Distribution of GABAergic Neurons in the Nuclei of the Pneumotaxic Center in the Early Postnatal Period in Health and Prenatal Insufficiency of the Serotoninergic System in Rats

The aim of the present work was to study the distribution of GABAergic neurons in structures of the pneumotaxic center (medial subnucleus of the parabrachial complex and the Kölliker–Fuse nucleus) in health and in conditions of serotoninergic system insufficiency during the prenatal period of development in Wistar rats. Endogenous serotonin content was decreased in fetuses by inhibition of tryptophan hydroxylase with parachlorophenylalanine, which was given to females on day 16 of pregnancy. Specimens from the pons from experimental and control (intact) rat pups were investigated at early postnatal (days 5, 10, and 12) and juvenile (day 20) ages. Groups of 5–6 experimental and control rat pups were used at each time point. GABAergic neurons were detected using antibodies to its synthetic enzyme glutamate decarboxylase (GAD67). The results showed that the Kölliker–Fuse nucleus contained a population of GABAergic neurons during the early periods of postnatal development, the numbers of cells in this population persisting to juvenile age. The medial subnucleus of the parabrachial complex contained an insignificant number of GABAergic neurons at the early time points, with a slight increase by juvenile age, though neurons continued to give weak immune reactions. Serotonin deficiency in structures of the pneumotaxic center led to decreases in the number of GABAergic neurons and decreases in the numbers of GABAergic synapses and their accumulations. The decrease in serotonin during the prenatal period could induce impairments of inhibitory afferentation of the nuclei of the pneumotaxic center and changes in local inhibitory GABAergic networks in its nuclei, which could result in impairments to inhibitory processes in the structures of this center. © 2015, Springer Science+Business Media New York.