Steroidogenesis in bovine granulosa cells: the effect of short-term changes in dietary intake

The nutritional status of a cow is a key factor in the regulation of both follicle growth and oocyte quality. In this study, the effect of diets designed to increase circulating insulin and insulin-like growth factor I (IGF-I) concentrations on steroid production by granulosa cells in vitro was examined to analyse the mechanisms through which these changes occur. Hereford x Friesian heifers (n = 24) were offered maintenance or twice maintenance diets during the experimental period (17 days). Circulating concentrations of FSH did not differ between the two dietary groups, whereas insulin and IGF-I concentrations showed significant diet x day of oestrous cycle interactions. Ovaries were collected on day 3 of the first follicle wave after synchronization of oestrus. Granulosa cells were isolated from small (1-4 mm) and medium-sized (4-8 mm) follicles and cultured in the presence of long R3-IGF-I or bFSH or both. After 4 days in culture, granulosa cells isolated from small follicles, but not medium-sized follicles, collected from cattle offered the twice maintenance diet secreted significantly higher (P < 0.05) amounts of oestradiol compared with granulosa cells collected from cattle offered the maintenance diet. The effect was apparent in either the presence or absence of FSH and long R3-IGF-I. This nutritional effect on aromatase activity in granulosa cells was not apparent after day 6 of culture. There was no effect of diet on progesterone production by granulosa cells after 4 or 6 days of culture. These results support the hypothesis that dietary-induced changes in circulating insulin and IGF-I concentrations have a direct effect on the steroidogenic potential of bovine granulosa cells from small follicles. The dietary-induced increases in aromatase activity in small follicles combined with the increased concentration of metabolic hormones are possible mechanisms through which short-term changes in nutrition may affect follicle dynamics.

This article has been cited by other articles:

				M Zachut, A Arieli, H Lehrer, N Argov, and U Moallem Dietary unsaturated fatty acids influence preovulatory follicle characteristics in dairy cows Reproduction, May 1, 2008; 135(5): 683 - 692. [Abstract] [Full Text] [PDF]

				H. Kadokawa, N. Tameoka, M. Uchiza, Y. Kimura, and M. Yonai Short Communication: A Field Study on the Relationship Between Body Condition and Embryo Production in Superovulated Holstein Yearling Heifers J Dairy Sci, March 1, 2008; 91(3): 1087 - 1091. [Abstract] [Full Text] [PDF]

				L. M. Chagas, J. J. Bass, D. Blache, C. R. Burke, J. K. Kay, D. R. Lindsay, M. C. Lucy, G. B. Martin, S. Meier, F. M. Rhodes, et al. Invited Review: New Perspectives on the Roles of Nutrition and Metabolic Priorities in the Subfertility of High-Producing Dairy Cows J Dairy Sci, September 1, 2007; 90(9): 4022 - 4032. [Abstract] [Full Text] [PDF]

				S Freret, B Grimard, A A Ponter, C Joly, C Ponsart, and P Humblot Reduction of body-weight gain enhances in vitro embryo production in overfed superovulated dairy heifers. Reproduction, April 1, 2006; 131(4): 783 - 794. [Abstract] [Full Text] [PDF]

				S.J. Adamiak, K. Mackie, R.G. Watt, R. Webb, and K.D. Sinclair Impact of Nutrition on Oocyte Quality: Cumulative Effects of Body Composition and Diet Leading to Hyperinsulinemia in Cattle Biol Reprod, November 1, 2005; 73(5): 918 - 926. [Abstract] [Full Text] [PDF]

				M Munoz-Gutierrez, D Blache, G B Martin, and R J Scaramuzzi Ovarian follicular expression of mRNA encoding the type I IGF receptor and IGF-binding protein-2 in sheep following five days of nutritional supplementation with glucose, glucosamine or lupins Reproduction, December 1, 2004; 128(6): 747 - 756. [Abstract] [Full Text] [PDF]

				R. Webb, P. C. Garnsworthy, J.-G. Gong, and D. G. Armstrong Control of follicular growth: Local interactions and nutritional influences J Anim Sci, January 1, 2004; 82(13_suppl): E63 - 74. [Abstract] [Full Text] [PDF]