Valence-specific effects of BDNF Val66Met polymorphism on dopaminergic stress and reward processing in humans.

Brain-derived neurotrophic factor (BDNF) levels in dopaminergic (DA) cells within the ventral tegmental area (VTA)/nucleus accumbens (NAc) circuitry appear to be a candidate mechanism for the neuroadaptive changes that follow stress and reward responses in animal models. However, the role of the BDNF gene variants in responses to salient cues through DA neurotransmission in humans remains unexplored. Here, we studied the effect of the common functional BDNF Val(66)Met (rs6265) polymorphism on rewarding experiences in the striatum and DA-mediated responses to stress.

FAAH selectively influences placebo effects.

Endogenous opioid and cannabinoid systems are thought to act synergistically regulating antinociceptive and reward mechanisms. To further understand the human implications of the interaction between these two systems, we investigated the role of the common, functional missense variant Pro129Thr of the gene coding fatty acid amide hydrolase (FAAH), the major degrading enzyme of endocannabinoids, on psychophysical and neurotransmitter (dopaminergic, opioid) responses to pain and placebo-induced analgesia in humans. FAAH Pro129/Pro129 homozygotes, who constitute nearly half of the population, reported higher placebo analgesia and more positive affective states immediately and 24 h after placebo administration; no effects on pain report in the absence of placebo were observed.

Age-of-onset of menopause is associated with enhanced painful and non-painful sensitivity in fibromyalgia.

Fibromyalgia (FM) is a chronic pain condition characterized by high prevalence in women. In particular, estrogen deficit has been considered as a potentially promoting factor of FM symptoms. This study was aimed to examine the relationship between age-of-onset of menopause and pain sensitivity in FM.

Somatosensory activity modulation during observation of other's pain and touch.

We examined whether somatosensory activity could be modulated by the observation of bodily experiences. For this purpose, somatosensory-evoked potentials elicited by non-painful stimulation were recorded when subjects were viewing a hand penetrated by a needle, touched by a cotton swab or at resting without stimulation. Participants were instructed to adopt an egocentric perspective when viewing the videos and to rate pain intensity and unpleasantness supposedly experienced by the model, as well as the unpleasantness induced by the video clips.

Pain sensitivity in fibromyalgia is associated with catechol-O-methyltransferase (COMT) gene.

Background: Recent evidence suggests that genetic factors might contribute to individual differences in pain sensitivity, risk for developing clinical pain conditions and efficacy of pain treatments. The purpose of the present study was to investigate the relationship of three common haplotypes of COMT gene affecting the metabolism of catecholamines on pain sensitivity in patients with fibromyalgia (FM).

Methods: One hundred and thirteen FM patients and 65 age-matched healthy volunteers participated in the study.