Nicotinamide-streptozotocin-induced type 2 diabetes mellitus leads to impaired function of the main olfactory system in male WISTAR ra

Patients with diabetes mellitus have a decreased olfactory function compared to healthy individuals. Hyposmia is more common in type 2 diabetes (DM2) and is characterized by a decreased ability to recognize odors, impaired olfactory memory, which reduces the quality of life of patients. The mechanisms of hyposmia require studies in animal models, but no such studies have been performed in most commonly used animal models of DM2. The aim of the present study was to investigate olfactory function in the model of nicotinamide-streptozotocin-induced DM2 in rats using widely used behavioral tests of food search performance by smell and olfactory preference. The model of DM2 in male rats showed a decrease in performance and an increase in the time spent on searching for food objects by smell, compared to the control group, which suggests that diabetic animals develop hyposmia. The results of the test for differentiation of the pheromonal mimetic isovaleric acid from bio-indifferent odorants showed no differences between the groups. These results indicate that the development of DM2 in adult rats predominantly affects the functioning of the main olfactory system rather than the functioning of the additional system responsible for the perception of pheromones and pheromonal mimetics.