Objective: To explore the protective effect and possible mechanism of electroacupuncture (EA) pretreatment at "Zhongliao" (BL 33) and "Tianshu" (ST 25) on ovarian in rats with premature ovarian insufficiency (POI).
Methods: A total of 32 SD female rats with regular estrus were randomly divided into a blank group, a model group, an EA group and an immobilization group, 8 rats in each one. The rats in the model group, EA group and immobilization group were treated with intraperitoneal injection of 4-vinylcyclohexene diepoxide (160 mg/kg) for 15 days to establish the model. From the beginning of model establishment, the rats in the EA group were treated with EA pretreatment at "Zhongliao" (BL 33) and "Tianshu" (ST 25), once a day for the first two weeks (5 treatments per week) and once every two days for the last two weeks (3 treatments per week). EA was given 20 min per treatment for four weeks. The rats in the immobilization group were treated with immobilization with identical duration, frequency and total amount as the EA group. No treatment was given in the blank group and model group. When model was successfully established in the model group, rats were sacrificed to test the weight of sexual gland and the sexual gland index; the ELISA method was applied to test the level of anti-müllerian hormone (AMH) and inhibin B; the radioimmunoassay method was applied to test the level of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), progesterone (P) and testosterone (T). In addition, the morphology and the number of ovarian follicles were observed; and western blot method was applied to test the expression of B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax) in ovarian tissue.
Results: Compared with the blank group, the bilateral ovary weight, ovary index, uterus weight and uterus index decreased (P<0.05, P<0.01); serum AMH, inhibin B, E2 and P reduced, while serum FSH, LH and T increased in the model group (all P<0.01); primordial follicles and primary follicles decreased, while atretic follicles increased in the model group (all P<0.01); the expression of Bax protein increased, while the expression of Bcl-2 protein decreased in the model group (both P<0.01). Compared with the model group, the bilateral ovary weight, ovary index and uterus weight increased (P<0.05, P<0.01); serum AMH, inhibin B, E2 and P increased, while serum FSH and LH reduced (P<0.05, P<0.01); primordial follicles and primary follicles increased, while atretic follicles reduced (P<0.05, P<0.01); the expression of Bax protein reduced, while the expression of Bcl-2 protein increased in the EA group (P<0.05, P<0.01). The differences of each outcome indexes were not significant between the model group and immobilization group (all P>0.05).
Conclusion: EA pretreatment at "Zhongliao" (BL 33) and Tianshu (ST 25) for 4 weeks has certain protective effect on ovarian in POI rats, which is likely to be related with up-regulating ovarian granular cells, inhabiting the expression of Bcl-2 protein and down-regulating the expression of Bax protein.
Keywords: Point BL 33 (Zhongliao); Point ST 25 (Tianshu); electroacupuncture (EA); ovarian protection; premature ovarian insufficiency (POI); sex hormone.