An animal model of gestational obesity and prediabetes: HISS-dependent insulin resistance induced by a high-sucrose diet in Sprague Dawley rats.

Abstract

This study developed an animal model of gestational obesity and prediabetes in Sprague Dawley rats using 35% sucrose supplementation (SS). Postprandially, insulin stimulates glucose uptake and nutrient partitioning via insulin-dependent action as well as hepatic insulin sensitizing substance (HISS) - dependent action. HISS is glycogenic in heart, kidney, and skeletal muscle (contrasting insulin's lipogenic actions in liver and adipose tissue) and is responsible for the vasodilatory action of insulin. Postprandial insulin sensitivity was quantified using the rapid insulin sensitivity test (RIST). Animals at 15-day gestation and virgin animals received SS for 8 weeks (with a 2-week recovery), 10 weeks, or 22 weeks. SS in pregnant and virgin rats eliminated HISS-dependent glucose uptake, resulting in compensatory hyperinsulinemia and resultant hypertriglyceridemia and obesity. In groups with SS for 8 weeks followed by a 2-week recovery, there was spontaneous partial recovery of HISS-dependent glucose uptake in virgins and complete recovery in pregnancy. The 10-week SS resulted in complete absence of HISS-dependent glucose uptake and produced a model of gestational obesity and prediabetes. The 22-week SS did not produce hyperglycemia or worsen hyperinsulinemia but did increase hypertriglyceridemia above 10-week SS. This substantiates the use of 10-week SS as a model of gestational obesity and (or) prediabetes, allowing further studies into treatments of gestational obesity and insulin resistance.