Kamishoyosan potentiates pentobarbital-induced sleep in socially isolated, ovariectomized mice

ETHNOPHARMACOLOGICAL RELEVANCE

Sleep disorders are among the most common symptoms in both peri- and post-menopausal women. Kamishoyosan (KSS) is a Kampo medicine prescribed for the treatment of sleep disorders in menopausal women in Japan. However, its precise mechanism of action remains unclear.

AIM OF THE STUDY

In the present study, we developed a new animal model of menopausal sleep disorders by inducing social isolation stress in ovariectomized mice. Using pentobarbital-induced sleeping time as an index, we aimed to investigate the effects of KSS and involvement of the benzodiazepine receptors.

MATERIALS AND METHODS

Eight-week-old, female ddY mice were ovariectomized or subjected to a sham operation (control) and housed in social isolation or groups for 9 weeks. The animals were divided into four groups, group-housed sham-operated, isolated sham-operated, group-housed ovariectomized, and socially isolated ovariectomized. Pentobarbital (50 mg/kg) was administered intraperitoneally (i.p.). Sleeping time was considered the period between the loss of righting reflex and its return (up to 180 min). KSS was administered orally (p.o.) 60 min before the test. Diazepam and flumazenil were administered i.p. 30 and 45 min before the test, respectively. On the day after administration, the mice were euthanized, and their uteri were weighed.

RESULTS

Socially isolated, ovariectomized mice had shorter sleeping times than mice in all other groups. In mice with intact ovaries, diazepam (1 mg/kg, i.p.) considerably prolonged the pentobarbital-induced sleeping time, but KSS (30-1000 mg/kg, p.o.) did not. However, KSS (100 mg/kg, p.o.) significantly prolonged the pentobarbital-induced sleeping time in socially isolated ovariectomized mice. The prolongation of sleeping time mediated by KSS was reversed by flumazenil (3 mg/kg, i.p.).

CONCLUSIONS

KSS potentiated pentobarbital-induced sleep in socially isolated, ovariectomized mice, and the benzodiazepine receptors are possibly involved in its pharmacological mechanism. These findings suggest that KSS is beneficial for the treatment of menopausal sleep disorders.

Chloral hydrate as a sedating agent for neurodiagnostic procedures in children

BACKGROUND

This is an updated version of a Cochrane Review published in 2017. Paediatric neurodiagnostic investigations, including brain neuroimaging and electroencephalography (EEG), play an important role in the assessment of neurodevelopmental disorders. The use of an appropriate sedative agent is important to ensure the successful completion of the neurodiagnostic procedures, particularly in children, who are usually unable to remain still throughout the procedure.

OBJECTIVES

To assess the effectiveness and adverse effects of chloral hydrate as a sedative agent for non-invasive neurodiagnostic procedures in children.

SEARCH METHODS

We searched the following databases on 14 May 2020, with no language restrictions: the Cochrane Register of Studies (CRS Web) and MEDLINE (Ovid, 1946 to 12 May 2020). CRS Web includes randomised or quasi-randomised controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, the Cochrane Central Register of Controlled Trials (CENTRAL), and the specialised registers of Cochrane Review Groups including Cochrane Epilepsy.

SELECTION CRITERIA

Randomised controlled trials that assessed chloral hydrate agent against other sedative agent(s), non-drug agent(s), or placebo.

DATA COLLECTION AND ANALYSIS

Two review authors independently evaluated studies identified by the search for their eligibility, extracted data, and assessed risk of bias. Results were expressed in terms of risk ratio (RR) for dichotomous data and mean difference (MD) for continuous data, with 95% confidence intervals (CIs).

MAIN RESULTS

We included 16 studies with a total of 2922 children. The methodological quality of the included studies was mixed. Blinding of the participants and personnel was not achieved in most of the included studies, and three of the 16 studies were at high risk of bias for selective reporting. Evaluation of the efficacy of the sedative agents was also underpowered, with all the comparisons performed in small studies. Fewer children who received oral chloral hydrate had sedation failure compared with oral promethazine (RR 0.11, 95% CI 0.01 to 0.82; 1 study; moderate-certainty evidence). More children who received oral chloral hydrate had sedation failure after one dose compared to intravenous pentobarbital (RR 4.33, 95% CI 1.35 to 13.89; 1 study; low-certainty evidence), but there was no clear difference after two doses (RR 3.00, 95% CI 0.33 to 27.46; 1 study; very low-certainty evidence). Children with oral chloral hydrate had more sedation failure compared with rectal sodium thiopental (RR 1.33, 95% CI 0.60 to 2.96; 1 study; moderate-certainty evidence) and music therapy (RR 17.00, 95% CI 2.37 to 122.14; 1 study; very low-certainty evidence). Sedation failure rates were similar between groups for comparisons with oral dexmedetomidine, oral hydroxyzine hydrochloride, oral midazolam and oral clonidine. Children who received oral chloral hydrate had a shorter time to adequate sedation compared with those who received oral dexmedetomidine (MD -3.86, 95% CI -5.12 to -2.6; 1 study), oral hydroxyzine hydrochloride (MD -7.5, 95% CI -7.85 to -7.15; 1 study), oral promethazine (MD -12.11, 95% CI -18.48 to -5.74; 1 study) (moderate-certainty evidence for three aforementioned outcomes), rectal midazolam (MD -95.70, 95% CI -114.51 to -76.89; 1 study), and oral clonidine (MD -37.48, 95% CI -55.97 to -18.99; 1 study) (low-certainty evidence for two aforementioned outcomes). However, children with oral chloral hydrate took longer to achieve adequate sedation when compared with intravenous pentobarbital (MD 19, 95% CI 16.61 to 21.39; 1 study; low-certainty evidence), intranasal midazolam (MD 12.83, 95% CI 7.22 to 18.44; 1 study; moderate-certainty evidence), and intranasal dexmedetomidine (MD 2.80, 95% CI 0.77 to 4.83; 1 study, moderate-certainty evidence). Children who received oral chloral hydrate appeared significantly less likely to complete neurodiagnostic procedure with child awakening when compared with rectal sodium thiopental (RR 0.95, 95% CI 0.83 to 1.09; 1 study; moderate-certainty evidence). Chloral hydrate was associated with a higher risk of the following adverse events: desaturation versus rectal sodium thiopental (RR 5.00, 95% 0.24 to 102.30; 1 study), unsteadiness versus intranasal dexmedetomidine (MD 10.21, 95% CI 0.58 to 178.52; 1 study), vomiting versus intranasal dexmedetomidine (MD 10.59, 95% CI 0.61 to 185.45; 1 study) (low-certainty evidence for aforementioned three outcomes), and crying during administration of sedation versus intranasal dexmedetomidine (MD 1.39, 95% CI 1.08 to 1.80; 1 study, moderate-certainty evidence). Chloral hydrate was associated with a lower risk of the following: diarrhoea compared with rectal sodium thiopental (RR 0.04, 95% CI 0.00 to 0.72; 1 study), lower mean diastolic blood pressure compared with sodium thiopental (MD 7.40, 95% CI 5.11 to 9.69; 1 study), drowsiness compared with oral clonidine (RR 0.44, 95% CI 0.30 to 0.64; 1 study), vertigo compared with oral clonidine (RR 0.15, 95% CI 0.01 to 2.79; 1 study) (moderate-certainty evidence for aforementioned four outcomes), and bradycardia compared with intranasal dexmedetomidine (MD 0.17, 95% CI 0.05 to 0.59; 1 study; high-certainty evidence). No other adverse events were significantly associated with chloral hydrate, although there was an increased risk of combined adverse events overall (RR 7.66, 95% CI 1.78 to 32.91; 1 study; low-certainty evidence).

AUTHORS' CONCLUSIONS

The certainty of evidence for the comparisons of oral chloral hydrate against several other methods of sedation was variable. Oral chloral hydrate appears to have a lower sedation failure rate when compared with oral promethazine. Sedation failure was similar between groups for other comparisons such as oral dexmedetomidine, oral hydroxyzine hydrochloride, and oral midazolam. Oral chloral hydrate had a higher sedation failure rate when compared with intravenous pentobarbital, rectal sodium thiopental, and music therapy. Chloral hydrate appeared to be associated with higher rates of adverse events than intranasal dexmedetomidine. However, the evidence for the outcomes for oral chloral hydrate versus intravenous pentobarbital, rectal sodium thiopental, intranasal dexmedetomidine, and music therapy was mostly of low certainty, therefore the findings should be interpreted with caution. Further research should determine the effects of oral chloral hydrate on major clinical outcomes such as successful completion of procedures, requirements for an additional sedative agent, and degree of sedation measured using validated scales, which were rarely assessed in the studies included in this review. The safety profile of chloral hydrate should be studied further, especially for major adverse effects such as oxygen desaturation.

