Comparison of the global gene expression profiles in the bovine endometrium between summer and autumn

Abstract

Heat stress compromises fertility during summer in dairy and beef cows by causing nutritional, physiological and reproductive damages. To examine the difference in endometrial conditions in cows between summer and autumn, gene expression profiles were compared using a 15 K bovine oligo DNA microarray. The trial was conducted in the summer (early in September) and autumn (mid-November) seasons of two consecutive years (2013-2014) in Morioka, Japan. Endometrial samples were collected from the cows using a biopsy technique. The expressions of 268 genes were significantly higher in the endometrium collected in summer than those collected in autumn, whereas the expressions of 369 genes were lower (P<0.05 or lower). Messenger RNA expressions of glycoprotein 2 (GP2), neurotensin (NTS),E-cadherin (CDH1) and heat shock 105kDa/110kDa protein 1 (HSPH1) were validated by quantitative real-time PCR. Transcripts of GP2 and NTS were more abundant in the endometrium from summer than in the endometrium from autumn (P < 0.05). In contrast, the mRNA expressions of CDH1 were lower (P < 0.05) and those of HSPH1 tended to be low (P = 0.09) in the endometrium from summer. Immunohistochemical staining showed that GP2, NTS and HSPH1 were expressed in the endometrial epithelial or glandular epithelial cells. The serum concentrations of NTS collected from the cows in summer were higher than those collected from cows in autumn (P < 0.05). Collectively, the different gene expression profiles may contribute to functional differences in the endometrium between summer and autumn, and the increases in GP2 and NTS may have a relationship with the endometrial deficiency that causes infertility of cows in summer.

Fig. 1.

Changes in relative amounts of (A) glycoprotein 2, (B) neurotensin, (C) E-cadherin and (D) heat shock protein 1 mRNA expressions in the endometrium obtained from the cows in summer and autumn. Data are the means ± SEM for six cows per season and are expressed as relative ratios of the mRNAs to 18S ribosomal RNA (RN18S1). Asterisks show significant differences between summer and autumn (* P < 0.05).

Fig. 2.

Localization of a) glycoprotein 2, b) neurotensin, c) E-cadherin and d) heat shock protein 1 in the bovine endometrium evaluated by immunohistochemistry. Intensive immunoreactivities were observed in epithelial or glandular epithelial cells (black arrowheads). No positive immunoreactivity was observed in the negative control (inserted panels). Scale bar = 50 µm.

Fig. 3.

Concentrations of (A) neurotensin and (B) E-cadherin in the plasma obtained from the cows in summer and autumn evaluated by ELISA. Data are the means ± SEM for six cows per season. Asterisks show significant differences between summer and autumn (* P < 0.05).