Behavioural brain research
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Spinal nerve L5/L6 ligation (SNL) in rats has become the standard for mechanistic studies of peripheral neuropathy and screening for novel analgesics. Conventional SNL in our hybrid mice resulted in a wide range of allodynia. Anatomical evaluation indicated that a variable number of lumbar vertebrae existed, resulting in L4/L5 or L5/L6 being ligated. ⋯ Ligation of mouse L4 and L5 spinal nerves produces consistent, robust neuropathic pain behaviors and is suitable as a model for investigating mechanisms of neuropathic pain and for testing of novel analgesics. Gabapentin, used as a validation drug in neuropathic pain models and as a reference compound for novel analgesics, significantly reduced allodynia in the mice tested (L4/L5 ligations). Given the ease of surgery, robust allodynia, and larger von Frey sensitive area, we conclude that combined ligation of spinal nerves L4 and L5 optimizes the SNL model in mice.
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Transcranial direct current stimulation (tDCS) protocols applied over the primary motor cortex are associated with changes in motor performance. This transcranial magnetic stimulation (TMS) study examines whether cathodal tDCS prior to motor training, combined with anodal tDCS during motor training improves motor performance and off-line learning. Three study groups (n=36) were trained on the grooved pegboard test (GPT) in a randomized, between-subjects design: SHAM-sham stimulation prior and during training, STIM1-sham stimulation prior and atDCS during training, STIM2-ctDCS stimulation prior and atDCS during training. ⋯ For STIM2 these neuromodulatory effects were retained until T3. It is concluded that application of atDCS during the training improves pegboard performance and that additional priming with ctDCS has a positive effect on off-line learning. These cumulative behavioral gains were indicated by the preceding neuromodulatory changes.
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In humans and other mammals, the unexpected loss of a resource can lead to emotional conflict. Consummatory successive negative contrast (cSNC) is a laboratory model of reward devaluation meant to capture that conflict. In this paradigm, animals are exposed to a sharp reduction in the sucrose concentration of a solution after several days of access. ⋯ The current analysis applied latent growth mixture modeling to test for and characterize heterogeneity in recovery from cSNC among rats (N=262). Although most animals exhibited recovery of consummatory behavior after a sharp drop in consumption in the first postshift trial (Recovery class; 83%), two additional classes were identified including animals that did not change their consumption levels after downshift (No Contrast class; 6%), and animals that exhibited an initial response similar to that of the Recovery class but did not recover to preshift consumption levels (No Recovery class; 11%). These results indicate heterogeneity in recovery from reward loss among rats, which may increase the translatability of this animal model to understand diverse responses to loss among humans.
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The rodent has been the preferred research model for evaluating the mechanisms related to, and potential treatments for, traumatic brain injury (TBI). Many therapies previously determined to be effective in pre-clinical investigations have failed to show the same effectiveness in clinical trials. The environment a rodent is housed in plays an important role in brain and behavioral development. ⋯ The TBI and sham groups that were raised, and remained, in the SE performed worse than any of the EE groups on the RR. TBI rats that were placed in the EE had larger cortices and more cells in the hippocampus than the TBI rats housed in the SE. These data strongly suggest that the pre-injury housing environment should be considered as investigators refine pre-clinical models of TBI.
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The effects of curcumin on depressive-like behavior in mice after lipopolysaccharide administration.
Current evidence supports that inflammation and increased cytokine levels are associated with depression-like symptoms and neuropsychological disturbances in humans. Curcumin has anti-inflammatory, antioxidant and anti-depressant-like properties. Here, we examined the effects of curcumin on lipopolysaccharide (LPS)-induced depressive-like behavior and inflammation in male mice. ⋯ Moreover, pre-treatment with curcumin attenuated LPS-induced microglial activation and overproduction of pro-inflammatory cytokine (interleukin-1β and tumor necrosis factor-α), as well as the levels of inducible nitric oxide synthase and cyclooxygenase-2 mRNA in the hippocampus and prefrontal cortex (PFC). In addition, curcumin ameliorated LPS-induced NF-κB activation in the hippocampus and PFC. The results demonstrate that curcumin may be an effective therapeutic agent for LPS-induced depressive-like behavior, partially due to its anti-inflammatory aptitude.