Objective:To observe the effects of electroacupuncture (EA) at different time on somatostatin (SOM)mRNA expression in the spinal ganglia and spinal cord in rats. Methods: A total of 40 SD rats were evenly randomized into EA and control groups which were further divided into 23-o'clock (Zi Shi)

5-o'clock (Mao Shi)

11-o'clock (Wu Shi) and 17-o'clock (You Shi) subgroups respectively

with 5 cases being in each subgroup. EA (3 V

2 Hz

wave width 1 ms) was applied to unilateral “Huantiao”(GB 30) for 30 min. After acupuncture

these rats anesthetized with urethane were infused with 1% paraformaldehyde

1.25% glutaraldehyde plus 0.1 mol/L HCl buffer solution. Then

L_5 segment of the spinal cord and dorsal root ganglia were taken out to be cut into sections (25 μm). SOMmRNA expression was detected by using in situ hybridization method. Results: After EA of “Huantiao”(GB 30)

the number of the densely-stained SOMmRNA positive neurons in the spinal ganglia and laminaⅠandⅡ of the posterior horn of the spinal cord increased markedly at 11-o'clock compared with that of control group at the same time course (P<0.05)

but no significant differences were found between two groups at the other time courses. Conclusion: After EA

the expression of SOMmRNA positive neurons in the spinal ganglia and spinal cord is upregulated at 11.00 in rats.