Fatty acids and exercise affect glucose transport but not tumour growth in F-344 rats.

Abstract

This study examined the effect of diet and exercise on tumour growth, and the effect of dietary fatty acids on glucose uptake. Male Fischer 344 rats were divided into 4 dietary groups and fed for 2 weeks. The diets were 5% (wt/wt) safflower oil, 10% safflower oil, 5% docosahexaenoic acid(DHA)-rich, and 10% DHA-rich. On Day 14 the animals were injected with rat fibrosarcoma tumour cells. After 3 days of tumour growth the animals in each diet group were divided into exercise and nonexercise groups. Exercise was achieved by voluntary wheel running. Dietary intake, body weight, tumour growth, and distance run were determined daily. Two weeks later the animals were euthanized and the following tissues were dissected out: tumour, liver, heart, epididymal fat pads, gastrocnemius, epitrochlearis, and soleus muscles. Glucose transport experiments were performed on the epitrochlearis and soleus muscles whereas phospholipid analysis was completed on the gastrocnemius muscle. We observed no effect of either diet or exercise on tumour growth. The glucose transport data demonstrates that short-term voluntary running can cause increased insulin-sensitive transport and that DHA may inhibit transport. DHA-containing diets were associated with increased oxidation products TBARM. In conclusion, exercise benefits on glucose disposal are maintained in tumour-bearing animals but are influenced by fat content and composition. High DHA diets may also increase oxidative damage in muscle through enhanced TBARM production.