Uso de esteroides sistémicos en quemaduras de segundo grado en modelo animal / Systemic steroid use in second degree burns in an animal model

El uso de esteroide está reconocido en el tratamiento crítico del paciente quemado y es útil en el choque séptico que no responde a vasopresores. Este grupo de medicamentos ayuda a regular la respuesta hemodinámica mejorando el aporte de sangre a la piel, aunque sabemos que tienen un efecto nocivo en el proceso de cicatrización. Evaluamos el efecto histopatológico del empleo de esteroides en quemaduras usando un modelo animal. Empleamos 2 grupos de 10 ratas (Wistar) en las que colocamos un cilindro de metal en el dorso durante 15 segundos a 95oC, produciendo una quemadura. En ese momento, uno de los grupos recibió esteroide a dosis de estrés (hidrocortisona 5 mg/kg) y el otro no recibió ningún medicamento. Al quinto día resecamos la escara y cubrimos el defecto con cultivo de queratinocitos. Los animales fueron sacrificadas a los 14 días. Realizamos análisis histopatológico. Macroscópicamente evaluamos la (..) (AU)

The use of steroids is well recognized in critical care specially in septic shock. There are some reports of their utility in severe burns. It helps to regulate the hemodynamic response in order to improve the blood supply to the skin, although it is well known their negative effect in wound healing. Our objective is to know the hystopathologic effect of steroids in burn healing. We used 2 groups of 10 rats (Wistar). Both groups were exposed in their backs to a metallic cylinder at 95 oC for 15 seconds. At the moment of the burn, one group was given steroid (hydrocortisone at stress dose 5 mg/kg) and the other group didn't received any medication. The scar was removed at the 5th day and the burn injury was covered with queratinocyte culture. The rats were sacrificed at 14th day. We evaluated the presence of clinical signs of infection and the percentage of new epithelium. In the microscope we evaluated the following parameters: fibrosis, inflammatory process, presence of fibroblast and vascular proliferation. We compared both groups using Chi2 test (SPSS program version 10). A p =/<. 05 was considered as statistical significant. We found no difference between each group in fibrosis (p .47), inflammatory process (p .27), or fibroblast presence (p.16). But there was a difference in vascular proliferation (p .05) against the first group (steroid group). There were no signs of infection and all of them were epithelised at the 14th day. In conclusion, the use of steroids in burns in an animal model could have a final effect in wound healing. In humans it is important to say that they can be helpful in those cases with clear evidence of benefit, as for example failure to vassopresor response in septic shock. We are not sure about the final effect in wound healing in the steroid group as for example wound contracture in long term (AU)

Systemic DL-kynurenine and probenecid pretreatment attenuates quinolinic acid-induced neurotoxicity in rats.

Kynurenine (KYN) is the precursor of kynurenic acid (KYNA), an endogenous antagonist of the glycine site of the NMDA (N-methyl-D-aspartate) receptor. Probenecid (PROB), blocks the excretion of KYNA from the extracellular fluid. KYNA antagonizes the toxic action of quinolinic acid (QUIN), an endogenous NMDA receptor agonist. In this study, we tested the effect of the systemic administration of KYN and PROB, either alone or in combination, on QUIN-induced circling behavior and gamma-aminobutyric acid (GABA) depletion in rats. Circling behavior and GABA depletion induced by QUIN were both partially prevented by PROB (200 and 300 mg/kg) and KYN (300 and 450 mg/kg) treatments. Lower doses of drugs administered separately were nonprotective. However, when administered in combination, doses of 150 or 300 mg/kg KYN plus 100 mg/kg PROB significantly protected animals against QUIN neurotoxicity. These findings suggest a role of KYN and PROB as promoters of KYNA-mediated NMDA receptor antagonism, via an increase of kynurenate in brain extracellular spaces.