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Season of sampling and season of birth influence serotonin metabolite levels in human cerebrospinal fluid.

  • Author(s): Luykx, Jurjen J
  • Bakker, Steven C
  • Lentjes, Eef
  • Boks, Marco PM
  • van Geloven, Nan
  • Eijkemans, Marinus JC
  • Janson, Esther
  • Strengman, Eric
  • de Lepper, Anne M
  • Westenberg, Herman
  • Klopper, Kai E
  • Hoorn, Hendrik J
  • Gelissen, Harry PMM
  • Jordan, Julian
  • Tolenaar, Noortje M
  • van Dongen, Eric PA
  • Michel, Bregt
  • Abramovic, Lucija
  • Horvath, Steve
  • Kappen, Teus
  • Bruins, Peter
  • Keijzers, Peter
  • Borgdorff, Paul
  • Ophoff, Roel A
  • Kahn, René S
  • et al.

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. METHODOLOGY/PRINCIPAL FINDINGS: 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. CONCLUSION: 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.

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