GABA- AND GLYCINE-IMMUNOREACTIVE SYNAPSES IN THE SPINAL CORD OF THE FROG
RANA TEMPORARIA
V. O. Adanina,1 J.-P. Rio,2 A. S. Adanina,1 J. Reperant,2 N. P. Vesselkin 1
1 I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, St. Petersburg, Russia,
and 2 Museum National d’Histoire Naturelle, Paris, France;
e-mail: Adanina@rambler.ru
Postembedding immunogold method was used to examine the distribution of gamma-aminobutyric acidand
glycine-immunoreactives synapses on the motoneurons and primary afferent axons in frog spinal cord. Analysis
of all labeled boutons on dendrites and somata of motoneurons showed that 7 % were labeled for GABA,
23 % only for glycine and approximately 70 % were immunoreactive for both GABA and glycine. These results
confirm the predominant role of glycine in postsynaptic inhibition of motoneuronal activity. Three populations
of synaptic boutons were found on primary afferent axons: GABA-immunoreactive (25 %), glycine-immunoreactive
(5 %) and the majority of the immunoreactive synapses exhibited colocalization of two inhibitory transmitters.
Greater proportion of axo-axonal synases was organized in synaptic triads. The possible roles of glycine
in the axo-axonal synapses on the primary afferent fibers are discussed.
Key words: GABA- and glycine-immunoreactive synapses, frog Rana temporaria, motoneurons, primary
afferent axons
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