Toxicity of Methyl tert-butyl ether (MTBE) on the male reproductive system under cold conditions

The problem of the common effects of pollutants and low temperatures on the organism remains current. The purpose of our vivisection was to compare the toxic effect of methyl tert-butyl ether (MTBE) on the reproductive system of the laboratory animals exposed directly to MTBE. Therefore this experiment was arranged under two thermal conditions: thermal comfort (25 ± 2 °C) or cold (cold stress) (4 ± 2 °C). This subacute toxicity experiments were performed on 24 sexually mature male WAG rats. To each test group (2 × 6 rats) MTBE was administered 30 times in the stomach at a dose of 500 mg / kg of animal weight. This application to the fasting animals was carried out by a special metal tube as a water solution. Under the same test conditions the 12 animals in the two control groups were instilled with an equivalent amount of distilled water. Thereafter, for 4 hours in each case one group was exposed to thermal comfort and the other to cold stress. After the thirty-day recovery period — measured from the last instillation of MTBE or aquadest — the experiments were repeated in order to answer the question of reversibility. The MTBE-effect under cold does not result in a modification of the total number of spermatozoa contained in the testis. In contrast the individual effect of MTBE causes a reduction of the total compared to the control group: 28,8 ± 4,66 vs. 76,83 ± 6,09. Furthermore, both test groups showed a statistically safe spermatozoa motility time reduction compared to the two control groups. The results show that the gonad-toxical effect of the MTBE was confirmed both under the conditions of thermal comfort and the stressor cold. Male gonads can be considered the target for toxic effects of MTBE. Besides, under cold conditions the MTBE causes more considerable impairment of the spermatozoa function. Furthermore, the effects of reversibility were very low. Thus, combining the effects of MTBE and cold causes significant effects and shifts outside the physiological area, such as sperm motility time, number of their dead and pathological forms. In summary, under cold conditions the MTBE exposure shows an exhaustion of compensation capabilities and the beginning of decompensation period.