Effects Of Ethylene Glycol Monomethyl Ether Research Articles

Effects of ethylene glycol monomethyl ether and its metabolite, 2-methoxyacetic acid, on organogenesis stage mouse limbs in vitro.

Exposure to ethylene glycol monomethyl ether (EGME), a glycol ether compound found in numerous industrial products, or to its active metabolite, 2-methoxyacetic acid (2-MAA), increases the incidence of developmental defects. Using an in vitro limb bud culture system, we tested the hypothesis that the effects of EGME on limb development are mediated by 2-MAA-induced alterations in acetylation programming. Murine gestation day 12 embryonic forelimbs were exposed to 3, 10, or 30 mM EGME or 2-MAA in culture for 6 days to examine effects on limb morphology; limbs were cultured for 1 to 24 hr to monitor effects on the acetylation of histones (H3K9 and H4K12), a nonhistone protein, p53 (p53K379), and markers for cell cycle arrest (p21) and apoptosis (cleaved caspase-3). EGME had little effect on limb morphology and no significant effects on the acetylation of histones or p53 or on biomarkers for cell cycle arrest or apoptosis. In contrast, 2-MAA exposure resulted in a significant concentration-dependent increase in limb abnormalities. 2-MAA induced the hyperacetylation of histones H3K9Ac and H4K12Ac at all concentrations tested (3, 10, and 30 mM). Exposure to 10 or 30 mM 2-MAA significantly increased acetylation of p53 at K379, p21 expression, and caspase-3 cleavage. Thus, 2-MAA, the proximate metabolite of EGME, disrupts limb development in vitro, modifies acetylation programming, and induces biomarkers of cell cycle arrest and apoptosis

Toxicity of ethylene glycol monomethyl ether: impact on testicular gene expression

Methoxyacetic acid (MAA), the active biological oxidation product of the industrial solvent ethylene glycol monomethyl ether (EGME), causes acute toxicity in several species including humans. MAA primarily affects tissues with rapidly dividing cells and high rates of energy metabolism, including testes, thymus and the fetus. Testicular toxicity, one of the most prominent consequences of EGME, and MAA, exposure, results from apoptosis of primary spermatocytes and is associated with changes in the expression of various genes and signalling pathways. This review of EGME metabolism and its organ-specific toxicities emphasizes genes and signalling pathways that are modulated by EGME exposure and their relevance to the molecular mechanisms underlying EGME and MAA toxicity. Of particular importance are the genes that code for oxidative stress response factors, protein kinases, and nuclear hormone receptors. Nuclear receptors and protein kinases regulate multiple cellular processes and are critical for signalling events required for spermatogenesis. De-regulation of their activity by EGME or MAA leads to inappropriate signalling in testicular cells. Oxidative stress in spermatocytes exposed to MAA triggers mitochondrial release of cytochrome C, activation of caspases and ultimately apoptosis. Detailed investigation of the molecular responses to MAA exposure may help elucidate the overall impact and extent of toxicity seen following EGME exposure. Finally, given the effects of EGME on multiple genes and signalling pathways in the testis, mixture studies combining EGME, or MAA, with other testicular toxicants may help identify toxicities that are aggravated by EGME exposure.

Acute Testicular Toxicity of 1,3-Dinitrobenzene and Ethylene Glycol Monomethyl Ether in the Rat: Evaluation of Biochemical Effect Markers and Hormonal Responses

The studies described in this paper were undertaken to evaluate the use of plasma enzymes of testicular origin and plasma hormones as markers of acute testicular toxicity. Rats were dosed by gavage with a single dose of either 1,3-d'nitrobenzene (1,3-DNB) or ethylene glycol monomethyl ether (EGME). Two experimental designs were used: a dose response and a time-dose response course. Lactate dehydrogenase isozyme C4 (LDH-C4) and sorbitol dehydrogenase (SDH) were used as germ cell markers and leucine aminotransferase (LAT) and androgen binding protein (ABP) were used as Sertoli cell markers. Luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone were also monitored. Histopathology confirmed the known testicular toxicity of 1,3-DNB and EGME. 1,3-DNB induced Sertoli cell damage with associated degenerative changes in late pachytene spermatocytes. The effects of EGME were mainly on early and late pachytene and dividing spermatocytes. No changes in either testicular or plasma SDH or LAT were found. Similarly no effects were observed for plasma LH or testosterone. However testicular LDH-C4 and testosterone, plasma LDH-Q, ABP, and FSH did show compound related effects. LDH-C4 was reduced in testis and increased in plasma with both compounds and plasma LDH-C4 remained elevated up to 14 days after dosing. ABP levels in plasma were increased with 1,3-DNB and EGME. A reduction in testicular testosterone levels was recorded and plasma FSH concentrations were elevated after EGME treatment. It is concluded that plasma LDH-C4 activity and ABP may be of diagnostic value in acute testicular toxicity. Increases in plasma LDH-C4 precede noticeable histological findings.

