Differential effects of etomidate and its pyrrole analogue carboetomidate on the adrenocortical and cytokine responses to endotoxemia.

OBJECTIVE: We developed a novel pyrrole analog of etomidate, (R)-ethyl 1-(1-phenylethyl)-1H-pyrrole-2-carboxylate (carboetomidate), which retains etomidate's desirable anesthetic and hemodynamic properties but lacks its potent inhibitory affect on adrenocorticotropic hormone-stimulated steroid synthesis. The objective of this study was to test the hypothesis that in contrast to etomidate, carboetomidate neither suppresses the adrenocortical response to endotoxemia nor enhances the accompanying production of proinflammatory cytokines. DESIGN: Animal study. SETTING: University research laboratory. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: For both single and multiple anesthetic dose studies, rats were injected with Escherichia coli lipopolysaccharide immediately followed by a hypnotic dose of etomidate, carboetomidate, or vehicle alone (dimethyl sulfoxide) as a control. For single-dose studies, no additional anesthetic (or vehicle) was administered. For multiple anesthetic dose studies, additional doses of anesthetic (or vehicle) were administered every 15 mins for a total of eight anesthetic (or vehicle) doses. MEASUREMENTS AND MAIN RESULTS: Plasma adrenocorticotropic hormone, corticosterone, and cytokine concentrations were measured before lipopolysaccharide administration and intermittently throughout the 5-hr experiment. In single anesthetic dose studies, plasma adrenocorticotropic hormone and cytokine concentrations were not different at any time point among the etomidate, carboetomidate, and vehicle groups, whereas plasma corticosterone concentrations were briefly (60-120 mins) reduced in the etomidate group. In multiple anesthetic dose studies, plasma corticosterone concentrations were persistently lower and peak plasma interleukin-1ß and interleukin-6 concentrations were higher in the etomidate group vs. the carboetomidate and control groups. Peak plasma interleukin-10 concentrations were similarly elevated in the etomidate and carboetomidate groups vs. the control group. CONCLUSIONS: Compared with etomidate, carboetomidate produces less suppression of adrenocortical function and smaller increases in proinflammatory cytokine production in an endotoxemia model of sepsis. These findings suggest that carboetomidate could be a useful alternative to etomidate for maintaining anesthesia for a prolonged period of time in patients with sepsis.

In vivo and in vitro pharmacological studies of methoxycarbonyl-carboetomidate.

BACKGROUND: We previously developed 2 etomidate analogs that retain etomidate's favorable hemodynamic properties but whose adrenocortical effects are reduced in duration or magnitude. Methoxycarbonyl (MOC)-etomidate is rapidly metabolized and ultrashort acting whereas (R)-ethyl 1-(1-phenylethyl)-1H-pyrrole-2-carboxylate (carboetomidate) does not potently inhibit 11ß-hydroxylase. We hypothesized that MOC-etomidate's labile ester could be incorporated into carboetomidate to produce a new agent that possesses favorable properties individually found in each agent. We describe the synthesis and pharmacology of MOC-(R)-ethyl 1-(1-phenylethyl)-1H-pyrrole-2-carboxylate (MOC-carboetomidate), a "soft" analog of carboetomidate. METHODS: MOC-carboetomidate's octanol:water partition coefficient was determined chromatographically and compared with those of etomidate, carboetomidate, and MOC-etomidate. MOC-carboetomidate's 50% effective concentration (EC(50)) and 50% effective dose for loss of righting reflexes (LORR) were measured in tadpoles and rats, respectively. Its effect on γ-aminobutyric acid A (GABA(A)) receptor function was assessed using 2-microelectrode voltage clamp electrophysiological techniques and its metabolic stability was determined in pooled rat blood using high performance liquid chromatography. Its duration of action and effects on arterial blood pressure and adrenocortical function were assessed in rats. RESULTS: MOC-carboetomidate's octanol:water partition coefficient was 3300 ± 280, whereas those for etomidate, carboetomidate, and MOC-etomidate were 800 ± 180, 15,000 ± 3700, and 190 ± 25, respectively. MOC-carboetomidate's EC(50) for LORR in tadpoles was 9 ± 1 µM and its EC(50) for LORR in rats was 13 ± 5 mg/kg. At 13 µM, MOC-carboetomidate enhanced GABA(A) receptor currents by 400% ± 100%. Its metabolic half-life in pooled rat blood was 1.3 min. The slope of a plot of the duration of LORR in rats versus the logarithm of the hypnotic dose was significantly shallower for MOC-carboetomidate than for carboetomidate (4 ± 1 vs 15 ± 3, respectively; P = 0.0004123). At hypnotic doses, the effects of MOC-carboetomidate on arterial blood pressure and adrenocortical function were not significantly different from those of vehicle alone. CONCLUSIONS: MOC-carboetomidate is a GABA(A) receptor modulator with potent hypnotic activity that is more rapidly metabolized and cleared from the brain than carboetomidate, maintains hemodynamic stability similar to carboetomidate, and does not suppress adrenocortical function.

