The arousal effect of hyperbaric oxygen through orexin/hypocretin an upregulation on ketamine/ethanol-induced unconsciousness in male rats.

Approaches that facilitate the recovery from coma would have enormous impacts on patient outcomes and medical economics. Orexin-producing neurons release orexins (also known as hypocretins) energy-dependently to maintain arousal. Hyperbaric oxygen (HBO) could increase ATP levels by preserving mitochondrial function. We investigated, for the first time, the arousal effects of HBO and orexins mechanisms in a rat model of unconsciousness induced by ketamine or ethanol. A total of 120 Sprague-Dawley male rats were used in this study. Unconsciousness was induced either by intraperitoneal injection of ketamine or ethanol. The HBO treatment (100% O2 at 3 ATA) was administered immediately after unconsciousness induction for 1 hr. SB334867, orexin-1 receptor (OX1R) inhibitor, or JNJ10397049, orexin-2 receptor (OX2R) inhibitor was administered 30 min intraperitoneally before unconsciousness induction. Loss of righting reflex test (LORR) and Garcia test were used to evaluate the unconsciousness duration and neurological deficits after recovering from unconsciousness, respectively. Enzyme-linked immunosorbent assay was used to measure brain tissue ATP and orexin A levels. Ketamine or ethanol injection resulted in LORR immediately and neurological deficits 6 hr after unconsciousness induction. HBO treatment significantly reduced the LORR duration, improved Garcia scores and unregulated ATP and orexin A levels in the brain tissue. Administration of OX1R inhibitor or OX2 R inhibitor abolished arousal and neurological benefits of HBO. In conclusion, HBO exerted arousal-promoting effects on unconscious rats induced by ketamine or ethanol. The underlying mechanism was via, at least in part, ATP/orexin A upregulation. HBO may be a practical clinical approach to accelerate unconsciousness recovery in patients.

Promotion of Wakefulness and Energy Expenditure by Orexin-A in the Ventrolateral Preoptic Area.

STUDY OBJECTIVES: The ventrolateral preoptic area (VLPO) and the orexin/hypocretin neuronal system are key regulators of sleep onset, transitions between vigilance states, and energy homeostasis. Reciprocal projections exist between the VLPO and orexin/hypocretin neurons. Although the importance of the VLPO to sleep regulation is clear, it is unknown whether VLPO neurons are involved in energy balance. The purpose of these studies was to determine if the VLPO is a site of action for orexin-A, and which orexin receptor subtype(s) would mediate these effects of orexin-A. We hypothesized that orexin-A in the VLPO modulates behaviors (sleep and wakefulness, feeding, spontaneous physical activity [SPA]) to increase energy expenditure. DESIGN AND MEASUREMENTS: Sleep, wakefulness, SPA, feeding, and energy expenditure were determined after orexin-A microinjection in the VLPO of male Sprague-Dawley rats with unilateral cannulae targeting the VLPO. We also tested whether pretreatment with a dual orexin receptor antagonist (DORA, TCS-1102) or an OX2R antagonist (JNJ-10397049) blocked the effects of orexin-A on the sleep/wake cycle or SPA, respectively. RESULTS: Orexin-A injected into the VLPO significantly increased wakefulness, SPA, and energy expenditure (SPA-induced and total) and reduced NREM sleep and REM sleep with no effect on food intake. Pretreatment with DORA blocked the increase in wakefulness and the reduction in NREM sleep elicited by orexin-A, and the OX2R antagonist reduced SPA stimulated by orexin-A. CONCLUSIONS: These data show the ventrolateral preoptic area is a site of action for orexin-A, which may promote negative energy balance by modulating sleep/wakefulness and stimulating spontaneous physical activity and energy expenditure.

Flow-through sensor array applied to cytotoxicity assessment in cell cultures for drug-testing purposes.

The viability of cells cultured in microsystems for drug screening purposes is usually tested with a variety of colorimetric/fluorescent methods. In this work we propose an alternative way of assessing cell viability-flow-through sensor array that can be connected in series with cell microbioreactors as compatible detection system. It is shown, that the presented device is capable of cytotoxic effect detection and estimation of cell viability after treatment with 1,4-dioxane and 5-fluorouracil, which proves that it can be used for truly non-invasive, fast, reliable, continuous cell culture monitoring in microscale.

Clazosentan: an endothelin receptor antagonist for treatment of vasospasm after subarachnoid hemorrhage.

