Neuroscience
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Comparative Study
Increased expression of sonic hedgehog in temporal lobe epileptic foci in humans and experimental rats.
Sonic hedgehog (Shh) is a soluble signaling protein that is crucial in regulating cell proliferation, migration and differentiation, axonal guidance and neural progenitor cell survival during nervous system development. Recent evidence suggests that the Shh plays an important role in adulthood in regulating structural plasticity. Here we investigated the expression of Shh in temporal lobe epileptic foci in patients and experimental animals in order to explore the probable relationship between Shh expression and temporal lobe epilepsy (TLE). ⋯ Compared to the control group, Shh expression was enhanced in the temporal neocortex of patients with intractable TLE. In experimental rats, Shh expression gradually increased from 7 to 60 days post-seizure in temporal neocortex and elevated from 3 to 60 days in hippocampus with the peak levels at 30 days as compared with the control group. These results suggest that Shh may play an important role in the development of TLE.
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The mammalian target of rapamycin (mTOR) pathway is important for regulating protein translation. The present study characterized the role of mTOR-dependent translation in the dorsal hippocampus (DH) during the consolidation and reconsolidation of contextual fear memory. ⋯ Additionally we showed that p70s6K was activated after retrieval of a previously stored fear memory, and inhibition of mTOR by DH infusion of RAP blocked the reconsolidation of contextual fear memory. Together these results demonstrate that within the DH translational control through the mTOR pathway is important for consolidation as well as the stability of fear memory after retrieval.
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Cannabis derivatives have become the most widely used illicit substances in developed countries, and constitute a major health concern. The psychoactive compounds contained in cannabis induce their pharmacological effects by the activation of at least two different receptors, CB1 and CB2 cannabinoid receptors. ⋯ The participation of other neurochemical systems in behavioural responses of cannabinoids related to their addictive effects has also been reported. This review describes the experimental methods now available to study the pharmacological responses of cannabinoids related to their addictive effects and how these methods have contributed to advance the knowledge of the specific contribution of different neurochemical systems in cannabis addiction.
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Acute low back pain (LBP) is associated with differential changes in motor coordination of deep and superficial trunk muscles. Whether this is related to differential changes in excitability of descending corticomotor inputs remains unclear and was investigated in nine healthy individuals. Fine-wire i.m. electrodes were inserted bilaterally into deep (transversus abdominis (TrA)) and superficial abdominal muscles (obliquus externus abdominis (OE)), and surface electrodes were placed bilaterally over obliquus internus abdominis (OI), rectus abdominis (RA) and lumbar erector spinae (LES) muscles. ⋯ During pain, amplitude of TrA MEPs to contralateral cortical stimulation was reduced, whereas amplitudes of OE and LES MEPs contralateral and ipsilateral to the stimulated cortex were increased. The findings highlight differential changes in excitability of corticomotor inputs to trunk muscles during acute LBP. Further work is required to reveal whether such changes involve spinal and/or supraspinal centres and their consequence for spine control.