Intraperitoneal injection of sodium pentobarbital has the potential to elicit pain in adult rats (Rattus norvegicus)

An effective and pain-free killing method is required to achieve the goal of euthanasia, a "good death". Overdose of sodium pentobarbital (PB) by intraperitoneal (IP) injection is a widely accepted technique in laboratory rats, but questions remain regarding pain associated with administration. As PB rapidly causes sedation and loss of consciousness, most studies have relied on indirect evidence of pain. The objective of this study was to assess pain associated with IP PB using an appropriate vehicle control. Adult male and female Sprague Dawley (SD) and female Wistar rats (N = 84) were block randomised by sex and strain to receive one of three treatments: 1) 800 mg/kg PB (pH 11), 2) saline or 3) vehicle controls (pH 11 or 12.5). Behavior (Rat Grimace Scale (RGS), writhing, back arching) was evaluated at baseline, before loss of righting reflex (LORR, PB group), and at 80s, 151s and 10 min post-injection (PI; saline and vehicle control groups). In the PB group, mean time to LORR was 78 ± 7.9 seconds. In the vehicle control groups, RGS scores were increased at 151s PI (SD: p = 0.0002, 95%CI 0.73 to 0.20) from baseline, as was relative frequency of writhing (SD: p < 0.0001; Wistar; p = 0.0004). RGS scores remained elevated 10 mins PI (SD: p = 0.0005, 95%CI 0.71 to 0.18; Wistar: p = 0.0234, 95%CI 0.91 to 0.07) but the relative frequency of writhing did not (p > 0.999). The RGS scores and the relative frequency of writhing remained low in the PB and saline groups (p > 0.05). These results show that, vehicle controls for IP PB result in signs associated with pain, pain may not be experienced following IP PB when LORR occurs quickly, and that the effects of PB limit behavioral pain assessments.

Review of Intraperitoneal Injection of Sodium Pentobarbital as a Method of Euthanasia in Laboratory Rodents

Euthanasia is one of the most commonly performed procedures in biomedical research, involving tens of millions of animals in North America and Europe every year. The use of sodium pentobarbital, injected intraperitoneally, for killing rodents is described as an acceptable technique by the AVMA and CCAC euthanasia guidelines. This drug and route are recommended over inhalant anesthetics, carbon dioxide, and physical methods for ethical and aesthetic reasons as well as efficiency. However, a growing body of evidence challenges the efficacy and utility of intraperitoneal pentobarbital. This methodology has been described as inconsistent and may induce pain and stress. With these considerations in mind, a review of the literature is needed to assess the evidence surrounding this killing method, the associated welfare implications, and potential for refinement.

Moringa oleifera Lam Seed Oil Augments Pentobarbital-Induced Sleeping Behaviors in Mice via GABAergic Systems

Moringa oleifera Lam. (MO), which is widely consumed as both food and herbal medicine in tropical and subtropical regions, has a wide spectrum of health benefits. Yet, whether the oil obtained from MO seeds could affect (improve) the sleep activity remains unclear. Herein, we used the locomotor activity, pentobarbital-induced sleeping, and pentetrazol-induced convulsions test to examine sedative-hypnotic effects (SHE) of MO oil (MOO) and explored the underlying mechanisms. Besides, the main components of MOO like oleic acid, β-Sitosterol, and Stigmasterol were also evaluated. The results showed that they possessed good SHE. Except for oleic acid and Stigmasterol, they could significantly elevate γ-amino butyric acid (GABA) and reduce glutamic acid (Glu) levels in the hypothalamus of mice. Moreover, SHE was blocked by picrotoxin, flumazenil, and bicuculline, except for oleic acid, which could not be antagonized by picrotoxin. Molecular mechanisms showed that MOO and β-Sitosterol significantly upregulated the amount of protein-level expression of Glu decarboxylase-65 (GAD₆₅) and α₁-subunit of GABA_A receptors in the hypothalamus of mice, not affecting GAD₆₇, γ₂ subunits. These data indicated that MOO modulates sleep architectures via activation of the GABA_A-ergic systems.

Localized anesthesia of a specific brain region using ultrasound-responsive barbiturate nanodroplets

Background: Targeted neuromodulation is a valuable technique for the study and treatment of the brain. Using focused ultrasound to target the local delivery of anesthetics in the brain offers a safe and reproducible option for suppressing neuronal activity. Objective: To develop a potential new tool for localized neuromodulation through the triggered release of pentobarbital from ultrasound-responsive nanodroplets. Method: The commercial microbubble contrast agent, Definity, was filled with decafluorobutane gas and loaded with a lipophilic anesthetic drug, before being condensed into liquid-filled nanodroplets of 210 ± 80 nm. Focused ultrasound at 0.58 MHz was found to convert nanodroplets into microbubbles, simultaneously releasing the drug and inducing local anesthesia in the motor cortex of rats (n=8). Results: Behavioral analysis indicated a 19.1 ± 13% motor deficit on the contralateral side of treated animals, assessed through the cylinder test and gait analysis, illustrating successful local anesthesia, without compromising the blood-brain barrier. Conclusion: Pentobarbital-loaded decafluorobutane-core Definity-based nanodroplets are a potential agent for ultrasound-triggered and targeted neuromodulation.

Perfused murine heart optical transmission spectroscopy using optical catheter and integrating sphere: Effects of ischemia/reperfusion

Tissue transmission optical absorption spectroscopy provides dynamic information on metabolism and function. Murine genetic malleability makes it a major model for heart research. The diminutive size of the mouse heart makes optical transmission studies challenging. Using a perfused murine heart center mounted in an integrating sphere for light collection with a ventricular cavity optical catheter as an internal light source provided an effective method of optical data collection in this model. This approach provided high signal to noise optical spectra which when fit with model spectra provided information on tissue oxygenation and redox state. This technique was applied to the study of cardiac ischemia and ischemia reperfusion which generates extreme heart motion, especially during the ischemic contracture. The integrating sphere reduced motion artifacts associated with a fixed optical pickup and methods were developed to compensate for changes in tissue thickness. During ischemia, rapid decreases in myoglobin oxygenation occurred along with increases in cytochrome reduction levels. Surprisingly, when ischemic contracture occurred, myoglobin remained fully deoxygenated, while the cytochromes became more reduced consistent with a further, and critical, reduction of mitochondrial oxygen tension during ischemic contraction. This optical arrangement is an effective method of monitoring murine heart metabolism.

Palmatine plays a role in sedation and hypnosis by increasing 5-hydroxytryptamine

Objective of this study was to investigate the sedative and hypnotic effects of palmatine and to observe whether its mechanism is related to 5-hydroxytryptamine (5-HT) and GABA. The sedative and hypnotic effects of palmatine on mice were observed with mouse autonomic activity test, direct sleep test, pentobarbital sodium in suprathreshold and subthreshold dose sleep test. The content of GABA and 5-HT in brain homogenate was determined by ELISA  method. Mouse brain specimens were observed by immunohistochemistry for 5-HT expression in the nucleus of mouse brain. Palmatine could reduce spontaneous activities of mice, prolong the sleep time of mice induced by pentobarbital sodium in suprathreshold dose and shorten the sleep latency.  And it could increase the number of mice falling asleep induced by pentobarbital sodium in subthreshold dose and the incidence of falling asleep, but with no direct sleep effect. In addition, it enhanced the 5-HT content in brain, but had no effect on GABA content, and had no toxicity to PC12 cells. Palmatine plays a significant role in sedation and hypnosis, which may be associated with the increase of intra-cerebral 5-HT.

[The Role of the Medical Profession in Euthanasia, Particularly in the Prescription of Sodium Pentobarbital]

The Role of the Medical Profession in Euthanasia, Particularly in the Prescription of Sodium Pentobarbital Abstract. The delivery of sodium pentobarbital as part of assisted suicide requires a doctor's prescription. This prescription must meet the legal and professional requirements as well as the corresponding ethical guidelines. Current legal practice restrictively permits suicide assistance in this form, especially in the case of patients who are willing to die and whose death is foreseeable. The new guidelines of the SAMS (2018) extend the possibility to patients who suffer intolerably due to disease symptoms and/or functional restrictions. The prescription of NaP in other cases or in violation of the duty of care provided for in the guidelines may result in supervisory, professional and criminal consequences. Suicide assistance itself is a decision of conscience, not a medical task, which is why there is no entitlement to it.

