Reported analgesic and anaesthetic administration to rodents undergoing experimental surgical procedures

Development of opioid analgesic tolerance in rat to extended-release buprenorphine formulated for laboratory subjects

Buprenorphine in an extended-release formulation intended for use in laboratory subjects is frequently administered to rats to provide extended analgesia without repeated handling. While levels of buprenorphine may persist in serum once extended-release buprenorphine has been introduced, exposure to opioids can cause opioid tolerance or opioid-induced hypersensitivity. This work examined the analgesic duration and efficacy of a single administration of extended-release buprenorphine intended for use in laboratory subjects in models of inflammatory pain and post-operative pain and the development of opioid tolerance in rat. After subcutaneous administration of 1 mg/kg extended-release buprenorphine, analgesic efficacy did not persist for the expected 72 hours. No changes were observed in mechanical thresholds in the hindpaws that were contralateral to the injury, suggesting a lack of centrally mediated opioid-induced hypersensitivity. To determine whether opioid tolerance arose acutely after one exposure to extended-release buprenorphine, we conducted the warm water tail flick assay; on Day 1 we administered either saline or extended-release buprenorphine (1 mg/kg) and on Day 3 we quantified the standard buprenorphine dose-response curve (0.1-3 mg/kg). Rats previously given extended-release buprenorphine displayed decreased analgesic responses after administration of standard buprenorphine as compared to the robust efficacy of standard buprenorphine in control subjects. Males appeared to show evidence of acute opioid tolerance, while females previously exposed to opioid did not demonstrate a decreased response at the doses examined. Taken together, these results suggest that opioid tolerance arises quickly in male rats after exposure to the extended-release formulation of buprenorphine. This tolerance may account for the brief period of antinociception observed.

TUNEL-n-DIFL Method for Detection and Estimation of Apoptosis Specifically in Neurons and Glial Cells in Mixed Culture and Animal Models of Central Nervous System Diseases and Injuries

Detection of merely apoptosis does not reveal the type of central nervous system (CNS) cells that are dying in the CNS diseases and injuries. In situ detection and estimation of amount of apoptosis specifically in neurons or glial cells (astrocytes, oligodendrocytes, and microglia) can unveil valuable information for designing therapeutics for protection of the CNS cells and functional recovery. A method was first developed and reported from our laboratory for in situ detection and estimation of amount of apoptosis precisely in neurons and glial cells using in vitro and in vivo models of CNS diseases and injuries. This is a combination of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and double immunofluorescent labeling (DIFL) or simply TUNEL-n-DIFL method for in situ detection and estimation of amount of apoptosis in a specific CNS cell type. An anti-digoxigenin (DIG) IgG antibody conjugated with 7-amino-4-methylcoumarin-3-acetic acid (AMCA) for blue fluorescence, fluorescein isothiocyanate (FITC) for green fluorescence, or Texas Red (TR) for red fluorescence can be used for in situ detection of apoptotic cell DNA, which is earlier labeled with TUNEL using alkali-stable DIG-11-dUTP. A primary anti-NeuN (neurons), anti-GFAP (astrocytes), anti-MBP (oligodendrocytes), or anti-OX-42 (microglia) IgG antibody and a secondary IgG antibody conjugated with one of the above fluorophores (other than that of ani-DIG antibody) are used for in situ detection of apoptosis in a specific CNS cell type in the mixed culture and animal models of the CNS diseases and injuries.

The immune response to systemically administered endotoxin in the murine intestinal microcirculation under pentobarbital versus isoflurane anesthesia

BACKGROUND

Pentobarbital and isoflurane are commonly used veterinary anesthetics. Due to the dangers of overdose by repeat-bolus regimen of pentobarbital, isoflurane has been recommended. However, literature suggests isoflurane-induced inhibition of cytokine and adhesion molecule release, impacting leukocyte adhesion.

OBJECTIVE

This study aims to characterize the impacts of pentobarbital versus isoflurane on leukocyte interactions within the intestinal microcirculation with and without endotoxin challenge.

