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Evidence for glycinergic respiratory neurons: Bötzinger neurons express mRNA for glycinergic transporter 2
Author(s) -
Schreihofer Ann M.,
Stornetta Ruth L.,
Guyenet Patrice G.
Publication year - 1999
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19990517)407:4<583::aid-cne8>3.0.co;2-e
Subject(s) - glycine receptor , gabaergic , biology , glutamate decarboxylase , strychnine , medulla oblongata , neuroscience , inhibitory postsynaptic potential , in situ hybridization , neurotransmitter , gamma aminobutyric acid , glycine , microbiology and biotechnology , central nervous system , biochemistry , messenger rna , receptor , amino acid , gene , enzyme
Bötzinger (BÖTZ) neurons in the rostral ventrolateral medulla fire during the late expiratory phase of the respiratory cycle. These cells inhibit phrenic motor neurons and several types of respiratory neurons in the medulla oblongata. BÖTZ cells produce a fast, chloride‐mediated inhibition of their target neurons, but the neurotransmitter used by these cells has not been determined. In the present study, we examine whether γ‐aminobutyric acid (GABA) or glycine could be the inhibitory neurotransmitter of BÖTZ cells. In chloralose‐anesthetized rats, we individually filled 20 physiologically characterized BÖTZ neurons with biotinamide by using a juxtacellular labeling method. Medullary sections containing the labeled BÖTZ neurons were processed for in situ hybridization by using digoxigenin‐labeled riboprobes for glutamic acid decarboxylase isoform 67 (GAD67), a marker for GABAergic neurons, or for glycine transporter 2 (GLYT2), a marker for glycinergic neurons. All BÖTZ cells examined contained GLYT2 mRNA (n = 10), whereas none had detectable levels of GAD67 mRNA (n = 10). For a positive control, 12 GABAergic neurons in the substantia nigra pars reticulata also were recorded and filled with biotinamide in vivo. Most of these cells, as expected, had detectable levels of GAD67 mRNA (11 out of 12). These results demonstrate that the juxtacellular labeling method can be combined with in situ hybridization to identify physiologically characterized cells with probable GABAergic or glycinergic phenotypes. Furthermore, these data suggest that BÖTZ neurons use the neurotransmitter glycine and not GABA to provide widespread inhibition of respiratory‐related neurons. J. Comp. Neurol. 407:583–597, 1999. © 1999 Wiley‐Liss, Inc.