title: Nutritional regulation of IGF-I expression during brain development in mice.
abstract: Although brain injury induced by undernutrition during early life is well described, the mechanisms that mediate the effects of undernutrition on brain development are not known. IGF-I plays an important role in the stimulation of postnatal somatic and brain growth. We have shown that IGF-I overexpression in brain ameliorates the effects of undernutrition on early postnatal brain growth, and thus, we postulated that alterations in IGF-I expression or action mediate the pathogenesis of malnutrition-induced brain injury. To begin to address this issue we evaluated the influence of undernutrition on brain IGF-I expression during early postnatal development in mice. Undernutrition was induced in mice by separating half of the pups in each litter from their lactating dams for a defined period each day. Pups were killed at postnatal day (P) 7, P14, P21, and P28. The changes in IGF-I mRNA were quantified by ribonuclease protection assay. At P7 IGF-I mRNA abundance in undernourished animals was increased in cerebral cortex (223% of controls), but decreased in diencephalon (36% of controls). At P14, IGF-I mRNA abundance was increased in diencephalon (230% of controls). Although there were no other statistically significant alterations of IGF-I mRNA in undernourished mice, IGF-I abundance in the cerebral cortex appeared increased at P14 (142% of controls), and in cerebellum it was consistently but modestly decreased (78 and 59% of controls) from P7 to P21, respectively. We conclude that nutrition regulates murine brain IGF-I expression in a developmentally specific fashion that is dependent on the region of expression. Importantly, the influence of undernutrition on IGF-I expression is markedly different in the brain than in liver, where nutritional deficiency profoundly decreases IGF-I expression. We speculate that the relative preservation of or increases in regional brain IGF-I expression explain, at least in part, the well-known finding that undernutrition during early postnatal development has less marked growth-retarding effects on the brain than it does on the soma.
authors.affiliation: Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7220, USA.
authors.forename: A
authors.initials: A
authors.lastname: Calikoglu
authors.forename: A
authors.initials: A
authors.lastname: Karayal
authors.forename: A
authors.initials: A
authors.lastname: D'Ercole
mesh_terms: D000818:Animals; D001835:Body Weight; D001921:Brain / Q000196:embryology*; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009747:Nutritional Physiological Phenomena; D009929:Organ Size; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I