Effect of environmental temperature changes on rat liver fatty acid desaturases

Female rats warm-adapted at 30–32 C for 20–25 days and then shifted to 13–15 C for 12, 24, 48, 72 and 120 hr showed that Δ9 desaturase and fatty acid synthetase activity decay after 24 hr of cold exposure, while Δ6 and Δ5 desaturases were increased after this period of time. These results were confirmed by an increase of arachidonic acid of heart and liver microsomes phosphatidylcholine and a decrease of oleic acid. Neither NADH-cyt b₅ reductase nor NADH-cyt c reductase activity of liver microsomes were significantly affected. Male rats warm-adapted under the same conditions and then shifted to 13–15 C for 120 hr did not show significant changes in fatty acid synthetase, Δ9 and Δ6 desaturases and enzymes of the microsomal electron transport chain. Therefore, the desaturase response to environmental temperature changes could be plausibly linked to female hormones.