Evaluation of a Commercially Available Euthanasia Solution as a Voluntarily Ingested Euthanasia Agent in Laboratory Mice

All currently accepted methods of euthanasia for laboratory mice involve some degree of stress, fear, anxiety, or pain. We evaluated the voluntary oral administration of a euthanasia drug in 99 male and 81 female mice of various strains. We first explored the palatability of sugar-cookie dough with various flavorings added. We placed the cookie dough in the cage with an adult mouse and recorded the amount ingested after 1 h. Mice readily ingested all flavors of sugar-cookie dough. We then added a euthanasia solution containing pentobarbital and phenytoin to all flavors of cookie dough and placed a small bolus in the cage of each mouse or mouse pair. We observed the mice for 1 h for clinical signs of pentobarbital intoxication and then weighed uneaten dough to determine the dose of pentobarbital ingested. Palatability declined sharply when euthanasia solution was present. Mice ingested higher doses of pentobarbital in cookie dough during the dark phase and after fasting. Ingestion caused ataxia in some mice but was not sufficient to cause loss of righting reflex, unconsciousness, or death in any mouse. We successfully identified sugar cookie dough as a drug vehicle that was readily and rapidly eaten by mice without the need for previous exposure. Additional research is needed to identify euthanasia compounds for mice that do not affect the palatability of cookie dough.

Influence of sedation on onset and quality of euthanasia in sheep

The purpose of this study was to determine if dexmedetomidine administered IV prior to euthanasia in sheep affected the speed or quality of euthanasia. Twenty clinically healthy Dorset-cross adult ewes between 1 and 3years of age were enrolled in a randomized blinded experimental trial. The subjects were randomly assigned to receive dexmedetomidine 5μg/kg IV or an equivalent volume of saline. Five minutes later, euthanasia was accomplished with a pentobarbital/phenytoin overdose given IV. The time to apnea, asystole, cessation of audible heartbeat, and absence of corneal reflex were recorded by two blinded investigators. If any muscle spasms, contractions, vocalization, and/or dysrhythmias were noted, the time was recorded and type of ECG abnormality was described. An overall score of the euthanasia event was assigned using a numeric rating scale (NRS) after the animal was declared dead. The time to loss of corneal reflex was significantly longer in sheep given dexmedetomidine compared with those who received saline (P=0.03). Although vocalization was observed only in some animals premedicated with dexmedetomidine, no significance was found for this event and no other significant differences between groups were noted. Dexmedetomidine at 5μg/kg IV 5min prior to injection of pentobarbital/phenytoin for euthanasia did not substantially affect the progress of euthanasia. Dexmedetomidine may be given to sedate sheep prior to euthanasia without concern for it adversely affecting the progress of euthanasia, however vocalization may occur.

The pedunculopontine tegmentum controls renal sympathetic nerve activity and cardiorespiratory activities in nembutal-anesthetized rats

Elevated renal sympathetic nerve activity (RSNA) accompanies a variety of complex disorders, including obstructive sleep apnea, heart failure, and chronic kidney disease. Understanding pathophysiologic renal mechanisms is important for determining why hypertension is both a common sequelae and a predisposing factor of these disorders. The role of the brainstem in regulating RSNA remains incompletely understood. The pedunculopontine tegmentum (PPT) is known for regulating behaviors including alertness, locomotion, and rapid eye movement sleep. Activation of PPT neurons in anesthetized rats was previously found to increase splanchnic sympathetic nerve activity and blood pressure, in addition to altering breathing. The present study is the first investigation of the PPT and its potential role in regulating RSNA. Microinjections of DL-homocysteic acid (DLH) were used to probe the PPT in 100-μm increments in Nembutal-anesthetized rats to identify effective sites, defined as locations where changes in RSNA could be evoked. A total of 239 DLH microinjections were made in 18 rats, which identified 20 effective sites (each confirmed by the ability to evoke a repeatable sympathoexcitatory response). Peak increases in RSNA occurred within 10–20 seconds of PPT activation, with RSNA increasing by 104.5 ± 68.4% (mean ± standard deviation) from baseline. Mean arterial pressure remained significantly elevated for 30 seconds, increasing from 101.6 ± 18.6 mmHg to 135.9 ± 36.4 mmHg. DLH microinjections also increased respiratory rate and minute ventilation. The effective sites were found throughout the rostal-caudal extent of the PPT with most located in the dorsal regions of the nucleus. The majority of PPT locations tested with DLH microinjections did not alter RSNA (179 sites), suggesting that the neurons that confer renal sympathoexcitatory functions comprise a small component of the PPT. The study also underscores the importance of further investigation to determine whether sympathoexcitatory PPT neurons contribute to adverse renal and cardiovascular consequences of diseases such as obstructive sleep apnea and heart failure.

Chloral hydrate as a sedating agent for neurodiagnostic procedures in children

BACKGROUND

Paediatric neurodiagnostic investigations, including brain neuroimaging and electroencephalography (EEG), play an important role in the assessment of neurodevelopmental disorders. The use of an appropriate sedative agent is important to ensure the successful completion of the neurodiagnostic procedures, particularly in children, who are usually unable to remain still throughout the procedure.

OBJECTIVES

To assess the effectiveness and adverse effects of chloral hydrate as a sedative agent for non-invasive neurodiagnostic procedures in children.

SEARCH METHODS

We used the standard search strategy of the Cochrane Epilepsy Group. We searched MEDLINE (OVID SP) (1950 to July 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, Issue 7, 2017), Embase (1980 to July 2017), and the Cochrane Epilepsy Group Specialized Register (via CENTRAL) using a combination of keywords and MeSH headings.

SELECTION CRITERIA

We included randomised controlled trials that assessed chloral hydrate agent against other sedative agent(s), non-drug agent(s), or placebo for children undergoing non-invasive neurodiagnostic procedures.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the studies for their eligibility, extracted data, and assessed risk of bias. Results were expressed in terms of risk ratio (RR) for dichotomous data, mean difference (MD) for continuous data, with 95% confidence intervals (CIs).

MAIN RESULTS

We included 13 studies with a total of 2390 children. The studies were all conducted in hospitals that provided neurodiagnostic services. Most studies assessed the proportion of sedation failure during the neurodiagnostic procedure, time for adequate sedation, and potential adverse effects associated with the sedative agent.The methodological quality of the included studies was mixed, as reflected by a wide variation in their 'Risk of bias' profiles. Blinding of the participants and personnel was not achieved in most of the included studies, and three of the 13 studies had high risk of bias for selective reporting. Evaluation of the efficacy of the sedative agents was also underpowered, with all the comparisons performed in single small studies.Children who received oral chloral hydrate had lower sedation failure when compared with oral promethazine (RR 0.11, 95% CI 0.01 to 0.82; 1 study, moderate-quality evidence). Children who received oral chloral hydrate had a higher risk of sedation failure after one dose compared to those who received intravenous pentobarbital (RR 4.33, 95% CI 1.35 to 13.89; 1 study, low-quality evidence), but after two doses there was no evidence of a significant difference between the two groups (RR 3.00, 95% CI 0.33 to 27.46; 1 study, very low-quality evidence). Children who received oral chloral hydrate appeared to have more sedation failure when compared with music therapy, but the quality of evidence was very low for this outcome (RR 17.00, 95% CI 2.37 to 122.14; 1 study). Sedation failure rates were similar between oral chloral hydrate, oral dexmedetomidine, oral hydroxyzine hydrochloride, and oral midazolam.Children who received oral chloral hydrate had a shorter time to achieve adequate sedation when compared with those who received oral dexmedetomidine (MD -3.86, 95% CI -5.12 to -2.6; 1 study, moderate-quality evidence), oral hydroxyzine hydrochloride (MD -7.5, 95% CI -7.85 to -7.15; 1 study, moderate-quality evidence), oral promethazine (MD -12.11, 95% CI -18.48 to -5.74; 1 study, moderate-quality evidence), and rectal midazolam (MD -95.70, 95% CI -114.51 to -76.89; 1 study). However, children with oral chloral hydrate took longer to achieve adequate sedation when compared with intravenous pentobarbital (MD 19, 95% CI 16.61 to 21.39; 1 study, low-quality evidence) and intranasal midazolam (MD 12.83, 95% CI 7.22 to 18.44; 1 study, moderate-quality evidence).No data were available to assess the proportion of children with successful completion of neurodiagnostic procedure without interruption by the child awakening. Most trials did not assess adequate sedation as measured by specific validated scales, except in the comparison of chloral hydrate versus intranasal midazolam and oral promethazine.Compared to dexmedetomidine, chloral hydrate was associated with a higher risk of nausea and vomiting (RR 12.04 95% CI 1.58 to 91.96). No other adverse events were significantly associated with chloral hydrate (including behavioural change, oxygen desaturation) although there was an increased risk of adverse events overall (RR 7.66, 95% CI 1.78 to 32.91; 1 study, low-quality evidence).

AUTHORS' CONCLUSIONS

The quality of evidence for the comparisons of oral chloral hydrate against several other methods of sedation was very variable. Oral chloral hydrate appears to have a lower sedation failure rate when compared with oral promethazine for children undergoing paediatric neurodiagnostic procedures. The sedation failure was similar for other comparisons such as oral dexmedetomidine, oral hydroxyzine hydrochloride, and oral midazolam. When compared with intravenous pentobarbital and music therapy, oral chloral hydrate had a higher sedation failure rate. However, it must be noted that the evidence for the outcomes for the comparisons of oral chloral hydrate against intravenous pentobarbital and music therapy was of very low to low quality, therefore the corresponding findings should be interpreted with caution.Further research should determine the effects of oral chloral hydrate on major clinical outcomes such as successful completion of procedures, requirements for additional sedative agent, and degree of sedation measured using validated scales, which were rarely assessed in the studies included in this review. The safety profile of chloral hydrate should be studied further, especially the risk of major adverse effects such as bradycardia, hypotension, and oxygen desaturation.