Clazosentan (Ro 61-1790, VML-588 or AXV-034) is under study in clinical trials for the treatment of patients with aneurysmal subarachnoid hemorrhage (SAH) by Actelion Pharmaceuticals. It is a synthetic endothelin (ET) A receptor antagonist that decreases and reverses cerebral vasospasm after experimental SAH. Remarkable dose-dependent effects were observed on angiographic vasospasm in the CONSCIOUS-1 human clinical trial, supporting proceeding with a Phase III clinical trial. This study (CONSCIOUS-2) will enroll approximately 765 patients randomized 2:1 to clazosentan 5 mg/h intravenously or placebo. All patients will undergo neurosurgical aneurysm clipping and outcome will be assessed primarily based on mortality and vasospasm-related morbidity.

An algorithm-directed two-component library synthesized via solid-phase methodology yielding potent and orally bioavailable p38 MAP kinase inhibitors.

Previously we reported the identification of RPR200765A, a potent orally bioavailable pyridine-imidazole inhibitor of p38 mitogen-activated protein (MAP) kinase which suppressed paw swelling and joint pathology in streptococcal cell wall-induced arthritis. Herein, we report the use of solid-phase combinatorial organic synthesis for the parallel processing of a related pyrimidine-imidazole-based library with two points of structural variability. We report also that the application of a computer algorithm, the Monte Carlo Monomer Selection, maximized both the combinatorial synthetic efficiency and the bioavailability of the final compounds. In conjunction with the synthetic protocols, the polymer-supported quench technique was applied to the purification of the final compounds. Through rapid evaluation of the library using a p38 kinase assay and permeability assays, it was possible to identify a number of potent and orally bioavailable p38 MAP kinase inhibitors suitable for further biological investigation.

Functional assessment of alpha 1-adrenoceptor subtypes in porcine coronary artery.

1. alpha 1-Adrenoceptors are known to play an important role in vasoconstriction in response to adrenergic stimulation. However, the functional importance of alpha 1-adrenoceptor subtypes at the epicardial coronary artery remains unclear. We examined alpha 1-adrenoceptor subtypes by comparing functional affinities for alpha-adrenoceptor antagonists on noradrenaline (NA)-induced vasoconstriction in porcine denuded right coronary arteries. 2. Noradrenaline induced a dose-dependent vasoconstriction in incubated vessel rings. Prazosin and phentolamine were potent and competitive antagonists for NA-induced contraction (pA2 10.27 and 9.03, respectively). In contrast, the selective alpha 2-adrenoceptor antagonist yohimbine had a low affinity (pA2 6.13). Two selective alpha 1A-adrenoceptor antagonists, WB 4101 and 5-methyl urapidil, were potent and competitive antagonists of alpha 1-adrenoceptor-induced contraction (pA2 10.67 and 8.90, respectively) and the selective alpha 1D-adrenoceptor antagonist BMY 7378 had a low affinity (pA2 6.06). Noradrenaline-induced contraction was insensitive to the alkylating effects of chlorethylclonidine. These observations indicate that the vasoconstriction is predominantly mediated by the alpha 1A-adrenoceptor subtype. This was also supported by a good correlation between pA2 values from the present study and reported binding affinities (pKi) of various alpha-adrenoceptor antagonists with cloned human alpha 1A-adrenoceptors (r = 0.98), but not for alpha 1B- or alpha 1D-adrenoceptor subtypes (r = 0.77 and 0.41, respectively). 3. Our results indicate that the alpha 1A-adrenoceptor is the main functional receptor subtype in porcine denuded coronary arteries.

Delineation of rat kidney alpha 2A- and alpha 2B-adrenoceptors with [3H]RX821002 radioligand binding: computer modelling reveals that guanfacine is an alpha 2A-selective compound.

We developed a method for the simultaneous determination of drug affinity constants for rat alpha 2A- and alpha 2B-adrenoceptor subtypes by using [3H]RX821002 radioligand binding in the kidney. Three competition curves were obtained for each drug: one for the test compound in the absence of ARC 239 (a drug found to have 108-fold higher affinity for alpha 2B- than for alpha 2A-adrenoceptors), one in the presence of ARC 239, and one for ARC 239. It is possible to determine the Kds of a tested drug for both alpha 2A- and alpha 2B-adrenoceptors by simultaneous computer modelling because of the increased constraint in the calculations given by the inclusion of ARC 239 into the assay. Using this approach, we found guanfacine and oxymetazoline to be highly alpha 2A-selective. The most alpha 2B-selective were ARC 239, prazosin and corynanthine. A number of other drugs, for example UK-14,304, rilmenidine and clonidine, were non-selective or showed minor selectivity for alpha 2A- or alpha 2B-adrenoceptors. Moreover, using Monte Carlo simulations, we showed that the three-curve method gives more accurate estimates of drug binding constants for assays when two receptor sites are present than methods analysing only one competition curve.