Circadian rhythm of brain-derived neurotrophic factor in the rat suprachiasmatic nucleus

Expression and secretion of neurotrophins, including brain-derived neurotrophic factor (BDNF), are regulated also by neuronal activity. Data available in the literature suggest that BDNF central levels are influenced by light and dark. Diurnal changes of BDNF mRNA and protein contents have been demonstrated in the rat central nervous system. Based on these pieces of evidence, we investigated the hypothesis of a possible diurnal variation of BDNF circulating levels in human males. Moreover, we looked for a possible correlation with cortisol circadian rhythm, since both BDNF and cortisol are implicated in the maintenance of cerebral functions. In this study, 34 healthy young male volunteers were included. Five blood samples were drawn from each subject thrice in a month at regular 4-h intervals (0800, 1200, 1600, 2000, and 2400 h). BDNF and cortisol were measured in all samples. BDNF was determined by ELISA method. Our results show that plasma BDNF levels, as well as cortisol levels, are significantly higher in the morning when compared with the night (P<0.001), with a trend of constant decrease during the day. Furthermore, plasma BDNF and cortisol are positively correlated (Spearman index=0.8466). The present study is the first to demonstrate the presence of a diurnal rhythm of BDNF in humans. Moreover, the correlation found out between BDNF and cortisol circadian trend allows us to speculate that these two factors may be physiologically co-regulated, in order to maintain the homeostasis of integrated cerebral activities.

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Daily Variation of Plasma Brain-derived Neurotrophic Factor in Women with Endometriosis

Journal of Endometriosis ◽

10.5301/je.2011.8313 ◽

2011 ◽

Vol 3 (1) ◽

pp. 40-46

Author(s):

Fiorella Bucci ◽

Nicola Pluchino ◽

Stefano Luisi ◽

Vito Cela ◽

Paolo G. Artini ◽

...

Keyword(s):

Circadian Rhythm ◽

Neurotrophic Factor ◽

Daily Variation ◽

Brain Derived Neurotrophic Factor ◽

Follicular Phase ◽

Reproductive Age ◽

Healthy Women ◽

Peripheral Production ◽

Age Range

Purpose Endometriosis is a benign gynecological disease affecting women in their Reproductive age and characterized by chronic pelvic pain and infertility. Previous studies have demonstrated the role of neurotrophins (in particular brain-derived neurotrophic factor) in the pain pathway and in inflammation processes, which both characterize endometriosis. Our previous study revealed higher brain-derived neurotrophic factor levels in patients suffering from endometriosis than in healthy women during the follicular phase of the menstrual cycle, thus suggesting a neuroprotective role of this particular neurotrophin in response to a neuro-inflammatory reaction. The aim of this study is to assess whether the diurnal variation of brain-derived neurotrophic factor and the circadian rhythm of cortisol are preserved in this kind of patient. Methods We enrolled 11 healthy women (age range 20 to 30, BMI range 20.6 to 29.3), and 11 women suffering from endometriosis (age range 25 to 35, BMI range 20.5 to 27.2). Blood samples were withdrawn from each subject in the follicular phase at 8:00, 12:00, 16:00, 20:00, 24:00, and at 8:00 the following day, in order to assess BDNF and cortisol plasma levels during the day. Results We found a preserved cortisol circadian rhythm in patients with endometriosis, while the BDNF daily variation is blunted if compared to healthy women in follicular phase. Conclusions In endometriosis the biological rhythm is preserved, which is demonstrated by the cortisol's rhythm, and the lack of BDNF variation is probably only blunted by the increase in its peripheral production, because of the physiopathologic mechanisms of this disease.

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