Impact of α-tocopherol on Metronidazole and Tetracycline-induced Alterations in Reproductive Activities of Male Albino Rats

Oxytetracycline effects in specific biochemical pathways of detoxification, neurotransmission and energy production in Oncorhynchus mykiss

Oxytetracycline (OTC) is a tetracycline antibiotic, widely used in human and veterinary medicines, including in aquaculture. Given this use, OTC has been detected in different aquatic environments. Some recent works have demonstrated unintentional biological activity of OTC in non-target aquatic organisms. This study investigated the acute and chronic effects of OTC on the physiology of the fish species Oncorhynchus mykiss (rainbow trout), namely through the quantification of the activity of enzymes involved in different biochemical pathways, such as detoxification (phase II - glutathione S-transferases - GSTs, uridine-diphosphate-glucuronosyltransferases - UGTs), neurotransmission (acetylcholinesterase - AChE) and energy production (lactate dehydrogenase - LDH). The here-obtained data demonstrated the induction of GSTs activity in gills, and inhibition of AChE activity in eyes tissue, in chronically exposed organisms, as well as alterations in LDH activity following both exposures. Considering this set of results, we can infer that OTC exposure may have induced the glutathione pathway of detoxification in gills with the involvement of GSTs, or indirectly due to the metabolites that may have been produced. In turn, these metabolites may have interfered with the mechanism of neurotransmission, also causing physiological and biochemical disturbances in rainbow trout after OTC exposure, namely disturbances in energetic metabolism. In addition, it is important to stress that such occurrences took place at low, environmentally realistic levels of OTC, suggesting that organisms exposed in the wild may be putative targets of toxic effects by commonly used drugs such as antibiotics.

Antifertility potentials of metronidazole in male Wistar rats

There is a growing concern about the decline in the quality of human sperm in recent years. Following reports by previous studies on the toxic effects of metronidazole on testicular functions, this study is designed to investigate further its direct effects on fertility potentials and that of the introduction of vitamin E and testosterone to metronidazole treated rats. A total of 105 adult male and 50 female Wistar rats weighing 170 +/- 10 g (70-90 day old) were used for the experiment. The rats were randomly divided into a control and experimental groups. There were four major groups with 5 subgroups consisting of 5 rats each. Varying doses of metronidazole were used depending on the experiment. Experiment 1; animals were fed with 15 mg kg(-1) of metronidazole, experiment 2, fed with 30 mg kg(-1) of metronidazole, experiment 3, administered with 200 mg kg(-1) of metronidazole and experiment 4, fed with 400 mg kg(-1) of metronidazole. Each experimental group has 5 sub-groups. A: control, B: group fed with the experimental dose, C: experimental dose with vitamin E, D: experimental dose with testosterone, E: fed with experimental dose, vitamin E and testosterone and sub-group F, a reversal group which was left for 8 weeks after cessation of treatment. Parameters assessed were sperm count/motility, hormonal assay, Fertility test for control and treated rats were also carried out. Results showed that metronidazole at the therapeutic dose of 15 mg kg(-1) did not have significant negative effect on the parameters assessed. At the dose of 200 and 400 mg kg(-1), there was reduction in testosterone and follicle stimulating hormone while on the other hand, luteinizing hormone was increased mostly with 400 mg kg(-1) of metronidazole treatment. Body weight was also found to be significantly reduced in rats treated with 200 and 400 mg kg(-1) of metronidazole. The results of this study indicate that metronidazole administration (200 or 400 mg kg(-1)), for 8 weeks, caused a harmful effect on fertility potentials in male rats.