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δ 1‐OPIOID receptor‐mediated controlofacetylcholine (ACh) release in human neocortex slices
Author(s) -
Feuerstein T.J.,
Albrecht C.,
Wessler I.,
Zentner J.,
Jackisch R.
Publication year - 1998
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/s0736-5748(98)00086-0
Subject(s) - acetylcholine , enkephalin , chemistry , cholinergic , agonist , neocortex , somatostatin , endocrinology , neuroscience , medicine , opioid , receptor , biology , biochemistry
In slices of human neocortex, prelabelled with [ 3 H]‐choline, the release of [ 3 H]‐acetylcholine reflects the evoked release of endogenous acetylcholine whichwaselicited by the same electrical stimulation paradigm. [ 3 H]‐Acetylcholine releasewasdepressed by the δ ‐opioid receptor agonist d ‐Pen 2 ‐ d ‐Pen 5 ‐enkephalin. When the nerve endings were depolarized byelevatingextracellular potassium the evoked [ 3 H]‐acetylcholine release was similarlydepressed by d ‐Pen 2 ‐ d ‐Pen 5 ‐enkephalin in theabsence, but notin the presence, of tetrodotoxin which blocks action potential propagation.Therefore, the δ ‐opioid receptor inhibiting [ 3 H]‐acetylcholine release should notbe located tocholinergic nerve terminals, but rather to interneurons. The somatostatin 2 receptorpartial agonist octreotide per se did not influence action potential‐evoked [ 3 H]‐acetylcholine release, but prevented the inhibition of release of [ 3 H]‐acetylcholine by d ‐Pen 2 ‐ d ‐Pen 5 ‐enkephalin.Similarly, the δ 1 ‐opioid receptor antagonist 7‐benzylidenenaltrexon perse did notinfluence [ 3 H]‐acetylcholine release, but prevented of the inhibition ofrelease by d ‐Pen 2 ‐ d ‐Pen 5 ‐enkephalin. From the presentfindings we conclude : (1) The evoked release of [ 3 H]‐acetylcholine from humanneocortex slices reflects the release of endogenous acetylcholine.(2) It is inhibited in an indirectmanner by opioid receptors of the δ 1 ‐subtype,which (3) are not localized oncholinergic axon terminals but on soma and dendrites ofsomatostatin‐containing interneurons,where they inhibit somatostatin release. (4) Theseinterneurons innervate cholinergic nerveendings in the human neocortex and appear to facilitateacetylcholine release via somatostatin 2 receptors.