Neuroscience letters
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Neuroscience letters · Mar 2012
Involvement of transient receptor potential vanilloid 1 in ectopic pain following inferior alveolar nerve transection in rats.
Chronic pain often develops in the orofacial region after inferior alveolar nerve (IAN) injury. In animal models IAN injury often causes severe neuropathic pain-like behavior in the IAN-innervated region as well as the adjacent region that includes the whisker pad skin. However, the basis for the spreading of pain to adjacent facial areas after IAN injury is still unknown. ⋯ The number of phosphorylated extracellular signal-regulated kinase immunoreactive (IR) neurons in trigeminal spinal subnucleus caudalis and upper cervical spinal cord following capsaicin injection into the whisker pad region was significantly greater in IAN-transected rats than sham-operated rats. The number of TRPV1-IR trigeminal ganglion (TG) neurons innervating the whisker pad skin was also increased significantly after IAN transection. The present findings suggest that an increase in TRPV1 expression in TG neurons innervating the whisker pad skin after IAN transection may underlie the spreading of pain to the adjacent whisker pad skin.
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Neuroscience letters · Mar 2012
Effect of unilateral labyrinthectomy on the molecular composition of perineuronal nets in the lateral vestibular nucleus of the rat.
Disturbances in vestibular functions caused by unilateral labyrinthectomy (UL) are spontaneously restored during the process of vestibular compensation due to the plasticity of CNS. The underlying molecular background of vestibular compensation is not yet fully understood. Recent studies have shown that the extracellular matrix (ECM) molecules have either permissive or non-permissive effect on the neural plasticity. ⋯ In the neuropil, the intensity of the HA increased on the operated side, while the CSPGs reaction almost completely disappeared. The present study have demonstrated for the first time that the UL is accompanied by the modification of the HA, and CSPG staining pattern in the PNN of the LVN in the rat. As the reorganization of the PNN corresponds to the restoration of spontaneous activity of vestibular neurons, our study implies the role of HA and CSPGs in the vestibular compensation.
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Neuroscience letters · Mar 2012
Increased expression of tetrodotoxin-resistant sodium channels Nav1.8 and Nav1.9 within dorsal root ganglia in a rat model of bone cancer pain.
In attempt to understand the underlying mechanisms of cancer-induced bone pain, we investigated the presence of two tetrodotoxin-resistant sodium channels, Nav1.8 (SNS/PN3) and Nav1.9 (SNS2/NaN), in dorsal root ganglia (DRG) neurons in an animal model of bone cancer pain. Thirty-six female Sprague-Dawley rats were randomized into three groups: Sham operation group (Sham), cancer-bearing animals killed after 7 days (C7) and cancer-bearing animals killed after 14 days group (C14). After establishment of bone cancer pain model, behavioral tests were carried out to determine the paw withdrawal threshold (PWT) of mechanical and thermal hyperalgesia, respectively. ⋯ Compared to Sham group, the relative mRNA expression of Nav1.8 and Nav1.9 exhibited a significant up-regulation in C14 group (8.9 times and 9 times, respectively, P<0.01) but not C7 group (1.5 times and 2.4 times, respectively). Western blot and Immunofluorescence revealed an apparent increase of Nav1.8 (P<0.05) and Nav1.9 (P<0.05) protein in C14 group compared with Sham group. The up-regulation of mRNA and protein levels of Nav1.8 and Nav1.9 suggested their potential involvement in the development and maintenance of bone cancer pain.
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Early-life stress is a risk factor for irritable bowel syndrome (IBS), a common and debilitating functional gastrointestinal disorder that is often co-morbid with stress-related psychiatric disorders. In the rat, maternal separation (MS) stress has been shown to induce visceral hypersensitivity in adulthood and thus has become a useful model of IBS. However, development of mouse models of maternal separation has been difficult. ⋯ Wildtype and GABA(B(1b)) receptor knockout mice did not differ in baseline or stress-induced visceral sensitivity. To the best of our knowledge, this is the first study to show that early-life stress induces visceral hypersensitivity in a mouse model. These findings may provide a novel mouse model of visceral hypersensitivity which may aid our understanding of its underlying mechanisms in future studies.
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Neuroscience letters · Mar 2012
Evaluation of late cognitive impairment and anxiety states following traumatic brain injury in mice: the effect of minocycline.
Comorbidity of cognitive and stress disorders is a common clinical sequel of traumatic brain injury (TBI) that is essentially determined by the site and severity of the insult, but also by the extent of the ensuing neuroinflammatory response. The present study sought to examine the late effects of closed-head TBI on memory function and anxiety in mice, in order to further examine the potential efficacy of an acute anti-inflammatory treatment with minocycline. The mouse model of closed-head injury by mechanical percussion was applied on anesthetized Swiss mice. ⋯ Our results revealed a recognition memory deficit that was significant up to at least 13 weeks post-TBI. However, neither EPM nor EZM revealed any alteration in post-TBI anxiety levels albeit some mild disinhibition. Most importantly, minocycline was able to attenuate the memory impairment in an effective and lasting manner, highlighting its therapeutic potential in TBI.