Closed-loop continuous infusions of etomidate and etomidate analogs in rats: a comparative study of dosing and the impact on adrenocortical function.

BACKGROUND: Etomidate is a sedative-hypnotic that is often given as a single intravenous bolus but rarely as an infusion because it suppresses adrenocortical function. Methoxycarbonyl etomidate and (R)-ethyl 1-(1-phenylethyl)-1H-pyrrole-2-carboxylate (carboetomidate) are etomidate analogs that do not produce significant adrenocortical suppression when given as a single bolus. However, the effects of continuous infusions on adrenocortical function are unknown. In this study, we compared the effects of continuous infusions of etomidate, methoxycarbonyl etomidate, and carboetomidate on adrenocortical function in a rat model. METHODS: A closed-loop system using the electroencephalographic burst suppression ratio as the feedback was used to administer continuous infusions of etomidate, methoxycarbonyl etomidate, or carboetomidate to Sprague-Dawley rats. Adrenocortical function was assessed during and after infusion by repetitively administering adrenocorticotropic hormone 1-24 and measuring serum corticosterone concentrations every 30 min. RESULTS: The sedative-hypnotic doses required to maintain a 40% burst suppression ratio in the presence of isoflurane, 1%, and the rate of burst suppression ratio recovery on infusion termination varied (methoxycarbonyl etomidate > carboetomidate > etomidate). Serum corticosterone concentrations were reduced by 85% and 56% during 30-min infusions of etomidate and methoxycarbonyl etomidate, respectively. On infusion termination, serum corticosterone concentrations recovered within 30 min with methoxycarbonyl etomidate but persisted beyond an hour with etomidate. Carboetomidate had no effect on serum corticosterone concentrations during or after continuous infusion. CONCLUSIONS: Our results suggest that methoxycarbonyl etomidate and carboetomidate may have clinical utility as sedative-hypnotic maintenance agents when hemodynamic stability is desirable.

Interactions between SirT1 and STAT3 in the retinal pigmented epithelium cell / 眼科新进展

Objective To investigate the interactions between histone deacetylas-1 (silent information regulator of transcription 1,SirT1) and signal transducer and activator of transcription 3 (STAT3) following exposure to oxidative stress of retinal pigmented epithelium (RPE) cells through gene knockout and overexpression techniques.Methods RPE cell line was cultured in vitro,followed by addition of H2O2 for inducing oxidative stress.The targeting knockout strategy (siRNA/shRNA) was used for silencing SirT1/STAT3 gene and lentiviral vectors (pRC/CMV STAT3 and PCRC/CMV) were transfected to RPE cells.RT-qPCR and Western blot were used to detect the expression of SirT1/STAT3 due to gene knockout and overexpression and deeply analyze the effects of SirT1/STAT3 on RPE cells exposed to oxidative stress.Results SirT1 activator (resveratrol) significantly reduced the expression of STAT3 mRNA to (3.0 ± 0.2) (P =0.048);and after SifT1 knockout,the expression of STAT3 mRNA in RPE cells was significantly increased to (6.9 ± 1.1) (P =0.025).During the oxidative stress of RPE cells after SifT1 knockout,the expression of STAT3 and phosphorylated STAT3 protein were significantly increased to 0.990 ±0.031 and 0.544 ±0.019,respectively (P =0.000,0.003).With the condition of oxidative stress,the over-expression of STAT3 reduced the SirT1 mRNA expression to 0.42 ± 0.16 (P =0.022),but SifT1 mRNA expression was significantly increased to 2.8 ±0.85 (P =0.015) during STAT3 knockdown.Conclusion SifT1 has a negative effect on the regulation of STAT3 expression during oxidative stress,which suggests that there is an equilibrium mechanism between SirT1 and STAT3 against oxidative stress.