title: Excitatory and inhibitory synaptic function in the rostral nucleus of the solitary tract in embryonic rat.
abstract: The embryonic development of synapses in the rostral nucleus of the solitary tract (rNST) was investigated in rat to determine when synapses begin to function. Using a brain slice preparation we studied appearance of synaptic receptors on second order rNST neurons and investigated the development of postsynaptic responses elicited by afferent nerve stimulation. Prenatal excitatory and inhibitory synaptic responses were recorded as early as E14. Glutamatergic and GABAergic postsynaptic responses were detected as early as E16. Both NMDA and AMPA receptors contributed to glutamatergic postsynaptic responses. GABAergic postsynaptic responses resulted primarily from activation of GABA(A) receptors. However, functional GABA(C) receptors were also demonstrated. A glycinergic postsynaptic response was not found although functional glycine receptors were demonstrated at E16. Solitary tract (ST) stimulation-evoked EPSCs, first detected at E16, were eliminated by glutamate receptor antagonists. ST-evoked IPSPs, also detected at E16, were eliminated by GABA(A) receptor antagonist. Thus, considerable prenatal development of rNST synaptic connections occurs and this will ensure postnatal function of central taste processing circuits.
authors.affiliation: Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI 48109-1078, USA.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Suwabe
authors.forename: Charlotte M
authors.initials: CM
authors.lastname: Mistretta
authors.forename: Robert M
authors.initials: RM
authors.lastname: Bradley
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000196:embryology / Q000502:physiology; D064026:Calbindins; D003627:Data Interpretation, Statistical; D004558:Electric Stimulation; D047108:Embryonic Development; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D005260:Female; D007150:Immunohistochemistry; D008564:Membrane Potentials / Q000502:physiology; D016900:Neurofilament Proteins / Q000378:metabolism; D009473:Neuronal Plasticity / Q000502:physiology; D018408:Patch-Clamp Techniques; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D018009:Receptors, Glycine / Q000819:agonists; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D017552:Solitary Nucleus / Q000166:cytology / Q000196:embryology* / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D013649:Taste / Q000502:physiology
chemical_list: D064026:Calbindins; D016900:Neurofilament Proteins; D018009:Receptors, Glycine; D064030:S100 Calcium Binding Protein G