The Effect of Copper Chloride (‎CuCl2) on Pain and Inflammatory Paw Edema in Rats

As a crucial micronutrient, copper ion is engaged in various biochemical pathways and affects central nervous system, pain, and inflammation. Considering the significance of pain in physical and mental condition of patients, the present study aims to find new ways to reduce pain by investigating the effect of copper chloride on thermal and chemical pain and inflammatory edema through central and peripheral administrations.
In this empirical study, 77 male Wister rats (200–250g) were divided into 11 groups (n=7) including control group (with no treatment), sham 1 (saline, i.p) receiving 5, 10, 20 and 100 mg/kg CuCl2 intraperitoneally (i.p), sham 2 (saline, intrathecal (i.t)) receiving 0.002mg/10µl and 0.02mg/10µl CuCl2 intrathecally (i.t), sham 3 group receiving saline plus naloxone intraperitoneally (i.p) and the group receiving 10 mg/kg CuCl2 plus 2 mg/kg naloxone intraperitoneally (i.p). Thermal and chemical pain and the volume of inflammatory edema were assessed using tail flick, formalin and plethysmometery tests, respectively. Elevated plus maze and rotarod tests were used to examine the side effects of CuCl2.
FINDINGS: 10 and 20 mg/kg CuCl2 (i.p) respectively reduced thermal pain (1.69±0.38 and 1.55±0.53) (p Since administration of naloxone as opioid receptor antagonist abolished the analgesic effect of CuCl2, CuCl2 may induce analgesia by increasing the sensitivity of opioid receptors to endogenous opioids.