Neurobiology of disease
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Neurobiology of disease · Jan 2009
Insular cortex representation of dynamic mechanical allodynia in trigeminal neuropathic rats.
Dynamic mechanical allodynia is a widespread symptom of neuropathic pain for which mechanisms are still poorly understood. The present study investigated the organization of dynamic mechanical allodynia processing in the rat insular cortex after chronic constriction injury to the infraorbital nerve (IoN-CCI). Two weeks after unilateral IoN-CCI, rats showed a dramatic bilateral trigeminal dynamic mechanical allodynia. ⋯ Stimulus-evoked pERK-1/2 immunopositive cell bodies displayed rostrocaudal gradient and layer selective distribution in the insula, being predominant in the rostral insula and in layers II-III of the dysgranular and to a lesser extent, of the agranular insular cortex. In layers II-III of the rostral dysgranular insular cortex, intense pERK also extended into distal dendrites, up to layer I. These results demonstrate that trigeminal nerve injury induces a significant alteration in the insular cortex processing of tactile stimuli and suggest that ERK phosphorylation contributes to the mechanisms underlying abnormal pain perception under this condition.
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Neurobiology of disease · Jan 2009
The endocannabinoid system is modulated in response to spinal cord injury in rats.
Endocannabinoids are lipid mediators with protective effects in many diseases of the nervous system. We have studied the modulation of the endocannabinoid system after a spinal cord contusion in rats. In early stages, lesion induced increases of anandamide and palmitoylethanolamide (PEA) levels, an upregulation of the synthesizing enzyme NAPE-phospholipase D and a downregulation of the degradative enzyme FAAH. ⋯ We observed that CB(1) was constitutively expressed by neurons and oligodendrocytes and induced in reactive astrocytes. CB(2) receptor was strongly upregulated after lesion, and mostly expressed by immune infiltrates and astrocytes. The endocannabinoid system may represent an interesting target for new therapeutical approaches to spinal cord injury.