Expression of EAAT3 in spinal cord dorsal horn of arthritis rats with chronic morphine tolerance

Objective To study the expression of EAAT3 in the spinal cord dorsal horn of arthritis rats with chronic morphine tolerance.Methods Thirty-six healthy male SD rats implanted intrathecal catheter were randomized into 6 groups with 6 rats each. The model of adjuvant-induced arthritis was established in 24 rats,which were intrathecally given normal saline (group A),morphine 10 μg/kg(group B),morphine 20 μg/kg(group C),or morphine 10 μg/kg plus naloxone 10 μg/kg(group D). The rats in the other two groups without arthritis were administered intrathecally saline (group E) and morphine 20 μg/kg(group F),respectively. The drugs were administered twice daily for 7 days. Mechanical withdrawl threshold(MWT) of rats was examined to evaluate its behavior. Immunohistochemistry was used to detect the expression of EAAT3 in the spinal cord dorsal horn.Results Morphine tolerance was formmed stably in groups of B and C on the 7th day after morphine injection. The expression of GLAST in the spinal cord dorsal horn was downregulated.Conclusion Spinal EAAT3 may be involved in the development of morphine tolerance in rats with inflammatory pain.