[Effect of herbal cake-separated moxibustion on behavioral stress reactions and blood lactic acid level and muscular AMPK/PGC-1α signaling in rats with chronic fatigue syndrome].

OBJECTIVE: To observe the effect of herbal cake-separated moxibustion (HCSM) on serum lactic acid (BLA) level and AMPK/PGC-1α signaling pathway in the quadriceps femoris in chronic fatigue syndrome (CFS) rats, so as to explore its mechanisms underlying improvement of CFS.

METHODS: According to the random number table, 50 SD rats were divided into blank control, model, HCSM, sham HCSM and medication (herbal medicine gavage) groups, with 10 rats in each group. The CFS model was established by using chronic restraint and exhaustive swimming, alternately, once daily for 21 days. The herbal cake was made of Xiaoyao Powder (Mental Ease Powder, composed of [Danggui ( Radix Angelicae Sinensis ), Baishao ( Radix Paeoniae Alba ), Chaihu ( Radix Bupleuri ), Fuling ( Poria ), Baizhu ( Rhizoma Atractylodis, Macrocephalae ), etc.]. The HCSM was applied to "Shenque" (CV8), "Guanyuan "(CV4), bilateral "Zusanli" (ST36) and "Qimen" (LR14), 5 moxa-cones for each acupoint, once daily for 10 days. For sham HCSM, the excipient was instead of herbal cake, and the same 5 moxa-cones was given as the HCSM group. Rats of the medication group received gavage of Xiaoyao Powder suspension (60 mg·kg-1 ), once daily for 10 days. The open field test and tail suspension test were conducted for determining the animals' locomotor activity. The blood sample was taken from the abdominal aorta under anesthesia for assaying the levels of serum BLA, chemokine ligand CXCL9 and β-endorphin (EP) by ELISA. Bilateral quadriceps femoris were sampled for observing histopathological changes after staining with conventional H.E. technique, and for detecting the expression levels of phosphorylated AMP-activated protein kinase (p-AMPK) and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) by using immunohistochemistry.

RESULTS: Compared with the blank control group, the number of rearing and horizontal grid-crossing times, struggling times of tail suspension test were significantly decreased ( P <0.05), and the immobility time was obviously prolonged ( P <0.05) in the model group. Compared with the model group, both HCSM and medication groups had a significant increase of rearing, horizontal grid-crossing times and struggling times ( P <0.05), and the immobility time had a significant decrease ( P <0.05). But there were no significant differences in the total movement distance among the 5 groups ( P >0.05), and in the 5 indexes of behavioral measurements between the HCSM and medication groups ( P >0.05). The sham HCSM could also evidently increase the struggling times and reduce the immobility time ( P <0.05). The contents of serum BLA, CXCL9 and β-EP were obviously higher in the model group than in the blank control group ( P <0.05), as well as remarkably lower in the HCSM and medication groups than in the model group ( P <0.05). Whereas the expression levels of muscular p-AMPK and PGC-1α were considerably lower in the model group than in the blank control group ( P <0.05), and significantly increased in both HCSM and medication groups relevant to the model group ( P <0.05). Compared with the sham HCSM group, the contents of BLA, CXCL9 and β-EP in serum of the HCSM group and contents of CXCL9, β-EP in medication group were significantly decreased ( P <0.05), and the protein expressions of p-AMPK and PGC-1α in quadriceps femoris in both HCSM and medication groups were significantly increased ( P <0.05). H.E. staining showed smaller intercellular space, uneven cytoplasmic staining in some muscle fibers, nucleus pyknosis and condensation, and inflammatory cell infiltration in the model group, which was milder in both HCSM and medication groups.

CONCLUSION: HCSM can mitigate the stress behavioral state in CFS rats, which may be related with its functions in lowering the levels of serum BLA, CXCL9 and β-EP, and activating AMPK/PGC-1α signaling pathway (balancing energy metabolism) in the quadriceps femoris.