Efeitos da privação de sono paradoxal na resposta inflamatória de ratos e avaliação do efeito antinociceptivo do ATL-1, um análogo sintético de 15-epi-lipoxinas

Abstract

Sleep and immunity show a reciprocal relationship. Immune system activation alters sleep pattern and sleep disturbances can affect immune function. Moreover, it is well known that paradoxical sleep deprivation (PSD) leads to hyperalgesia and the treatment with classical drugs like opioids or tricyclic antidepressants is not able to reverse this hyperalgesia. In this work we investigated whether PSD could affect inflammatory response and survival in rats and if ATL-1 treatment would be able to reverse the hyperalgesia induced by PSD. All experimental protocols were previously approved by The Animal Care Ethical Committee of UERJ (CEUA/032/2010). Male Wistar rats were submitted to 96 h of PSD by single platform or modified multiple platforms methods. After 96 h of PSD animals were submitted to carrageenan-induced air pouch or pleurisy, or PSD was induced prior or after cecal ligation and puncture model (CLP). Animals presented an increase in leukocyte recruitment to the pouch cavity 4 h after carrageenan injection, however there was no difference between PSD and controls. The number of plasma leukocyte did not change after carrageenan injection. PSD animals submitted to pleurisy showed an increase in IL-6, IL-1β e TNF-α plasma levels, while IL-1β and IL-6 were increased in pleural exsudate of animals that received carrageenan. Leukocyte recruitment pattern to the site of injury was similar between controls and PSD 2 h, 4 h and 24 h after carrageenan injection. There was a progressive increase with time, reaching the maximum point at 24 h, but no differences were observed in PSD groups. PSD induced prior or after CLP decreased animals survival, however no difference was observed on neutrophil accumulation in both protocols. When PSD was induced prior CLP, IL-6 plasma levels were increased in PSD e PSDCLP groups, when PSD was induced after CLP, IL-6 and IL-1β plasma levels were increased in PSDCLP group. The effect of ATL-1 treatment (10 µg/kg, i.v.) on hyperalgesia induced by PSD was determined through formalin test. The treatment reduced the number of pain related behaviors in PSD animals and controls on inflammatory phase. Our results show that ATL-1 was able to revert the hyperalgesia induced by PSD possibly through its anti-inflammatory action. Furthermore, PSD for 96 h increased cytokine plasma levels and reduced survival, however it was not able to modify leukocyte recruitment when challenged by an inflammatory or infectious stimulus. However the inflammatory mediators increase observed in PSD animals could be related to hyperalgesia since treatment with ATL-1 reverted this effect, possibly through anti-inflammatory mechanisms.