Hypophysectomy and/or peroxisome proliferators strongly influence the levels of phase II xenobiotic metabolizing enzymes in rat testis.

The objectives of the present work were to determine the influence of hypophysectomy and/or peroxisome proliferators (PP) on certain xenobiotic-metabolizing enzyme activities, i.e. glutathione transferases (GST), glutathione peroxidase (GPX), phenol sulphotransferases (pSULT), phenol UDP-glucuronosyl transferases (pUGT), catalase, NADP(H) quinone oxidoreductase (QR) and epoxide hydrolases (EH) in the rat testes. Adult male rats, hypophysectomized and their sham-operated controls, were treated for 10 days with clofibrate (0.5%), perfluorooctanoic acid (0.05%, PFOA), acetylsalicylic acid (1%, ASA) and di(2-ethylhexyl)phthalate (2%, DEHP) in their diet. The results show that, in addition to both body and testis weight, hypophysectomy caused dramatic changes in most of the xenobiotic-metabolizing enzyme activities, which have been measured here. The most pronounced effects were seen in cytosolic QR (2.2-fold increase), pUGT (95% reduction), pSULT (75% reduction), mitochondrial catalase (75% reduction), microsomal EH (70% reduction) and microsomal GST (55% reduction). Treatment with PP, i.e. perfluorooctanoic acid (PFOA), clofibrate, acetyl salicylic acid (ASA) and di(2-ethylhexyl)phthalate (DEHP) showed varied effects on the xenobiotic-metabolizing enzyme activities, the highest effects (10-60% reduction) were seen in sham-operated animals. These effects were not so pronounced or were not seen in hypophysectomized rats except for the case of PFOA treatment, which caused increases of enzyme activities. The highest increases were seen with microsomal GST (70%), GPX (75%) and cytosolic EH (75%). It is concluded from these experiments that the regulation of several xenobiotic-metabolizing enzymes in the rat testis is affected by the pituitary and/or pituitary hormones and that different peroxisome proliferators have variable effects on the levels of these xenobiotic-metabolizing enzymes. The general trend of reduction in enzyme activities implies that the testis is less protected under conditions that can perturb hormonal status.

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