Relationship between hydrogen sulfide and P2X3 receptors in dorsal root ganglion of rats with neuropathic pain

Objective To evaluate the relationship between hydrogen sulfide (H2S) and P2X3 receptors in dorsal root ganglions (DRGs) of rats with neuropathic pain (NP). Methods Thirty-six healthy male Sprague-Dawley rats, aged 4-6 weeks, weighing 180-200 g, in which IT catheters were successfully implanted, were divided into 3 groups (n=12 each) using a random number table method: sham operation group (group S), group NP and endogenous H2S synthase(cystathionine beta-syntheses[CBS])inhibitor animooxyacetic acid(AOAA)group (group A). NP was induced by chronic constriction injury (CCI) to the sciatic nerve at 3 days after IT catheters were successfully implanted.AOAA (10 μg/kg) 10 μl and normal saline 10 μl were intrathecally injected once a day for 14 consecutive days starting from 1 day after CCI in group A, and normal saline 20 μl was intrathecally injected instead in S and NP groups.At 1 day before CCI and 1, 3, 7, 10 and 14 days after CCI, the thermal paw withdrawal latency (TWL) and mechanical paw withdrawal threshold (MWT) were measured at 30 min after intrathecal injection.The animals were sacrificed at 7 and 14 days after CCI, and ipsilateral DRGs of the lumbar segment (L4-6) were removed for detection of the expression of CBS and P2X3 receptors by Western blot. Results Compared with group S, the TWL was significantly shortened, MWT was decreased, and the expression of CBS and P2X3 receptors in DRGs was up-regulated at each time point after CCI in group NP (P<0.05). Compared with group NP, the TWL was significantly prolonged, the MWT was increased, and the expression of CBS and P2X3 receptors in DRGs was down-regulated at each time point after CCI in group A (P<0.05). Conclusion H2S in DRGs can up-regulate the expression of P2X3 receptors, which may be involved in the pathophysiological mechanism of NP in rats. Key words: Neuralgia; Ganglia, spinal; Receptors, purinergic P3; Hydrogen sulfide