Abstract: AIM: To study the inhibitory effects of domestic leuprolide acetate microsphere (LE-ms)on the growth of explanted endometrium in the rat models of EMT and its possible mechanisms.METHODS: The 60 rats models of EMT were induced surgically by the Jones method.Then the animals were treated with LE (20μg·^-1 ·d^-1, 28 d, sc), enanton(20 μg·^-1·d^-1, sc)and domestic LE-ms (2, 20, and 200 μg㎏^-1 ·d^-1, sc), respectively;another 30 rats were divided into sham group(N.S, 1 ml·kg^-1·d^-1, 21 d, sc), EMT + LE group(100 μg·kg^-1·d^-1, 21 d, sc)and EMT group(N.S, 1ml·kg^-1·d^-1, 21 d, sc).At the same time, estrous cycle was monitored daily by examination of vaginal cytologic smears.After 3 weeks, blood was drawn and the serum estradiol concentration was assayed.The volume of endometrial implant was assessed.Lateral uterus, bilateral ovary, thymus and spleen were weighed.The NK cell cytotoxicity in the spleen was evaluated with lactate dehydrogenase (LDH)release assay.RESULTS: Implants in control group continued to grow, while those in groups treated with the drugs showed remarkable atrophy.The inhibitory rates were 87.2 %, 78.3 %, 57.3 %, 89.0 % and 94.7 %, respectively.The regular estrous cycle of the model rats was abolished and serum estradiol reduced(P<0.05);the lateral uterine weight was reduced significantly(P<0.001);the thymus weight was increased(P<0.05);the spleen weight did not change significantly(P>0.05);and the NK cells activity was enhanced(P<0.05).CONCLUSION: Ectopic endometrium can be inhibited significantly with the treatment of domestic leuprolide microsphere, and its mechanism may be related to reduce estrogen level, which is important for both the growth of the ectopic endometrium and the enhancement of immune function.

Key words: leuprorelide, microspheres, endometriosis, estrogen, NK cells, rats