Efeitos antinociceptivos, analgésicos e histopatológicos de dexmedetomidina e bupivacaína intratecal em rato

Abstract

Background and Objectives: This study investigates analgesic and nociceptive effects of adding dexmedetomidine to bupivacaine neuraxial anesthesia through Tail-fl ick (TF) and Hot-plate (HP) tests and the pathohistological changes on spinal nerves and nerve roots through light microscopy. Methods: Forty anesthetized, male Sprague-Dawley rats were intrathecally catheterized. Basal values of TF and HP tests were measured before and after catheterization. Thirty-six successfully catheterized rats were assigned to four groups. Group B received 10 μg bupivacaine, Group BD3 received 10 μg bupivacaine + 3 μg dexmedetomidine, Group BD10 received 10 μg bupivacaine + 10 μg dexmedetomidine and Control group received 10 μL volume of artifi cial cerebrospinal fl uid. TF and HP tests were performed between the 5 th and 300 th minutes of drug administration. Twenty-four hours after administration of drugs, rats were sacrifi ced and spinal cord and nerve roots were removed for pathological investigation. Results: Baseline values of the TF and HP tests were not statistically different among the groups (6.8 ± 0.15 s). TF and HP latencies in the Control group did not change signifi cantly during the study. TF and HP test results showed that adding 3 and 10 μg dexmedetomidine caused a dosedependent increase in duration and amplitude of analgesic and nociceptive effect of bupivacaine (TF: 37.52 ± 1.08%, 57.86 ± 1.16% respectively, HP: 44.24 ± 1.15%, 68.43 ± 1.24% respectively). Conclusions: There were no apparent pathohistological changes at least 24 hours after the intrathecal administration of a single dose of dexmedetomidine 3 μg and 10 μg. Dexmedetomidine added to bupivacaine for spinal block improves analgesia and prolongs block duration.

Nocicepção Térmica em Ratos Tratados com Propiltiouracil

“…A familiarização/ambientação dos animais no teste de placa quente foi realizada 60 minutos antes do teste definitivo no interior do recipiente de vidro, porém com a placa mantida fria, visto que estudos demonstram que a exposição prévia a este procedimento, altera a resposta nociceptiva ocasionada pelo estresse, um fator notadamente considerado antinociceptivo. 25 Todos os dados obtidos (peso corpóreo, ingestão hídrica, consumo alimentar e latência em placa quente) foram submetidos ao teste de normalidade e de homocedasticidade (Assistat 7.7 beta). Uma vez satisfeitas as condições, foi usado o teste t de Student para comparação entre as médias e o critério estipulado em 5 %, ou seja, todas as probabilidades menores que 0,05 foram consideradas significativas.…”