Evaluation of Best Practices for the Euthanasia of Zebra Finches (Taeniopygia guttata)

Although zebra finches (Taeniopygia guttata) have been used in biomedical research for many years, no published reports are available about euthanizing these small birds. In this study, we compared 5 methods for zebra finch euthanasia: sodium pentobarbital (NaP) given intracoelomically with physical restraint but no anesthesia; isoflurane anesthesia followed by intracoelomic injection of NaP; and CO2 asphyxiation at 20%, 40%, and 80% chamber displacement rates (percentage of chamber volume per minute). Birds undergoing euthanasia were videorecorded and scored by 2 observers for behaviors potentially related to discomfort or distress. Time to recumbency and time until respiratory arrest (RA) were also assessed. RA was achieved faster by using NaP in a conscious bird compared to using isoflurane anesthesia followed by NaP; however, neither method caused behaviors that might affect animal welfare, such as open-mouth breathing, to any appreciable extent. Among the CO2 treatment groups, there was an inverse correlation between the chamber displacement rate used and the duration of open-mouth breathing, onset of head retroflexion, and time to RA. The results demonstrate that the intracoelomic administration of NaP in an awake, restrained zebra finch is a rapid and effective method of euthanasia. If CO2 is used to euthanize these birds, a high displacement rate (for example, 80%) will minimize the duration of the procedure and associated behaviors.

Effects of Surgical Anaesthesia on the Viability of Nigral Grafts in the Rat Striatum

Only a small proportion of dopamine neurons in nigral grafts typically survive transplantation into the adult striatum. Since many anaesthetics reduce blood flow and disturb a variety of brain metabolites, surgical anaesthesia may be one of the factors that compromise graft survival. Conversely, the lowered core body temperature induced by some anaesthetics might promote the survival of grafted cells by slowing their metabolism. In an initial screen, the widely-used surgical anaesthetic, equithesin, was found to reduce core temperature, mean arterial blood pressure, and to increase the partial pressure of oxygen in arterial blood without producing any significant alteration in arterial pH or the partial pressure of carbon dioxide. In the main experiment, rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal bundle received dopamine-rich embryonic nigral grafts injected into the deafferented neostriatum via previously implanted guide cannulae, which allowed comparison to be made of graft survival after transplantation into awake and in re-anaesthetised animals. There were no significant differences between groups in either the functional effects of the grafts to compensate amphetamine-induced rotation, or in the survival and growth of the grafts as measured in post mortem histology. We therefore conclude that anaesthesia per se is not a major contributory factor in the relatively poor survival of dopamine neurons following transplantation into the rat striatum.

Intraperitoneal Administration of Ethanol as a Means of Euthanasia for Neonatal Mice (Mus musculus)

The humane euthanasia of animals in research is of paramount importance. Neonatal mice frequently respond differently to euthanasia agents when compared with adults. The AVMA's Guidelines for the Euthanasia of Animals includes intraperitoneal injection of ethanol as "acceptable with conditions," and recent work confirmed that this method is appropriate for euthanizing adult mice, but neonatal mice have not been tested. To explore this method in neonatal mice, mouse pups (C57BL/6 and CD1, 162 total) were injected with 100% ethanol, a pentobarbital-phenytoin combination, or saline at 7, 14, 21, 28, or 35 d of age. Electrocardiograms, respiratory rates, and times to loss of righting reflex and death were recorded. Time to death (TTD) differed significantly between ethanol and pentobarbital-phenytoin at 7, 14, and 21 d and between ethanol groups at 7, 14, and 21 d compared with 35 d. The average TTD (± 1 SD) for ethanol-injected mice were: 7 d, 70.3 ± 39.8 min; 14 d, 51.7 ± 30.5 min; 21 d, 32.3 ± 20.8 min, 28 d, 14.0 ± 15.2; and 35 d, 4.9 ± 1.4. Mean TTD in pentobarbital-phenytoin-injected mice were: 7 d, 2.8 ± 0.4 min; 14 d, 2.9 ± 0.5 min; 21 d, 3.9 ± 1.2 min; 28 d, 3.9 ± 0.7 min; and 35 d, 4.4 ± 0.5. Although TTD did not differ between ethanol and pentobarbital-phenytoin at 28 d of age, the TTD in 3 of 12 mice was longer than 15 min after ethanol administration at this age. Therefore, ethanol should not be used as a method of euthanasia for mice younger than 35 d, because the criteria for humane euthanasia were met only in mice 35 d or older.

Conductance catheter measurement and effect of different anesthetics in a rat model of postresuscitation myocardial dysfunction

We demonstrate the usefulness of left ventricular pressure-volume (PV) loops generated by the use of conductance catheter measurements and investigate the influence of the type of general anesthesia on postresuscitation myocardial dysfunction in a rat model of cardiac arrest (CA) and subsequent cardiopulmonary resuscitation. A total of 42 Wistar-Han rats were randomized to receive general anesthesia with sevoflurane and resuscitation after CA, general anesthesia with pentobarbital intraperitoneally and resuscitation after CA, or general anesthesia with pentobarbital without CA (sham group). Myocardial function, assessed by analysis of PV loops, was measured continuously and in real-time by using a PV-conductance catheter. Rats were monitored for 3 h after restoration of spontaneous circulation (ROSC). The use of PV-conductance catheters supported objective and reliable evaluation of myocardial function and proved feasible in this rat model of CA. End-diastolic volume increased in rats anesthetized with pentobarbital after ROSC (before CA, 237 ± 45 μL; after ROSC, 402 ± 64 μL). Preloadadjusted maximal power before CA was the same in all groups but decreased in both resuscitated groups. The decrease was less pronounced in rats anesthetized with sevoflurane compared with pentobarbital (11.8 ± 4.9 mW/μL(2) compared with 4.8 ± 1.9 mW/μL(2) at 3 h after ROSC). This finding indicates that the type of general anesthesia influences postresuscitation myocardial dysfunction in this rat model of experimentally induced CA and cardiopulmonary resuscitation. Rats that were anesthetized with sevoflurane exhibited less postresuscitation myocardial dysfunction than did those anesthetized with pentobarbital.

Mannitol for acute traumatic brain injury

BACKGROUND

Mannitol is sometimes effective in reversing acute brain swelling, but its effectiveness in the ongoing management of severe head injury remains unclear. There is evidence that, in prolonged dosage, mannitol may pass from the blood into the brain, where it might cause increased intracranial pressure.

OBJECTIVES

To assess the effects of different mannitol therapy regimens, of mannitol compared to other intracranial pressure (ICP) lowering agents, and to quantify the effectiveness of mannitol administration given at other stages following acute traumatic brain injury.

SEARCH METHODS

We searched the Cochrane Injuries Group Specialised Register, CENTRAL (The Cochrane Library), MEDLINE (OvidSP), EMBASE (OvidSP), ISI Web of Science (SCI-EXPANDED & CPCI-S) and PubMed. We checked reference lists of trials and review articles, and contacted authors of trials. The search was updated on the 20th April 2009.

SELECTION CRITERIA

Randomised controlled trials of mannitol, in patients with acute traumatic brain injury of any severity. The comparison group could be placebo-controlled, no drug, different dose, or different drug. We excluded cross-over trials, and trials where the intervention was started more than eight weeks after injury.

DATA COLLECTION AND ANALYSIS

We independently rated quality of allocation concealment and extracted the data. Relative risks (RR) and 95% confidence intervals (CI) were calculated for each trial on an intention to treat basis.

MAIN RESULTS

We identified four eligible randomised controlled trials. One trial compared ICP-directed therapy to 'standard care' (RR for death = 0.83; 95% CI 0.47 to 1.46). One trial compared mannitol to pentobarbital (RR for death = 0.85; 95% CI 0.52 to 1.38). One trial compared mannitol to hypertonic saline (RR for death = 1.25; 95% CI 0.47 to 3.33). One trial tested the effectiveness of pre-hospital administration of mannitol against placebo (RR for death = 1.75; 95% CI 0.48 to 6.38).

AUTHORS' CONCLUSIONS

Mannitol therapy for raised ICP may have a beneficial effect on mortality when compared to pentobarbital treatment, but may have a detrimental effect on mortality when compared to hypertonic saline. ICP-directed treatment shows a small beneficial effect compared to treatment directed by neurological signs and physiological indicators. There are insufficient data on the effectiveness of pre-hospital administration of mannitol.

