Influence of different anaesthetics on pro-inflammatory cytokine expression in rat spleen

We examined the effect of five anaesthetic drugs commonly used in laboratory animal research (tribromoethanol, ketamine/xylazine, chloral hydrate, pentobarbital, and urethane) on the expression of four pro-inflammatory cytokines. The anaesthetic agents were applied at dosages normally used for deep surgical anaesthesia. Semiquantitative image analysis of interleukin (IL)-1beta, IL-2, IL-6, and tumour necrosis factor alpha (TNFalpha) mRNA expression in the spleen of male Wistar rats 4 h after application of the anaesthetic drugs showed that these had moderate immunomodulatory effects. Ketamine/xylazine, chloral hydrate, and pentobarbital enhanced the basal expression of IL-1beta and IL-6 mRNA in rat spleen, while urethane reduced splenic IL-1beta mRNA expression. Tribromoethanol, ketamine/xylazine, and urethane reduced the basal TNFalpha mRNA levels, whereas TNFalpha mRNA expression was unaffected by chloral hydrate and by pentobarbital. The data demonstrate that these anaesthetics have slight, but significant, effects on the basal immune status of rats.