The ability of medium chain
triglyceride-enriched
total parenteral nutrition to support host tissue in a model of
cancer cachexia was assessed by measuring
tumor growth,
body weight,
nitrogen balance, energy expenditure,
leucine kinetics, fractional
protein synthetic rate of
tumor, liver, and abdominis rectus muscle, and plasma levels of
glucose and
albumin. Male Sprague-Dawley rats (85-90 gm) received 10(7) cells of viable
Yoshida sarcoma subcutaneously on day 0. Control rats received
injections of sterile saline. On day 10 rats underwent central venous cannulation and were randomized to one of three isocaloric diets. One group received
amino acids and
dextrose, while the other two groups were infused with
amino acids,
dextrose, and fat as either long chain
triglyceride or a physical mixture of medium chain
triglyceride: long chain
triglyceride (3:1). On day 14 L-1-(14)C-leucine was added to the diet to study
protein kinetics, and energy metabolism was measured by indirect calorimetry. Both
tumor-bearing and nontumor-bearing rats demonstrated improved
nitrogen balance when given medium chain
triglyceride-enriched
total parenteral nutrition.
Tumor-bearing rats had reduced resting energy expenditure vs. nontumor-bearing, while rats receiving
total parenteral nutrition without fat had significantly greater respiratory quotients.
Tumor-bearing rats had lower total
body weight vs. nontumor-bearing on day 10, but
body weight of
tumor-bearing and nontumor-bearing did not differ on day 14. Whole body
protein breakdown decreased and
leucine balance increased in
tumor-bearing rats as compared to nontumor-bearing. Total liver mass was greater in
tumor-bearing rats, but liver
protein fractional
protein synthetic rate decreased in
tumor-bearing rats vs. nontumor-bearing.
Tumor growth rate and fractional
protein synthetic rate were not altered by the parenteral diet. The data confirm an altered metabolism in the
tumor-bearing host, and suggest that medium chain
triglyceride can better support host tissue.