Season of sampling and season of birth influence serotonin metabolite levels in human cerebrospinal fluid.
BACKGROUND
Animal studies have revealed seasonal patterns in cerebrospinal fluid (CSF) monoamine (MA) turnover. In humans, no study had systematically assessed seasonal patterns in CSF MA turnover in a large set of healthy adults.


RESULTS
Standardized amounts of CSF were prospectively collected from 223 healthy individuals undergoing spinal anesthesia for minor surgical procedures. The metabolites of serotonin (5-hydroxyindoleacetic acid, 5-HIAA), dopamine (homovanillic acid, HVA) and norepinephrine (3-methoxy-4-hydroxyphenylglycol, MPHG) were measured using high performance liquid chromatography (HPLC). Concentration measurements by sampling and birth dates were modeled using a non-linear quantile cosine function and locally weighted scatterplot smoothing (LOESS, span = 0.75). The cosine model showed a unimodal season of sampling 5-HIAA zenith in April and a nadir in October (p-value of the amplitude of the cosine = 0.00050), with predicted maximum (PC(max)) and minimum (PC(min)) concentrations of 173 and 108 nmol/L, respectively, implying a 60% increase from trough to peak. Season of birth showed a unimodal 5-HIAA zenith in May and a nadir in November (p = 0.00339; PC(max) = 172 and PC(min) = 126). The non-parametric LOESS showed a similar pattern to the cosine in both season of sampling and season of birth models, validating the cosine model. A final model including both sampling and birth months demonstrated that both sampling and birth seasons were independent predictors of 5-HIAA concentrations.


CONCLUSIONS
In subjects without mental illness, 5-HT turnover shows circannual variation by season of sampling as well as season of birth, with peaks in spring and troughs in fall.
Department of Psychiatry, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands.
Jurjen J
JJ
Luykx
Steven C
SC
Bakker
Eef
E
Lentjes
Marco P M
MP
Boks
Nan
N
van Geloven
Marinus J C
MJ
Eijkemans
Esther
E
Janson
Eric
E
Strengman
Anne M
AM
de Lepper
Herman
H
Westenberg
Kai E
KE
Klopper
Hendrik J
HJ
Hoorn
Harry P M M
HP
Gelissen
Julian
J
Jordan
Noortje M
NM
Tolenaar
Eric P A
EP
van Dongen
Bregt
B
Michel
Lucija
L
Abramovic
Steve
S
Horvath
Teus
T
Kappen
Peter
P
Bruins
Peter
P
Keijzers
Paul
P
Borgdorff
Roel A
RA
Ophoff
René S
RS
Kahn
D000328:Adult; D000775:Anesthesia, Spinal; D017558:Elective Surgical Procedures; D005260:Female; D006801:Humans; D008297:Male; D015233:Models, Statistical; D036801:Parturition / Q000134:cerebrospinal fluid* / Q000378:metabolism; D011446:Prospective Studies; D012621:Seasons; D012701:Serotonin / Q000134:cerebrospinal fluid* / Q000378:metabolism*
D012701:Serotonin