Increased atherosclerotic lesion area in apoE deficient mice overexpressing bovine growth hormone

Human growth hormone (GH) excess is linked to increased cardiovascular morbidity and mortality. However, little is known about the effect of GH excess on atherosclerosis. We developed a new mouse model to assess the hypothesis that GH overexpression accelerates atherosclerotic lesion formation. apoE−/− mice were crossed with bovine GH (bGH) transgenic mice to yield apoE−/− mice overexpressing bGH (apoE−/−/bGH). The mice were fed either standard or Western diet. At 22 weeks, atherosclerotic lesion area of thoracic aorta was larger in apoE−/−/bGH mice compared with littermate apoE−/− mice fed either diet (standard: +161 ± 50%, Western: +430 ± 134%). Aortic sinus lesions were more severe in apoE−/−/bGH mice fed standard diet compared with littermate apoE−/− mice. apoE−/−/bGH mice had lower (VLDL + LDL)/HDL ratios compared with littermate apoE−/− mice, while systolic blood pressure was higher in apoE−/−/bGH mice, irrespective of diet. The levels of serum amyloid A and hepatic CRP mRNA were higher in apoE−/−/bGH mice than in littermate apoE−/− mice. In conclusion, this study shows that excess GH augments the development of atherosclerosis in apoE−/− mice. The mechanisms could be direct effects of GH on cellular processes in the vessel wall or the result of concomitant processes such as hypertension or a general inflammatory state.