Expression of GABAergic and glutamatergic neurons after olfactory stimulation in the mouse piriform cortex during postnatal development

Introduction. The control of the survival and differentiation of immature neurons in the piriform cortex of rodents, which can transform into GABAergic and/or glutamatergic neurons under the influence of olfactory stimuli, is an important factor for prevention of neurological dysfunction. The aim of the study was to assess the expression of GABAergic and glutamatergic neurons after olfactory stimulation (OS) in the mouse piriform cortex during postnatal development. Materials and methods. The study was carried out on CD1 male mice aged 2 (n = 20; group Р2), 21 (n = 20; group Р21) and 60 (n = 20; group Р60) days. The mice were presented with olfactory stimuli, and brain tissue was collected for immunohistochemical analysis 2 hours, 24 hours and 7 days later, to assess glutamic acid decarboxylase 67 (GAD67) and vesicular glutamate transporter 1 (VGlut1) expression. Results. OS in the group P2 animals increased VGlut1 expression in the first 2 hours after OS, followed by a return to baseline level by day 7, while GAD67 expression showed no significant changes. The animals in group P21 showed increased expression of VGlut1 and GAD67 two hours after OS, followed by a significant decrease. Expression of both molecules demonstrated a statistically significant increase in the group P60 animals 24 hours after OS, and remained at the same level on day 7 (GAD67) or returned to baseline levels (VGlut1). Conclusion. OS increases the number of GABAergic (GAD67+) и glutamatergic (VGlut1+) neurons in the piriform cortex (P60). The predominance of glutamatergic effects is a possible mechanism for associative memory cell recruitment.