Antinociceptive and Cardiorespiratory Effects of a Single Dose of Dexmedetomidine in Laboratory Mice Subjected to Craniotomy under General Anaesthesia with Isoflurane and Carprofen or Meloxicam.

Pain refinement represents an important aspect of animal welfare in laboratory animals. Refining analgesia regimens in mice undergoing craniotomy has been sparsely investigated. Here, we sought to investigate the effect of dexmedetomidine in combination with other analgesic drugs on intraoperative anti-nociceptive effects and cardiorespiratory stability.

Machine learning reveals interhemispheric somatosensory coherence as indicator of anesthetic depth.

The goal of this study was to identify features in mouse electrocorticogram recordings that indicate the depth of anesthesia as approximated by the administered anesthetic dosage. Anesthetic depth in laboratory animals must be precisely monitored and controlled. However, for the most common lab species (mice) few indicators useful for monitoring anesthetic depth have been established.

Error-prone protein synthesis recapitulates early symptoms of Alzheimer disease in aging mice.

Age-related neurodegenerative diseases (NDDs) are associated with the aggregation and propagation of specific pathogenic protein species (e.g., Aβ, α-synuclein).

A role for spindles in the onset of rapid eye movement sleep.

Sleep spindle generation classically relies on an interplay between the thalamic reticular nucleus (TRN), thalamo-cortical (TC) relay cells and cortico-thalamic (CT) feedback during non-rapid eye movement (NREM) sleep. Spindles are hypothesized to stabilize sleep, gate sensory processing and consolidate memory. However, the contribution of non-sensory thalamic nuclei in spindle generation and the role of spindles in sleep-state regulation remain unclear.

Evaluation of Poultry Stunning with Low Atmospheric Pressure, Carbon Dioxide or Nitrogen Using a Single Aversion Testing Paradigm.

Low atmospheric pressure stunning (LAPS) has been suggested for use in poultry under 4 kg in the abattoir as a more humane alternative to carbon dioxide (CO). However, there are currently no studies offering a direct comparison of the aversion between methods. Here, we trained adult female broiler breeders to relinquish a food reward by moving to another area of the gas chamber in response to aversive stimuli.

REM sleep stabilizes hypothalamic representation of feeding behavior.

During rapid eye movement (REM) sleep, behavioral unresponsiveness contrasts strongly with intense brain-wide neural network dynamics. Yet, the physiological functions of this cellular activation remain unclear. Using in vivo calcium imaging in freely behaving mice, we found that inhibitory neurons in the lateral hypothalamus (LH) show unique activity patterns during feeding that are reactivated during REM, but not non-REM, sleep.

Rapid fast-delta decay following prolonged wakefulness marks a phase of wake-inertia in NREM sleep.

Sleep-wake driven changes in non-rapid-eye-movement sleep (NREM) sleep (NREMS) EEG delta (δ-)power are widely used as proxy for a sleep homeostatic process. Here, we noted frequency increases in δ-waves in sleep-deprived mice, prompting us to re-evaluate how slow-wave characteristics relate to prior sleep-wake history. We identified two classes of δ-waves; one responding to sleep deprivation with high initial power and fast, discontinuous decay during recovery sleep (δ2) and another unrelated to time-spent-awake with slow, linear decay (δ1).

Case report - azygos vein drainage into the left atrium in a dog with cor triatriatum dexter and a patent foramen ovale.

A 2-year-old Airedale terrier was presented with exercise intolerance since birth and newly developed chylous pleural effusion. Imaging procedures including echocardiography, cardiac magnetic resonance imaging, computed tomography, and selective angiography revealed an aberrant connection of the azygos vein and the left atrium, a membrane in the right atrium consistent with cor triatriatum dexter, and a patent foramen ovale with right-to-left shunt. Balloon dilation of the membrane in the right atrium seemed to result in transient improvement of exercise tolerance compared with the previous 2 years.

Humanely Ending the Life of Animals: Research Priorities to Identify Alternatives to Carbon Dioxide.

The use of carbon dioxide (CO) for stunning and killing animals is considered to compromise welfare due to air hunger, anxiety, fear, and pain. Despite decades of research, no alternatives have so far been found that provide a safe and reliable way to induce unconsciousness in groups of animals, and also cause less distress than CO. Here, we revisit the current and historical literature to identify key research questions that may lead to the identification and implementation of more humane alternatives to induce unconsciousness in mice, rats, poultry, and pigs.

Oscillating circuitries in the sleeping brain.

Brain activity during sleep is characterized by circuit-specific oscillations, including slow waves, spindles and theta waves, which are nested in thalamocortical or hippocampal networks. A major challenge is to determine the relationships between these oscillatory activities and the identified networks of sleep-promoting and wake-promoting neurons distributed throughout the brain. Improved understanding of the neurobiological mechanisms that orchestrate sleep-related oscillatory activities, both in time and space, is expected to generate further insight into the delineation of sleep states and their functions.

Alternatives to Carbon Dioxide-Taking Responsibility for Humanely Ending the Life of Animals.

Carbon dioxide (CO) is commonly used to kill rodents. However, a large body of research has now established that CO is aversive to them. A multidisciplinary symposium organized by the Swiss Federal Food Safety and Veterinary Office discussed the drawbacks and alternatives to CO in euthanasia protocols for laboratory animals.

Is xenon a suitable euthanasia agent for mice?

Objective: To compare behavioural and electrophysiological variables of mice undergoing gas euthanasia with either xenon (Xe) or carbon dioxide (CO).

