Distribution of GABAergic Neurons and Expression Levels of GABA Transporter 1 in the Rat Neocortex during the Neonatal Period after Perinatal Hypoxic Exposure.

The aim of this work was to study the distribution of GABA-expressing neurons and the expression level of GABA transporter 1 (GAT₁) in different layers of the rat neocortex in the neonatal period after perinatal hypoxia. Perinatal hypoxic exposure was carried out on neonatal day 2 for 1 h (7.8% O₂ in the breathing gas mixture). GABA and GAT₁ were localized immunohistochemically. The neocortical somatosensory area was studied on postnatal days 5 and 10 (P5, P10). It was found that at the early neonatal stage (P5), perinatal hypoxic exposure leads to an increase in the number of GABAergic inhibitory interneurons in all layers of the neocortex. By the end of the neonatal period (P10), their number in the cortical layers decreases, while in layer V, decreases significantly. In control animals, GAT₁ expression levels gradually increase throughout the neonatal period in all layers of the neocortex. After perinatal hypoxic exposure, GAT₁ expression decreases significantly, including in the neocortical layers, where the number of GABAergic neurons corresponds to the control value. These findings indicate that the exposure to acute perinatal hypoxia can lead to changes in GABAergic synaptic transmission in all layers of the neocortex at the end of the neonatal period. [ABSTRACT FROM AUTHOR]