Summary
Preobese “fatty” rats have been identified by their lower rectal temperature. Of 51 pups born from matings of heterozygote (Fafa) parents, 16 had low rectal temperatures from day 16 onward (34.6±0.2° C v 35.4±0.3° C) and all subsequently became obese. No animal with the higher ‘normal’ rectal temperature developed obesity. Hepatic fatty acid synthesis (preobese 0.6±0.1; lean 0.6±0.1 μmol/ g/h), hepatic glucose-6-phosphate dehydrogenase activity (G6PDH) (preobese 0.68±0.07; lean 0.71 ±0.03 μmol/g/min) and serum insulin (preobese 64 ±2; lean 58±4 μU/ml) were unchanged in 18 day preobese, suckling fafa rats. 3 days after weaning hepatic lipogenesis (preobese 25.3±2.0; lean 5.4±0.7 μmol/g/h) and G6PDH activity (preobese 4.5±0.5; lean 0.90±0.05 μmol/g/min) had increased in both lean and preobese rats although the values attained in preobese rats were significantly greater than in lean rats. When weaning was delayed there was no enhancement in lipogenesis, G6PDH or serum insulin in the preobese rat. The results suggest that the primary genetic defect in ‘fatty’ rats is not related to the increase in lipogenesis or serum insulin but may reflect a defective thermogenic process.
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Godbole, V., York, D.A. & Bloxham, D.P. Developmental changes in the fatty (fafa) rat: Evidence for defective thermogenesis preceding the hyperlipogenesis and hyperinsulinaemia. Diabetologia 15, 41–44 (1978). https://doi.org/10.1007/BF01219327
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DOI: https://doi.org/10.1007/BF01219327