PLoS ONE (Jan 2012)

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

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

DOI
https://doi.org/10.1371/journal.pone.0030497
Journal volume & issue
Vol. 7, no. 2
p. e30497

Abstract

Read online

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.