ABSTRACT
Aim To evaluate the antinociception of ω-SO3,a novel Omega-superfamily conotoxin,in rat formalin test.Methods Potency and duration of ω-SO3 antinociception compared with morphine were investigated in rat formalin test after acute intrathecal administration.Development of tolerance or cross tolerance to analgesia of ω-SO3 and morphine was tested in formalin test after chronic intrathecal administration.Locomotor activity of rat after acute intrathecal administration was tested to evaluate possible central side effects.Results In rat formalin test after intrathecal bolus injection,ω-SO3 produced dose-and time-dependent antinociception by suppressing acute(ED_(50),1.79 ng·g~(-1))and tonic phases(ED_(50),0.41 ng·g~(-1)),which was approximately 10-fold potency and twice longer-acting of morphine in blocking tonic phase responses.After repeated intrathecal injections twice daily for 5 consecutive days,ω-SO3 produced analgesia without loss of potency whereas morphine produced analgesia tolerance in rat formalin test;further,ω-SO3 still produced potent analgesia in morphine-tolerant rats.No changes in motor function were seen in rats receiving above antinociceptive doses.Conclusion sNovel ω-SO3 produces potent and long-acting spinal antinociception without observable motor dysfunction and after chronic intrathecal administration.ω-SO3 produces neither tolerance nor cross-tolerance to morphine analgesia.
ABSTRACT
O treinamento físico, de intensidade moderada, melhora os sistemas de defesa, enquanto que o treinamento intenso causa imunossupressão. Os mecanismos subjacentes estão associados à comunicação entre os sistemas nervoso, endócrino e imunológico, sugerindo vias autonômicas e modulação da resposta imune. Células do sistema imune, quando expostas a pequenas cargas de estresse, desenvolvem mecanismo de tolerância. Em muitos tecidos tem-se demonstrado que a resposta a situações agressivas parece ser atenuada pelo treinamento físico aplicado previamente, isto é, o treinamento induz tolerância para situações agressivas/estressantes. Nesta revisão são relatados estudos sugerindo os mecanismos adaptativos do sistema imunológico em resposta ao treinamento físico.
Moderate physical training enhances the defense mechanisms, while intense physical training induces to immune suppression. The underlying mechanisms are associated with the link between nervous, endocrine, and immune systems. It suggests autonomic patterns and modulation of immune response. Immune cells, when exposed to regular bouts of stress, develop a mechanism of tolerance. In many tissues, it has been demonstrated that the response to aggressive conditions is attenuated by moderate physical training. Thus, training can induce tolerance to aggressive/stressful situations. In this review, studies suggesting the adaptation mechanisms of the immune system in response to physical training will be reported.
ABSTRACT
Objective:To assess whether intrathecal orphanin FQ can develop the antinociceptive effect tolerance,and whether there is a cross tolerance between the antinociceptive effect of intrathecal orphanin FQ and the ? opioid receptor agonist morphine.Methods: Tail flick test was used to observe the change of antinociceptive effect after orphanin FQ/morphine intrathecal microinjection into the rats tolerant to acute or chronic morphine/orphanin FQ.Results:Like morphine,large dosage of continuous intrathecal orphanin FQ microinjection produced tolerance to the antinociceptive effect,but there was no apparent cross tolerance between the orphanin FQ and morphine; Hyperalgesic response was found in morphine tolerant rats,but not in orphanin FQ tolerant rats.Conclusion:Lack of cross tolerance between the antinociceptive effect of intrathecal orphanin FQ and morphine indicates that the mechanism of tolerance to orphanin FQ may differ from that to morphine; The antinociceptive effect of intrathecal orphanin FQ may be largely related with its specific receptor in the spinal cord.