Lipogenic enzyme activities in primary cultures of adult mouse hepatocytes.

The effects of various unsaturated fatty acids such as oleic (18:1n-9), linoleic (18:2n-6) and arachidonic (20:4n-6) on the activities of fatty acid synthetase (FAS), malic enzyme (ME), glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) all were determined in primary cultures of mouse hepatocytes. Activities of FAS and ME were found to decrease with time in culture regardless of whether hepatocyte donors were fed diets containing polyunsaturated fatty acid-free hydrogenated cottonseed oil (HCTO) or corn oil (CO). On the other hand, while G6PDH activity also declined in cultured hepatocytes obtained from HCTO-fed mice, the activity of this enzyme increased in cells cultured from CO-fed mice.

Effects of dietary fat on mammary development relative to age and hormones in BALB/c mice.

Earlier studies reported that mammary ducts grew faster if the 10% fat in the diet was composed of oils containing polyunsaturated fatty acids (corn oil: CO) compared to hydrogenated cottonseed oil (HCTO), which is devoid of such fatty acids. These experiments were primarily carried out in immature mice and left unanswered questions regarding the effects of dietary fats on more differentiated stages of mammary development. The use of transplanted ducts permitted the study of mammary growth rates in adult mice.

Effect of dietary fat on growth kinetics of transplantable mammary adenocarcinoma in BALB/c mice.

The growth of mammary adenocarcinomas in BALB/c mice fed a diet containing 10% corn oil (CO), which has about 60% of its fatty acids as linoleate, was significantly greater than that for tumors in mice fed diets containing either 10% hydrogenated cottonseed oil (HCTO), which has no linoleate, or 10% CO plus 0.003% indomethacin (IM). The proportion of the tumor occupied by the various cell types was quantitated from histologic sections for 2 different mammary adenocarcinomas.

Effect of dietary fat on tumorigenesis in the mouse mammary gland.

The effects of dietary polyunsaturated fat in BALB/c mice were determined for several stages of mammary tumorigenesis: a) growth of intact and transplanted normal mammary tissue, b) growth of hyperplastic alveolar nodule (HAN) lines D1/ UCD and Z5C1 , c) incidence of tumors occurring in D1/ UCD , and d) growth rate of the tumors. Growth of transplanted normal mammary epithelium as well as intact glands was faster in mice fed a 10% corn oil (CO) diet, which contains linoleate, than in those fed 10% hydrogenated cottonseed oil ( HCTO ), a diet free of the polyunsaturated fatty acid. We concluded that transplantation itself does not alter the response of mammary tissue to dietary fat.

Effect of specific dietary fatty acids on lipogenesis in the livers and mammary glands of lactating mice.

The effects of linoleic, linolenic and columbinic acids fed as 4% of a high carbohydrate (50% glucose) diet on the activities and the amounts of several enzymes associated with fatty acid synthesis in livers and mammary glands of lactating mice were compared with those for stearic and oleic acids. Fatty acid synthesis, measured in vivo, was significantly lower in livers of mice ingesting all 3 polyunsaturated fatty acids (PUFA), whereas in mammary glands synthesis was lower only in mice receiving columbinic acid. The activities of fatty acid synthetase (FAS) and acetyl CoA carboxylase were significantly reduced in liver by all 3 PUFA, as wee activities of glucose-6-phosphate dehydrogenase, malic enzyme (ME) and citrate cleavage enzyme (CCE), also associated with lipogenesis.