Fasting-induced increases in food hoarding are elevated in adult hamsters treated neonatally with monosodium glutamate (MSG).

Abstract

Despite the increased consumption of fast food, >80% of all food eaten occurs at home. In addition, hungry humans and fasted hamsters hoard more food than there non-hungry counterparts. Given the increasing prevalence of obesity, understanding the mechanisms underlying appetitive ingestive behaviors (foraging, food hoarding) may provide a new target for intervention beyond that more well-studied consummatory ingestive behavior (food intake). Neuropeptide Y (NPY) and agouti-related protein (AgRP) are two neuropeptides that play a role in both phases of ingestion in a variety of species. Central injections of either peptide increase food intake in laboratory rats and food hoarding in Siberian hamsters. The likely source of NPY and AgRP subserving these responses endogenously is NPY/AgRP synthesizing arcuate (Arc) neurons. Because fasting increases Arc NPY and AgRP synthesis in rats and Siberian hamsters and because fasting increases food hoarding in hamsters, we tested whether destruction of NPY/AgRP-producing Arc neurons by neonatal treatment with MSG blocks fasting-induced increases in food hoarding in adult Siberian hamsters. Surprisingly, food hoarding in MSG-treated animals was increased 100% more than controls with refeeding after a 56 h fast, with the greatest increase occurring during the first hour postfast. The underlying cause of this increase could be MSG-induced increased NPY receptors shown to occur in MSG-treated rats that also have an exaggerated NPY-induced increased food intake. These data suggest a similar increase in NPY receptors with MSG treatment in Siberian hamsters. This work was funded by NIH R01 DK 78358.