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Localization of components of glycinergic synapses during rat spinal cord development
Author(s) -
Colin I.,
Rostaing P.,
Augustin A.,
Triller A.
Publication year - 1998
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(19980831)398:3<359::aid-cne5>3.0.co;2-z
Subject(s) - glycine receptor , gephyrin , postsynaptic potential , biology , inhibitory postsynaptic potential , spinal cord , postsynaptic density , glycine , synaptogenesis , microbiology and biotechnology , neuroscience , receptor , biochemistry , amino acid
The sequence of events leading to the chemical matching of presynaptic neurotransmitters and postsynaptic transmitter receptors is investigated here in vivo for the spinal glycine receptor (GlyR) by using immunocytochemical methods. In the ventral horn of adult rat spinal cord, GlyRs are only present at glycinergic postsynaptic differentiations where they are stabilized by the associated protein gephyrin. With quantitative confocal microscopy, we found that gephyrin is detected before GlyRs at embryonic day (E)13–E14 and at E15, respectively, inside the cytoplasm and at plasmalemmal loci. Around the time of birth, the number of cell surface gephyrin‐immunoreactive (‐IR) spots exceeds that of GlyR. They first match 10 days after birth. The densities of postsynaptic gephyrin‐ and GlyR‐IR were quantified between birth and the adult stage with post‐embedding immunogold staining. Immunostaining for gephyrin and GlyR was not detected in the extrasynaptic membrane. The density of staining in postsynaptic membrane increased progressively with development. The inhibitory amino‐acid content of the presynaptic terminal boutons opposed to gephyrin‐IR sites was also analyzed. In the newborn, postnatal day 10, and adult, more than 90% of these boutons were immunostained for glycine. As seen with serial sections, 38% and 51.2% of the terminals also contained γ‐aminobutyric acid (GABA) in neonate and adult, respectively. These data indicate that around the time of birth, most glycine‐containing boutons, some also containing GABA, are opposed to gephyrin‐IR postsynaptic densities, whereas GlyRs are not present. Our results suggest that gephyrin determines subsynaptic loci on the plasma membrane where GlyR will subsequently accumulate. J. Comp. Neurol. 398:359–372, 1998. © 1998 Wiley‐Liss, Inc.