Strain variability in Zucker rats affects their response to oral oleoyl-estrone.
There is a considerable variability in the responses of Zucker fa/fa rats in metabolic studies, which could not be solely attributed to the leprfa mutation. In order to fathom the extent of this variability, we compared the response to oleoyl-estrone (OE), a powerful lipid-mobilising agent, of two strains of Zucker lean and obese rats: Harlan (H) and Charles River (CR). Rats were given an oral gavage of 10 micromol/day/kg of OE in sunflower oil, and were compared with oil-receiving controls. Body composition, energy and water balances, and plasma parameters were studied after 10 days of treatment. H rats showed a higher water turnover than CR rats; OE treatment reduced water intake, partly compensated by metabolic water, and decreased stool water. H rats accrued more cholesterol than CR animals, which showed higher cholesterolaemia. OE facilitated cholesterol disposal in lean (CR and H) and H obese rats. CR rats had higher body and liver lipids than H animals. No differences in energy balance were found. Insulin decrease following OE treatment was greater in lean CR than in H rats, but this trend was reversed in the obese rats, lacking effective responses to leptin. The red cell glucose compartment was smaller in H than in CR rats; the higher insulin levels in H rats may be partly responsible for that difference. Obese H maintained glycaemia (and liver glycogen) with higher insulin levels than CR animals. The extent to which the leprfa mutation affects the responses of Zucker fa/fa rats could not be singled out unless the metabolic environment of the batch used is known. This variability must be taken into account when developing a metabolic or hormonal study in which this model of obesity is used.
Díaz-Silva
M
M
Centre Especial de Recerca en Nutrició i Ciència dels Aliments, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
Grasa
M M
MM
Blay
M
M
Fernández-López
J A
JA
Remesar
X
X
Alemany
M
M
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001823:Body Composition; D001834:Body Water / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D004326:Drinking; D004435:Eating; D004734:Energy Metabolism; D004970:Estrone / Q000008:administration & dosage* / Q000031:analogs & derivatives*; D005243:Feces / Q000737:chemistry; D007328:Insulin / Q000097:blood; D008055:Lipids / Q000032:analysis / Q000097:blood; D008099:Liver / Q000737:chemistry; D009154:Mutation; D009765:Obesity / Q000097:blood / Q000378:metabolism; D009829:Oleic Acids / Q000008:administration & dosage*; D010938:Plant Oils; D051381:Rats; D011924:Rats, Zucker / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics; D054411:Receptors, Leptin; D013045:Species Specificity; D000074242:Sunflower Oil; D015431:Weight Loss
D001786:Blood Glucose; D007328:Insulin; D008055:Lipids; D009829:Oleic Acids; D010938:Plant Oils; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D000074242:Sunflower Oil; D004970:Estrone; C108709:oleoyl-estrone; D002784:Cholesterol