Inhibitory effect of ethylene glycol monoethyl ether on rat sperm motion

Syringic acid demonstrates an anti-inflammatory effect via modulation of the NF-κB-iNOS-COX-2 and JAK-STAT signaling pathways in methyl cellosolve-induced hepato-testicular inflammation in rats

Syringic acid (SACI) is an emerging nutraceutical and antioxidant used in modern Chinese medicine. It has potential neuroprotective, anti-hyperglycemic, and anti-angiogenic properties. Methyl cellosolve (MCEL) has been reported to induce tissue inflammation in the testis, kidney, liver, and lung. This study aimed to investigate the effect and probable mechanism of action of SACI on MCEL-induced hepatic and testicular inflammation in male rats. Compared to the control group, administration of MCEL to rats significantly increased the levels of IL-6, TNF-α, iNOS, COX-2, and NF-κB in the liver and testis. Additionally, the total mRNA expressions of JAK1 (in the liver only), STAT1, and SOCS1 were significantly increased in both the liver and testis, while testicular JAK1 total mRNA levels were significantly decreased. The expression of PIAS1 protein was significantly higher in the liver and testis. Treatments with SACI at 25 (except liver iNOS), 50, and 75 mg/kg significantly decreased the levels of IL-6, TNF-α, iNOS, COX-2, and NF-κB compared to the control group. Furthermore, the total mRNA expressions of JAK1 and SOCS1 in the liver were significantly reduced by all doses of SACI investigated, while the total mRNA levels of liver and testis STAT1 were significantly reduced by 25 and 50 mg/kg of SACI only. In the testis, the mRNA level of SOCS1 was significantly reduced by all doses of SACI compared to MCEL only. Additionally, SACI (at 75 mg/kg) significantly reduced PIAS1 protein expression in the liver, while in the testis, SACI at all investigated doses significantly reduced the expression of PIAS1. In conclusion, SACI demonstrated a hepatic and testicular anti-inflammatory effect by inhibiting the MCEL-induced activation of the NF-κB and JAK-STAT signaling pathways in rats.

Nicotinamide Mononucleotide Restores the Meiotic Competency of Porcine Oocytes Exposed to Ethylene Glycol Butyl Ether

Ethylene glycol butyl ether (EGBE), a type of glycol ethers, is a common chemical used in both industrial and household products. Increasing animal studies have indicated that it produces reproductive problems, such as testicular damage, reduced female fertility, death of embryos, and birth defects. However, how it influences the female germ cells has not yet determined. Here, we found that EGBE exposure resulted in the defective porcine oocyte maturation via disruption of cytoskeleton dynamics, showing the abnormal spindle assembly, chromosome alignment, and actin organization. Meanwhile, EGBE exposure perturbed the mitochondrial distribution and function, leading to the accumulation of reactive oxygen species (ROS) and generation of DNA damage and apoptosis. Of note, nicotinamide mononucleotide (NMN) supplementation rescued the meiotic defects caused by EGBE exposure via restoring NAD⁺ level and mitochondrial function and thus eliminating the excessive ROS. Taken together, our observations illustrate that NMN supplementation is an effective strategy to protect oocyte quality against environmental pollutant-induced deterioration, contributing to improve the animal and human fertility.

Induction of oxidative damage in the testes and spermatozoa and hematotoxicity in rats exposed to multiple doses of ethylene glycol monoethyl ether

The effects of ethylene glycol monoethyl ether (EGEE) on the antioxidant systems of the testes and epididymal spermatozoa were investigated in rats at dose levels of 0, 100, 200 and 400 mg kg-1 body weight (bw) administered orally by gavage for 14 consecutive days. The bw gain of the EGEE-treated rats decreased significantly at 200 and 400 mg kg- 1 bw compared with the control group. There were no significant changes in the weights of the testes, epididymis, seminal vesicles and prostate glands of the EGEE-treated rats. In the testes, while EGEE treatment resulted in significant decrease in glutathione (GSH) level, superoxide dismutase (SOD) and catalase (CAT) activities, it markedly increased the malondialdehyde (MDA) level, glutathione-S-transferase (GST) and lactate dehydrogenase (LDH) activities at 200 and 400 mg kg-1 dose levels but vitamin C content remained unaffected in all the groups. In the spermatozoa, administration of EGEE caused significant decrease in the activities of CAT, GST and LDH as well as in the levels of vitamin C and GSH but significantly increased the MDA level and SOD activity compared with the control rats. Histopathological examination showed severe degeneration of the testes, such as generalized erosion and necrosis of the germinal epithelium of the testes, but mildly affected the epididymis at 400 mg kg-1 dose only. Data on spermatozoa analysis of EGEE-treated rats revealed significant decrease in the epididymal spermatozoa number, testicular spermatozoa number, daily spermatozoa production and spermatozoa motility but significantly increased the total spermatozoa abnormalities without affecting the spermatozoa live-dead ratio at all dose levels when compared with the control group. Results of haematological examination showed that white blood cells (WBC), platelets neutrophils and mean corpuscular haemoglobin concentration (MCHC) were significantly lower whereas lymphocytes were increased in 200 and 400 mg/kg EGEE-exposed rats than in the controls. EGEE at 100 mg/kg bw produced minor effect on haematological parameters but adversely affected testes and spermatozoa. In summary, short term administration of EGEE is hematotoxic and gonadotoxic and its effects on male reproduction could be due to the induction of oxidative stress in testes and spermatozoa.

Reproductive toxicity of ethylene glycol monoethyl ether in Aldh2 knockout mice

Ethylene glycol monoethyl ether (EGEE) can cause damage to testes and sperm, and its metabolites are believed to play an important role in its toxicity. Aldehyde dehydrogenase 2 (ALDH2) is involved in the metabolism of this chemical. To investigate whether and how the enzyme affects the toxicity of EGEE, we conducted experiments comparing Aldh2 knockout mice with wild-type mice. Administration of EGEE at 100 and 600 mg/kg/day for one week did not induce any significant change in the weight and body weight ratios of testes, prostate and epididymides in either Aldh2 knockout or wild-type mice. However, motion of sperm from the spermaduct, as analyzed with a Hamilton-Thorne Sperm analyzer, was slightly decreased in the low dose group, and significantly lower in the high dose group; and the percentage of progressive sperm was also reduced in the two EGEE groups. This effect of EGEE treatment was observed in the wild-type, but not in the Aldh2 knockout mice. Sperm motion from the cauda epididymides was not affected. On the other hand, the concentration of ethoxyacetic acid, a metabolite of EGEE, in 24 h pooled urine of EGEE-treated Aldh2 knockout mice was not significantly lower than that of the wild-type mice on most days of urine sampling. These results suggest that inactivation of the ALDH2 enzyme due to gene mutation may be linked to differences in the susceptibility to EGEE-induced sperm toxicity.