Brain research
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Repeated blast exposures commonly induce traumatic brain injury (TBI) characterized by diffuse axonal injury (DAI). We hypothesized that degradation of cytoskeletal proteins in the brain can lead to DAI, and evaluated α-II spectrin degradation in the pathophysiology of blast-induced TBI using the tightly-coupled three repetitive blast exposure mice model with a 1-30 min window in between exposures. Degradation of α-II spectrin and the expression profiles of caspase-3 and calpain-2, the major enzymes involved in the degradation were analyzed in the frontal cortex and cerebellum using Western blotting with specific antibodies. ⋯ The expression of another α-II spectrin degrading enzyme, calpain-2, showed a rapid increase in the frontal cortex after blast exposure and it was significantly higher in the cerebellum at later time points. Neuropathological analysis showed significant levels of DAI at the frontal cortex and cerebellum at multiple time points after repeated blast injury. In summary, repeated blast exposure results in specific degradation of α-II spectrin in the brain along with differential expression of caspase-3/calpain-2 suggesting cytoskeletal breakdown as a possible contributor of DAI after repeated blast exposure.
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Peripheral polyneuropathy is a frequent complication of diabetes. One of its consequences is neuropathic pain which is often chronic and difficult to treat. This pain management classically involves anticonvulsant drugs or tricyclic antidepressant drugs (TCA). ⋯ Chronic but not acute treatment with nortriptyline alleviates allodynia caused by the diabetic neuropathy. This effect depends on β2 adrenoceptors but not on α2 adrenoceptors, as shown by the blockade with repeated co-administration of the β2 adrenoceptor antagonist ICI118551 but not with repeated co-administration of the α2 adrenoceptor antagonist yohimbine. Direct stimulation of β2 adrenoceptors appears sufficient to relieve allodynia, as shown with chronic terbutaline treatment. δ but not mu opioid receptors seem important to these action since acute naltrindole, but not acute naloxonazine, reverses the effect of chronic nortriptyline or terbutaline treatment.