Neuroanatomic relationships between the GABAergic and serotonergic systems in the developing human medulla

Abstract

Abstractγ-Amino butyric (GABA) critically influences serotonergic (5-HT) neurons in the raphé and extraraphé of the medulla oblongata. In this study we hypothesize there are marked changes in the developmental profile of markers of the human medullary GABAergic system relative to the 5-HT system in early life. We used single-and double-label immunocytochemistry and tissue receptor autoradiography in 15 human medullae from fetal and infant cases ranging from 15 gestational weeks to 10 postnatal months, and compared our findings with an extensive 5-HT-related database in our laboratory. In the raphé obscurus, we identified two subsets of GABAergic neurons using glutamic acid decarboxylase (GAD65/67) immunostaining: one comprised of small, round neurons; the other, medium, spindle-shaped neurons. In three term medullae cases, positive immunoflorescent neurons for both tryptophan hydroxylase and GAD65/67 were counted within the raphé obscurus. This revealed approximately 6% of the total neurons counted in this nucleus expressed both GAD65/67 and TPOH suggesting co-production of GABA by a subset of 5-HT neurons. The distribution of GABA A binding was ubiquitous across medullary nuclei, with highest binding in the raphé obscurus. GABA A receptor subtypes α1 and α3 were expressed by 5-HT neurons, indicating the site of interaction of GABA with 5-HT neurons. These receptor subtypes and KCC2, a major chloride transporter, were differentially expressed across early development, from mid-gestation (20wks) and thereafter. The developmental profile of GABAergic markers changed dramatically relative to the 5-HT markers. These data provide baseline information for medullary studies of human pediatric disorders, such as sudden infant death syndrome.

Developmental exposure to paracetamol causes biochemical alterations in medulla oblongata

“…During early human development several subtypes of GABA receptors are expressed through serotonergic system located in the medulla (Broadbelt et al, 2010). In our study, the level of γ-aminobutyric acid did not change significantly after administration of paracetamol, however, numerous studies show the anatomical relationships between serotonergic and GABAergic system.…”

Mapping of endogenous morphine‐like compounds in the adult mouse brain: Evidence of their localization in astrocytes and GABAergic cells

“…The staining observed on Western blot was blocked when incubation with the peptide was performed. In immunohistochemistry on mouse brain sections, no immunostaining was observed after a pre-incubation of the antibody with saturating concentration of the target protein (Broadbelt et al, 2010). …”

“…Anti-GAD65/67 antibodies recognize a specific band size of 65 kDa molecular weight on Western blot of human infant medulla lysate (Broadbelt et al, 2010). The staining observed on Western blot was blocked when incubation with the peptide was performed.…”

Brainstem Deficiency of the 14-3-3 Regulator of Serotonin Synthesis: A Proteomics Analysis in the Sudden Infant Death Syndrome

“…In addition, in the controls there were significant positive correlations between the 14-3-3 levels and 5-HT 1A receptor binding in the paragigantocellularis lateralis (correlation coefficient 0.99; p ϭ 0.010) and gigantocellularis (correlation coefficient 0.98; p ϭ 0.016), and a marginally significant correlation in the raphé obscurus (correlation coefficient 0.95; p ϭ 0.054) ( Table VI). The statistically significant correlations (p Ͻ 0.05) between 14-3-3 levels and 5-HT parameters in (18,20,54 the SIDS cases were not compelling to us because of the low correlation coefficients (Ͻ0.50), (Table VI). Stage 3, we used analyzed Western blotting data involving the gigantocellularis from an expanded Data set 4 with five additional SIDS cases and three additional acute controls accrued after the closure of the original Data set 4 (Table I).…”