Abstract
The anti-inflammatory actions of sevoflurane postconditioning are suggested as an important mechanism of sevoflurane postconditioning-induced neuroprotection against cerebral ischemia. Here, we determined whether the anti-inflammatory effects of sevoflurane postconditioning were mediated via inhibition of the toll-like receptor (TLR)-4/nuclear factor kappa B (NF-κB) pathway after global transient cerebral ischemia in rats. Forty-five rats were randomly assigned to five groups as follows: (1) control (10 min of ischemia, n = 10); (2) sevoflurane postconditioning (two periods of sevoflurane inhalation after ischemia for 10 min with a wash period of 10 min, n = 10); (3) resatorvid (intraperitoneal injection of a selective TLR-4 antagonist (3 mg/kg) 30 min before ischemia, n = 10); (4) sevoflurane postconditioning plus resatorvid (n = 10), and sham (n = 5). The numbers of necrotic and apoptotic cells in the hippocampal CA1 region, the expression levels of TLR-4, NF-κB, cleaved caspase-3, and tumor necrosis factor alpha (TNF-α) in the anterior part of each brain, and the serum levels of TNF-α, interleukin 6 (IL-6), and interleukin 1 beta (IL-1β) were assessed 1 day after ischemia. The necrotic cell counts and expression levels of TLR-4, NF-κB, caspase-3, and TNF-α in brain tissue as well as serum levels of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) were significantly higher in the control group than in the other groups. Our findings suggest that the anti-inflammatory actions of sevoflurane postconditioning via inactivation of the TLR-4/NF-κB pathway and subsequent reduction in pro-inflammatory cytokine production, in part, contribute to sevoflurane postconditioning-induced neuroprotection after global transient cerebral ischemia in rats.
Highlights
Sevoflurane is an inhalation agent used for general anesthesia
A previous study investigating the anti-inflammatory effects of sevoflurane postconditioning demonstrated that serum levels of pro-inflammatory cytokines (for example, tumor necrosis factor (TNF)-α and interleukin (IL)-1β) were considerably lower in rats treated with sevoflurane postconditioning during early reperfusion compared with those in rats with only transient global cerebral ischemia [3]
In a view of neuroprotection, the effects of pre- or postconditioning of inhalation agents on toll-like receptor (TLR)-4-mediated anti-inflammation are not fully investigated, a recent study demonstrated that isoflurane preconditioning provided neuroprotection in rats subjected to transient focal cerebral ischemia by suppressing microglial TLR-4 expression [13]
Summary
Sevoflurane is an inhalation agent used for general anesthesia. Sevoflurane postconditioning has been highlighted in neuroprotection against cerebral ischemia/reperfusion (I/R) injury, as it exerts neuroprotective effects in various experimental models of cerebral injury [1,2,3,4,5,6]. A previous study investigating the anti-inflammatory effects of sevoflurane postconditioning demonstrated that serum levels of pro-inflammatory cytokines (for example, tumor necrosis factor (TNF)-α and interleukin (IL)-1β) were considerably lower in rats treated with sevoflurane postconditioning during early reperfusion compared with those in rats with only transient global cerebral ischemia [3]. In a view of neuroprotection, the effects of pre- or postconditioning of inhalation agents on TLR-4-mediated anti-inflammation are not fully investigated, a recent study demonstrated that isoflurane preconditioning provided neuroprotection in rats subjected to transient focal cerebral ischemia by suppressing microglial TLR-4 expression [13]. No study has investigated the effect of sevoflurane postconditioning on TLR-4-related inflammatory responses that develop after global cerebral I/R injury
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