Evidence for strychnine-sensitive glycine receptors in human amygdala.
Recent studies suggested the existence of strychnine-sensitive glycine-receptors in mammalian amygdala. In the present study, we investigated the amino acid concentrations as well as immunocytochemical and pharmacological properties of glycine-receptors in fresh human amygdala tissue obtained from epilepsy surgery. High pressure liquid chromatography revealed a considerable amount of glycine and its precursors and glycine-receptors agonists L-serine and taurine in this tissue. Immunohistochemistry using the monoclonal antibody mAb4a, recognizing an epitope common to all alpha-subunit variants of glycine receptors, displayed a specific labeling at the soma and on proximal dendrites of mostly tripolar, large-sized neurons of irregular distribution and arrangement. To elucidate the pharmacological properties of the glycine-receptors found slices of human amygdala were preloaded with [(3)H]-choline and superfused. Glycine induced an overflow of [(3)H]-acetylcholine, which was inhibited by strychnine in a concentration-dependent manner. Furthermore, the glycine-induced release of [(3)H]-acetylcholine was significantly inhibited by furosemide, indicating glycine-induced actions to be attributed to chloride channels. These actions of glycine were not influenced by MK-801, D-CP-Pene or bicuculline. Thus, the effects of glycine did not seem to be mediated through NMDA or GABA receptors. These observations indicate that strychnine-sensitive, chloride-conducting glycine receptors, which elicit the release of [(3)H]-acetylcholine, are present at the soma and on proximal dendrites of neurons in human amygdala. It is hypothesized that glycine may display a regulatory role in amygdaloid functions, probably via cholinergic interneurons.
Dudeck
O
O
Abteilung für Allgemeine Neurochirurgie, Neurozentrum, Breisacherstrasse 64, 79106, Freiburg, Germany.
Lübben
S
S
Eipper
S
S
Knörle
R
R
Kirsch
M
M
Honegger
J
J
Zentner
J
J
Feuerstein
T J
TJ
D000109:Acetylcholine / Q000096:biosynthesis; D000328:Adult; D000679:Amygdala / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002851:Chromatography, High Pressure Liquid; D004833:Epilepsy, Temporal Lobe / Q000378:metabolism; D005998:Glycine / Q000097:blood / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008875:Middle Aged; D019579:Neocortex / Q000378:metabolism; D021122:Protein Subunits / Q000378:metabolism; D051381:Rats; D018009:Receptors, Glycine / Q000378:metabolism*; D012160:Retina / Q000166:cytology; D012694:Serine / Q000378:metabolism; D013331:Strychnine / Q000494:pharmacology*; D013654:Taurine / Q000378:metabolism; D014018:Tissue Distribution; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D021122:Protein Subunits; D018009:Receptors, Glycine; D013654:Taurine; D012694:Serine; D005680:gamma-Aminobutyric Acid; D013331:Strychnine; D000109:Acetylcholine; D005998:Glycine