Olfactory Dysfunction in Obesity and Type 2 Diabetes

• Published in: Journal of evolutionary biochemistry and physiology Vol. 60; no. 3; pp. 1144 - 1162
• Main Authors: Bigdai, E. V., Zuikova, A. A., Pozdnyakov, A. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.05.2024; Springer Nature B.V
• Subjects: Animal Physiology; Appetite; Biochemistry; Biomedical and Life Sciences; Chemical stimuli; Diabetes; Diabetes mellitus (non-insulin dependent); Energy balance; Evolutionary Biology; Food; Food consumption; Food intake; Food quality; Food selection; Hypothalamus; Information processing; Insulin; Life Sciences; Metabolic disorders; Metabolism; Obesity; Odor; Olfaction; Olfactory bulb; Olfactory perception; Olfactory stimuli; Quality of life; Receptor mechanisms; Reviews; Satiety; Sensory evaluation; Sensory integration; Sensory neurons; Sensory properties; type 2 diabetes mellitus; olfactory epithelium; olfactory bulb; olfactory dysfunction; intranasal insulin; obesity
• ISSN: 0022-0930; 1608-3202
• DOI: 10.1134/S0022093024030220

The article surveys literature data on a close relationship between energy balance and the sense of smell. Olfaction is one of the main modalities for hedonic food evaluation. Odor is one of the most important sensory signals, which predicts food quality and plays a key role in food selection and consumption. Appetite can be stimulated by a variety of factors, but the leading role belongs to olfactory cues (tasty smells) and hormone levels that signal hunger or satiety. Olfactory perception is subject to hormonal modulation. In this regard, a special focus in the article is on the modulating function of insulin. Insulin, one of the main metabolic hormones, controls food intake and has an anorexigenic effect at the level of not only the hypothalamus but also the olfactory pathway, being particularly strong in the olfactory bulb. It is the olfactory bulb where the rate of insulin transport is two to eight times higher than in other parts of the brain, and that contains highest levels of insulin and insulin receptor kinase. Thus, insulin is not only able to penetrate to the site of olfactory information processing but does it quickly. Insulin and its receptors localize in the olfactory epithelium, in mature olfactory sensory neurons. Therefore, insulin influences the primary stage of odorous molecule perception, odor detection, which occurs at the level of the olfactory epithelium. In obesity and type 2 diabetes, the sense of smell is impaired up to its complete loss, worsening the quality of life in such patients. The article also addresses the effectiveness of intranasal insulin administration for restoring olfactory function in metabolic disorders and other diseases.