Objective To observe the effect of electroacupuncture(EA) on physical strength and expression levels of hepatic AMP-activated protein kinase(AMPK)

mammalian target of rapamycin(mTOR)

unc-51 like autophagy activating kinase 1(ULK1) proteins and Atg5

Atg7

Atg13

Beclin1 and ULK1 mRNAs in aging(senescence accelerated mouse/prone 8

SAMP8)mice

so as to explore its mechanism underlying delaying aging by activating AMPK/mTOR/ULK1 signaling pathway. Methods Twenty-four male SAMP8 mice were randomly divided into model group

rapamycin(autophagy inducer) group

EA group and EA+autophagy inhibitor(EA+inhibitor) group

with 6 mice in each group

and 6 homologous anti-rapid aging male(SAMR1) mice in the same age were used as the control group. Mice of the rapamycin group received intraperitoneal injection of rapamycin solution(2 mg·kg

(-1)

·d(-1)·d

(-1)

). EA(2 Hz

1 mA) was applied to bilateral “Taichong”(LR3)and “Shenshu”(BL23) for 15 min each time. Mice of the EA+inhibitor group received intraperitoneal injection of mTOR inhibitor 3-methyladenine(1.5 mg·kg(-1)). EA(2 Hz

1 mA) was applied to bilateral “Taichong”(LR3)and “Shenshu”(BL23) for 15 min each time. Mice of the EA+inhibitor group received intraperitoneal injection of mTOR inhibitor 3-methyladenine(1.5 mg·kg

(-1)

·d(-1)·d

(-1)

) before the EA intervention each time. The above-mentioned interventions were conducted 6 times a week for 2 consecutive weeks. Physical conditions of mice were assessed by exhaustive swimming tests. Histopathological changes of the liver were observed by H.E. staining. Western blot was used to detect the expression of AMPK

phosphorylated AMPK(p-AMPK)

mTOR

phosphorylated mTOR(p-mTOR)

ULK1 and phosphorylated ULK1(p-ULk1) in the liver tissues. The expression levels of Atg5

Atg7

Atg13

Beclin1 and ULK1(cellular autophagy-related genes) mRNAs in the liver were detected by quantitative real-time PCR. The immunoactivity(IA) of heme oxygenase 1(HO-1) in the liver was detected by immunohistochemistry

and the activity of superoxide dismutase(SOD) and the content of malondialdehyde(MDA) of the liver were measured by hydroxylamine method for assessing the level of oxidative stress. Results Compared with the control group

the duration of exhaustive swimming

the expression levels of AMPK

p-AMPK

ULK1 and p-ULK1 proteins

and Atg5

Atg7

Atg13

Beclin1 and ULK1 mRNA

HO-1 IA and SOD activity were considerably down-regulated(P

<

0.01)

while the expression levels of mTOR and p-mTOR and MDA content were significantly up-regulated(P

<

0.01) in the model group. In comparison with the model group

the duration of the exhausted swimming

the expression levels of AMPK

p-AMPK

ULK1 and p-ULK1 proteins

and Atg5

Atg7

Atg13

Beclin1 and ULK1 mRNAs

HO-1 IA and SOD activity were significantly up-regulated(P

<

0.01

P

<

0.05)

whereas the expression levels of mTOR and p-mTOR proteins and MDA content were notably down-regulated(P

<

0.01

P

<

0.05) in the rapamycin

EA and EA+inhibitor groups. The improvement of the abovementioned indexes of EA+inhibitor group was not as good as rapamycin and EA groups(P

<

0.01)

suggesting an elimination of the therapeutic effects after administration of 3-methyladenine. No significant differences were found between the rapamycin and EA groups in the abovementioned indexes(P

>

0.05) except p-mTOR and mTOR which were higher in the EA group(P

<

0.01). H.E. staining showed ambiguous boundary of the liver lobule

disordered arrangement of hepatocytes with a large amount of fat vacuoles at different size and deviation of nucleus

and lysis of some hepatocytes. These situations were relatively milder in the rapamycin and EA groups. Conclusion EA may enhance physical strength and promote cellular autophagy in the liver of aging mice by regulating AMPK/mTOR/ULK1 signaling

thereby inhibiting excessive oxidative stress

and delaying aging process to some extent.