CAFETERIA DIET-INDUCED OBESE RATS HAVE AN INCREASED SOMATOSTATIN PROTEIN-CONTENT AND GENE-EXPRESSION IN THE PERIVENTRICULAR NUCLEUS

In human obesity, spontaneous and GRF stimulated growth hormone secret ion have been shown to be blunted. We used cafeteria diet fed obese ra ts as a model to study the central mechanisms involved in growth hormo ne secretion changes which are observed in obesity. We analysed somato statin messenger RNA and protein levels in the hypothalamic periventri cular nucleus of the rats by non radioactive in situ hybridization and immunocytochemistry respectively, The optical density of somatostatin mRNA, measured by a computerized image system, was significantly high er in cafeteria diet fed rats (1014 +/- 87 vs 444 +/- 45; p < 0.05). T he integrated optical density of somatostatin protein was also signifi cantly higher in cafeteria rats compared to the control rats (222 +/- 36 vs 114 +/- 24; p < 0.05). In conclusion, cafeteria diet induced obe se rats have a higher somatostatin biosynthesis in the periventricular nucleus. Further studies are needed to establish the possible link of this increased somatostatin gene expression with the decreased GH pro duction. (C) 1997, Editrice Kurtis.