title: Developmental regulation of inhibitory synaptic currents in the dorsal motor nucleus of the vagus in the rat.
abstract: Prior immunohistochemical studies have demonstrated that at early postnatal time points, central vagal neurons receive both glycinergic and GABAergic inhibitory inputs. Functional studies have demonstrated, however, that adult vagal efferent motoneurons receive only inhibitory GABAergic synaptic inputs, suggesting loss of glycinergic inhibitory neurotransmission during postnatal development. The purpose of the present study was to test the hypothesis that the loss of glycinergic inhibitory synapses occurs in the immediate postnatal period. Whole cell patch-clamp recordings were made from dorsal motor nucleus of the vagus (DMV) neurons from postnatal days 1-30, and the effects of the GABAAreceptor antagonist bicuculline (1-10 μM) and the glycine receptor antagonist strychnine (1 μM) on miniature inhibitory postsynaptic current (mIPSC) properties were examined. While the baseline frequency of mIPSCs was not altered by maturation, perfusion with bicuculline either abolished mIPSCs altogether or decreased mIPSC frequency and decay constant in the majority of neurons at all time points. In contrast, while strychnine had no effect on mIPSC frequency, its actions to increase current decay time declined during postnatal maturation. These data suggest that in early postnatal development, DMV neurons receive both GABAergic and glycinergic synaptic inputs. Glycinergic neurotransmission appears to decline by the second postnatal week, and adult neurons receive principally GABAergic inhibitory inputs. Disruption of this developmental switch from GABA-glycine to purely GABAergic transmission in response to early life events may, therefore, lead to adverse consequences in vagal efferent control of visceral functions.
authors.affiliation: Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania.
authors.forename: Caitlin A
authors.identifier: 0000-0002-7988-8406
authors.initials: CA
authors.lastname: McMenamin
authors.affiliation: Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania.
authors.forename: Laura
authors.initials: L
authors.lastname: Anselmi
authors.affiliation: Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania.
authors.forename: R Alberto
authors.initials: RA
authors.lastname: Travagli
authors.affiliation: Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania knb13@psu.edu.
authors.forename: Kirsteen N
authors.identifier: 0000-0002-5062-3703
authors.initials: KN
authors.lastname: Browning
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001640:Bicuculline / Q000494:pharmacology; D058787:GABA-A Receptor Antagonists / Q000494:pharmacology; D018684:Glycine Agents / Q000494:pharmacology; D007150:Immunohistochemistry; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D008526:Medulla Oblongata / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D055369:Miniature Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000378:metabolism; D018009:Receptors, Glycine / Q000037:antagonists & inhibitors / Q000378:metabolism; D013331:Strychnine / Q000494:pharmacology; D046509:Tissue Culture Techniques; D014630:Vagus Nerve / Q000166:cytology / Q000254:growth & development / Q000378:metabolism
chemical_list: D058787:GABA-A Receptor Antagonists; D018684:Glycine Agents; D011963:Receptors, GABA-A; D018009:Receptors, Glycine; D013331:Strychnine; D001640:Bicuculline
keywords: brain stem; development; glycine; vagus; γ-aminobutyric acid