Article date: August 1993
By: Henry P. Nowak, Cathy D. Mahle, Frank D. Yocca, in Volume 109, Issue 4, pages 1206-1211
[3H]‐5‐hydroxytryptamine (5‐HT) has been shown to radiolabel at least five types of 5‐HT binding sites in mammalian brain tissue, 5‐HT1A, 5‐HT1B, 5‐HT1C, 5‐HT1D and 5‐HT1E (Frazer et al., 1990). Selective masking of 5‐HT1A and 5‐HT1C receptors, has uncovered binding sites which display both high (5‐HT1D) and low (5‐HT1E) affinity for 5‐carboxamidotryptamine (5‐CT). By utilizing [3H]‐5‐CT we have eliminated a portion of the complex binding (5‐HT1E) seen when [3H]‐5‐HT is used as a radioligand.
[3H]‐5‐CT binding to 5‐HT1D sites in bovine substantia nigra was rapid, reversible and saturable, displaying high affinity (Kd = 0.38 ± 0.04 nm) and low non‐specific binding (> 90% specific binding).
In bovine substantia nigra, [3H]‐5‐CT labelled an equivalent number of binding sites to [3H]‐5‐CT (403 ± 18 and 362 ± 20 fmol mg−1 protein, respectively) and binding was sensitive to guanine nucleotides.
A linear correlation (r2 = 0.99) existed between the potency of compounds to displace [3H]‐5‐HT and [3H]‐5‐CT in bovine substantia nigra.
Therefore, [3H]‐5‐CT is a novel radioligand for the examination of 5‐HT1‐like binding sites, which under proper experimental conditions can be used to radiolabel selectively 5‐HT1D‐like binding sites.
[3H]‐5‐hydroxytryptamine (5‐HT) has been shown to radiolabel at least five types of 5‐HT binding sites in mammalian brain tissue, 5‐HT1A, 5‐HT1B, 5‐HT1C, 5‐HT1D and 5‐HT1E (Frazer et al., 1990). Selective masking of 5‐HT1A and 5‐HT1C receptors, has uncovered binding sites which display both high (5‐HT1D) and low (5‐HT1E) affinity for 5‐carboxamidotryptamine (5‐CT). By utilizing [3H]‐5‐CT we have eliminated a portion of the complex binding (5‐HT1E) seen when [3H]‐5‐HT is used as a radioligand.
[3H]‐5‐CT binding to 5‐HT1D sites in bovine substantia nigra was rapid, reversible and saturable, displaying high affinity (Kd = 0.38 ± 0.04 nm) and low non‐specific binding (> 90% specific binding).
In bovine substantia nigra, [3H]‐5‐CT labelled an equivalent number of binding sites to [3H]‐5‐CT (403 ± 18 and 362 ± 20 fmol mg−1 protein, respectively) and binding was sensitive to guanine nucleotides.
A linear correlation (r2 = 0.99) existed between the potency of compounds to displace [3H]‐5‐HT and [3H]‐5‐CT in bovine substantia nigra.
Therefore, [3H]‐5‐CT is a novel radioligand for the examination of 5‐HT1‐like binding sites, which under proper experimental conditions can be used to radiolabel selectively 5‐HT1D‐like binding sites.
DOI: 10.1111/j.1476-5381.1993.tb13750.x
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