[Impact of acupuncture on NP-1 expression in spared dorsal root ganglion]

To investigate the impact of acupuncture on NP-1 expression in spared dorsal root ganglion (DRG).

Twenty-five male adult cats were divided into five groups. The five cats in the pseudo-operation group were kept intact. Ten cats were subjected to unilateral root rhizotomy(unilateral L1-L5 DRGs were transected, but L6 DRG was spared), with five sacrificed seven days later and another five sacrificed 14 days later. Ten cats with unilateral root rhizotomy received acupuncture (electron-needle stimulation in Zusanli, Xuanzhong, Futu and Sanyinjiao which are located in the distribution area of L6 spinal nerve) for 30 minutes per day. Five cats in the acupuncture group were sacrificed seven days and 14 days later respectively. The L6 DRG from the experimental side of each animal was taken and made into frozen sections 20 microm in thickness. The sections were stained under the same conditions using NP-1 specific antibody (1:600, Santa) by immunohistochemistry ABC method. The amounts of NP-1 immunoreaction neurons of DRG were measured.

The NP-1 immunoreactants were mainly located in the small and medium-sized neurons and a few large sized neurons in the cats of the pseudo-operation group. Less NP-1 positive medium-small sized neurons were found seven days after partial dorsal root rhizotomy (P<0.05). But they returned back to the original level 14 days after operation. The NP-1 positive large neurons had no significant changes after operations. With seven days of acupuncture, the amounts of NP-1 positive small and medium-sized neurons increased significantly (P<0.05) but were still less than the original level (P<0.05). There were no differences in neurons 14 days after operations between the acupuncture and non-acupuncture group (P>0.05) and between the groups with seven days acupuncture and 14 days of acupuncture (P>0.05).

Acupuncture increases the expression of NP-1 in small and medium-sized neurons of spared DRG.