Dietary preferences in monosodium glutamate-lesioned rats: age-variable influence of hypothalamic neuropeptide Y

In this study, we measured hypothalamic neuropeptide Y (NPY) and the food preference in weanling and adult monosodium glutamate (MSG)-lesioned and control rats. The MSG lesion was induced by three subcutaneous injections (4 g/kg body wt) during the first week of life of the rats. All treated and control weanling rats strongly preferred a high carbohydrate (HC) diet to a high fat (HF) diet. Adult control rats ate 60% more HF diet (P < 0.001) and 25% less HC diet (P < 0.01) than MSG-treated rats. At weaning and in adulthood, NPY concentrations in MSG-rats were markedly lower in the arcuate and paraventricular nuclei (P < 0.01 or less) than in control rats. The MSG treatment did not affect carbohydrate preference observed at weaning. It was associated with a limited development of fat appetite in adulthood. NPY could influence the dietary preferences more in adulthood, likely when all neuropeptidergic systems are mature.