Neuroscience
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Current cognitive models suggest that the processing of dynamic facial attributes, including social signals such as gaze direction and facial expression, involves the superior temporal sulcus, whereas the processing of invariant facial structure such as the individuals' identity involves the fusiform face area. Where facial attractiveness, a social signal that may emerge from invariant facial structure, is processed within this dual-route model of face perception is uncertain. Here, we present two studies. ⋯ Second, we performed a functional magnetic resonance imaging study in healthy subjects that included an implicit and explicit processing of facial attractiveness. We found increased neural activity when explicitly judging facial attractiveness within a number of cortical regions including the fusiform face area, but not the superior temporal sulcus, indicating a potential contribution of the fusiform face area to this judgment. Thus, converging neuropsychological and neuroimaging evidence points to a critical role of the inferior occipitotemporal cortex in the processing of facial attractiveness.
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Tumor necrosis factor alpha (TNFalpha), a pro-inflammatory cytokine, enhances the development of pain and hyperalgesia, although the molecular mechanisms are not well understood. This study evaluated the hypothesis that TNFalpha increases the sensitivity of rat trigeminal neurons to capsaicin via two different mechanisms triggered by either brief or sustained exposure to the cytokine. A brief (5 min) application of TNFalpha significantly sensitized capsaicin-evoked accumulation of intracellular calcium ([Ca2+]i) (226.4+/-37.7 nM vs. 167.5+/-31.3 nM) and increased capsaicin-evoked nocifensive behavior (78.3+/-9.7 vs. 30.9+/-3.6 s) as compared with vehicle pretreatment (P<0.01 for both). ⋯ Demonstration of colocalization of TNFalpha receptor subtypes I and II with TRPV1 in almost all (>90%) TRPV1 expressing neurons provides evidence consistent with a direct interaction on the same subpopulation of sensory neurons. In summary, our data demonstrate that TNFalpha directly enhances the sensitivity of rat trigeminal neurons to capsaicin via both rapid, non-genomic mechanisms as well as sustained genomic regulation in TRPV1 expression. Thus, increased sensitization and up-regulation of TRPV1 constitutes a potential mechanism by which TNFalpha mediates inflammatory hyperalgesia and pain.
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Lipoprotein lipase (LPL), which plays an essential role in plasma lipoprotein metabolism and transportation, appears to be a risk factor for ischemic vascular diseases. Several studies have recently reported the presence of relationship between HindIII, PvuII, Ser447Ter (C-->G) polymorphisms of LPL and ischemic vascular diseases. ⋯ Our study suggests that PvuII and Ser447Ter polymorphisms are associated with lipid profile and CI.
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Opioid mechanisms are involved in the control of water and NaCl intake and opioid receptors are present in the lateral parabrachial nucleus (LPBN), a site of important inhibitory mechanisms related to the control of sodium appetite. Therefore, in the present study we investigated the effects of opioid receptor activation in the LPBN on 0.3 M NaCl and water intake in rats. Male Holtzman rats with stainless steel cannulas implanted bilaterally in the LPBN were used. ⋯ The results show that opioid receptor activation in the LPBN induces hypertonic sodium intake in satiated and normohydrated rats, an effect not due to general ingestive behavior facilitation. In addition, sodium depletion induced 0.3 M NaCl intake also partially depends on opioid receptor activation in the LPBN. The results suggest that deactivation of inhibitory mechanisms by opioid receptor activation in the LPBN releases sodium intake if excitatory signals were activated (sodium depletion) or not.
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Effects of nitrous oxide on dopamine release in the rat nucleus accumbens and expectation of reward.
Recently we have shown that nitrous oxide (N2O) was able to block the expression of morphine-induced conditioned place preference (CPP) in mice. Because dopamine (DA) has also been associated with the positive place conditioning we hypothesize that exposure to N2O would be significantly associated with a modification of extracellular level of DA. Unbiased place conditioning method was used for mice and rats. ⋯ Results of animals placed in the morphine-paired compartment showed a 75% increase in the extracellular levels of DA, which was blocked by exposure of animals to N2O. In conclusion we showed the capacity of N2O to block the expression of morphine-induced CPP in mice and in rats. Then we demonstrated an increase of DA extracellular level in the Nac when animals were placed in the morphine-paired compartment and these increase of DA level was blocked by N2O.