The time-dependent adverse effects of a high-fat diet on sperm parameters.

BACKGROUND: Studies indicate a relationship between a high-fat diet (HFD) and sperm quality. However, the time-dependent adverse effects of a HFD on sperm parameters and the underlying mechanisms remain unclear. OBJECTIVES: The present study was designed to determine the effects of a HFD on sperm quality at various time points in order to assess whether a HFD causes cumulative damage to sperm. MATERIAL AND METHODS: Male C57BL/6 mice were fed a normal diet (the ND group) or a HFD (the HFD group) for 16, 30 or 42 weeks (n = 6 for each group). Body weight, lipid profile, sperm parameters, testicular morphology, and testicular oxidative stress levels were evaluated alongside the proliferation, DNA damage and rate of germ cell apoptosis. RESULTS: Sperm quality was reduced in HFD-fed animals in a time-dependent manner, which was demonstrated by a decline in sperm density, motility and progressive motility. Further analysis showed a progressive deterioration of the testicular histoarchitecture of HFD-fed mice, which was accompanied by a decrease in DEAD-box helicase 4 (DDX4) expression and superoxide dismutase (SOD) levels, increased malondialdehyde (MDA) levels and gamma-H2A histone family member X (γ-H2AX) expression, and increased apoptosis of germ cells. CONCLUSIONS: These findings demonstrate that a HFD exerted adverse effects on sperm quality, and the deteriorating effect was progressive with long-term feeding. The inhibited proliferation and apoptosis of germ cells, and the increased oxidative stress levels and DNA damage may be the underlying mechanisms.

Effect of iodoacetic acid on the reproductive system of male mice.

Iodoacetic acid (IAA) is one of the most common water disinfection byproducts (DBPs). Humans and animals are widely and continuously exposed to it. Many species of water DBPs are harmful to the reproductive system of organisms. Nevertheless, the potential effects of IAA exposure on testosterone and spermatogenesis in vivo remain ambiguous. Spermatogenous cells are the site of spermatogenesis, Leydig cells are the site of testosterone synthesis, and Sertoli cells build the blood-testis barrier (BTB), providing a stable environment for the aforementioned important physiological functions in testicular tissue. Therefore, we observed the effects of IAA on spermatogenic cells, Leydig cells, and Sertoli cells in the testis. In this study, we found that oral administration of IAA (35 mg/kg body weight per day for 28 days) in male mice increased serum LH levels and reduced sperm motility, affecting average path velocity and straight line velocity of sperm. In addition, IAA promoted the expression of γH2AX, a marker for DNA double-strand breaks. Moreover, IAA downregulated the protein expression of the scavenger receptor class B type 1 (SRB1), and decreased lipid droplet transport into Leydig cells, which reduced the storage of testosterone synthesis raw materials and might cause a drop in testosterone production. Furthermore, IAA did not affect the function of BTB. Thus, our results indicated that IAA exposure affected spermatogenesis and testosterone synthesis by inducing DNA damage and reducing lipid droplet transport.