Ethylene glycol monomethyl ether-induced testicular oxidative stress and time-dependent up-regulation of apoptotic, pro-inflammatory, and oncogenic markers in rats

Abstract

Ethylene glycol monomethyl ether (EGME) is a major component of paints, lacquers, inks, and automobile brake fluids. As a result, exposures to humans are inevitable. We therefore, investigated in this study, its effect on testicular cells in a time-course manner in male Wistar rats. Animals were orally administered 50 mg/kg body weight of EGME for duration of 7, 14, and 21 days. Following 7 days of the administration, levels of NO and GSH were significantly reduced, while levels of c-Myc, K-Ras, caspase-3, IL-6, TNF-α, and IL-1β were significantly increased compared with control. At the end of 14 days exposure, GPx, and SOD activities, as well as IL-10 level were significantly decreased, while levels of c-Myc, K-Ras, p53, Bax, caspase-3, IL-6, TNF-α, IL-1β, and GST activity were significantly elevated compared with control. After 21 days of EGME administration, Bcl-2, IL-10, and NO levels were significantly decreased, while levels of c-Myc, K-Ras, p53, Bax, caspase-3, IL-6, TNF-α, IL-1β, MDA and GST activity were significantly increased compared with control. After 7, 14, and 21 days of EGME administrations, testis histopathology showed severe loss of seminiferous tubules, the seminiferous epithelium revealed very few spermatocytes, spermatids, spermatogonia, spermatozoa, and Sertoli cells, while the interstitial tissue is eroded, with scanty abnormal Leydig cells, compared with the control that appeared normal. We therefore, concluded that EGME-induced testicular toxicity as a result of EGME administration could be via the disorganization of the endogenous antioxidant systems as well as up-regulation of pro-inflammatory, apoptotic and oncogenic mediators in rats.

Keywords: Apoptosis; Bax, Bcl-2 associated X; Bcl-2, B-cell lymphoma 2; CAT, catalase; Ethylene glycol monomethyl ether; GPx, glutathione peroxidase; GSH, reduced glutathione; GST, glutathione S-transferase; Histopathology; IL-1β, interleukin-1 beta; IL-6, interleukin-6; Inflammation; K-Ras, Kirsten rat sarcoma viral oncogene; MDA, malondialdehyde; NO, nitric oxide; Oncogenes; Oxidative stress; SOD, superoxide dismutase; TNF-α, tumor necrosis factor alpha; Testis; c-Myc, myelocytomatosis; p53, tumor suppressor protein.

Fig. 1

Time course effect of EGME on relative testes weight. Results are written as mean ± standard error of the mean (n = 5). Bars containing different labels are significant statistically (p < 0.05).

Fig. 2

Time course effect of EGME on testis MDA (2A), NO (2B), and GSH (2C) concentrations. Results are written as mean ± standard error of the mean (n = 5). Bars containing different labels are significant statistically (p < 0.05).

Fig. 3

Time course effect of EGME on testis GPx (3A), GST (3B), SOD (3C), and CAT (3D) activities. Results are written as mean ± standard error of the mean (n = 5). Bars containing different labels are significant statistically (p < 0.05).

Fig. 4

Time course effect of EGME on testis TNF-α (4A), IL-1β (4B), IL-6 (4C), and IL-10 (4D) levels. Results are written as mean ± standard error of the mean. Bars containing different labels are significant statistically (p < 0.05).

Fig. 5

Time course effect of EGME on testis p53 (5A), Bax (5B), Bcl-2 (5C) and caspase-3 (5D) levels. Results are written as mean ± standard error of the mean. Bars containing different labels are significant statistically (p < 0.05).

Fig. 6

Time course effect of EGME on testis c-myc (6A) and K-Ras (6B) levels. Results are written as mean ± standard error of the mean. Bars containing different labels are significant statistically (p < 0.05).

Fig. 7

Testis microphotographs (x 100) showing (A) normal architecture; (B) mild loss of seminiferous tubules, the seminiferous epithelium consisting of few spermatogonia, spermatocytes, spermatids, spermatozoa and Sertoli cells; (C) loss of seminiferous tubules, the seminiferous epithelium consisting of spermatogonia, spermatocytes, and spermatids. There is a loss of spermatozoa and Sertoli cells, and a disrupted interstitial tissue with few Leydig cells; and (D) severe loss of seminiferous tubules, the seminiferous epithelium consisting of very few spermatogonia, spermatocytes, spermatids, spermatozoa, and Sertoli cells, while the interstitial tissue are eroded, having scanty abnormal Leydig cells. A = Day 0; B = Day 7; C = Day 14; D = Day 21.