Study Design: Single animals chronically instrumented for electroencephalography (EEG) recording were randomized to undergo euthanasia with either CO or Xe (n = 6 animals per group).

Animals: Twelve adult (>6 weeks old) male C57Bl6/n mice.

Nitrogen gas produces less behavioural and neurophysiological excitation than carbon dioxide in mice undergoing euthanasia.

Carbon dioxide (CO2) is one of the most commonly used gas euthanasia agents in mice, despite reports of aversion and nociception. Inert gases such as nitrogen (N2) may be a viable alternative to carbon dioxide. Here we compared behavioural and electrophysiological reactions to CO2 or N2 at either slow fill or rapid fill in C57Bl/6 mice undergoing gas euthanasia.

Influence of injection protocol and measurement technique on computed tomographic assessment of glomerular filtration rate in healthy Beagles.

OBJECTIVE To compare values of CT-derived glomerular filtration rate (GFR) determined by 3 contrast-medium injection protocols and 4 measurement techniques in healthy Beagles. ANIMALS 9 healthy Beagles (mean ± SD weight, 13.2 ± 1.

Sleep-wake control and the thalamus.

Sleep is an essential component of animal behavior, controlled by both circadian and homeostatic processes. Typical brain oscillations for sleep and wake states are distinctive and reflect recurrent activity amongst neural circuits spanning localized to global brain regions. Since the original discovery of hypothalamic centers controlling both sleep and wakefulness, current views now implicate networks of neuronal and non-neuronal cells distributed brain-wide.

Thalamic dual control of sleep and wakefulness.

Slow waves (0.5-4 Hz) predominate in the cortical electroencephalogram during non-rapid eye movement (NREM) sleep in mammals. They reflect the synchronization of large neuronal ensembles alternating between active (UP) and quiescent (Down) states and propagating along the neocortex.

Epileptiform activity during inert gas euthanasia of mice.

Carbon dioxide (CO2) is one of the most commonly used euthanasia agents for mice, yet it is highly aversive and nociceptive. Inert gases are a possible alternative, however there are qualitative reports of seizures resulting from exposure. Here we evaluate epileptiform activity caused by inert gases (N2, He, Ar and Xe) and CO2 in mice chronically instrumented for EEG/EMG undergoing single-gas euthanasia.

Effects of contrast medium injection technique on attenuation values of adrenal glands in healthy dogs during contrast-enhanced computed tomography.

Objective: To assess the effects of 3 contrast medium injection techniques on attenuation values for canine adrenal glands during contrast-enhanced CT.

Animals: 9 healthy Beagles.

Procedures: 3 protocols were evaluated in a randomized cross-over design study: 700 mg of iodine/kg at a constant injection rate over 20 seconds (full-dose constant rate), the same dose at a rate following an exponential decay curve over 20 seconds (full-dose decelerated rate), and 350 mg of iodine/kg at a constant injection rate over 10 seconds (half-dose constant rate).

Altered activity in the central medial thalamus precedes changes in the neocortex during transitions into both sleep and propofol anesthesia.

How general anesthetics cause loss of consciousness is unknown. Some evidence points toward effects on the neocortex causing "top-down" inhibition, whereas other findings suggest that these drugs act via subcortical mechanisms, possibly selectively stimulating networks promoting natural sleep. To determine whether some neuronal circuits are affected before others, we used Morlet wavelet analysis to obtain high temporal resolution in the time-varying power spectra of local field potentials recorded simultaneously in discrete brain regions at natural sleep onset and during anesthetic-induced loss of righting reflex in rats.

Staying awake--a genetic region that hinders α2 adrenergic receptor agonist-induced sleep.

How external stimuli prevent the onset of sleep has been little studied. This is usually considered to be a non-specific type of phenomenon. However, the hypnotic drug dexmedetomidine, an agonist at α2 adrenergic receptors, has unusual properties that make it useful for investigating this question.

Neuraxial morphine induced pruritus in two cats and treatment with sub anaesthetic doses of propofol.

History: Two cats were presented for orthopaedic surgery.

Physical Examination: With the exception of the orthopaedic injuries found, clinical examination showed no abnormality.

Management: As part of anaesthetic management, one cat received intrathecal morphine, the other epidural morphine.

Nexplanon, a radiopaque etonogestrel implant in combination with a next-generation applicator: 3-year results of a noncomparative multicenter trial.

Objective: To investigate the efficacy, safety, removal characteristics, and x-ray visibility of Nexplanon, a radiopaque etonogestrel contraceptive implant combined with a next-generation applicator.

Study Design: A 3-year, nocomparative, multicenter study in women aged 18-40 years at 23 clinical sites.

Results: Of 301 women who had an implant inserted, none became pregnant while the implant was in situ.

An unexpected role for TASK-3 potassium channels in network oscillations with implications for sleep mechanisms and anesthetic action.

TASK channels are acid-sensitive and anesthetic-activated members of the family of two-pore-domain potassium channels. We have made the surprising discovery that the genetic ablation of TASK-3 channels eliminates a specific type of theta oscillation in the cortical electroencephalogram (EEG) resembling type II theta (4-9 Hz), which is thought to be important in processing sensory stimuli before initiating motor activity. In contrast, ablation of TASK-1 channels has no effect on theta oscillations.

The involvement of hypothalamic sleep pathways in general anesthesia: testing the hypothesis using the GABAA receptor beta3N265M knock-in mouse.

The GABA(A) receptor has been identified as the single most important target for the intravenous anesthetic propofol. How effects at this receptor are then translated into a loss of consciousness, however, remains a mystery. One possibility is that anesthetics act on natural sleep pathways.