Effect of reactive oxygen species of the psoas major muscle in complete Freund’s adjuvant-induced inflammatory pain in rats

Abstract

Lower limb pain is a common clinical disease that affects millions of people worldwide. It is found in previous studies that reactive oxygen species is closely related to neuropathic, cancer, chemotherapy, and inflammatory pain, which can be relieved by reactive oxygen species scavengers. Furthermore, acupuncture or electroacupuncture on the psoas major muscle has a great effect on adjuvant-induced arthritis and lower back pain. In our study, we investigated the function of reactive oxygen species scavengers locally injecting into the ipsilateral psoas major muscle on complete Freund’s adjuvant-induced inflammatory pain. Our results demonstrated that in the development of complete Freund’s adjuvant-induced inflammatory pain, early local continuous application of N-tert-Butyl-α-phenylnitrone (PBN, 1 and 5 mg/kg/0.2 ml) on the ipsilateral psoas major muscle effectively reduced mechanical and cold hyperalgesia. However, intraperitoneal injection of PBN (1 and 5 mg/kg) or local injection of PBN (1 and 5 mg/kg/0.2 ml) into contralateral psoas major muscle, ipsilateral quadratus lumborum, and ipsilateral erector spinae showed limited effect. In the developed inflammatory pain model, local injection of PBN into the ipsilateral psoas major muscle also alleviated pain and paw edema. In addition, reactive oxygen species level increased in ipsilateral psoas major muscle at seven days after complete Freund’s adjuvant injection. In general, PBN reduces complete Freund’s adjuvant-evoked inflammatory pain by inhibiting reactive oxygen species in the psoas major muscle.

Nrf2 Activation Mediates Antiallodynic Effect of Electroacupuncture on a Rat Model of Complex Regional Pain Syndrome Type-I through Reducing Local Oxidative Stress and Inflammation

“…ROS and lipid peroxidation products as a result of oxidative stress contribute to chronic pain via multiple mechanisms, including direct activation of nociceptor TRPA1 in the periphery and activation of microglia in the spinal cord, affecting spinal synaptic plasticity or producing pain-inducing substances [32,[58][59][60]. ROS scavengers or NADPH oxidase inhibitors, which reduce oxidative stress and ROS production, ameliorate chronic pain [61][62][63][64]. The Nrf2 antioxidant signaling is an endogenous machinery to counteract oxidative stress.…”

Effects of administration of α2 adrenergic receptor agonist into psoas major muscle on inflammatory pain induced by injection of complete Freund’s adjuvant in rats

“… 28 Findings from our previous study showed that local injection of the ROS scavenger N-tert-Butyl-a-phenylnitrone (PBN) to psoas major muscle significantly ameliorated pain and swelling in the hind paws of inflamed rats. 13 These findings indicate that local injection of α 2 adrenergic receptor agonists into the psoas major muscle of rats may result in analgesic and anti-inflammatory effects. In the present study, low-dose α 2 adrenergic agonists, dexmedetomidine and clonidine, were administered into the psoas major muscle of CFA-induced inflammatory rats to explore the local analgesic effect and mechanism of α 2 adrenergic agonists.…”

“…Inflammatory model was established as described previously. 13 Rats were anesthetized and were subjected to 3% sevoflurane by inhalation to maintain mild anesthesia. The skin of the left foot base was disinfected using 75% medical alcohol.…”

“…The experimental method was the same as described in our previous methods. 13 Rats were anesthetized with sevoflurane and the back skin was disinfected with 75% medical alcohol. The position of the psoas major muscle was determined through anatomical landmarks.…”

“…Administration of ROS scavenging agent to the psoas major muscle alleviated the pain and swelling of the posterior paw of rats. 13 This implies that ROS in psoas major muscle is involved in occurrence and maintenance of inflammatory pain. Dexmedetomidine is a highly selective α 2 adrenergic receptor agonist.…”