METHODS

Female BALB/c mice were subjected to pentobarbital or isoflurane (N = 20) and challenged with endotoxin or saline by intraperitoneal injection. The mice were kept under anesthesia for 2 hours. Fluorochromes, rhodamine-6 G and fluorescein isothiocyanate, were injected intravenously. To visualize leukocyte adhesion within the intestinal microcirculation, laparotomy and intravital microscopy was performed. Leukocyte rolling and adhesion was quantified offline in a blinded fashion.

RESULTS

Within collecting venules, leukocyte rolling and adhesion showed no significant differences between pentobarbital and isoflurane anesthesia under basal conditions. Endotoxin challenge caused a similar response in both anesthetic groups. Within postcapillary venules, no statistical differences between the two anesthetics were found for adhering leukocytes under basal conditions or following endotoxin challenge either. However, leukocyte rolling after LPS-challenge was significantly decreased in postcapillary venules during isoflurane anesthesia compared to pentobarbital anesthesia.

CONCLUSIONS

Isoflurane anesthesia showed only minor differences in the immune response to endotoxin within the intestinal microcirculation compared to pentobarbital anesthesia. Due to the superior safety profile of volatile anesthetics, immunological studies may choose isoflurane over pentobarbital as the veterinary anesthetic of choice.

Mouse isoflurane anesthesia using the drop method

Anesthesia with isoflurane prior to carbon dioxide euthanasia is recommended as a refinement, but vaporizer access can be limited. An alternative to vaporizers is the 'drop' method, introducing a fixed volume of isoflurane into the induction chamber. Previous work suggests that isoflurane administered at a concentration of 5% via the drop method is effective but aversive to mice; lower concentrations have not been tested. We assessed mouse behavior and insensibility with induction using the drop method for isoflurane concentrations below 5%. Male Crl:CD-1 (ICR) mice (n = 27) were randomly allocated to one of three isoflurane concentrations: 1.7%, 2.7%, and 3.7%. During induction, measures of insensibility and stress-related behaviors were recorded. All mice reached a surgical plane of anesthesia, and mice exposed to higher concentrations did so more quickly; as concentrations increased from 1.7 to 2.7 and 3.7%, the time to recumbency (Least squares means ± SE: 120.5 s ± 8.1, 97.9 s ± 8.1, and 82.8 s ± 8.1, respectively), loss of righting reflex (149.1 s ± 8.5, 127.7 s ± 8.5, and 100.7 s ± 8.5, respectively), and loss of pedal withdrawal reflex (214.5 s ± 8.3, 172.2 s ± 8.3, and 146.4 s ± 8.3, respectively) all declined. Rearing was the most frequently performed stress-related behavior, and was most pronounced immediately following isoflurane administration for all treatments. Our results indicate that the drop method can be used to effectively anesthetize mice with isoflurane concentrations as low as 1.7%; future work should assess mouse aversion.

Medetomidine/midazolam/fentanyl narcosis alters cardiac autonomic tone leading to conduction disorders and arrhythmias in mice

Arrhythmias are critical contributors to cardiovascular morbidity and mortality. Therapies are mainly symptomatic and often insufficient, emphasizing the need for basic research to unveil the mechanisms underlying arrhythmias and to enable better and ideally causal therapies. In translational approaches, mice are commonly used to study arrhythmia mechanisms in vivo. Experimental electrophysiology studies in mice are performed under anesthesia with medetomidine/midazolam/fentanyl (MMF) and isoflurane/fentanyl (IF) as commonly used regimens. Despite evidence of adverse effects of individual components on cardiac function, few data are available regarding the specific effects of these regimens on cardiac electrophysiology in mice. Here we present a study investigating the effects of MMF and IF narcosis on cardiac electrophysiology in vivo in C57BL/6N wild-type mice. Telemetry transmitters were implanted in a group of mice, which served as controls for baseline parameters without narcosis. In two other groups of mice, electrocardiogram and invasive electrophysiology studies were performed under narcosis (with either MMF or IF). Basic electrocardiogram parameters, heart rate variability parameters, sinus node and atrioventricular node function, and susceptibility to arrhythmias were assessed. Experimental data suggest a remarkable influence of MMF on cardiac electrophysiology compared with IF and awake animals. While IF only moderately reduced heart rate, MMF led to significant bradycardia, spontaneous arrhythmias, heart rate variability alterations as well as sinus and AV node dysfunction, and increased inducibility of ventricular arrhythmias. On the basis of these observed effects, we suggest avoiding MMF in mice, specifically when studying cardiac electrophysiology, but also whenever a regular heartbeat is required for reliable results, such as in heart failure or imaging research.

