0.06， 0.39 ±0.06 vs 0.82 ± 0.10）， p-STAT3/STAT3 （0.77 ± 0.05， 0.61 ± 0.04， 0.45 ± 0.03 vs 0.91 ± 0.06） were decreased， while Gi， IL-4 and IL-10 increased （all P ＜ 0.05）， and these changes were in a dose dependent manner.

Conclusion

BT can alleviate neuroinflammation and inhibit the JAK2/STAT3 signaling pathway in CIRI rats.

Key words: Butorphanol, Janus kinase 2/signal transduction and transcription activating factor 3, Cerebral ischemia reperfusion injury, Neuroinflammation