CB1 and CB2 contribute to antinociceptive and anti-inflammatory effects of electroacupuncture on experimental arthritis of the rat temporomandibular joint

Abstract

Electroacupuncture (EA) and cannabinoids have been reported to have anti-inflammatory and antinociceptive effects in animal models of arthritis. Male Wistar rats were injected with saline or zymosan (2 mg) into the temporomandibular joint (TMJ). EA (10 Hz, 30 min) was performed 2 h after or 1 h before zymosan administration. AM251 or AM630 (3 mg/kg, i.p.)were administered before EA treatment. Mechanical hypernociception was accessed after zymosan administration. Rats were sacrificed 6 h after zymosan administration and the joint was removed for histopathological analysis. The gene expression of CB₁ and CB₂ receptors was assessed after sacrifice of the TMJ arthritic animals. EA inhibited zymosan-induced hypernociception (p < 0.05). AM251 reversed significantly the antinociceptive effect of EA, suggesting that the CB₁ receptor is involved in this effect. AM630 reversed the anti-inflammatory effect of EA. CB₁ and CB₂ receptor gene expression was upregulated 6 h after zymosan-induced arthritis in the EA-treated group. We observed downregulation of CB₂ receptor gene expression in the EA group at the 24th hour compared with the 6th hour. Higher CB₁ receptor gene expression was also found compared with the 6th hour. EA produced antinociceptive and anti-inflammatory effects, and these effects appeared to be mediated through CB₁ and CB₂ receptor activation.

Comprehensive RNA-Seq Expression Analysis of Sensory Ganglia with a Focus on Ion Channels and GPCRs in Trigeminal Ganglia

“…However, because of this large number of expressed GPCRs, we focused on the 30 most highly expressed GPCRs (Figure 3, Ref. [ 47 – 61 ]).…”

Cannabinoid Receptor CB2 Is Involved in Tetrahydrocannabinol‐Induced Anti‐Inflammation against Lipopolysaccharide in MG‐63 Cells

“…NF- κ B locates in the nucleus, and CB2 is mainly expressed in the cell membrane and cytoplasm [ 28 , 29 ]; thus we infer that THC may activate CB2 receptors expressed in the cell membrane and cytoplasm of MG-63 cells and then inhibit NF- κ B expression to reduce the inflammatory factors release from the MG-63 cells exposed to LPS. Similarly, Gondim et al reported that CB2 is involved in electroacupuncture- (EA-) induced anti-inflammatory effects in a rat model of arthritis [ 30 ]. And Zarruk et al reported that the activation of microglial CB2 receptor brings about neuroprotection against brain ischemic injury by decreasing the proinflammatory cytokines release in mice [ 31 ].…”

Peripheral and Spinal Mechanisms of Pain and Dry Needling Mediated Analgesia: A Clinical Resource Guide for Health Care Professionals

“…The endocannabinoid system primarily consists of two types of receptors, cannabinoid CB1 and CB2 receptors. By employing AM251 and AM630 to block CB1 and CB2 receptors, respectively, Gondim et al demonstrated that both receptor types mediate the anti-nociceptive and anti-inflammatory effects of EDN [175]. However, inflamed tissue has been shown to express 10-100 times the number of CB2 receptors compared to CB1 receptor mRNA, suggesting that EDN may act primarily through CB2 receptors [176,177].…”