RNA expression in sperm as markers of sperm-quality
Year: 2012
Type: dissertation
Abstract: VI Abstract In the last decades, an apparent decline in sperm-quality has been observed in the western world. The reasons for this development are largely unknown, but environmental agents may play a role. Polycyclic aromatic hydrocarbons (PAH) are widespread toxicants known to negatively affect reproductive health, and have been shown to damage sperm DNA, by forming bulky DNA adducts and oxidative DNA damage. An important cause of poor spermquality is believed to be sperm DNA damage, which is linked to pregnancy loss after assisted fertilization, disturbances in embryo development and increased risk of childhood cancer. Obviously, the sperm DNA integrity seems to be important for fertilization and early embryo development, therefore, finding sperm-quality markers would help to understand the causes of male infertility and to improve the male reproductive health. Sperm contain a complex population of RNA, and the utility of sperm RNA in fertility research are currently being explored. In this study, the aim was to examine if RNA can be used as sperm-quality markers, by investigating the expression of some selected sperm mRNA and miRNA species after exposing mice to Benzo[a]pyrene (BaP), commonly used as model for exposure to PAH. Testis and liver was included for comparison. Importantly, we wanted to establish a procedure to isolate good quality RNA from individual sperm samples. The mRNA and miRNA expression was analyzed 24 days after exposure using real-time quantitative PCR (qPCR). The RNA isolation procedure was successfully established, but there is a need for the future inclusion of a marker of potential somatic cell contamination. Our results showed no effect of BaP on gene expression in liver, however, a differential expression of a few genes in testis and sperm was indicated. To our surprise, we observed a marked effect of vehicle exposure on gene expression in all three tissues examined. Interestingly, the ratio of the protamine1 and protamine2 genes was slightly altered in testis, and markedly changed in sperm, in response to both corn oiland BaP-exposure (not significant). The protamine ratio is believed to be associated with sperm-quality in humans. The miRNA expression data are preliminary, but we did succeed in the identification of the selected transcripts in sperm. The findings suggested that RNA expression can be reliably analysed using sperm isolated from single mice. This makes RNA expression studies attractive for both experimental and clinical studies. We showed some significant effects on gene expression in sperm from BaP and/or corn oil exposed mice. Corn oil has previously been shown to induce and potentiate oxidative damage in sperm which could thus be an explanation of the responses seen in the present study. The prm1:prm2 ratio in testis and sperm may be used as predictive sperm-quality
Author: Hanne Kildemo
Language: English
Subfield: Reproductive Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2407637563