Effects of injectable anesthetic combinations on left ventricular function and cardiac morphology in Sprague-Dawley rats

Novel anesthetic agents or combinations may provide superior general anesthesia for echocardiography in rodents with the potential for reduced adverse effects. This study sought to characterize the effects of 3 injectable anesthetics on left ventricular (LV) systolic function and cardiac morphology in healthy male and female rats. Rats underwent echocardiographic assessment after general anesthesia via pentobarbital or combinations of ketamine and medetomidine (KME) and ketamine and midazolam (KMI) according to a crossover Latin-square design. Blood samples for serum estradiol measurements were obtained from all females after echocardiography with each anesthetic. Rats given KMI showed superior LV systolic function with the highest values for fractional shortening (FS), ejection fraction (EF) and stroke volume, whereas heart rate was greatest with pentobarbital, followed by KMI and then KME. KME produced the greatest effects on cardiac morphology, most notably during systole, including reduced septal and posterior wall thickness and increased LV chamber dimensions and volumes. In addition, KME had the greatest cardiac-depressing effects on LV systolic function, including reduced FS, EF, and heart rate values. Compared with male rats, female rats had superior LV function with greater EF and FS values, whereas male rats showed higher heart rate. Significant negative correlations were noted between serum estradiol levels and FS and EF values in female rats receiving KME. We conclude that the combination of KMI may be a superior anesthetic for use in male and female rats undergoing echocardiography.

Successful treatment of permethrin toxicosis in two cats with an intravenous lipid administration

The present work describes successful treatment of permethrin toxicosis in two cats with a novel therapy of intravenous lipid administration. Two cats presented in lateral recumbency and with generalized tremor after they had been incidentally treated with permethrin for flea control by their owners. Initial therapy consisted of diazepam, propofol, bathing, and intravenous fluids. After an initial bolus of 2mg/kg BW pentobarbital a pentobarbital continuous rate infusion (CRI) was started. Both cats received an emulsion of 20% soybean oil and 80% olive oil, commonly used as fat component of total parenteral nutrition in humans, later in the course of therapy. A bolus of 2 ml/kg BW of the emulsion followed by a CRI of 4 ml/kg BW/h for 4 hours was administered via a jugular catheter as reported previously. One cat received two cycles of therapy with intravenous lipid whereas the other cat needed just one application. Both cats recovered completely without requiring any further treatment. In conclusion, administration of intravenous lipids for permethrin toxicosis in cats is a novel treatment approach which seems to be highly effective in shortening the recovery time for permethrin toxicosis and possibly other fat-soluble toxins.

[Assisted suicide - medical, legal, and ethical aspects]

Unlike in most European countries, assisted suicide is not illegal in Switzerland. The number of assisted suicides procured by right-to-die organisations such as Exit or Dignitas has sharply increased in the last twenty years. Central part of the doctor's involvement is the prescription of a lethal dose of sodium pentobarbital. In doing so, the doctor has to apply to the rules of medical due care. A proper examination of the patient is required, who must be informed about his diagnosis, about the expected prognosis, and about different treatment options. Verification of the patient's decisional capacity is crucial. In general, a staff member of the organisation but not the doctor is present during suicide. Following death, the assisted suicide has to be reported to the police as an extraordinary death case.

Increased GABA(A) receptor ε-subunit expression on ventral respiratory column neurons protects breathing during pregnancy

GABAergic signaling is essential for proper respiratory function. Potentiation of this signaling with allosteric modulators such as anesthetics, barbiturates, and neurosteroids can lead to respiratory arrest. Paradoxically, pregnant animals continue to breathe normally despite nearly 100-fold increases in circulating neurosteroids. ε subunit-containing GABA_ARs are insensitive to positive allosteric modulation, thus we hypothesized that pregnant rats increase ε subunit-containing GABA_AR expression on brainstem neurons of the ventral respiratory column (VRC). In vivo, pregnancy rendered respiratory motor output insensitive to otherwise lethal doses of pentobarbital, a barbiturate previously used to categorize the ε subunit. Using electrode array recordings in vitro, we demonstrated that putative respiratory neurons of the preBötzinger Complex (preBötC) were also rendered insensitive to the effects of pentobarbital during pregnancy, but unit activity in the VRC was rapidly inhibited by the GABA_AR agonist, muscimol. VRC unit activity from virgin and post-partum females was potently inhibited by both pentobarbital and muscimol. Brainstem ε subunit mRNA and protein levels were increased in pregnant rats, and GABA_AR ε subunit expression co-localized with a marker of rhythm generating neurons (neurokinin 1 receptors) in the preBötC. These data support the hypothesis that pregnancy renders respiratory motor output and respiratory neuron activity insensitive to barbiturates, most likely via increased ε subunit-containing GABA_AR expression on respiratory rhythm-generating neurons. Increased ε subunit expression may be critical to preserve respiratory function (and life) despite increased neurosteroid levels during pregnancy.

Inhibition of firefly luciferase by general anesthetics: effect on in vitro and in vivo bioluminescence imaging

Bioluminescence imaging is routinely performed in anesthetized mice. Often isoflurane anesthesia is used because of its ease of use and fast induction/recovery. However, general anesthetics have been described as important inhibitors of the luciferase enzyme reaction.

Aim

To investigate frequently used mouse anesthetics for their direct effect on the luciferase reaction, both in vitro and in vivo.

Materials and Methods

isoflurane, sevoflurane, desflurane, ketamine, xylazine, medetomidine, pentobarbital and avertin were tested in vitro on luciferase-expressing intact cells, and for non-volatile anesthetics on intact cells and cell lysates. In vivo, isoflurane was compared to unanesthetized animals and different anesthetics. Differences in maximal photon emission and time-to-peak photon emission were analyzed.

Results

All volatile anesthetics showed a clear inhibitory effect on the luciferase activity of 50% at physiological concentrations. Avertin had a stronger inhibitory effect of 80%. For ketamine and xylazine, increased photon emission was observed in intact cells, but this was not present in cell lysate assays, and was most likely due to cell toxicity and increased cell membrane permeability. In vivo, the highest signal intensities were measured in unanesthetized mice and pentobarbital anesthetized mice, followed by avertin. Isoflurane and ketamine/medetomidine anesthetized mice showed the lowest photon emission (40% of unanesthetized), with significantly longer time-to-peak than unanesthetized, pentobarbital or avertin-anesthetized mice. We conclude that, although strong inhibitory effects of anesthetics are present in vitro, their effect on in vivo BLI quantification is mainly due to their hemodynamic effects on mice and only to a lesser extent due to the direct inhibitory effect.

Electroencephalographic and physiologic changes after tricaine methanesulfonate immersion of African clawed frogs (Xenopus laevis)

The objective of this study was to determine electroencephalographic and complementary physiologic changes in Xenopus leavis frogs after bath immersion in MS222. We also evaluated the addition of sodium pentobarbital injected intracoelomi- cally 2 h after MS222 immersion to achieve euthanasia. Frogs (n = 9) weighing 105.5 ± 8.4 g (mean ± 1 SD) were immersed in MS222 at either 1 or 3 g/L until anesthesia was achieved; a conductive stainless steel screw then was implanted in the skull on top of the outer pial surface of the brain. Frogs were immersed again in MS222 at the same concentration as previously, and electroencephalograms, heart rate, oxygen saturation, and respiratory movements were recorded. Amplitude and mean frequency of the electroencephalographic signal were evaluated at 15-min intervals until a flat-line signal was achieved. At 2 h after induction, frogs were injected intracoelomically with sodium pentobarbital (0.5 mL; 240 mg/mL) to accelerate euthanasia. Immersion of frogs in 1 or 3 g/L of MS222 depressed cerebral activity within 30 min without a significant effect on cardiac function. Intracoelomic injection of sodium pentobarbital at 2 h after MS222 administration rapidly (3.2 ± 1.7 min) induced cardiac arrest. In conclusion, immersion in MS222 can be used for the collection of organs from X. laevis frogs, but the addition of pentobarbital is required to achieve euthanasia.

Sedation and anesthesia for CT: emerging issues for providing high-quality care

During the past decades, the use of CT to diagnose conditions and monitor treatment in the pediatric setting has increased. Infants and children often require procedural sedation to maintain a motionless state to ensure high-quality imaging. Various medication regimens have been recommended to achieve satisfactory sedation for this painless procedure. While the incidence of adverse events remains low, procedural sedation carries the risk of serious morbidity and mortality. The use of evidence-based, structured approaches to procedural sedation should be used to reduce variation in clinical practice and improve outcomes.

Evaluation of methods of rapid mass killing of segregated early weaned piglets

The operational logistics of mass killing of healthy, surplus piglets by manual blunt force trauma, controlled blunt force trauma, intraperitoneal injection of barbiturate, and free bullet were recorded. Objective performance variables evaluated were, speed of application, human resource and input cost, animal restraint required, and failure rate. Subjective evaluation of esthetics and difficulty of application indicated manual blunt force trauma is an unacceptable technique. Under field conditions, physical methods of killing were superior to intraperitoneal injection of concentrated pentobarbital. Considering animal welfare metrics in isolation, controlled blunt force trauma was superior to all other techniques attempted.

