![]() |
|
|
Vol. 280, Issue 2, 650-655, 1997
Department of Pharmacology, Institute of Experimental Medicine,
Hungarian Academy of Sciences, Budapest, Hungary
The effects of selective nicotinic acetylcholine (ACh) receptor (nAChR)
agonists and antagonists on the stimulation-evoked release of
[3H]ACh were studied in rat isolated superior cervical
ganglion loaded with [3H]choline and superfused in a 2-ml
chamber. Nicotine and 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP),
but not cytisine, increased the stimulation (2 Hz)-evoked release of
[3H]ACh in a concentration-dependent manner. The rank
order of potency to increase stimulation-evoked release for the nAChR
agonists (nicotine > DMPP
cytisine) suggests that the
4
subunit of nAChRs is not involved in the release. The finding that
-bungarotoxin was effective in preventing the effect of DMPP and
itself significantly reduced the release indicates that the
7
subunit is located presynaptically and may be involved in the positive
feedback modulation. Hexamethonium inhibited the effect of DMPP with an
apparent dissociation constant (Kd) of 11.5 ± 1.5 µM.
Hexamethonium and other nAChR antagonists, i.e.,
(+)-tubocurarine (100 µM), mecamylamine (3 µM),
dihydro-
-erythroidine (3 µM), pancuronium (10 µM) and
-bungarotoxin (2 µM), also decreased the stimulation-evoked
release of [3H]ACh. The effect of hexamethonium was
independent of stimulation frequency (2, 10 and 30 Hz) applied.
Atropine enhanced the stimulation-evoked release of ACh, indicating
that there is negative feedback modulation of ACh release associated
with neuronal activity. In contrast, when the nicotinic positive
feedback was prevented by hexamethonium, atropine failed to enhance the
release. These findings indicate that muscarinic receptor-mediated
inhibition of ACh release functions in cases in which the release is
enhanced by ACh via stimulation of presynaptic nAChRs. A
similar interaction was found between A1 receptor-mediated
reduction and nAChR-mediated positive feedback modulation of
[3H]ACh release. The results suggest the presence of
positive feedback modulation of ACh release via
presynaptic nAChRs in rat superior cervical ganglion.
This article has been cited by other articles:
![]() |
H. Wen Lin, C.-Z. Liu, D. Cao, P.-Y. Chen, M.-F. Chen, S.-Z. Lin, M. Mozayan, A. F. Chen, L. S. Premkumar, D. S. Torry, et al. Endogenous methyl palmitate modulates nicotinic receptor-mediated transmission in the superior cervical ganglion PNAS, December 9, 2008; 105(49): 19526 - 19531. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Lendvai and E. S. Vizi Nonsynaptic Chemical Transmission Through Nicotinic Acetylcholine Receptors Physiol Rev, April 1, 2008; 88(2): 333 - 349. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Peters, M. Conrad, C. Hubold, U. Schweiger, B. Fischer, and H. L. Fehm The principle of homeostasis in the hypothalamus-pituitary-adrenal system: new insight from positive feedback Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2007; 293(1): R83 - R98. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Rassadi, A. Krishnaswamy, B. Pie, R. McConnell, M. H. Jacob, and E. Cooper A Null Mutation for the {alpha}3 Nicotinic Acetylcholine (ACh) Receptor Gene Abolishes Fast Synaptic Activity in Sympathetic Ganglia and Reveals That ACh Output from Developing Preganglionic Terminals Is Regulated in an Activity-Dependent Retrograde Manner J. Neurosci., September 14, 2005; 25(37): 8555 - 8566. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Fabian-Fine, P. Skehel, M. L. Errington, H. A. Davies, E. Sher, M. G. Stewart, and A. Fine Ultrastructural Distribution of the {alpha}7 Nicotinic Acetylcholine Receptor Subunit in Rat Hippocampus J. Neurosci., October 15, 2001; 21(20): 7993 - 8003. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. C. Gahring, N. G. Carlson, E. L. Meyer, and S. W. Rogers Cutting Edge: Granzyme B Proteolysis of a Neuronal Glutamate Receptor Generates an Autoantigen and Is Modulated by Glycosylation J. Immunol., February 1, 2001; 166(3): 1433 - 1438. [Abstract] [Full Text] [PDF] |
||||
![]() |
D Kristufek, E Stocker, S Boehm, and S Huck Somatic and prejunctional nicotinic receptors in cultured rat sympathetic neurones show different agonist profiles J. Physiol., May 1, 1999; 516(3): 739 - 756. [Abstract] [Full Text] [PDF] |
||||