cPKCγ membrane translocation is involved in herkinorin-induced neuroprotection against cerebral ischemia/reperfusion injury in mice

Herkinorin is an opiate analgesic with limited adverse effects, functioning as a primary selective atypical opioid µ agonist. The present study aimed to identify whether herkinorin has a positive effect on ischemic/reperfusion (I/R) injury. Adult male C57BL/6 mice were randomly divided into five groups: i) Naïve, ii) sham, iii) I/R, iv) I/R with dimethyl sulfoxide (I/R+D) and v) I/R with herkinorin (I/R+H). The I/R injury model was induced by occluding the middle cerebral artery for 1 h followed by 24 h or 7 days of reperfusion. Neurobehavioral scores and sensorimotor functions were examined 24 h and 7 days following reperfusion. In addition, infarct volumes were examined at these time points using a 2,3,5-triphenyltetrazolium chloride assay. Herkinorin treatment improved neurobehavioral and sensorimotor functional recovery from I/R-induced brain injury. There was a significant decrease in infarct volume in the I/R+H group at 24 h or 7 days following reperfusion compared with the I/R and I/R+D groups. Western blotting suggested that the decrease in conventional protein kinase C γ (cPKCγ) membrane translocation in the peri-infarct region may be attenuated by herkinorin pretreatment. These results indicated that herkinorin may be beneficial in I/R-induced mouse brain injury, and this may be attributed to the membrane translocation of cPKCγ following activation.