Pregnancy

The Contrasting Effects of Ad Libitum and Restricted Feeding of a Diet Very High in Saturated Fats on Sex Ratio and Metabolic Hormones In Mice

Abstract
Skewing of sex ratio towards males occurs among pups born to mice fed a very high saturated fat (VHF) diet. Here, we tested whether the fat content of the VHF diet rather than the calories consumed is responsible for the effect. Eight-week old NIH Swiss mice were placed on the VHF diet either ad libitum (VHF) or in a restricted manner (VHF-R). The VHF-R mice gained weight at a similar rate to controls fed a standard chow diet. Mice were bred at 15 and subsequently at 26 and 35 weeks old. Overall, the VHF, VHF-R and control groups delivered 244, 242, and 274 pups, respectively (proportion males, 0.60, 0.43, and 0.48). Pup sex ratios of the VHF group (favoring males) and VHF-R group (favoring females) each differed from 0.5 (P<0.01). Sex ratios also differed (P<0.0001) between the VHF and control, and between the VHF and VHF-R groups. Within diet groups, maternal body weight had no effect on sex ratio. Serum leptin concentrations among dams were similar in the VHF and VHF-R dams but higher than controls, while IGF1 and corticosterone levels were comparable in all three groups. The atypical sex ratios of offspring born to dams on the VHF diet seem, therefore, to be influenced by the amount of fat energy consumed. Since males fed the VHF diet had neither more Y-sperm nor sired more sons than daughters, the dietary effects are singularly through the female.

Key words: Pregnancy • Corticosterone • Leptin • IGF-1 • Mouse

This article has been cited by other articles:

				W. H James Evidence that mammalian sex ratios at birth are partially controlled by parental hormone levels around the time of conception J. Endocrinol., July 1, 2008; 198(1): 3 - 15. [Abstract] [Full Text] [PDF]