Changes of expression of GABAAα₁ receptor in ventrolateral periaqueductal gray in rats with neuropathic pain

Objective To investigate the expression of GABAAα₁ in the ventrolateral periaqueductal gray (vLPAG) and its involvement in neuropathic pain (NP) in rats. Methods Fifteen male SD rats were randomly divided into three groups:control group (group C), sham operation group (group S) and neuropathic pain model group (group NP). The model of neuropathic pain was established by using spared nerve injury (SNI). The thresholds of mechanical contractions were measured at 1 day before operation and at 1, 3, 5, 7 and 14 days after operation paw withdrawal mechanical threshold (PWMT). The relative expression of GABAAα₁ receptor at vLPAG was detected by wetern blotting. Results Compared with the rats in group C, the rats in group S showed no significant changes in PWMT. The expression level of γ-aminobutyric acid A receptor α₁ in the ventrolateral periaqueductal gray of the rats in group S was (0.699±0.027), which was not significantly different from (0.636±0.023) in group C. In group NP, PWMT was (0.907±0.251) g at 1 day after operation, which was significantly lower than that of group S at (8.216±1.428) g and decreased at the later stage (P< 0.05). The relative expression of γ-aminobutyric acid A receptor α₁ in the ventrolateral periaqueductal gray of group NP was (1.442±0.015), which was significantly higher than that of group S (0.699±0.027) (P< 0.05). Conclusion The expression of GABAAα₁ in vLPAG of rats with neuropathic pain up-regulates significantly, and it is negatively correlated with PWMT, which may be related to the pathogenesis of neuropathic pain.