Association between wind-up ratio and central serotonergic function in healthy subjects and depressed patients

Department of Psychiatry, Ruhr University Bochum, LWL University Hospital Bochum, Alexandrinenstrasse 1, 44791 Bochum, Germany.
Neuroscience Letters (Impact Factor: 2.06). 09/2011; 504(2):176-80. DOI: 10.1016/j.neulet.2011.09.033
Source: PubMed

ABSTRACT Temporal summation of C-fiber evoked responses generates an increase in action potential discharge in second-order neurons and in perceived pain intensity (wind-up). This may be related to the central serotonergic system which modulates and partly inhibits sensory input. Aim of the study was to investigate the relationship between wind-up and serotonergic activity using loudness dependence of auditory evoked potentials (LDAEP). 18 healthy subjects were compared to 18 patients with major depression, a disease with a putative serotonin deficit. They were examined with quantitative sensory testing (QST) using the protocol of the German Research Network on Neuropathic Pain (DFNS), including the wind-up ratio (WUR), LDAEP, and psychometric measurements. We found a slight positive correlation between WUR and LDAEP both in healthy controls and depressed patients combined (r=0.340, p=0.043), indicating that WUR may be modulated by serotonergic activity. It can be concluded that inhibitory control to noxious stimuli is partly associated with the central serotonergic function as indicated by LDAEP.

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    • "In other words, if the input stimulus yields an elevated pain rating (e.g., 100), then subsequent ratings can only stay the same or decrease and temporal summation cannot occur. Regarding stimulus modality, TSSP has been demonstrated using heat (Edwards and Fillingim, 2001; Granot et al., 2003), electrical (Pedersen et al., 1998), cold (Price et al., 2002), pinprick (Rolke et al., 2006; Uhl et al., 2011) and mechanical pressure stimuli (Staud et al., 2003; Nie et al., 2005). However, no study to date has directly compared TSSP response magnitude between two modalities, so it is unknown whether one type of stimulus confers an advantage over another in eliciting temporal summation, or whether there is intraindividual specificity of TSSP to stimuli. "
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