Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942013000200004
Brazilian Journal of Anesthesiology
Scientific Article

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

Anti-nociceptive, analgesic and pathohistological effects of intrathecal dexmedetomidine and bupivacaine in rats

Baş; ar Erdivanli; Murat Altun; Özlem K Sezen; Serhan A Çolakoğ; lu

http://dx.doi.org/10.1590/S0034-70942013000200004 Braz J Anesthesiol, vol.63, n2, p.183-187, 2013
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Resumo

JUSTIFICATIVA E OBJETIVOS: Este estudo investigou os efeitos analgésicos e nociceptivos da adição de dexmedetomidina à bupivacaína em anestesia do neuroeixo usando os testes de retirada da cauda (tail-flick [TF]) e da placa quente (hot-plate [HP]) e microscopia de luz para as alterações histopatológicas de nervos espinhais e raízes nervosas. MÉTODOS: Quarenta ratos Sprague-Dawley anestesiados, machos, foram cateterizados intratecalmente. Os valores basais dos testes TF e HP foram medidos antes e depois do cateterismo. Trinta e seis ratos cateterizados com sucesso foram distribuídos em quatro grupos. O Grupo B recebeu 10 µg de bupivacaína, o Grupo BD3 recebeu 10 µg de bupivacaína + 3 µg de dexmedetomidina, o Grupo BD10 recebeu 10 µg de bupivacaína + 10 µg de dexmedetomidina e o Grupo Controle recebeu 10 µL de líquido cefalorraquidiano artificial. Os testes TF e HP foram feitos entre cinco e 300 minutos a partir da administração das drogas. Vinte e quatro horas após a administração, os ratos foram sacrificados e retiradas as medulas espinhais e raízes nervosas para investigação patológica. RESULTADOS: Os valores basais dos testes TF e HP não foram estatisticamente diferentes entre os grupos (6,8 ± 0,15 s). As latências de TF e HP no Grupo Controle não apresentaram alteração significativa durante o estudo. Os resultados dos testes TF e HP mostraram que a adição de 3 e 10 µg de dexmedetomidina causou um aumento dose-dependente na duração e amplitude do efeito analgésico e nociceptivo de bupivacaína (TF: 37,52 ± 1,08%, 57,86 ± 1,16%, respectivamente; HP: 44,24 ± 1,15%, 68,43 ± 1,24%, respectivamente). CONCLUSÕES: Não houve alterações histopatológicas aparentes em pelo menos 24 horas após a administração intratecal da dose única de dexmedetomidina (3 µg e 10 µg). Dexmedetomidina adicionado à bupivacaína para raquianestesia melhora a analgesia e prolonga a duração do bloqueio.

Palavras-chave

ANESTESIA, Regional, raquianestesia, ANESTÉSICOS, Local, bupivacaína, ANALGÉSICOS, Dexmedetomidina, DOR; ANIMAL, Rato

Abstract

BACKGROUND AND OBJECTIVES: This study investigates analgesic and nociceptive effects of adding dexmedetomidine to bupivacaine neuraxial anesthesia through Tail-flick (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 artificial cerebrospinal fluid. TF and HP tests were performed between the 5th and 300th minutes of drug administration. Twenty-four hours after administration of drugs, rats were sacrificed 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 significantly 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.

Keywords

Bupivacaine, Dexmedetomidine, Pain Measurement, Rats, Sprague-Dawley, Anesthesia, Spinal

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