Distribution of nicotinic cholinergic receptors in the rat tel- and diencephalon: a quantitative receptor autoradiographical study using [3H]-acetylcholine, [alpha-125I]bungarotoxin and [3H]nicotine.
The topographical distribution of [alpha-125I]bungarotoxin [125I]BTX, [3H]nicotine ([3H]Nic), [3H]acetylcholine ([3H]ACh) (in the presence of atropine) binding in rat tel- and diencephalon was investigated using a quantitative receptor autoradiographical technique. With the [3H]ACh and [3H]Nic radioligands, a strong labelling was observed in various thalamic nuclei, including the medial habenula, a moderate labelling in different areas of the cortex cerebri, the nucleus caudatus putamen, the nucleus accumbens and tuberculum olfactorium and a uniform weak labelling in the hypothalamus. When the binding data for [3H]Nic were plotted against binding data for [3H]ACh in various brain nuclei, a significant correlation was obtained. Considering [125I]BTX, the strongest labelling was observed in the lateral mammillary nucleus and the hilus gyrus dentatus of the hippocampal formation. A weak labelling occurred in areas such as the nucleus causatus putamen, the thalamus and the cerebral cortex. No significant correlation was therefore obtained between the degree of [125I]BTX binding in various brain nuclei and the degree of binding observed with [3H]Nic or [3H]ACh. The present results underline the view that the high-affinity [3H]Nic and [3H]ACh binding sites label the same cholinergic nicotinic receptor binding site, while [125I]BTX labels another subpopulation of nicotinic cholinergic receptors, predominantly found in discrete areas of the hypothalamus and the limbic cortex.
Härfstrand
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A
Department of Histology and Neurobiology, Karolinska Institute, Stockholm, Sweden.
Adem
A
A
Fuxe
K
K
Agnati
L
L
Andersson
K
K
Nordberg
A
A
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D002038:Bungarotoxins / Q000378:metabolism; D004027:Diencephalon / Q000378:metabolism*; D008297:Male; D009538:Nicotine / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011978:Receptors, Nicotinic / Q000378:metabolism*; D013687:Telencephalon / Q000378:metabolism*
D002038:Bungarotoxins; D011978:Receptors, Nicotinic; D009538:Nicotine; D000109:Acetylcholine