Human platelet 5-HT2 receptor binding sites re-evaluated: a criticism of current techniques [corrected].
The human platelet 5-HT2 receptor may resemble a peripheral model of central 5-HT2 binding sites and has been linked to changes in 5-HT2 receptor function in depression. Therefore, evaluation of the human platelet 5-HT2 binding characteristics is important. Comparing [3H]ketanserin and [3H]LSD as ligands clearly indicated [3H]LSD as ligand of choice for binding studies dealing with the human platelet 5-HT2 receptor. [3H]LSD binding was specific, saturable, and depended upon incubation time, protein concentration and previous handling of tissue, i.e., use of fresh or frozen tissue. In contrast, studies with [3H]ketanserin were unsatisfactory. Although mean receptor densities and affinities have been relatively constant between individuals and over time in healthy subjects with [3H]LSD, examination of the individual data showed considerable variations within single subjects. Thus, KD ranged between 0.50 and 0.68 nM, and Bmax was in the range of 64.9 to 97.1 fmol/mg protein in healthy individual subjects. Therefore, we recommend [3H]LSD as ligand of choice to study platelet 5-HT2 receptor binding in humans. Furthermore, repeated measurement of individual data over time should be interpreted cautiously, especially when data from depressed patients are under examination.
Steckler
T
T
Department of Psychiatry, Free University of Berlin, Federal Republic of Germany.
Rüggeberg-Schmidt
K
K
Müller-Oerlinghausen
B
B
D000328:Adult; D001792:Blood Platelets / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D005069:Evaluation Studies as Topic; D006801:Humans; D066298:In Vitro Techniques; D007650:Ketanserin / Q000097:blood; D008024:Ligands; D008238:Lysergic Acid Diethylamide / Q000097:blood; D008297:Male; D011985:Receptors, Serotonin / Q000378:metabolism*
D001798:Blood Proteins; D008024:Ligands; D011985:Receptors, Serotonin; D008238:Lysergic Acid Diethylamide; D007650:Ketanserin