Sedative, hypnotic and anticonvulsant activities of the ethanol fraction from Rhizoma Pinelliae Praeparatum

ETHNOPHARMACOLOGICAL RELEVANCE

Rhizoma Pinelliae Praeparatum is the product of raw Rhizoma Pinellia processed with alkaline solution and Licorice, which had been widely used for treatment of insomnia in traditional Chinese medicine. The present study aimed to investigate the sedative, hypnotic and anticonvulsant activities of ethanol fraction from Rhizoma Pinelliae Praeparatum (EFRP) and to determine whether these effects were related to GABAergic mechanism.

MATERIALS AND METHODS

The sedative, hypnotic and anticonvulsant activities of EFRP were investigated with locomotion activity, pentobarbital-induced sleeping and nikethamide (NKTM)-induced convulsion tests, respectively. Additionally, the effects of flumazenil (an antagonist of GABA(A) receptor) and L-malic acid (blocker of synthetic enzyme for GABA) on the hypnotic activity of EFRP were evaluated.

RESULTS

EFRP at dose of 12 g/kg significantly inhibited the locomotion activity of mice. EFRP showed synergic effect on pentobarbital-induced sleeping by increased numbers of mice falling asleep, reduced the sleep latency and prolonged the sleeping time. L-malic acid and flumazenil inhibited the augment effects of EFRP on pentobarbital-induced sleeping. EFRP promoted a significant protection to NKTM-induced convulsion, by prolonged the death latency and decreased mortality.

CONCLUSION

EFRP possessed sedative, hypnotic and anticonvulsant activities and these activities may be related to the GABAergic system.

[Behavioral correlations of gradual forced administration of psychoactive drugs]

The study was aimed at evaluating the behavioral correlations of the forced administration of psychoactive drugs. Wistar rats received the following drugs in elevated doses (over 4 days, i. p.): (i) physiological saline (control; 0.1-0.2-0.4-0.8 ml/rat), (ii) psychostimulant amphetamine (0.5-1.0--2.0-4.0 mg/kg); (iii) opioid analgetic fentanyl (0.00625-0.0125--0.025-0.05 mg/kg), (iv) ethanol 40% solution (0.5-1.0--2.0-4.0 g/kg), (v) barbiturate sodium ethaminal (2.5-5--10-20 mg/kg); and(vi) synthetic glucocorticoid dexamethasone (0.5-1.0--2.0-4.0 mg/kg). The forced regime of drug administration led to gradual load of the organism and prevented drug tolerance. The dynamics of self-stimulation reaction of the lateral hypothalamus was registered every day over drug administration period and revealed the following regularities: (I) dose-dependent effect of psychostimulant amphetamine and opioid analgetic fentanyl; (II) dexamethasone modulated self-stimulation, increasing (2 day, 1 mg/kg) or decreasing it (3 day, 2 mg/kg); (III) ethanol (1-2 g/kg) activated self-stimulation slightly; (IV) sodium ethaminal slightly inhibited self-stimulation and increased the thresholds of self-stimulation. In 24 h and 72 h after the last administration of drugs, the rat behavior was assessed in open field, elevated plus maze, resident-intruder paradigm, and Porsolt's test. In the open field, significant signs of post-intoxication exposure of psychoactive drugs were revealed, which were registered for 24-72 h after drug withdrawal. The withdrawal of drugs was accompanied with reduction (in 24 h) and subsequent recovery (in 72 h) of the vertical motor activity, exploration behavior, and emotionality. The anxiety indexes were increased up to the 3rd day after withdrawal. The antidepressant effect was also increased. The system of aggression-defense was restored only in rats treated with ethanol. The indexes of individual behavior and communicability in the post-intoxication period were decreased as well. It is suggested that the forced regime of drug administration in increasing doses with subsequent withdrawal of drug injections is a suitable method to evaluate the behavioral elements of drug dependence.

Survey of euthanasia practices in animal shelters in Canada

Questionnaires on methods of euthanasia used in Canadian animal shelters were sent to 196 Canadian animal shelters yielding 67 responses. Sodium pentobarbital injection was the only method of euthanasia used by 61% of establishments that euthanized dogs and 53% of the establishments that euthanized cats. Many of these establishments used pre-medication. Sodium pentobarbital was mostly administered intravenously but some establishments also used intracardiac and intraperitoneal routes, and some only used intracardiac administration for cats. T-61 injection was the only method of euthanasia used by 23% of the establishments that euthanized dogs and 35% of the establishments that euthanized cats. All of these establishments used pre-medication, but the percentages of establishments that only used the intravenous route for administration of T-61 in dogs and cats were 45% and 7%, respectively. Further studies on the use of T-61, and the training and provision of counselling services for staff are recommended.

Hypnotic effect of jujubosides from Semen Ziziphi Spinosae

ETHNOPHARMACOLOGICAL SIGNIFICANCE

Semen Ziziphi Spinosae, the seed of Ziziphus jujuba Mill. var. spinosa (bunge) Hu ex H.F. Chow has been widely used in treating insomnia and anxiety.

AIM OF THE STUDY

In this study, we investigated the hypnotic effect of jujubosides, one of the major components (saponin) of Semen Ziziphi Spinosae, in both day and night period.

MATERIALS AND METHODS

After the administration of jujubosides (9 mg/kg once per day for 3 days), sleep parameters were examined by EEG and EMG analysis in normal rats and the action of jujubosides on pentobarbital-induced sleep assessed by the loss-of righting reflex.

RESULTS

During daytime (9:00-15:00), jujubosides significantly increased the total sleep and rapid eye movement (REM) sleep without significant influence on non-REM (NREM) sleep. During nighttime (21:00-3:00), jujubosides significantly increased the total sleep and NREM sleep especially the light sleep while showed no significant effect on REM sleep and slow wave sleep (SWS). In pentobarbital-treated mice, jujubosides significantly augmented the hypnotic effect of pentobarbital (45 mg/kg, i.p.), proved by increasing sleep time and this augmentative effect was potentiated by 5-hydroxytryptophan (2mg/kg, i.p.). Furthermore, jujubosides inhibited the para-chlorophenylalanine-induced suppression of pentobarbital-induced hypnosis.

CONCLUSIONS

These results suggested that the hypnotic effect of jujubosides on normal rats may be influenced by circadian rhythm and the serotonergic system may involve in the hypnotic effect of jujubosides. Jujubosides may be good source of lead compounds for novel hypnotics.

[Euthanasia of cattle: a clinical comparison of T 61 and pentobarbital (Eutha 77)]

The objective of this study was a comparison of pentobarbital and T 61 in the euthanasia of cattle. 397 cattle of different ages and breeds which had to be euthanised in the Clinic for Ruminants were enrolled. Following clinical examination, euthanasia was performed by intravenous injection of either 40 mg pentobarbital per kg body weight (BW) (0.1 ml Eutha 77) or 0.1 ml T 61/kg BW. The intervals between the beginning of injection and the following events were noted: collapse of the animal, cessation of respiration, cessation of cardiac action, disappearance of the palpebral and corneal reflexes, and maximum dilatation of the pupils. These post-injection events occurred significantly earlier with Eutha 77. In addition, events like excitations and vocalisations were recorded. Excitations occurred twice as often with T 61 (in 34% of cases) than with Eutha 77 (17%), and strong excitations (grade 3 of 3) were also more frequent with T 61 (9.8%) than with Eutha 77 (3%). Vocalisations were less frequent (30%) with T 61 than with pentobarbital (39%), but this difference was not significant. Severe vocalisations occurred very rarely. With both drugs, intervals between the beginning of injection until cessation of reflexes were longer in older animals. Following injection of Eutha 77, cessation of the corneal reflex and maximal dilatation of the pupils occurred earlier in cattle with severe disturbance of the general condition than in cattle with lesser disturbance; in the T 61-group this difference was only significant for the interval until cessation of the corneal reflex. In anaesthetized patients euthanized with T 61 cessation of cardiac action and respiration occurred earlier than in patients that were not under general anaesthesia when euthanized; in the Eutha 77 group, the difference was significant only for the interval until cessation of cardiac action.

Euthanasia method for mice in rapid time-course pulmonary pharmacokinetic studies

To develop a means of euthanasia to support rapid time-course pharmacokinetic studies in mice, we compared retroorbital and intravenous lateral tail vein injection of ketamine-xylazine with regard to preparation time, utility, tissue distribution, and time to onset of euthanasia. Tissue distribution and time to onset of euthanasia did not differ between administration methods. However, retroorbital injection could be performed more rapidly than intravenous injection and was considered to be a technically simple and superior alternative for mouse euthanasia. Retroorbital ketamine-xylazine, CO(2) gas, and intraperitoneal pentobarbital then were compared as euthanasia agents in a rapid time-point pharmacokinetic study. Retroorbital ketamine-xylazine was the most efficient and consistent of the 3 methods, with an average time to death of approximately 5 s after injection. In addition, euthanasia by retroorbital ketamine-xylazine enabled accurate sample collection at closely spaced time points and satisfied established criteria for acceptable euthanasia technique.

