Physiology & behavior
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Physiology & behavior · Apr 2014
Role of TNF-α/TNFR1 in intense acute swimming-induced delayed onset muscle soreness in mice.
The injection of cytokines such as TNF-α induces muscle pain. Herein, it was addressed the role of endogenous TNF-α/TNFR1 signaling in intense acute swimming-induced muscle mechanical hyperalgesia in mice. Mice were exposed to water during 30 s (sham) or to a single session of 30-120 min of swimming. ⋯ Exercise induced an increase of myeloperoxidase activity and decrease in reduced glutathione levels in an etanercept-sensitive and TNFR1-dependent manners in the soleus muscle, but not in the gastrocnemius muscle. Concluding, TNF-α/TNFR1 signaling mediates intense acute swimming-induced DOMS by an initial role in the soleus muscle followed by spinal cord, inducing muscle inflammatory hyperalgesia and oxidative stress. The knowledge of these mechanisms might contribute to improve the training of athletes, individuals with physical impairment and intense training such as military settings.
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Physiology & behavior · Apr 2014
Effects of developmental hyperserotonemia on juvenile play behavior, oxytocin and serotonin receptor expression in the hypothalamus are age and sex dependent.
There is a striking sex difference in the diagnosis of Autism Spectrum Disorder (ASD), such that males are diagnosed more often than females, usually in early childhood. Given that recent research has implicated elevated blood serotonin (hyperserotonemia) in perinatal development as a potential factor in the pathogenesis of ASD, we sought to evaluate the effects of developmental hyperserotonemia on social behavior and relevant brain morphology in juvenile males and females. ⋯ These data suggest that serotonin plays an organizing role in the development of the PVN in a sexually dimorphic fashion, and that elevated serotonin levels during perinatal development may disrupt normal organization, leading to neurochemical and behavioral changes. Importantly, these data also suggest that the inclusion of both juvenile males and females in studies will be necessary to fully understand the role of serotonin in development, especially in relation to ASD.
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Physiology & behavior · Apr 2014
Effects of light, food, and methamphetamine on the circadian activity rhythm in mice.
The circadian rhythm of locomotor activity in mice is synchronized to environmental factors such as light and food availability. It is well-known that entrainment of the activity rhythm to the light-dark cycle is attained by the circadian pacemaker in the suprachiasmatic nucleus (SCN). Locomotor activity is also controlled by two extra-SCN oscillators; periodic food availability entrains the food-entrainable oscillator (FEO) and constant consumption of low-dose methamphetamine reveals the output of the methamphetamine-sensitive circadian oscillator (MASCO). ⋯ To examine the effect of methamphetamine on the output of the FEO, we administered methamphetamine to mice undergoing restricted feeding and found that food-entrained activity was delayed by methamphetamine treatment. In addition, restricted feeding induced dissociation of the MASCO and SCN activity rhythms during short-term methamphetamine treatment, when these rhythms are typically integrated. In conclusion, our data suggest that the outputs of the SCN, FEO and MASCO collectively drive locomotor activity.