Enkephalinergic nerve terminals target inhibitory interneurons in the rat hippocampus.
Using correlated light and electron microscopic preembedding enkephalin immunocytochemistry combined with post-embedding GABA immunogold staining, we found morphological evidence of a direct connection between the enkephalinergic and GABAergic systems in the rat hippocampus. Enkephalin-immunoreactive boutons were found to be presynaptic to GABA-immunoreactive postsynaptic profiles, establishing type 2 symmetrical synapses on GABA-positive cell bodies and dendritic shafts in strata radiatum and lacunosum moleculare of the CA1 region. Thirty-six percent of all studied postsynaptic targets (n = 40) were non-pyramidal, including all somatic (n = 7) and 47% of the dendritic (n = 13) postsynaptic targets. The remaining 64% consisted of pyramidal dendritic shafts and spines. These results support previous physiological experiments suggesting that the opioidergic system takes part in disinhibitory processes in the hippocampal formation.
Füzesi
M
M
Department of Anatomy and Histology, University of Veterinary Science, Budapest, Hungary.
Rácz
B
B
Eliás
B
B
Halasy
K
K
D000818:Animals; D001369:Axons / Q000648:ultrastructure; D003712:Dendrites / Q000648:ultrastructure; D004743:Enkephalin, Leucine / Q000032:analysis* / Q000502:physiology; D005260:Female; D006624:Hippocampus / Q000166:cytology* / Q000502:physiology; D007150:Immunohistochemistry; D007395:Interneurons / Q000502:physiology / Q000648:ultrastructure*; D008297:Male; D016253:Microscopy, Immunoelectron; D009411:Nerve Endings / Q000502:physiology / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000648:ultrastructure
D004743:Enkephalin, Leucine