194 EFFECT OF MATERNAL AGE ON THE GRANULOSA CELL TRANSCRIPTOME OF PREOVULATORY FOLLICLES IN CATTLE
M. I. R. Khan A , F. C. F. Dias A , M. A. Sirard C , G. P. Adams A and J. Singh AA Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada;
B Department of Theriogenology, Faculty of Veterinary Sciences, University of Veterinary and Animal Sciences, Lahore, Punjab, Pakistan;
C Centre de Recherche en Biologie de la Reproduction, INAF, Université Laval, Québec, QC, Canada
Reproduction, Fertility and Development 27(1) 188-188 https://doi.org/10.1071/RDv27n1Ab194
Published: 4 December 2014
Abstract
The objective was to determine how maternal age influences the transcriptome of the dominant follicle during the preovulatory period. We tested the hypotheses that delayed ovulation in aged cows is associated with 1) altered gene expression of granulosa cells of the preovulatory follicle and 2) decreased synthesis of progesterone by granulosa cells of the preovulatory follicle. Granulosa cells of preovulatory follicles were obtained 24 h after LH treatment from aged Hereford cows (17.0 ± 2.5 years; n = 6) and their daughters (9.0 ± 0.6 years; n = 6), and compared using bovine specific microarrays (EMBV3, EmbryoGENE, Québec, QC, Canada). Results were confirmed by RT-qPCR. A total of 1340 genes or gene isoforms were expressed differentially (≥2-fold change; P ≤ 0.05) in aged cows v. their younger daughters. Differentially expressed up- and down-regulated genes were related to 1) LH response (↑RGS2, ↑SERPINE2, ↑PTGS2), 2) cellular differentiation and luteinization (↑TNFAIP6, ↑GADD45B, ↓VNN1), and 3) progesterone synthesis (↑STAR, ↑HSD3B2, ↑NR5A2, ↑NR4A1). Intra-follicular concentration of progesterone was lower (P < 0.05) in aged v. young cows. Pathway analysis of the dataset revealed that mechanisms of delayed ovulation in aged cows may involve 1) post-receptor desensitization of G-coupled protein receptors, 2) inactivation of tissue plasminogen activator, and 3) delayed production of prostaglandin E2. In conclusion, transcriptome analysis of granulosa cells from aged cows revealed a delayed or suboptimal response to the preovulatory LH stimulus, represented by delayed cellular differentiation, luteinization, and progesterone synthesis.
This study was supported by grants from the National Science and Engineering Research Council of Canada, and the EmbryoGene Network, Canada. M.I.R. Khan was supported by graduate assistant scholarship from the Higher Education Commission of Pakistan.