Evaluation and refinement of euthanasia methods for Xenopus laevis

The most common method of euthanasia for Xenopus species is by immersion in tricaine methane sulfonate solution (MS222). A wide range of doses of MS222 (0.5 to 5 g/L) have been recommended, but few reports describe dose-response testing, the time to loss of consciousness, or the reliability of euthanasia. The objective of this study is to evaluate the efficacy of immersing individual and groups of frogs in MS222 at concentrations ranging from 1 to 5 g/L for euthanasia and of 3 less-common methods: intracoelomic injection of MS222, intracoelomic injection of sodium pentobarbital with phenytoin, and ventral cutaneous application of benzocaine gel. Our results indicate that immersion for at least 1 h in a 5-g/L buffered solution of MS222, intracoelomic injection of 1100 mg/kg sodium pentobarbital with sodium phenytoin (equivalent to 0.3 mL solution per frog), or ventral cutaneous application of 182 mg/kg benzocaine (equivalent to a 2 cm x 1 mm of 20% benzocaine gel) is necessary to euthanize adult X. laevis and ensure complete cessation of the heartbeat without recovery. These doses are considerably higher than those previously recommended for this species.

[Expression of mRNA for corticoliberin and vasopressin in hypothalamus and amygdala on the background of administration of psychoactive drugs in rats]

Wistar male rats were injected intraperitoneally for 4 days in elevated doses with: (1) physiological saline (control; 0.1 - 0.2 - 0.4 - 0.8 ml/rat), (2) amphetamine (0.5 - 1.0 - 2.0 - 4.0 mg/kg); (3) fentanyl (0.00625 - 0.0125 - 0.025 - 0.05 mg/kg), (4) 40% aqueous ethanol solution (0.5 - 1.0 - 2.0 - 4.0 g/kg), (5) ethaminal sodium (2.5 - 5 - 10 - 20 mg/kg), and (6) dexamethasone (0.5 - 1.0 - 2.0 - 4.0 mg/kg). The forced regime of drug administration led to gradual load of the organism and prevented drug tolerance development. This method is widely used for the formation of drug dependence (or its features) due to various narcotic agents. The maximum level of mRNA expression for corticoliberin was registered in amygdala after the administration of dexamethasone (0.46 units compared to beta-actin), and the minimum level was observed after treatment with sodium ethaminal (0.07) and fentanyl (0.037). In hypothalamus, sodium ethaminal produced elevated mRNA expression (0.8 units), followed by ethanol (0.37) and fentanyl (0.039). Amphetamine activated mRNA expression for corticoliberin neither in hypothalamus nor in amygdala for all of the drugs studied. The mRNA expression for vasopressin was also not registered for all drugs in hypothalamus and amygdala. Therefore, the reinforcing system of hypothalamus supports the typical reaction on the administration of narcotic agents, while the extended amygdala system includes both the proper reinforcement and the stress reactivity elements.

Functional magnetic resonance imaging of hearing-impaired children under sedation before cochlear implantation

OBJECTIVE

To investigate functional magnetic resonance imaging (fMRI) in pediatric cochlear implantation candidates with residual hearing who are under sedation for evaluation of auditory function.

DESIGN

During fMRI, subjects heard a random sequence of tones (250-4000 Hz) presented 10 dB above hearing thresholds. Tones were interleaved with silence in a block-periodic fMRI design with 30-second on-off intervals. Twenty-four axial sections (5 mm thick) covering most of the brain were obtained every 3 seconds for a total acquisition time of 5.5 minutes.

SETTING

Single tertiary academic medical institution.

PATIENTS

Severely to profoundly hearing-impaired children (n=10; mean age, 49.1 months). During fMRI, subjects were awake (n=2) or sedated with pentobarbital sodium if their weight was 10 kg or greater (n=4) or chloral hydrate if their weight was less than 10 kg (n=4).

MAIN OUTCOME MEASURES

Detection of brain activation by fMRI in the primary auditory cortex (A1) in hearing-impaired patients under sedation, and correlation of A1 activation with hearing levels measured after cochlear implantation.

RESULTS

In most subjects, fMRI detected significant levels of activation in the A1 region before cochlear implantation. The improvement in hearing threshold after cochlear implantation correlated strongly (linear regression coefficient, R=0.88) with the amount of activation in the A1 region detected by fMRI before cochlear implantation.

CONCLUSIONS

Functional MRI can be considered a means of assessing residual function in the A1 region in sedated hearing-impaired toddlers. With improvements in acquisition, processing, and sedation methods, fMRI may be translated into a prognostic indicator for outcome after cochlear implantation in infants.

Dragon's blood from Croton urucurana (Baill.) attenuates visceral nociception in mice

Dragon's blood, the red sap from Croton urucurana Baill. (Euphorbiaceae) has a profound history of traditional use in conditions such as inflammation, diarrhoea and gastrointestinal distress. Previous studies established its anti-inflammatory, antidiarrhoeal and analgesic properties and in this study we verified its potential to suppress visceral pain, using capsaicin- and cyclophosphamide-induced models of visceral nociception. Mice that received intra-colonic capsaicin (0.3%, 50 microl/animal) or intraperitoneal injection of cyclophosphamide (400 mg/kg) manifested spontaneous nociceptive behaviors or crises, which were significantly suppressed in animal groups treated with red sap (200 and 400 mg/kg, p.o.) or that received N-acetylcysteine (750 mg/kg, i.p.) or morphine (7.5 mg/kg, s.c.), as positive controls. In capsaicin model, the antinociception produced by 200 mg/kg red sap was found to be naloxone-sensitive (2 mg/kg, i.p.), suggesting an opioid mechanism. In tests of open-field and pentobarbital-sleeping time, mice received 200mg/kg red sap showed no significant alterations in either locomotion frequency or on sleeping time, indicating that the observed antinociception is not a consequence of sedation or motor abnormality. These findings highlight the visceral antinociceptive property of Croton urucurana sap and further support its ethno-medical use to alleviate pain associated with gastrointestinal and other related disorders.

Pharmacological studies on the sedative and hypnotic effect of salidroside from the Chinese medicinal plant Rhodiola sachalinensis

This is the preliminary study of sedative and hypnotic activity of salidroside (a major component of Rhodiola sachalinensis) in mice by using synergism with pentobarbital as an index for the hypnotic effect. Loss of the righting reflex was used to determine the start of sleep. Sleep latency and sleeping time were evaluated in this experiment. The results showed that salidroside could obviously shorten the sleep latency and prolong the sleeping time of mice produced by pentobarbital sodium (55 mg/kg, i.p.). Salidroside produces significant sedative-hypnotic effect. The dose-effect relationship is remarkable.

Endotoxin-induced acute lung injury and organ dysfunction are attenuated by pentobarbital anaesthesia

1. Acute lung injury (ALI) as a result of sepsis is a major cause of mortality. Certain anaesthetic agents have been reported to suppress pro-inflammatory cytokines and inducible nitric oxide (NO) synthase (iNOS) activities. We investigated the effects of pentobarbital on ALI and organ functions after the administration of endotoxin. 2. Intravenous (i.v.) pentobarbital (20 or 40 mg/kg) was administered 5 min after lipopolysaccharide (LPS; 10 or 30 mg/kg via i.v. infusion). To avoid hypoxia and/or hypercapnia following anaesthesia, we installed a special chamber connected to a rodent ventilator to provide ventilation with 95% oxygen content and 5% nitrogen. The animal was kept at eucapnic conditions (arterial PCO2 at an average of 38 +/- 2 mmHg). 3. We monitored the arterial pressure (AP) and heart rate (HR). Acute lung injury was evaluated by lung weight changes, protein concentration in bronchoalveolar lavage, and Evans blue leakage. Plasma nitrate/nitrite, methyl guanidine and biochemical factors were determined. Pathological and immunofluorescent examinations were performed to observe the lung changes and to determine the activities of pro-inflammatory cytokines, nitrotyrosine and iNOS. 4. Lipopolysaccharide caused dose-dependent systemic hypotension with an increase in the extent of ALI. The lung pathology included oedema and inflammatory cell infiltration. Accompanying the ALI, LPS elevated plasma nitrate/nitrite, methyl guanidine, blood urea nitrogen, lactic dehydrogenase, creatinine phosphokinase, glutamic transaminase and amylase. The lung tissue content of tumour necrosis factor-alpha, interleukin-lbeta, iNOS and nitrotyrosine was increased following LPS administration. These changes were abrogated by pentobarbital anaesthesia. 5. Our results indicated that pentobarbital anaesthesia significantly augmented the LPS-induced systemic hypotension. However, it attenuated the LPS-induced ALI and organ dysfunctions. This agent also improved the survival rate following LPS at high and low doses. This mechanism may be related to the inhibitory effects on the increases in the production or activity of NO, free radicals, pro-inflammatory cytokines, nitrotyrosine and iNOS.

