OBJECTIVETo observe the effects of CMTM2 on cyclophosphamide (CP)-induced reproductive toxicity and the expression of steroidogenic acute regulatory (StAR) protein in the transgenic mouse model.

METHODSTwenty CMTM2 transgenic mice were equally divided into a CMTM2 + CP and a CMTM2 + NS group, the former intraperitoneally injected with CP at 50 mg per kg per d, while the latter with the equivalent dose of normal saline, both for 7 days. Another 20 wild C57BL/6J mice were randomly assigned to a WT + CP and a WT + NS group, treated the same way above. After 30 days, all the mice were sacrificed and their epididymides and testes removed for measurement of the serum testosterone level by radioimmunoassay, determination of sperm concentration and motility by light microscopy and detection of the expression of StAR by Western blot.

RESULTSThe levels of serum testosterone, sperm concentration and sperm motility were significantly decreased in the CMTM2 + CP group as compared with the CMTM2 + NS group ([42.98 +/- 3.25] nmol/L vs [46.74 +/- 3.38] nmol/L, [16.89 +/- 1.17 ] x 10(6)/ml vs [24.68 +/- 0.95 ] x 10(6)/ml, [72.75 +/- 1.25]% vs [85.14 +/- 1.12]%, P < 0.05), but remarkably less than in the WT + CP group ([37.97 +/- 4.17] nmol/L, [12.75 +/- 1.02] x 10(6)/ml, [50.52 +/- 1.37] %) (P < 0.05). However, the expression of StAR was significantly higher in the CMTM2 + CP than in the WT + CP group (1.16 +/- 0.07 vs 0.69 +/- 0.08, P < 0.05).

CONCLUSIONCMTM2 antagonizes cyclophosphamide-induced reproductive toxicity via regulating the expression of StAR, and hence plays a protective role in the reproductive system.