Seasonal changes in blood lipids, adrenaline, noradrenaline, glucose and insulin in Norwegian reindeer.

Plasma concentrations of free fatty acids (FFA), glycerol, adrenaline, noradrenaline, glucose and insulin, as well as serum concentrations of triacylglycerols, total cholesterol and high density lipoprotein (HDL)-bound cholesterol, were measured at intervals during a I-year period in Norwegian reindeer. Free fatty acids and glycerol were high in January-March, low in April-July, and high again in August-September. Glucose was low in November-February and high but variable in March-October. Triacylglycerols, total and HDL-bound cholesterol were all low in November-March, but increasing in April and reaching a peak in August-September. Plasma noradrenaline and adrenaline did not change significantly throughout the year. Plasma insulin was low in October-April, increasing significantly from June-August/September. The seasonal changes in the serum concentrations of triacylglycerols, total and HDL-bound cholesterol, as well as the plasma concentration of glucose, coincided with the seasonal changes in food intake. Free fatty acids and, to some extent, glycerol were, in contrast, inversely related to feed intake. It is suggested that insulin may play an important role in the long-term regulation of fat mobilization, while the importance of catecholamines in this respect is questionable.