Istituto di Ingegneria Biomedica     
Pacini G., Ahren M., Ahren B. Reappraisal of the intravenous glucose tolerance index for a simple assessment of insulin sensitivity in mice. In: American Journal of Physiology-Regulatory Integrative and Comparative Physiology, vol. 296 pp. R1316 - 24. American Physiological Society, 2009.
Mice are increasingly used in studies where measuring insulin sensitivity (IS) is a common procedure. Glucose clamp is labor intensive, cannot be used in large numbers of animals, cannot be repeated in the same mouse and has been questioned as a valid tool for IS in mice; thus, the minimal model with 50min-intravenous glucose (IVGTT) data was adapted in mice. However, specific software and particular ability is needed. Aim of this study was to establish a simple procedure for evaluating IS during IVGTT in mice (CSI). IVGTT (n=520) were performed in NMRI and C57BL/6J mice (20-25g). After glucose injection (1 g/kg), 7 samples were collected until 50 min for glucose and insulin measurements, analyzed with minimal model which provided the validated reference IS (SI). By using the regression CSI=alpha1+alpha2xKG/AUCD, IS was calculated in 134 control animals randomly selected (regression CSI vs. SI: r=0.66, p<0.0001) and yielded alpha1=1.93 and alpha2=0.24. KG is the slope of log(glucose5-20) and AUCD is the mean dynamic area under insulin curve in the IVGTT. By keeping fixed alpha1 and alpha2, CSI was validated in 143 control mice (4.7+/-0.2 min(-1)microU(-1)ml, virtually identical to SI: 4.7+/-0.3, r=0.89, p<0.0001; and in 123 mice in different conditions: transgenic, addition of neuropeptides, incretins, insulin (CSI: 6.0+/-0.4 vs. SI: 6.1+/-0.4, r=0.94, p<0.0001). In other 120 animals, CSI revealed its ability to segregate different categories, as SI does. This easily usable formula for calculating CSI overcomes many experimental obstacles and may be a simple alternative to more complex procedures when large numbers of mice or repeated experiments in the same animals are required. Key words: glucose tolerance, insulin resistance, glucose effectiveness, animal model.
URL: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=19211728
DOI: 10.1152/ajpregu.90575.2008
Subject Insulin resistance
Glucose effectiveness
Animal model
Pituitary adenylate cyclase-activating polypeptide
Glucagon-like peptide-1
Intravenous glucose tolerance test

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