Avaliação da eficácia preemptiva da dipirona sódica pela análise imuno-histoquímica da expressão de c-fos na medula espinhal: estudo num modelo experimental de dor pós-operatória em ratos / The evaluation of the preemptive efficacy of dipyrone in a model of postoperative pain: an immunohistochemical c-fos expression study in the rat spinal cord

Este trabalho avaliou a eficácia preemptiva da dipirona (100 e 200 mg/kg EV), em ratos anestesiados, antes ou após a sutura de uma incisão cirúrgica na pata.Os animais foram sacrificados 2h após para avaliar-se a contagem dos neurônios imunorreativos para a proteína Fos (Fos-ir) na medula espinhal. A redução de Fos-ir não se relacionou com o momento de administração da dipirona (pré ou pós-incisional), não se caracterizando eficácia preemptiva para este fármaco.This prospective, randomized and placebo-controlled study aimed at evaluate the preemptive value of 100 and 200 mg/kg IV dipyrone given 10 minutes before or immediately after closure of a surgical incision in the plantar aspect of the right hindpaw of anesthetized rats. Rats were sacrificed 2h after and spinal cords were studied to quantify the laminar distribution of Fos-immunoreactive neurons (Fos-ir) (laminae I-X).c-fos reduction was not related to timing of administration of dipyrone (pre versus post-incisional); therefore, no preemptive efficacy was observed...

Inflammatory response of the spinal cord to multiple episodes of blood-brain barrier disruption and toxic demyelination in Wistar rats

Multiple episodes of blood-brain barrier disruption were induced by sequential intraspinal injections of ethidium bromide. In addition to the barrier disruption, there was toxic demyelination and exposure of myelin components to the immune system. Twenty-seven 3-month-old Wistar rats received 2, 3 or 4 injections of 1 mul of either 0.1 percent ethidium bromide in normal saline (19 rats) or 0.9 percent saline (8 rats) at different levels of the spinal cord. The time intervals between the injections ranged from 28 to 42 days. Ten days after the last injection, all rats were perfused with 2.5 percent glutaraldehyde. The spinal sections were evaluated macroscopically and by light and transmission electron microscopy. All the lesions demonstrated a mononuclear phagocytic infiltrate apparently removing myelin. Lymphocytes were not conspicuos and were found in only 34 percent of the lesions. No perivascular cuffings were detected. In older lesions (38 days and older) they were found only within Virchow-Robin spaces. This result suggests that multiple blood-brain barrier disruptions with demyelination and exposure of myelin components to the immune system were not sufficient to induce an immune-mediated reaction in the central nervous system.