Objective - to compare the reaction of rat olfactory bulb astrocytes to capsaicin administration at different stages of postnatal ontogenesis. Materials and methods. On serial paraffin sections of the olfactory bulbs of 70 male Wistar rats aged 30 to 240 days, astrocytes and mature neurons were detected using GFAP and NeuN markers. NeuN was demonstrated in the perinuclear cytoplasm and nucleus of mature neurons, glial fibrillary acidic protein (GFAP) of astrocytes - in the cytoplasm and astrocyte processes. The numerical density of mature neurons and astrocytes (pcs/ mm2), as well as the average area of astrocyte processes (μm2) were assessed in norm and after neurotoxic exposure to subcutaneous administration of capsaicin in rats of different age groups. Results. Postnatal changes in the studied microstructural parameters of the olfactory bulb in rats were normally observed from 30 to 180 days. In adulthood, stabilization of both the numerical density of neurons and astrocytes, and the average area of the processes of astrocytes were observed. It was found that neurotoxic exposure caused neuronal death and an increase in the numerical density of astrocytes in different layers of olfactory bulb, caused by a response to damage. More profound microstructural changes in the primary and secondary neurogenic niches were noted. Conclusions. Neuronal death was maximal at 15-30 days and reactive gliosis - at 30 days after neurotoxin administration. In infantile rats the intensity of gliosis decreased by the 60th day of the experiment, in adulthood gliosis did not tend to decrease.