Systemic lupus erythematosus (SLE) is an unpredictable autoimmune disease where the body’s immune system mistakenly attacks healthy tissues in many parts of the body. Chronic pain is one of the most frequently reported symptoms among SLE patients. We previously reported that MRL lupus prone (MRL/lpr) mice develop hypersensitivity to mechanical and heat stimulation. In the present study, we found that the spinal protease-activated receptor-1(PAR1) plays an important role in the genesis of chronic pain in MRL/lpr mice. Female MRL/lpr mice with chronic pain had activation of astrocytes, over-expression of thrombin and PAR1, enhanced glutamatergic synaptic activity, as well as suppressed activity of adenosine monophosphate-activated protein kinase (AMPK) and glial glutamate transport function in the spinal cord. Intrathecal injection of either the PAR1 antagonist, or AMPK activator attenuated heat hyperalgesia and mechanical allodynia in MRL/lpr mice. Furthermore, we also identified that the enhanced glutamatergic synaptic activity and suppressed activity of glial glutamate transporters in the spinal dorsal horn of MRL/lpr mice are caused by activation of the PAR1 and suppression of AMPK signaling pathways. These findings suggest that targeting the PAR1and AMPK signaling pathways in the spinal cord may be a useful approach for treating chronic pain caused by SLE.
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