Hepatic receptors for insulin and glucagon in relation to plasma hormones and metabolites in pregnant and unmated ewes.

Glucagon and insulin receptors were examined in relation to plasma concentrations hormones and metabolites in unmated and in 110- and 140-day pregnant ewes (four animals per group). The concentrations of insulin, growth hormone and non-esterified fatty acids in the circulation, together with the maintenance of body weight, suggested that the animals were in energy surplus. When compared with the unmated group the binding insulin to isolated hepatocytes increased by 110 days of pregnancy, attaining statistical significance (P less than 0.02) after 140 days. Conversely, glucagon binding was reduced by 110 days of pregnancy, also attaining statistical significance (p less than 0.02) after 140 days. The changes in both insulin and glucagon binding were primarily due to changes in the number of receptors on each hepatocyte, although some fluctuation in receptor affinity were also found. These observations suggested that the number of hepatic insulin and glucagon receptors are altered during the metabolic demands of pregnancy in sheep, but unlike the changes reported during lactation in the ewe and restricted energy intake in the goat, they are not related either to energy deficit or to changes in the concentration on insulin, and probably of glucagon, in the circulation.