Neuropeptides
Volume 41, Issue 1 , Pages 59-63, February 2007

Diurnal and seasonal variation of cholecystokinin peptides in humans

  • Kristina Lundberg

      Affiliations

    • Department of Neuroscience and Locomotion, Psychiatry Section, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden
  • ,
  • Ann Josefsson

      Affiliations

    • Department of Molecular and Clinical Medicine, Division of Obstetrics and Gynaecology, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden
  • ,
  • Conny Nordin

      Affiliations

    • Department of Neuroscience and Locomotion, Psychiatry Section, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden
    • Corresponding Author InformationCorresponding author. Tel.: +46 13 22 38 64; fax: + 46 13 22 33 92.

Received 19 June 2006; accepted 15 September 2006. published online 09 January 2007.

Abstract 

Cholecystokinin (CCK) was determined in plasma obtained from 10 female (aged 23.4±SD 2.3 years) and nine male (aged 22.0±SD 1.4 years) healthy volunteers. Blood samples were drawn three times (8.00a.m., 12 noon and 8.00a.m.) on each of two sessions, one in the winter (November–December) and one in the summer (April–July). The participants had fasted (and were nicotine-free) since midnight preceding the sampling. A standardized breakfast was served after the first sampling. CCK was determined by radioimmunoassay.

The area under the curve 0–24h (AUC)CCK Winter was lower than AUCCCK Summer (F1:17=4.73; P=0.0440) in the whole group of volunteers.

On comparing the CCK concentrations within each session, there was an overall difference in winter (F2:36=14.81; P<0.0001) as well in summer (F2:36=18.39; P<0.0001). Post hoc comparisons yielded a difference between the 8.00a.m. and 12 noon concentrations on the first day in winter (t=−3.96; P=0.0009) as well as in summer (t=−4.64; P=0.0002).

The difference between the summer and winter AUCsCCK correlated with the difference between AUCs for temperatures in summer and winter (r=0.58; P=0.0089). The correlation was accounted for by the females (r=0.73; P=0.0171).

The results are in accord with a diurnal and a seasonal variation of CCK in human plasma.

Keywords: Cholecystokinin, Diurnal variation, Seasonal variation

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 This study was supported by Grants from the County Council of Östergötland, Sweden.

PII: S0143-4179(06)00114-4

doi:10.1016/j.npep.2006.09.049

Neuropeptides
Volume 41, Issue 1 , Pages 59-63, February 2007