Circannual variations in the binding of [3H]lysergic acid diethylamide to serotonin2A receptors and of [3H]paroxetine to serotonin uptake sites in platelets from healthy volunteers.
BACKGROUND
Circannual variations occur in several serotonergic parameters, including platelet serotonin uptake and platelet [3H]imipramine binding.


METHODS
Binding of [3H]lysergic acid diethylamide ([3H]LSD) to platelet serotonin (5-HT)2A receptors and binding of [3H]paroxetine to platelet serotonin uptake sites were studied longitudinally for 1 year in 12 healthy volunteers.


RESULTS
For [3H]LSD, the number of binding sites (Bmax) showed no significant seasonal variation (two-way analysis of variance), although Bmax was significantly higher during the months October through February than during the months April through August (32.6 vs. 29.8 fmol/mg protein; p = .015). For [3H]paroxetine, Bmax showed a significant seasonal variation (p = .003) with maximum in August (1322 fmol/mg protein) and minimum in February (1168 fmol/mg protein). The affinity constant (Kd) showed a significant seasonal variation for [3H]LSD binding (p = .046), but not for [3H]paroxetine binding. The seasonal fluctuations in [3H]LSD binding and in paroxetine binding tended to be inversely correlated for Bmax (r = -.70; p = .08) and were significantly negatively correlated for Kd (r = -.88; p = .009).


CONCLUSIONS
The present study demonstrates a seasonal effect on platelet serotonin uptake site binding and indicates a possible seasonal effect on 5-HT2A receptor binding. The results imply that circannual fluctuations should be taken into account when these platelet serotonin markers are studied.
Spigset
O
O
Division of Clinical Pharmacology, Norrland University Hospital, Umeå, Sweden.
Allard
P
P
Mjörndal
T
T
D000328:Adult; D001792:Blood Platelets / Q000378:metabolism*; D002352:Carrier Proteins / Q000097:blood*; D005260:Female; D006801:Humans; D008238:Lysergic Acid Diethylamide / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D017374:Paroxetine / Q000493:pharmacokinetics*; D010507:Periodicity; D044402:Receptor, Serotonin, 5-HT2A; D011955:Receptors, Drug / Q000097:blood*; D011985:Receptors, Serotonin / Q000097:blood*; D012016:Reference Values; D012621:Seasons
D002352:Carrier Proteins; D044402:Receptor, Serotonin, 5-HT2A; D011955:Receptors, Drug; D011985:Receptors, Serotonin; C092604:paroxetine receptor; D017374:Paroxetine; D008238:Lysergic Acid Diethylamide