Objective      To study the protective effect of icariin (ICA) on

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Co-γ-induced damage of Laydig cells in rats.       Methods      Fifty male Wistar rats were randomly divided into five groups with 10 in each group including Group A (control)

Group B (radiation control)

Group C (ICA irrigation for 3 d)

Group D (ICA irrigation for 7 d)

and Group E (ICA irrigation for 15 d). The rats of Group A and Group B were irrigated with normal saline for 15 d

while those of Group C

Group D and Group E were irrigated with ICA [80 mg/(kg·d)

]

for 3

7 and 15 d before irradiation

respectively. Then the lower abdomen of rats in Group B

Group C

Group D and Group E were exposed to the uniform radiation of

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Co-γ with 8 Gy. All the animals were sacrificed 12 h later. The histological observation of the testis tissues were performed by microscopy

the levels of testosterone (T) and luteinizing hormone (LH) were determined by ELISA

and the expression of P450scc mRNA was determined by RT-PCR.       Results      Compared with Group A and Group B had a decreasing tendency for T (P0.05) and an increasing tendency for LH (

P

0.05). Group C

Group D and Group E all had increasing trends for T and decreasing trends for LH as compared with Group B

and the difference between Group B and Group E was statistically significant (

P

0.05). The expression of P450scc mRNA in Group B was significantly lower than that in Group A (

P

0.05). Compared with group B

the expression of P450scc mRNA increased in Group C

Group D and Group E

and the difference between Group B and Group E was statistically significant (

P

0.05).       Conclusion      Traditional Chinese medicine monomer of ICA has a protective effect on radiation damage of Laydig cells in rats

especially in the group of ICA irrigation for 15 d.