Increased insulin sensitivity and responsiveness during lactation in rats.
In 12-day lactating rats blood glucose and plasma insulin were decreased by, respectively, 20 and 35% when compared with nonlactating rats, despite a 25% increase of their glucose turnover rate. Then, by using the euglycemic hyperinsulinemic clamp technique, dose-response curves for the effects of insulin on glucose production and utilization in lactating and nonlactating rats were performed. Glucose production rate was totally suppressed at 250 microU/ml of insulin in lactating rats and for plasma insulin concentrations higher than 500 microU/ml in nonlactating rats. Plasma insulin level inducing half-maximal inhibition of glucose production was decreased by 60% during lactation. The maximal effect of insulin on glucose utilization rate and glucose metabolic clearance rate was, respectively, increased 1.5- and 2.4-fold during lactation and was obtained for plasma insulin concentrations lower in lactating than in nonlactating rats (250 vs. 500 microU/ml). Insulin concentrations inducing half-maximal stimulation of glucose utilization and glucose metabolic clearance were decreased by 50% during lactation. In conclusion, this study has shown that insulin sensitivity and responsiveness of liver and peripheral tissues are improved at peak lactation in the rat.
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000096:biosynthesis; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D007774:Lactation / Q000502:physiology*; D008657:Metabolic Clearance Rate; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains
D001786:Blood Glucose; D007328:Insulin; D005947:Glucose