Development and validation of a cynomolgus macaque grimace scale for acute pain assessment

Cynomolgus macaques may undergo surgical procedures for scientific and veterinary purposes. Recognition and assessment of pain using validated tools is a necessary first step for adequately managing pain in these primates. Grimace scales are one means of assessing the occurance of acute pain using action units such as facial expressions and posture. The aim of this study was to create and validate a Cynomolgus Macaque Grimace Scale (CMGS). Cynomolgus macaques (n = 43) were video recorded before and after a surgical procedure. Images were extracted from videos at timepoints at which breakthrough pain might be expected based on analgesic pharmacokinetics. Using the CMGS images were scored by 12 observers blinded to animal identification, times, and conditions. To validate the tool, detailed behavioral analyses emphasizing changes to baseline activity ethograms were compared to grimace scores. Four action units were identified related to potential pain including orbital tightening, brow lowering, cheek tightening, and hunched posture. The CMGS tool was found to have moderate inter- (ICC_average action unit mean ± SD: 0.67 ± 0.28) and good intra- (ICC_single mean ± SD: 0.79 ± 0.14) observer reliability. Grimace scores increased significantly (p < 0.0001) in the first four post-operative timepoints compared to baseline, correlating with behavioral findings (rho range = 0.22-0.35, p < 0.001). An analgesic intervention threshold was determined and should be considered when providing additional pain relief. The CMGS was shown to be a reliable and valid tool; however, more research is needed to confirm external validity. This tool will be highly valuable for refining analgesic protocols and acute peri-procedural care for cynomolgus macaques.

Transversus abdominis plane block in rats: Preliminary cadaveric studies

The transversus abdominis plane (TAP) block is an ultrasound guided regional anaesthetic technique used to provide analgesia to the abdominal wall. Research in humans and cats has demonstrated that TAP blocks reduce pain and post-operative opioid requirements after abdominal surgery. To date TAP blocks have not been described in rats. The optimal technique to employ when performing TAP blocks is controversial with single point injection techniques failing to reliably provide adequate coverage of the cranial abdominal wall. It has been suggested that performing a two point injection may provide more reliable coverage of the cranial abdominal wall.The objective of this study was to determine the feasibility of performing ultrasound guided TAP blocks in rat cadavers and to evaluate whether performing a two point technique provides greater spread of injectate than a one point technique when administering the same total volume of methylene blue solution.Twenty-three, four-month-old, female Sprague Dawley rat cadavers weighing 506 ± 78 g were used. TAP blocks were performed using a total of 1 ml/kg of methylene blue solution.Overall success rates for injections were 21.7% (13.6-32.8%). Single point injection area of spread was 87.8 ± 32 mm² compared with 102.4 ± 17 mm² for the two point injection technique.Due to the low success rate the use of TAP blocks using the current technique cannot be recommended. Two point injection technique appears to provide greater spread; however, additional data is required to draw meaningful conclusions.

Treatment of Pain in Rats, Mice, and Prairie Dogs

Recent myomorph and scuiromorph rodent analgesia studies are reviewed and evaluated for potential clinical application. Differences between laboratory animal studies and clinical use in diseased animals are discussed. Analgesia classes reviewed include local anesthetics, nonsteroidal anti-inflammatories, acetaminophen, opioids, and adjuvants such as anticonvulsants. Routes of administration including sustained-release mechanisms are discussed, as are reversal agents. Drug interactions are reviewed in the context of beneficial multimodal analgesia as well as potential adverse effects. Dosage recommendations for clinical patients are explored.

