[Cross-regulation between olfaction and energy homeostasis in obesity and type 2 diabetes: from mouse models to humans].

This review highlights the crucial role of olfaction in regulating energy homeostasis. Neurons in the olfactory system stimulate the limbic and hedonic pathways involved in food-related behaviors. These neurons are modulated by the body's energy metabolism status, which they, in turn, help to regulate. Olfactory sensitivity is reduced in obesity, while bariatric surgery restores olfactory function. In type 2 diabetes, the onset of olfactory dysfunction is predictive of cognitive decline. Finally, in a mouse model of obesity, local activation of glucagon-like peptide 1 (GLP-1) and its receptors in the olfactory bulb -the main brain structure responsible for encoding odorsleads to improved glycemic control and regulation of food intake. Activation of this new neurometabolic pathway connecting the olfactory system to the pancreas leads to increased insulin secretion and sensitivity to this hormone.