The effects of dietary protein intake by the dam and by the offspring on mammary gland development in young female rats

Studies were conducted to determine the effects of different intakes of dietary protein (casein) at different ages on mammary gland development in first generation female Sprague Dawley rats. Offspring were fed the same diet as fed to their dams during gestation and lactation, or offspring were crossed over at weaning to different protein intakes, from control dams fed 16% casein during lactation and gestation. The dams nursed female offspring where possible with litter size adjusted to reduce protein and caloric deficits. Mammary gland development was assessed by counting the number of terminal end buds (TEB) in twelve identical areas of mammary glands for comparisons of the total area occupied by these structures. TEB were used as an index because they are the target tissue for the carcinogen 1,2 dimethylbenz(a)anthracene (DMBA) and the carcinogen N-ethyl-N-nitrosourea. Contralateral mammary glands from offspring at 56 and 161 days were analyzed for moisture, fat, protein, DNA, and RNA by sampling a 2 cm disc of mammary tissue adjacent to and including the nipple. The tissue was digested with 1 mg collagenase per ml of normal saline for three hours after freeze drying. The results of these studies show that female offspring eating diets containing 8.5% casein and weaned from dams fed 8.5% casein (LL offspring) had retarded mammary gland development as measured by TEB at 40 and 56 days of age compared to controls fed diets with 17% casein and weaned from dams fed 17% casein (CC offspring). At 56 days offspring fed 8.5% casein and weaned from control dams fed 17% casein (CL offspring) showed total numbers of TEB between the extremes of LL and CC offspring and not significantly different from either group. When nursing liter size was raised from 3 to 5 in dams fed 8.5% casein, mammary gland development in their offspring was further retarded. Mammary glands examined at 161 days of age were atrophic regardless of dietary treatment. At 56 days, offspring weaned to 8.5% casein diets had slightly more water and less fat per gram of dry fat-free tissue than controls. DNA and RNA concentrations per gram off dry fat-free tissue were similar for offspring weaned to the 8.5% casein diet or the 17% casein control diet. Offspring fed 33% casein diets weaned from dams fed the same diet had more DNA per gram of dry fat-free tissue compared to control offspring fed the 17% casein diet, while offspring weaned to 33% casein diet from dams fed the control 17% diet had DNA concentrations similar to control offspring.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Agriculture, Animal Culture and Nutrition

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Olsowka, Eugene S.

• Agriculture, Animal Culture and Nutrition

Statement dc:rights

• Copyright 1989 Olsowka, Eugene S.

Language dc:language

eng

Identifier

AAI9010973
(UMI)AAI9010973

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/21264