ABDOMINAL POSITION OF THE RAT TESTIS IS ASSOCIATED WITH HIGH-LEVEL OFLIPID-PEROXIDATION

Experimental cryptorchidism in the adult rat induces lipid peroxidatio n as a sign of oxidative stress, To further elucidate the role of free radicals and antioxidant enzymes in the degeneration of testis in cry ptorchidism, we first studied testes of untreated rats before and afte r the normal testicular descent, In the second experiment, primary uni lateral cryptorchidism was induced by surgically attaching one testis of each rat to the abdomen before testicular descent. The level of lip id peroxidation was detected by formation of fluorescent chromolipids and diene conjugates. At the age of testicular descent (18-21 days), t he level of fluorescent chromolipids dropped to one third (p < 0.05). Correspondingly, the level of diene conjugates was 69% (p < 0.05) high er at 18 than at 30 days of age. The antioxidant enzyme activities did not change at the time of testicular descent. Primary unilateral cryp torchidism was induced at the age of 13 days. At 25 or 35 days of age, the level of diene conjugates was higher in the cryptorchid testes th an in the contralateral scrotal testes (+39%, p < 0.01, and +51%, p < 0.001, respectively). In the abdominal testes, the mRNA of CuZn supero xide dismutase (SOD) was increased by 69% (p < 0.05) at 25 days, where as by 35 days of age enzymatic CuZn SOD activity was slightly decrease d and catalase activity increased, The present results show that the a bdominal position of the testis, either before normal testicular desce nt or in experimental cryptorchidism, is associated with a high level of lipid peroxidation. The data provide evidence that increased produc tion of reactive oxygen species could contribute to degeneration of th e cryptorchid testis. The oxidative stress in the cryptorchid testis i s not explained by inactivation of antioxidant enzymes.