ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: α-Bungarotoxin (α-BGT), a snake venom polypeptide, interacts potently and specifically with a nicotinic receptor population in neuronal tissue. However, the identity of this site is unclear, because, unlike at the neuromuscular junction and in electroplax, in nervous tissue the toxin does not block nicotinic cholinergic responses. Therefore, we sought endogenous compounds other than acetylcholine that could interact with the neuronal α-BGT site. In the present experiments, thymopoietin, a polypeptide isolated from the thymus, is shown to inhibit potently α-BGT binding to brain membranes in a dose-dependent manner (IC50= 3.1 nM). This effect was not shared by a wide variety of other peptides, including thysplenin, a closely related polypeptide. Thymopoietin did not inhibit the binding of other radioligands known to interact with different populations of cholinergic receptors, such as [3H]nicotine and [3H]methylcarbachol, which bind to nicotinic receptors, or [3H]quinuclidinylbenzilate, which binds to muscarinic receptors. These results show that thymopoietin potently and specifically affects l25I-α-BGT binding to brain membranes and suggest that thymopoietin might be an endogenous ligand for α-BGT receptors in neuronal tissue.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1989.tb07431.x
