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Presence of NK 2 binding sites in the rat brain
Author(s) -
Saffroy Monique,
Torrens Yvette,
Glowinski Jacques,
Beaujouan JeanClaude
Publication year - 2001
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2001.00633.x
Subject(s) - neurokinin a , binding site , neuropeptide , population , chemistry , tachykinin receptor , substance p , ligand (biochemistry) , agonist , hippocampal formation , hippocampus , medicine , endocrinology , biophysics , biology , receptor , biochemistry , environmental health
Attempts were made to label tachykinin NK 2 binding sites in the adult rat brain using [ 125 I]neurokinin A (NKA) as ligand in the presence of NK 1 and NK 3 agonist or antagonist to avoid labelling of NK 1 and NK 3 binding sites, respectively. A high‐affinity, specifically NK 2 ‐sensitive, [ 125 I]NKA‐binding, temperature‐dependent, reversible, sensitive to GTPγS and correspondence to a single population of binding sites ( K D and B max values: 2.2 n m and 7.3 fmol/mg protein) was demonstrated on hippocampal membranes. Competition studies performed with tachykinins and tachykinin‐related compounds indicated that the pharmacological properties of these NK 2 ‐sensitive [ 125 I]NKA binding sites were identical to those identified in the rat urinary bladder and duodenum. NKA, neuropeptide K, and neuropeptide γ, as well as the potent and selective NK 2 antagonists SR 144190, SR 48968 and MEN 10627, presented a nanomolar affinity for these sites. The regional distribution of these NK 2 ‐sensitive [ 125 I]NKA binding sites differs markedly from those of NK 1 and NK 3 binding sites, with the largest labeling being found in the hippocampus, the thalamus and the septum. Binding in other brain structures was low or negligible. A preliminary autoradiographic analysis confirmed [ 125 I]NKA selective binding in hippocampal CA1 and CA3 areas, particularly, and in several thalamic nuclei.

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