ObjectiveTo explore the effect of spinal cord neuronal apoptosis mediated by adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (MTOR) signaling pathway in postherpetic neuralgia (PHN) induced by resiniferatoxin. MethodsThirty SD rats were randomly divided into control group, PHN group, PHN-AMPK activated group (Acadesine［AICAR］ group), with 10 rats in each group. The PHN model was established by intraperitoneal injection of resiniferatoxin in rats of the PHN group and the AICAR group. After 7-day injection of resiniferatoxin, rats in the AICAR group and the PHN group received intraperitoneal injection of AICAR and normal saline, respectively, for a 7-day continuous intervention, whereas the control group did not receive any intervention. Paw mechanical withdrawal threshold (PMWT) and paw thermal withdrawal latency (PTWL) of rats in the 3 groups were measured before 1 day of resiniferatoxin injection and after 1, 3, 5, 7, 9, 11, 13, and 15 days of injection. The L4-6 spinal cord tissues were obtained after killing rats in various groups on the next day after the end of intervention. The Western blot was used to detect phosphorylated AMPK (p-AMPK)/AMPK value, phosphorylated MTOR (p-MTOR)/MTOR value, and protein expressions of B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X protein (Bax), Caspase-3 in spinal cord tissues. The number of apoptotic cells in the spinal cord tissues was detected by the TUNEL staining method. Results(1) At various time points after 3-15 days of resiniferatoxin injection, the PHN and AICAR groups exhibited a lower PMWT, while a longer PTWL as compared with the control group (P＜0.05); furthermore, at various time points after 9-15 days of resiniferatoxin injection, the AICAR group yielded a higher PMWT, whereas a shorter PTWL as compared with the PHN group (P＜0.05). Compared with 1 day before and after resiniferatoxin injection, the PHN and AICAR groups interpreted a decreased PMWT, while a prolonged PTWL at various time points after 3-7 days of resiniferatoxin injection (P＜0.05); in addition, compared with 3-7 days after resiniferatoxin injection, the AICAR group depicted an elevated PMWT, while a shorter PTWL at various time points after 9-15 days of resiniferatoxin injection (P＜0.05). (2) Compared with the control group, the number of apoptotic cells in spinal cord tissues was increased in the PHN and AICAR groups (P＜0.05); moreover, compared with the PHN group, the AICAR group yielded decreased number of apoptotic cells in spinal cord tissues (P＜0.05). (3) Compared with the control group, p-AMPK/AMPK value was decreased, p-MTOR/MTOR value was increased, and protein expressions of Bcl-2, Bax, and Caspase-3 were elevated in spinal cord tissues of the PHN and AICAR groups (P＜0.05); in addition, compared with the PHN group, the AICAR group exhibited elevated p-AMPK/AMPK value and Bcl-2 protein expression, whereas decreased p-MTOR/MTOR value and protein expressions of Bax and Caspase-3 in spinal cord tissues (P＜0.05). ConclusionAMPK/MTOR signaling pathway may be involved in the process of neuronal apoptosis in spinal cord dorsal horn tissues of PHN rats, and activation of AMPK expression in spinal cord dorsal horn tissues may be a potential plan for the treatment of neuropathic pain.

无