Acute testicular toxicity of 1,3-dinitrobenzene and ethylene glycol monomethyl ether in the rat: Evaluation of biochemical effect markers and hormonal responses

The studies described in this paper were undertaken to evaluate the use of plasma enzymes of testicular origin and plasma hormones as markers of acute testicular toxicity. Rats were dosed by gavage with a single dose of either 1,3-dinitrobenzene (1,3-DNB) or ethylene glycol monomethyl ether (EGME). Two experimental designs were used: a dose response and a time-dose response course. Lactate dehydrogenase isozyme C 4 (LDH-C 4) and sorbitol dehydrogenase (SDH) were used as germ cell markers and leucine aminotransferase (LAT) and androgen binding protein (ABP) were used as Sertoli cell markers. Luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone were also monitored. Histopathology confirmed the known testicular toxicity of 1,3-DNB and EGME. 1,3-DNB induced Sertoli cell damage with associated degenerative changes in late pachytene spermatocytes. The effects of EGME were mainly on early and late pachytene and dividing spermatocytes. No changes in either testicular or plasma SDH or LAT were found. Similarly no effects were observed for plasma LH or testosterone. However testicular LDH-C 4 and testosterone, plasma LDH-C 4, ABP, and FSH did show compound related effects. LDH-C 4 was reduced in testis and increased in plasma with both compounds and plasma LDH-C 4 remained elevated up to 14 days after dosing. ABP levels in plasma were increased with 1,3-DNB and EGME. A reduction in testicular testosterone levels was recorded and plasma FSH concentrations were elevated after EGME treatment. It is concluded that plasma LDH-C 4 activity and ABP may be of diagnostic value in acute testicular toxicity. Increases in plasma LDH-C 4 precede noticeable histological findings.

Calcium homeostasis in pregnant rats treated with ethylene glycol monomethyl ether (EGME)

The industrial solvent ethylene glycol monomethyl ether (EGME) is a known teratogen that has been reported to alter calcium metabolism in guinea pigs during chronic exposure. Because of the tremendous demand of reproduction on maternal calcium stores, the effects of EGME on calcium and vitamin D metabolism during gestation were examined. Timed pregnant rats were treated by gavage with 0, 50, or 100 mg/kg EGME in 10 ml/kg distilled water on Days 9–15 of gestation (sperm = Day 1) and examined on Days 16 and 21. Virgin rats were treated for 7 days with 0 or 100 mg/kg EGME and examined 5 days later. EGME exposure did not affect body or kidney weight in virgin or pregnant rats, but liver weight was reduced in near-term pregnant rats treated with 100 mg/kg EGME. EGME (50 mg/kg) reduced litter size and fetal body weight and caused a significant number of live fetuses to have visceral abnormalities. EGME (100 mg/kg) caused all fetuses to be resorbed. In nonpregnant rats, 100 mg/kg did not affect serum 1,25-dihydroxyvitamin D (1,25(OH) 2D 3) 25-hydroxyvitamin D, ionic calcium, total calcium, or parathyroid hormone. EGME appeared to have a dose-dependent effect on calcium and vitamin D metabolism during gestation. On Day 21 of gestation, total calcium and ionic calcium were increased and 1,25(OH) 2D 3 was reduced in rats treated with EGME compared with nontreated controls. However, significant alterations in calcium homeostasis were evident only in dams that completely resorbed their litters. The changes in calcium and vitamin D metabolism during gestation appear to be secondary to the EGME-induced loss of litters.