Differential Linkage of Triglyceride and Glucose Levels on Rat Chromosome 4 in Two Segregating Rat Populations

The PD/Cub is a recently established model of the IRS. The BN.SHR4 congenic strain was derived by introgression of the chromosome 4 seg- ment of SHR origin (including the defective Cd36/Fat allele) onto the BN/Cub genetic back- ground. We investigated the linkage of metabolic and morphometric phenotypes (total body weight, OGTT, fasting serum levels of TG, FFA) on chromo- some 4 in two separate F2 rat populations: the PD/Cub x BN/Cub and PD/Cub x BN.SHR4 (total N = 243). In the PD/Cub x BN.SHR4 F2s, we found sig- nificant linkage for fasting TG levels (LOD = 3.26) and suggestive linkage for fasting glycaemia (LOD = 2.80) in the interval Il-6 n D4Bro1, i.e. the part of chromosome 4 of SHR origin in the BN.SHR4 con- genic. However, no linkage for fasting TG concen- trations, fasting glycaemia or any other followed parameter was found in the second, PD/Cub x BN/Cub F2. The differential linkage of TG and glu- cose levels to the centromeric part of rat chromo- some 4q in the studied F2s points to the importance of this region for the lipid and carbohydrate metab- olism at the specific age (10 months) and diet (stan- dard chow) combination. The Cd36/Fat and Il-6 genes are the preliminary positional candidates for the observed effect.