Neuroscience
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The rat femoral nerve is a valuable model allowing studies on specificity of motor axon regeneration. Despite common use of this model, the functional consequences of femoral nerve lesions and their relationship to precision of axonal regeneration have not been evaluated. Here we assessed gait recovery after femoral nerve injuries of varying severity in adult female Wistar rats using a video-based approach, single-frame motion analysis (SFMA). ⋯ The results also suggest that MNs' projection patterns may influence their contribution to muscle performance. In addition to the experiments described above, we performed repeated measurements and statistical analyses to validate the SFMA. The results revealed high accuracy and reproducibility of the SFMA measurements.
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Remifentanil administration may subsequently cause paradoxical hyperalgesia in animals and humans, but mechanisms remain unclear. Manganese superoxide dismutase (MnSOD) nitration and inactivation caused by generation of reactive oxygen species and activation of N-methyl-D-aspartate (NMDA) receptors are involved in the induction and maintenance of central neuropathic pain. Hydrogen which selectively removes superoxide has gained much attention in recent years. ⋯ Ro25-6981 not 5 μg but 10 and 50 μg dosage-dependently attenuated hyperalgesia, and inhibited MnSOD nitration. Hyperalgesia and MnSOD nitration were attenuated after the combination of HRS (2.5 ml/kg) and Ro25-6981 (5 μg). In conclusion, HRS (10 ml/kg) might reverse remifentanil-induced hyperalgesia, through regulating NR2B-containing NMDAR trafficking to control MnSOD nitration and enhance MnSOD activity.
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Adrenomedullin (AM) belongs to a calcitonin gene-related peptide (CGRP) family and has been demonstrated to recruit CGRP following chronic use of morphine and neuronal nitric oxide synthase (nNOS) in inflammation. The present study investigated the possibility that AM initiates the changes of other molecules contributing to the development of morphine tolerance in its chronic use. Intrathecal (i.t.) co-administration of the AM receptor antagonist AM22-52 (35.8 μg) inhibited tolerance to morphine-induced analgesia while a daily injection of the AM receptor agonist AM1-50 (8 μg, i.t., bolus) for 9 days induced a decrease in the potency of morphine analgesia and thermal hyperalgesia. ⋯ Particularly, the co-administration of AM22-52 (35.8 μg) inhibited the morphine-induced alterations in nNOS and BAM22. These results indicated that the increase in nNOS and CGRP expressions and the decrease in BAM22 were attributed to the increased AM receptor signaling induced by chronic morphine. The present study supports the hypothesis that the enhancement of AM bioactivity triggered upregulation of pronociceptive mediators and downregulation of pain-inhibiting molecule in a cascade contributing to the development of morphine tolerance.
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Over human leg muscles, three motor responses (MR) can commonly be elicited, namely short-latency reflex (SLR), medium-latency reflex (MLR), and long-latency reflex (LLR). The MLR is less well understood than SLR and LLR. As the response to subsequent stimuli may be used to characterize central influences of an MR, we were interested, whether the MLR differs from SLR and LLR with respect to its habituation and facilitation behavior. ⋯ After train stimuli, the LLR but not SLR and MLR gained significantly in amplitude as compared with single stimuli. Different to SLR and LLR, the MLR showed significant habituation behavior at a stimulus repetition rate of 1Hz but not of 0.4 Hz. Thus, inhibitory interneurons seem to be involved in the MLR pathway.
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Synapsins are a family of synaptic vesicle (SV)-associated phosphoproteins that have been identified in several vertebrates and invertebrates. We report here the cloning and expression of synapsin family genes in the zebrafish Danio rerio. ⋯ As very few data are available describing the expression of synapsin family genes during CNS development in vertebrate models, our results may help to achieve a better understanding of the complex functions of these molecules. Finally, new interesting evidence from our temporal gene expression studies suggests that synapsins have also maternal functions.