Free Access
Reprod. Nutr. Dev.
Volume 45, Number 2, March-April 2005
Page(s) 185 - 192
Reprod. Nutr. Dev. 45 (2005) 185-192
DOI: 10.1051/rnd:2005010

Ovarian effects of a high lactose diet in the female rat

Gentao Liua, Fangxiong Shib, Uriel Blas-Machadoc, Quynh Duonga, Vicki L. Davisd, Warren G. Fostere and Claude L. Hughesf, g

a  Cedars-Sinai Burns and Allen Research Institute, Cedars-Sinai Medical Center/University of California Los Angeles School of Medicine, CA, USA
b  College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
c  College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA
d  Duquesne University, Pittsburgh, PA, USA
e  Obstetrics & Gynaecology, McMaster University Medical Center, Hamilton, ON, Canada
f  Department of Medical & Scientific Services, Quintiles, Research Triangle Park, NC, USA
g  Department of Biology, East Carolina University, Greenville, NC, USA

(Received 20 October 2004; accepted 14 January 2005)

Abstract - Young women with galactosemia experience ovarian failure at a very early age raising concern about the ovarian toxicity of galactose. While galactose may be present in the diet as a monosaccharide, it is predominantly derived from cleavage of the disaccharide lactose within the intestine. Our previous studies in animals have shown that high galactose diets inhibit ovarian follicular development and long-term exposure to high lactose diets retards growth of rats. The objective of the present study was to determine whether galactose exposure in the form of dietary lactose mimics the effects found previously with diets rich in galactose. Sixty female Long-Evans rats (25-day-old) were randomly assigned to two groups and fed a control diet (41.9% glucose in AIN93G [American Institute of Nutrition], CON) before lactose treatment. Unilateral ovariectomy (uOVX) was performed on half of the rats in each group to determine baseline ovarian follicle numbers. The study diet was a high lactose diet (HLD) containing 41.9% lactose in AIN93G. Study diet exposure started 1 month after uOVX (3 months old) and continued for 7 months in the treatment group. The control group remained on the 41.9% glucose diet throughout. Vaginal cytology, ovarian morphometric analyses, and serum concentrations of estradiol and progesterone were examined. Long-term exposure to the HLD decreased the body weights of animals and progesterone concentrations in the serum but produced no harmful effects on ovarian morphology or function. Beginning at 5 months of age (two months of lactose treatment) increasing numbers of females began to cycle irregularly but there was no difference between the glucose and lactose diet groups. These negative findings imply that administration of galactose in the form of lactose seems to be much less toxic than when galactose is fed to animals. From a human health perspective, these results are somewhat reassuring, since in general, women eat lactose-containing foods rather than foods that contain large amounts of free galactose.

Key words: lactose / galactose / ovary / toxicology / rat

Corresponding author: Claude L. Hughes

© INRA, EDP Sciences 2005