CELLULAR DISTRIBUTION OF CHEMOKINE SYSTEM CX3CL1/CX3CR1 IN THE PERIAQUEDUCTAL GREY OF EXPERIMENTAL MODEL OF OROFACIAL NEUROPATHIC PAIN
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| Year of publication | 2023 |
| Type | Appeared in Conference without Proceedings |
| Citation | |
| Description | Trigeminal neuropathic pain (TNP) is one of the most debilitating chronic neuropathic disorders resulting from injury of the trigeminal nerve. The ventrolateral (vlPAG) and dorsolateral (dlPAG) compartments play different roles in trigeminal nociceptive modulation. There is limited knowledge of the cellular distribution and changes of the CX3CL1/CX3CR1 signaling axis in vlPAG compared to dlPAG following the trigeminal nerve injury. We investigated the cellular distribution of CX3CL1 and CX3CR1 in vlPAG of TNP induced by unilateral ligature of the infraorbital nerve (IONL). The naive, sham- and IONL-operated rats survived for 1, 3, 7, and 14 days (n=6 for each group) and were used for immunofluorescence staining. The rats were perfused with Zamboni solution and brainstems were dissected. Cryostat sections (12µm) were immunostained to explore the immunodetection of CX3CL1 and CX3CR1. Double immunostaining with NeuN, OX42, and GFAP was used for cellular distribution in neurons, activated microglia, and reactive astrocytes, respectively. Robust astrocyte reactivation and microgliosis were observed in vlPAG than dlPAG after IONL. CX3CL1 immunofluorescence (IF) was found in the neurons and reactive astrocytes predominantly in vlPAG compared to dlPAG up to 3 days after the IONL, but then the levels were decreased in reactive astrocytes at 7 and 14 days. CX3CR1-IF was progressively increased in the vlPAG neurons with the time of IONL survival. Activated microglia and reactive astrocytes in vlPAG displayed always CX3CR1-IF through all periods, but levels slowly decrease in later periods. The changes in the cellular distribution of the CX3CL1/CX3CR1 were observed predominantly in vlPAG compared to dPAG after sham- and IONL operation. Our results suggested that CX3CL1/CX3CR1 chemokine signaling axis in PAG contains activated microglia, reactive astrocytes, and also neurons in reaction to both sham- and IONL operation. |
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