[Pharmacological effects of volatile oil of Valeriana amurensis on CNS]

OBJECTIVE

To study the pharmacological effects of volatile oil of Valeriana amurensis on central nervous system.

METHODS

The pharmacological effects of volatile oil of Valeriana amurensis on the autonomic activities of mice, the sleeping synergistic action of mice with pentoharbital sodium at subthreshold and hypnotic dosages, the sleep phases of rats, the writhing response of mice caused by acetic acid and the convulsion of mice induced by thio-semicarbazide were investigated.

RESULTS

The autonomic activities of mice were significantly inhibited by the volatile oil of Valeriana amurensis. The rate of falling sleep and the extension of sleeping time of mice were significantly increased by the synergic action of pentobarbital sodium with the volatile oil. The sleep phases of SWS2 and REMS of rats were obviously extended by the volatile oil of Valeriana amurensis. In addition, the frequency of writhing response of mice caused by acetic acid was reduced, and the convulsion of mice induced by thio-semicarbazide was antagonized with the administration of the volatile oil.

CONCLUSION

The volatile oil of Valeriana amurensis has significantly sedative analgesic and anti-hyperspasmia effects.

Renal function and histology after acute hemorrhage in rats under dexmedetomidine action

PURPOSE: About 50 % of indications for dialysis in acute renal failure are related to problems originated during the perioperative period. Intraoperative hemodynamic changes lead to renal vasoconstriction and hypoperfusion. Previous studies have not defined the dexmedetomidine renal role in hemorrhage situations. This study evaluated the effect of dexmedetomidine on renal function and histology after acute hemorrhage in rats. METHODS: Covered study with 20 Wistars rats, anesthetized with sodium pentobarbital, 50 mg. kg-1, intraperitoneal, randomized into 2 groups submitted to 30% volemia bleeding: DG - iv dexmedetomidine, 3 µg. kg-1 (10 min) and continuous infusion - 3 µg. kg-1. h-1; CG - pentobarbital. For renal clearance estimative, sodium p-aminohippurate and iothalamate were administered. Studied attributes: heart rate, mean arterial pressure, rectal temperature, hematocrit, iothalamate and p-aminohippurate clearance, filtration fraction, renal blood flow, renal vascular resistance, and histological evaluations of the kidneys. RESULTS: DG showed smaller values of heart rate, mean arterial pressure, and renal vascular resistance, but iothalamate clearance and filtration fraction values were higher. There was similarity in p-aminohippurate clearance and renal blood flow. Both groups had histological changes ischemia-like, but dexmedetomidine determined higher tubular dilatation scores. CONCLUSION: In rats, after acute hemorrhage, dexmedetomidine determined better renal function, but higher tubular dilation scores.

Anesthesia increases in vivo N-([18F]fluoroethyl)piperidinyl benzilate binding to the muscarinic cholinergic receptor

The in vivo binding of N-[18F]fluoroethyl-piperidinyl benzilate ([18F]FEPB) to the muscarinic cholinergic receptor was measured in awake and anesthetized rats. Studies were done using an equilibrium infusion technique to provide estimates of specific binding as distribution volume ratios. Anesthesia with either isoflurane or sodium pentobarbital produced a significant (65-90%) increase of radiotracer binding in receptor-rich brain regions (striatum, cortex, hippocampus) relative to awake controls. Pretreatment of anesthetized animals with the acetylcholinesterase inhibitor phenserine produced no further increases in radioligand binding, in contrast to the large (>70%) increases previously observed in awake animals following drug treatment. These studies demonstrate that anesthesia can produce significant changes in baseline biochemical measures that can obscure even very large effects of pharmacological challenges.

Nociception after intraperitoneal injection of a sodium pentobarbitone formulation with and without lidocaine in rats quantified by expression of neuronal c-fos in the spinal cord--a preliminary study

After a search on Medline, it appears that intraperitoneal injection of sodium pentobarbitone is often used for anaesthesia and euthanasia of rodents. In the present pilot study in rats, spinal nociception after intraperitoneal injection of sodium pentobarbitone, with and without lidocaine, was examined by estimation of the number of c-fos-expressing neurones in the spinal dorsal horn. One group of rats received an intraperitoneal injection of 0.4 mL/kg sodium pentobarbitone (100 mg/mL; n=4). Another group of rats received a similar intraperitoneal injection of sodium pentobarbitone formulated with lidocaine 10 mg/mL (n=4); a control group received a similar intraperitoneal injection of 0.9% saline (n=4). After 3 h, the animals were re-anaesthetized and perfused with 4% formaldehyde, and the spinal cord was collected and processed by immunohistochemistry for stereological quantification of the number of neurones with c-fos-like immunoreactivity (FLI). Intraperitoneal injection of the sodium pentobarbitone formulation caused a significantly increased number of neurones with FLI in the spinal cord (3930+/-247; mean+/-SEM; P<0.001) compared with the saline control group (765+/-131). The lidocaine added to the sodium pentobarbitone formulation significantly reduced the number to 2716+/-393 (P<0.05). In conclusion, intraperitoneal injection of sodium pentobarbitone caused a significant increase in nociception which was lowered by adding lidocaine to the formulation, although it was still significantly higher than the control level. Further studies are needed with the aim of optimizing the lidocaine concentration and also to examine the effect of the combination of lidocaine with a long-acting local anaesthetic agent, e.g. bupivacaine.

Sédation au pentobarbital par voie rectale pour enregistrement des PEA chez l'enfant

OBJECTIVES

The aim of our study was to determine if rectal sedation with pentobarbital sodium provides safe and effective sedation for children undergoing auditory brainstem response (ABR) testing.

MATERIAL AND METHODS

A prospective study was conducted in the ENT pediatric department of Robert Debre's hospital (APHP, Paris). 68 children under 8 years of age were given rectal pentobarbital for ABR testing at a dosage of about 5 mg/kg.

RESULTS

61 children of 68 (89.7%) were adequately sedated with rectal pentobarbital. The mean elapsed time from drug administration to full sedation was 36,1 minutes. No adverse event was reported in 84.1% of children.

CONCLUSION

Pentobarbital provides safe and effective sedation. Rectal administration is easy, painless and with brief duration of action. It's a good alternative to general anesthesia for young children undergoing ABR testing.

Changes in relative potency among positive GABA(A) receptor modulators upon discontinuation of chronic benzodiazepine treatment in rhesus monkeys

RATIONALE

Benzodiazepine treatment can result in dependence as evidenced by signs of withdrawal upon discontinuation of use.

OBJECTIVE

Positive GABA(A) receptor modulators were examined for their capacity to attenuate flumazenil-like discriminative stimulus effects (i.e., withdrawal) that emerge upon discontinuation of chronic benzodiazepine treatment.

METHODS

Rhesus monkeys receiving chronic diazepam (5.6 mg(-1) kg(-1) 24 h(-1) p.o.) discriminated flumazenil (0.1 mg/kg s.c.) from vehicle.

RESULTS

Upon discontinuation of diazepam treatment, responding switched from the vehicle to the flumazenil lever, although at different times among monkeys. The shorter-acting benzodiazepine lorazepam (3.2 mg(-1) kg(-1) 8 h(-1)) was substituted for diazepam and, 11 h after lorazepam, monkeys consistently responded on the flumazenil lever. Flumazenil-lever responding after acute lorazepam deprivation was attenuated not only by benzodiazepines (lorazepam and midazolam) but also by positive GABA(A) receptor modulators acting at neuroactive steroid (pregnanolone and alfaxalone) and barbiturate sites (pentobarbital). Deprivation-induced responding on the flumazenil lever was not attenuated by low efficacy positive GABA(A) modulators (bretazenil and L-838,417) or non-GABA(A) receptor ligands (ketamine and cocaine). Neuroactive steroids were relatively more potent than other positive GABA(A) receptor modulators in attenuating deprivation-induced flumazenil-lever responding, as compared to their relative potency in monkeys discriminating midazolam and otherwise not receiving benzodiazepine treatment.

CONCLUSIONS

These results suggest that positive GABA(A) receptor modulators acting at different sites attenuate withdrawal induced by discontinuation of benzodiazepine treatment, consistent with previous studies suggesting that the same compounds attenuate flumazenil-precipitated withdrawal. Differences in the relative potency of positive modulators as a function of acute versus chronic benzodiazepine treatment suggest that neuroactive steroids, in particular, are especially potent in benzodiazepine-dependent animals.