Tumor Necrosis Factor-α Reduces Ketamine- and Propofol-Induced Anesthesia Time in Rats

In utero Exposure to Anesthetics Alters Neuronal Migration Pattern in Developing Cerebral Cortex and Causes Postnatal Behavioral Deficits in Rats

During fetal development, cerebral cortical neurons are generated in the proliferative zone along the ventricles and then migrate to their final positions. To examine the impact of in utero exposure to anesthetics on neuronal migration, we injected pregnant rats with bromodeoxyuridine to label fetal neurons generated at embryonic Day (E) 17 and then randomized these rats to 9 different groups receiving 3 different means of anesthesia (oxygen/control, propofol, isoflurane) for 3 exposure durations (20, 50, 120 min). Histological analysis of brains from 54 pups revealed that significant number of neurons in anesthetized animals failed to acquire their correct cortical position and remained dispersed within inappropriate cortical layers and/or adjacent white matter. Behavioral testing of 86 littermates pointed to abnormalities that correspond to the aberrations in the brain areas that are specifically developing during the E17. In the second set of experiments, fetal brains exposed to isoflurane at E16 had diminished expression of the reelin and glutamic acid decarboxylase 67, proteins critical for neuronal migration. Together, these results call for cautious use of anesthetics during the neuronal migration period in pregnancy and more comprehensive investigation of neurodevelopmental consequences for the fetus and possible consequences later in life.

The modulating effects of propofol and its lipid carrier on canine neutrophil functions

Propofol (2,6-diisopropylphenol), being used as an intravenous sedative and anesthetic agent, influences not only upon nervous system but also for host inflammatory response through modulating neutrophil functions. This study is designed to evaluate the modulating effects of propofol and its lipid carrier administration at clinically relevant rate on canine neutrophil functions. Clinically healthy beagle dogs were received propofol (8.8 mg/kg) from cephalic vein and maintained with propofol dropping infusion (26.4 mg/kg/hr). Blood samples were collected from the dogs before infusion and 30 min after the start of propofol administration, and neutrophil functions were evaluated. The dogs were also administered lipid carrier, and neutrophil functions were evaluated in the same manner as propofol administration. Peripheral white blood cell and neutrophil counts decreased after the propofol or lipid carrier administration. The administration of propofol or lipid carrier significantly reduced neutrophil adherence ability. The superoxide production of neutrophils was measured by luminol-dependent chemiluminescence response using with opsonized zymosan. Peak height of neutrophil chemiluminescence curve was reduced by propofol and lipid carrier administration, on the contrary, peak time of neutrophil chemiluminescence curve was delayed. Administration of propofol or lipid carrier also reduced neutrophil adherence ability to nylon fibers. In the present study, we showed the modulating effects of propofol and its lipid carrier on canine neutrophil functions. However, there was no significant difference in the modulating effects between propofol group and lipid carrier group. Therefore, the modulating effects observed here were deeply concerned in lipid carrier administration.

Direct assessment of the antioxidant properties of midazolam by electron spin resonance spectroscopy

Some antioxidant anesthetics directly inhibit lipid peroxidation mediated via the generation of reactive oxygen species (ROS). To date, the scavenging effects of midazolam on ROS have not been directly assessed. We investigated the inhibitory effect of midazolam on ROS [hydroxyl radical (HO(·)) and superoxide (O (2) (·-) )] by in vitro X-band electron spin resonance with the spin-trapping agent 5,5-dimethyl-1-pyrroline-N-oxide. Our results indicated that HO(·) and O (2) (·-) were not affected by midazolam at clinically relevant concentrations, but were directly scavenged by midazolam at high concentrations (i.e., >4.6 and >1.5 mM, respectively).

Upregulation of cerebrospinal fluid and peripheral prostaglandin E2 in a rat postoperative pain model

Analgesic management of postoperative pain associated with thoracic surgery remains a difficult clinical challenge. In the present study we used a thoracic muscle incision model to characterize pain-related behavior and changes in prostaglandin E2 (PGE2) in both thoracic cerebrospinal fluid (CSF) and incision site tissues. A deep muscle incision was made in the left thoracic region of rats anesthetized with isoflurane, propofol, or spinal bupivacaine. Thoracic CSF and incision site tissue concentrations of PGE2 were monitored for 6 h using microdialysis loop catheters. Postoperative pain-related behavior was assessed by recording exploratory locomotive activity. Thoracic muscle surgery decreased rearing and ambulation. Oral ketorolac or rofecoxib 3 mg/kg restored normal rearing and ambulation. Postoperative CSF PGE2 concentration increased most (threefold) with spinal anesthesia, and not at all with propofol. With surgery under isoflurane or spinal bupivacaine, presurgical oral administration of ketorolac or rofecoxib 3 mg/kg reduced postsurgical CSF PGE2 levels and tissue PGE2 levels. Intrathecal ketorolac (4 microg) reduced CSF PGE2 after surgery without affecting tissue PGE2 levels, whereas intrathecal L-745,337 (80 microg) did not reduce CSF PGE2. Thoracic surgical wounds increase pain-related behavior and CSF and tissue PGE2 levels, all of which can be attenuated by oral cyclooxygenase inhibitors.

Differential effects of anesthetics on endotoxin-induced liver injury

BACKGROUND

The liver is both a source and a target of inflammatory and anti-inflammatory mediators during sepsis. The oxidative stress proteins inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1) are upregulated in the liver during sepsis but have opposite roles. Upregulation of HO-1 has hepatoprotective effects, whereas iNOS has injurious effects to the liver. Although recent studies indicate that ketamine anesthesia has anti-inflammatory effects during sepsis, the effects of other anesthetics are unknown. We hypothesized that ketamine, but not isoflurane, would attenuate lipopolysaccharide (LPS)-induced liver injury through differential modulation of iNOS and HO-1.

METHODS

Adult rats were given no anesthesia (saline), continuous isoflurane inhalation, or intraperitoneal ketamine (70 mg/kg). One hour later, saline or LPS (20 mg/kg intraperitoneally) was given for 5 hours. Rats were killed, serum prepared for determination of hepatocellular enzymes, and the liver assessed for iNOS and HO-1 by Western immunoblot.

RESULTS

LPS significantly increased serum aspartate aminotransferase levels, iNOS, and HO-1 immunoreactivity in the liver. Ketamine but not isoflurane attenuated LPS-induced liver injury, upregulated HO-1, and downregulated iNOS.

CONCLUSION

These data indicate that anesthetics differ in their effects on the liver in a rat model of sepsis with LPS. Ketamine has hepatoprotective effects against LPS-induced liver injury that appear to be mediated, at least in part, by differential modulation of the oxidative stress proteins iNOS and HO-1. Thus, ketamine may be the anesthetic agent of choice for septic patients requiring anesthesia.