Objective To observe the effect of electroacupuncture(EA)on anti-oxidant function of Leydig cells in aged rats with low testosterone

so as to reveal its underlying mechanism of anti-aging of male reproduction.Methods Eighteen 20 months old SD rats were divided into aged control

medication and EA groups(n=6 in each group)

and other6 young male SD rats(2 months of age)were used as the youth control group. The rats of the youth and the aged control groups received subcutaneous injection of 0. 9% normal saline(7 mg·kg-1·3 d-1)for 8 weeks

and those of the medication group received abdominal subcutaneous injection of Testosterone Propionate(7 mg·kg-1·3 d-1) for 8 weeks. EA(2 Hz/100 Hz

1 mA)was applied to bilateral"Shenshu"(BL23)and"Guanyuan"(CV4)for 15 min

once daily for 8 weeks except the weekends. The levels of serum total testosterone(TT)and free testosterone(FT)were determined by enzyme linked immune sorbent assay(ELISA)

the immunoactivity of phosphorylated extracellular signalregulated protein kinase(p-ERK)was detected by immunohistochemistry

and the expression levels of ERK

p-ERK

nuclear factor erythroid 2-related factor 2(Nrf2)and heme oxygenase-1(HO-1)proteins in the testis tissues were determined by Western blot.Results Before and after the treatment

the levels of serum TT and FT in the aged control group were significantly lower than those of the youth control group(P<0. 01). After the treatment

the serum TT and FT contents in the EA and medication groups were obviously higher than those in the aged control group(P<0. 01). Compared with the youth control group

the expression levels of ERK

p-ERK

Nrf2 and HO-1 proteins were significantly down-regulated in the aged control group(P<0. 01)

while in comparison with the aged control group

the expression levels of ERK

p-ERK

Nrf2 and HO-1 proteins were significantly up-regulated in the medication and EA groups(P<0. 01). The therapeutic effect of EA was notably superior to that of medication in up-regulating the immunoactivity of p-ERK

and the expression levels of ERK

p-ERK

Nrf2 and HO-1 proteins(P<0. 01). No significant differences were found between the EA and medication groups in the increased levels of serum TT and FT after the intervention(P>0. 05).Conclusion EA intervention may increase testosterone level of the aged rats

which may be related to its effects in triggering ERK/Nrf2/HO-1 signaling(anti-oxidative stress signal pathway)in the testis.