Behaviour and hormonal status in healthy rats on a diet rich in Maillard reaction products with or without solvent extractable aroma compounds.

Maillard reaction products (MRPs) are generated upon thermal processing of foods, modifying their colour and flavour. We asked whether aroma compounds generated via Maillard-type reactions modulate the in vivo effects of MRP-rich diets (MRPD). Male Wistar rats were fed for 3weeks either with a standard rat chow, an aroma compounds containing MRPD comprising 25% bread crust, or an aroma-extracted MRPD. In contrast to standard rat chow, consumption of MRPDs affected glucose control, induced hyper-leptinemia and hyper-adiponectinemia. Plasma adipokines were significantly higher in rats on aroma containing MRPD in comparison with those consuming aroma-extracted MRPD. Consumption of both MRPDs significantly increased the expression of the insulin receptor in the olfactory bulb, and mildly in the hypothalamus. Administration of the aroma containing MRPD significantly increased the leptin receptor expression in the olfactory bulb, and in the hypothalamus. Under both MRPDs, strong expression of c-fos indicated an increased neuronal activity in the olfactory bulb. Neuronal activity in brain areas involved in the central regulation of food intake and energy homeostasis was more pronounced in rats fed by the aroma containing MRPD. In conclusion, short-term consumption of a MRPD fortified with bread crust, particularly if containing solvent extractable volatile aroma compounds, affected the leptin-induced central signalling of anorexigenic/orexigenic hormones, and the neuronal activity in the central nervous system. Behavioural changes and altered glucose control were more evident in rats on the aroma containing MRPD. Our data suggest that volatile aroma compounds in foods might affect endocrine signalling and neuronal regulation of metabolism.