Insulin and Glucagon Binding to Hepatocytes in Relation to Circulating Hormones and Metabolites in Goats Maintained on Different Diets

Summary

Insulin and glucagon receptors were measured on hepatocytes in relation to circulating hormones (insulin, glucagon and growth hormone) and metabolites (non-esterified fatty acids, volatile fatty acids, glucose, total lipids, urea and α-amino nitrogen), in twelve, two-year old, castrated male goats, fed rations of different composition and dietary energy.

The goats were separated into four groups; group 1 was fed a restricted ration of 600 g clover hay/day, group 2 a ration high in carbohydrate (rolled barley), group 3 a ration high in fat (protected tallow) and group 4 a ration high in protein (fish meal). Rations in groups 2-4 were fed at 1300 g/day supplemented with 600 g of clover hay.

The binding of insulin to hepatocyte receptors was increased by restricting dietary intake when compared to the high energy intake groups (P < 0.01). There was no significant difference between the insulin binding of groups 2-4.

Glucagon receptor binding was increased on the high protein diet in comparison with the ration high in carbohydrate (P < 0.05) or in fat (P < 0.01). The glucagon binding was reduced by restricting feed intake when compared with feeding high protein (P < 0.02), but slightly increased when compared with feeding diets high in both carbohydrate or fat (P < 0.02). There was no significant difference between the high carbohydrate or high fat fed groups.

These changes in hormone receptors were accompanied by inverse changes in plasma Insulin and glucagon.

Key-Words:

Insulin - Glucagon - Hepatocytes - Receptors - Goats - Growth Hormone - Non-Esterified Fatty Acids - Glucose - Total Lipids - Urea - α-Amino Nitrogen - Volatile Fatty Acids