A total of 200 SPF male SD rats were randomly divided into control group and low， middle， and high doses of cigarette exposure groups （given 10， 20， and 30 cigarettes per rat per day）. The rats were anesthetized at 2rd， 4th， 6th， 8th， and 12th weeks， respectively. The plasma inhibin B levels of the rats in various groups were detected， the expression levels of miR-138-5p in testicular tissue of the rats in various groups were detected by real-time fluorescence quantitative PCR（RT-qPCR） method， and the expression levels of vimentin in testicular TM4 cells of the rats in various groups were detected by immunohistochemistry. The testicular TM4 cells （control group） were cultured in vitro. The cigarette smoke extract （CSE） stock solution was diluted to 5% and 10% and to treat the TM4 cells，and used as 5% CSE group and 10% CSE group. The survival rates of the testicular TM4 cells and lactate dehydrogenase （LDH） activities in the testicular TM4 cells in various groups were detected by MTT method， and the apoptotic rates of the cells in various groups were detected by flow cytometry and TUNEL method. After transfected with miR-138-5p plasmid，the testicular TM4 cells were divided into control group， 5% CSE group， 5% CSE+Pri-mirna-138-5p Ctrl group， 5% CSE+Pri-mirna-138-5p group， 10% CSE group， 10% CSE+Pri-mirna-138-5p Ctrl group， and 10% CSE+Pri-mirna-138-5p group. The survival rates of the cells， LDH activities in the cells and apoptotic rates of the cells in various groups were detected by the above methods.

Compared with control group， the plasma inhibin B levels of the rats in different doses of cigarette exposure groups were decreased； compared with control group， the plasma inhibin levels of the rats in high dose of cigarette exposure group at the 8 weeks and in middle and high doses of cigarette expasure groups at the 12 th week were decreased （P<0.05）. The light microscope detection results showed that the cytoplasm of the testicular cells in control group showed positive yellow staining， and the expression levels of vimentin in the testicular TM4 cells of the rats in cigarette exposure groups were decreased gradually； compared with control group， the expression levels of vimentin in testicular TM4 cells of the rats in high dose of cigarette exposure group at different time points were decreased （P<0.05）. Compared with control group， the expression levels of miR-138-5p in testicular tissue of the rats in middle and high doses of cigarette exposure groups at the 8 th week and in different doses of cigarette exposure groups at the 12th week were decreased （P<0.05）. The survival rates of the cells in 5% CSE group and 10% CSE group were significantly lower than that in control group （P<0.01）. Compared with control group， the activities of LDH in testicular TM4 cells of the rats in 5% CSE group and 10% CSE group were decreased （P<0.05 or P<0.01）. After over-expression of miR-138-5p， compared with control group， the proliferation rates of testicular TM4 cells in 5% CSE group， 5% CSE+Pri-mirna-138-5p Ctrl group， 5% CSE+Pri-mirna-138-5p group， 10% CSE group， 10% CSE+Pri-mirna-138-5p Ctrl group，and 10% CSE+Pri-mirna-138-5p group were decreased（P<0.05 or P<0.01）； compared with 5% CSE group， the proliferation rate of testicular TM4 cells in 5% CSE+Pri-mirna-138-5p group was increased （P<0.05 or P<0.01）， and the apoptotic rate was decreased （P<0.05 or P<0.01）； compared with 10% CSE group， the proliferation rate of testicular TM4 cells in 10% CSE+Pri-mirna-138-5p group was increased （P<0.05 or P<0.01）， and the apoptotic rate was decreased （P<0.05）.

Long-term exposure to heavy cigarette smoking can induce the irreversible damage of testicular sertoli cells， and miR-138-5p plays an important protective role in the process.