Insulin during infancy attenuates insulin-induced hypoglycemia in adult male rats.
To examine whether insulin during infancy affects later glucose regulation, 60 rat pups of both sexes were injected daily on postnatal Days 9-20 with either insulin (2 or 8 U/kg), 2-deoxy-D-glucose (2DG; 200 or 400 mg/kg), or saline. Two hours postinjection on Day 15, pups given insulin were hypoglycemic and pups given 2DG were hyperglycemic; both groups were normoglycemic at 6 h. The two insulin doses produced similar long-term effects, as did the 2DG doses, so doses were combined to make single insulin and 2DG groups. On Day 44, baseline plasma glucose for rats given insulin or 2DG during infancy was below saline control levels (111.3, 114.5, and 120.7 mg/dL, respectively, p < 0.05). On Days 60 and 62, plasma glucose was assessed 2 h after injection of 3 U/kg insulin; food was allowed between the insulin injection and the glucose test on only one of these days. When food was present after injection of insulin, the early treatments did not influence either amount of food ingested or plasma glucose levels. When food was withheld, however, males given insulin before weaning maintained a higher plasma glucose than did males given 2DG or saline before weaning (67.4, 40.1, and 16.4 mg/dL, respectively, p < 0.01); females were unaffected by the early treatment. Postweaning body weights did not differ from control values for rats given early insulin or 2DG. On Day 72, there were no effects of early treatment on plasma insulin, plasma glucose, liver weight, or kidney weight. These results suggest that preweaning exposure to insulin attenuates the hypoglycemia of adult males given insulin without food.
Thompson
C I
CI
Department of Psychology, Wabash College, Crawfordsville, IN 47933, USA. ThompsoC@Wabash.edu
Munford
J W
JW
Ryker
R M
RM
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000502:physiology; D005260:Female; D007003:Hypoglycemia / Q000139:chemically induced*; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley
D001786:Blood Glucose; D007328:Insulin