Changes in the mRNA Expressions of Sperm Transforming Growth Factor β-isoforms and their Receptors with Reference to Fertility during in vitro Storage of Fowl Semen

Abstract

Our goal was to determine whether there is any correlation between the mRNA expressions of transforming growth factor β (TGFβ)-isoforms/their receptors and the fertility in chicken sperm stored in vitro for different times. The semen collected from White Leghorn roosters was divided into diluted (in Lake's solution) and undiluted groups, and stored for 0, 24, 48 and 72h at 37°C to observe sperm viability, fertility of the eggs after artificial insemination (AI) and mRNA expressions of TGFβs and TGFβ receptors (TβRs) in the sperm. Sperm viability was assessed using propidium iodide (PI) and egg fertility was observed by judging the development of embryo. The mRNA expressions of three types of TGFβ-isoforms (β2, β3 and β4) and three types of their receptors (TβR1, TβR2 and TβR3) in both the diluted and undiluted sperm were examined by semi-quantitative RT-PCR. Sperm viability in diluted semen declined slowly from 97% to 73% (75% declines against the initial value), whereas fertility was declined from 88% to 23% (26% declines against the initial value) by 72h of sperm storage. The mRNA expressions of sperm TGFβs and TβRs were also declined gradually during the storage of sperm. Correlation and regression analysis also showed a positive correlation between the sperm TGFβs/TβRs and fertility. In undiluted semen, egg fertility and the expressions of TGFβs/TβRs became negligible by 24h of storage, although 29% sperm were alive. These results suggest that expression of TGFβs and TβRs by sperm is one of the factors responsible in fertility, probably by maintaining the sperm survivability in the hen oviduct.

Keywords

• egg fertility
• sperm
• sperm storage in oviduct
• tgfβ
• tgfβ receptor