Reproductive Hormones Imbalance, Germ Cell Apoptosis, Abnormal Sperm Morphophenotypes and Ultrastructural Changes in Testis of African Giant Rats (Cricetomys gambianus, Waterhouse, 1840) Exposed to Sodium Metavanadate Intoxication

Environmental exposure to vanadium has been on the increase in recent time. This metal is a known toxicant. The current study was conducted to investigate the reproductive toxicity of sodium metavanadate (SMV) in male African giant rats. Administration of SMV was done intraperitoneally daily for 14 consecutive days at a dosage of 3mg/kg body weight. Sterile water was administered to the control group. We analyzed serum reproductive hormones, sperm reserve and quality as well as testicular ultrastructural changes following SMV treatment. Our results showed SMV exposed AGR group had statistically increased progesterone but decreased testosterone, FSH and LH concentrations. Also, SMV treated group had statistically decreased sperm motility and mass activity with increased percentage of abnormal morphophenotypes of spermatozoa and upregulation of P53 immunopositive cell. Ultrastructural study revealed vocuolation of germ and Sertoli cells, cytoplasmic and nucleus; and mitochondrial swelling and vacuolations were also observed. There was severe disintegration of the seminiferous tubules, atrophy and degeneration of myeloid cells and apoptosis of the Leydig, Sertoli and germ cells. In conclusion, intraperitoneal SMV exposure exerts severe adverse effects on some serum reproductive hormones, reduction of sperm reserve and quality, apoptosis and degenerative changes of the Leydig, Sertoli and germ cells which can lead to infertility.

Effects of sodium metavanadate on the electrical stimulation of sciatic nerve of toads (Bufo regularis)

Introduction: Vanadium and its compounds have been documented to exert toxic effects on almost all systems in living organisms including cardiovascular, reproductive and nervous systems. In the nervous system however, toxicity assays have been on the brain and its structures with little information on its effects on peripheral nerves. This study was therefore conducted to examine the toxicity of vanadium in the peripheral nervous system. Methods: Vanadium as sodium metavanadate was used in the study. Fifteen toads (Bufo regularis) were randomly distributed into 3 groups (A-C); A served as control and was administered distilled water during the experiment, B were intraperitoneally (i.p.) administered with sodium metavanadate at 3 mg/kg while C were administered with sodium metavanadate at 5 mg/kg i.p. for 7 consecutive days. Nerve conduction was studied in isolated toad sciatic nerve-gastrocnemius muscle preparation following electrical stimulation. The recordings were obtained on a kymograph for each group. Results: The results showed significant (p<0.05) reduction in the peak amplitude of the action potential and an increase in the latency of the onset of the action potential at 5 mg/kg sodium metavanadate. Furthermore, an increased threshold stimulus voltage was also observed in group administered with 5 mg/kg sodium metavanadate. The values of these parameters in the 3 mg/kg sodium metavanadate group were not statistically different from the control group. Significance: The findings of this preliminary study suggest that vanadium at 5 mg/kg may result in decrease speed of impulse conduction which may be as a result of demyelination in the sciatic nerve.