PMID- 8534270
OWN - NLM
STAT- MEDLINE
DCOM- 19960130
LR  - 20231213
IS  - 0006-2952 (Print)
IS  - 0006-2952 (Linking)
VI  - 51
IP  - 1
DP  - 1996 Jan 12
TI  - Radiolabelling of the human 5-HT2A receptor with an agonist, a partial agonist 
      and an antagonist: effects on apparent agonist affinities.
PG  - 71-6
AB  - Previous work has shown that 5-hydroxytryptamine (5-HT)2A receptors can be 
      radiolabelled with various radioligands, including partial agonists, such as 
      [125I]-DOI and [3H]-DOB, and antagonists, such as [3H]-ketanserin and 
      [3H]-spiperone. Because 5-HT has high affinity for the 5-HT2A receptor when 
      displacing [3H]-DOB, the purpose of the present study was to determine whether or 
      not the receptor could be labelled with [3H]-5-HT and what would be the effect of 
      labelling the receptor with various radioligands having differing efficacies at 
      the receptor. Consequently, the human 5-HT2A receptor stably expressed in NIH 3T3 
      cells was radiolabelled with the endogenous agonist [3H]-5-HT, the partial 
      agonist [3H]-DOB, and the antagonist [3H]-ketanserin. The receptor could be 
      radiolabelled with [3H]-5-HT with a Kd value of 1.3 +/- 0.1 nM and a Bmax value 
      of 3461 +/- 186 fmoles/mg protein and the radiolabelling was sensitive to the 
      stable guanosine 5'-triphosphate (GTP) analogue guanylyl-imidodiphosphate 
      (GMP-PNP). Ketanserin labeled significantly more receptors (Kd = 1.1 +/- 0.1 nM: 
      Bmax = 27,684 +/- 1500 fmoles/mg protein) than [3H]-DOB (Kd = 0.8 +/- 0.08 nM: 
      Bmax = 8332 +/- 16 fmoles/mg protein) which, in turn, labelled significantly more 
      receptors than [3H]-5-HT. The apparent affinity of antagonists did not change 
      when the receptor was radiolabelled with either [3H]-agonists or 
      [3H]-antagonists; however, agonists had a higher apparent affinity for 
      [3H]-agonist-labeled receptors than for [3H]-antagonist-labeled receptors. 
      Therefore, the apparent affinity of agonists for the 5-HT2A receptor estimated 
      from displacement experiments depends on the intrinsic efficacy of the 
      radioligand used.
FAU - Sleight, A J
AU  - Sleight AJ
AD  - Pharma Division, Preclinical Research, F. Hoffmann-La Roche Ltd, Basel, 
      Switzerland.
FAU - Stam, N J
AU  - Stam NJ
FAU - Mutel, V
AU  - Mutel V
FAU - Vanderheyden, P M
AU  - Vanderheyden PM
LA  - eng
PT  - Journal Article
PL  - England
TA  - Biochem Pharmacol
JT  - Biochemical pharmacology
JID - 0101032
RN  - 0 (Receptor, Serotonin, 5-HT2A)
RN  - 0 (Receptors, Serotonin)
RN  - 0 (Recombinant Proteins)
RN  - 0 (Serotonin Antagonists)
RN  - 0 (Serotonin Receptor Agonists)
RN  - 15588-95-1 (DOM 2,5-Dimethoxy-4-Methylamphetamine)
RN  - 32156-26-6 (2,5-dimethoxy-4-bromoamphetamine)
RN  - 333DO1RDJY (Serotonin)
RN  - 97F9DE4CT4 (Ketanserin)
SB  - IM
MH  - DOM 2,5-Dimethoxy-4-Methylamphetamine/analogs & derivatives/metabolism
MH  - 3T3 Cells
MH  - Animals
MH  - Binding, Competitive
MH  - Cell Membrane/metabolism
MH  - Humans
MH  - Ketanserin/metabolism
MH  - Mice
MH  - Radioligand Assay
MH  - Receptor, Serotonin, 5-HT2A
MH  - Receptors, Serotonin/*metabolism
MH  - Recombinant Proteins
MH  - Serotonin/metabolism
MH  - Serotonin Antagonists/*chemistry
MH  - Serotonin Receptor Agonists/*chemistry
EDAT- 1996/01/12 00:00
MHDA- 1996/01/12 00:01
CRDT- 1996/01/12 00:00
PHST- 1996/01/12 00:00 [pubmed]
PHST- 1996/01/12 00:01 [medline]
PHST- 1996/01/12 00:00 [entrez]
AID - 0006295295021221 [pii]
AID - 10.1016/0006-2952(95)02122-1 [doi]
PST - ppublish
SO  - Biochem Pharmacol. 1996 Jan 12;51(1):71-6. doi: 10.1016/0006-2952(95)02122-1.