Anesthesia and analgesia for experimental craniotomy in mice and rats: a systematic scoping review comparing the years 2009 and 2019

Experimental craniotomies are a common surgical procedure in neuroscience. Because inadequate analgesia appears to be a problem in animal-based research, we conducted this review and collected information on management of craniotomy-associated pain in laboratory mice and rats. A comprehensive search and screening resulted in the identification of 2235 studies, published in 2009 and 2019, describing craniotomy in mice and/or rats. While key features were extracted from all studies, detailed information was extracted from a random subset of 100 studies/year. Reporting of perioperative analgesia increased from 2009 to 2019. However, the majority of studies from both years did not report pharmacologic pain management. Moreover, reporting of multimodal treatments remained at a low level, and monotherapeutic approaches were more common. Among drug groups, reporting of pre- and postoperative administration of non-steroidal anti-inflammatory drugs, opioids, and local anesthetics in 2019 exceeded that of 2009. In summary, these results suggest that inadequate analgesia and oligoanalgesia are persistent issues associated with experimental intracranial surgery. This underscores the need for intensified training of those working with laboratory rodents subjected to craniotomies.

Systematic review registration

https://osf.io/7d4qe.

Pain Recognition in Rodents

Available methods for recognizing and assessing pain in rodents have increased over the last 10 years, including the development of validated pain assessment scales. Much of this work has been driven by the needs of biomedical research, and there are specific challenges to applying these scales in the clinical environment. This article provides an introduction to pain assessment scale validation, reviews current methods of pain assessment, highlighting their strengths and weaknesses, and makes recommendations for assessing pain in a clinical environment.

Effects of buprenorphine on acute pain and inflammation in the adjuvant-induced monoarthritis rat model

Background and aim

Animal modelling of arthritis is often associated with pain and suffering. Severity may be reduced with the use of analgesia which is, however, often withheld due to concerns of introducing a confounding variable. It is therefore important to design and validate pain relief protocols that reduce pain without compromising the scientific objectives. The present study evaluated the effect of buprenorphine analgesia in the immediate post-induction period of an adjuvant-induced monoarthritic rat model. The aim of this study was to extend previous work on refinement of the model by alleviating unnecessary pain.

Methods

Male and female Sprague Dawley rats were injected with 20 μl of complete Freund's adjuvant (CFA) into the left ankle. Rats were treated with buprenorphine, either injected subcutaneously or ingested voluntarily, and were compared to rats given subcutaneous injections with vehicle (saline or pure nut paste) or carprofen the first three days post CFA-injection. Measurements of welfare, clinical model-specific parameters and pain-related behaviour were assessed.

Results

Buprenorphine, administered either subcutaneously (0.10 or 0.15 mg/kg, twice daily) or by voluntary ingestion in nut paste (1.0 or 3.0 mg/kg, twice daily), improved mobility, stance, rearing and lameness scores significantly 7 h post CFA-injection. Mechanical hyperalgesia peaked at 7 h and was significantly lower in buprenorphine-treated animals, compared to vehicle-treated animals. Joint circumference was highest 24–72 h after CFA injection. Animals treated with buprenorphine did not decrease in joint circumference, opposite carprofen treated animals.

Conclusion

Buprenorphine, administered either subcutaneously or by voluntary ingestion, provides adequate analgesia for both sexes within the first 24 h post CFA-injection. Buprenorphine treatment improved clinical scores and appeared not to suppress the inflammatory response. The present study supports previous findings that voluntarily ingested buprenorphine is an effective alternative to repeated injections.

