[Bone-edge electroacupuncture relieves pain by regulating expression of GRK5, β-arrestin 2 and PKCα proteins in locus coeruleus in bone cancer pain rats with morphine tolerance].

Objective: To observe the effect of bone-edge electroacupuncture (EA) intervention on mechanical pain threshold (PT) and expression of G protein-coupled receptor kinase (GRK5), β-arrestin 2, total and phosphorylated PKC alpha (p-PKCα) proteins in the locus coeruleus (LC) of rats with bone cancer pain induced morphine tolerance, so as to reveal its partial central mechanisms underlying pain relief.

Methods: Forty SD rats were randomly divided into 5 groups, namely sham bone cancer, bone cancer pain, morphine tolerance, bone-edge EA, and sham EA (＝ 8 rats in each group). The bone cancer with morphine tolerance model was established by intramedullary injection of MRMT-1 cells into the tibial cavity, and then intraperitoneal injection of morphine hydrochloride injection.

[Electroacupuncture intervention relieves pain possibly by promoting MOR endocytosis in locus coeruleus in bone cancer pain rats with morphine tolerance].

Objective: To observe the effect of electroacupuncture (EA) on pain behavior and expression of µ-opioid receptor (MOR) and Rab5 (an important protein molecule for internalization of MOR) in the locus coeruleus (LC) region in bone cancer pain (BCP) rats with morphine tolerance (MT), so as to explore its mechanisms underlying improvement of BCP and MT.

Methods: The present study included two parts. In the first part, 23 female SD rats were randomized into sham BCP (＝6), BCP (＝9) and BCP＋MT (＝8) groups, and in the second part, 61 female SD rats were randomized into 5 groups: sham BCP (＝11), BCP (＝11), BCP＋MT (＝13), BCP＋MT＋EA (＝13) and BCP＋MT＋sham EA (＝13).