Challenges with Assessing and Treating Pain in Research Primates: A Focused Survey and Literature Review

Research primates may undergo surgical procedures making effective pain management essential to ensure good animal welfare and unbiased scientific data. Adequate pain mitigation is dependent on whether veterinarians, technicians, researchers, and caregivers can recognize and assess pain, as well as the availability of efficacious therapeutics. A survey was conducted to evaluate primate veterinary approaches to pain assessment and alleviation, as well as expressed challenges for adequately managing primate pain. The survey (n = 93 respondents) collected information regarding institutional policies and procedures for pain recognition, methods used for pain relief, and perceived levels of confidence in primate pain assessment. Results indicated that 71% (n = 60) of respondents worked at institutions that were without formal experimental pain assessment policies. Pain assessment methods were consistent across respondents with the majority evaluating pain based on changes in general activity levels (100%, n = 86) and food consumption (97%, n = 84). Self-reported confidence in recognizing and managing pain ranged from slightly confident to highly confident, and there was a commonly expressed concern about the lack of objective pain assessment tools and science-based evidence regarding therapeutic recommendations of analgesics for research primates. These opinions correspond with significant gaps in the primate pain management literature, including limited specific pharmacokinetic data and efficacy testing for commonly used analgesics in research primate species as well as limited research on objective and specific measures of pain in research primates. These results demonstrate that there are inconsistencies in institutional policies and procedures surrounding pain management in research primates and a lack of objective pain assessment methods. Demonstrating the gaps and challenges in primate pain management can inform guideline development and suggest areas for future research.

Simple Field Anesthesia for Free-Ranging Microtines

Although physical restraint without anesthesia is a common way to immobilize microtines in field settings, tagging can cause pain and stress, and escape-response movements may reduce marking quality. To evaluate if inhaled isoflurane may be a tool to minimize these issues, we anesthetized free-ranging voles (Microtus and Myodes spp.) undergoing subcutaneous injection of a passive integrated transponder tag and dorsal fur clipping. We anesthetized 24 voles for short-duration anesthesia using two 0.2-mL isoflurane doses in a simple drop-chamber system. We used the first dose to induce unconsciousness and the second dose to immediately restore unconsciousness after the vole regained consciousness from the first dose. Median induction times were 54 s for the first dose (interquartile range [IQR], 47-61) and 50 s for the second dose (IQR, 38-55). Median recovery times were 33 s for the first dose (IQR, 26-60) and 62 s for the second dose (IQR, 35-104). No mortalities occurred during the holding period. The technique was simple, inexpensive, and effective. We therefore recommend using isoflurane delivered in a drop chamber when tagging or marking microtines in the field to improve handling.

Chronic Central Leptin Infusion Promotes an Anti-Inflammatory Cytokine Profile Related to the Activation of Insulin Signaling in the Gastrocnemius of Male Rats

Leptin is involved in the modulation of insulin signaling in peripheral tissues, being closely associated with changes in lipid metabolism. This adipokine modifies inflammatory pathways that can interact with insulin targets in peripheral organs; however, the mechanisms remain unclear. Inflammatory and insulin signaling targets, cytokines, adiponectin, irisin and non-esterified fatty acid (NEFA) levels and enzymes of fatty acid anabolism were studied in the gastrocnemius of chronic centrally infused leptin (L), pair-fed and control rats. The phosphorylation of signal transducer and activator of transcription 3 (STAT3) and c-Jun N-terminal kinase (JNK) was reduced in L rats (59% and 58%, respectively). The phosphorylation of the insulin receptor and Akt and adiponectin and irisin content was increased in L rats (154%, 157%, 308% and 329%, respectively). The levels of glucose-6-phosphate dehydrogenase, the mRNA content of acetyl Co-A carboxylase and NEFA concentrations were diminished in the muscles of L rats (59%, 50% and 61%, respectively). The activation of JNK correlated positively with STAT3 phosphorylation, tumoral necrosis factor-α and NEFA and negatively with irisin and Akt phosphorylation. These data suggest that the activation of insulin signaling targets and a decrease in NEFA content are associated with a reduction in muscle inflammation parameters, suggesting that leptin may integrate these pathways.

Animal welfare requirements in publishing guidelines

Descriptions of measures taken to optimize animal welfare are often absent from scientific reports of animal experiments. One reason may be that journal guidelines inadequately compel authors to provide such information. In this study, online English language versions of the 'Guidelines to authors' (GTAs) from 54 national biomedical journals were examined for neutral (unrelated to welfare) and non-neutral keywords referring to: animal welfare; the '3Rs'; the ARRIVE (2010) guidelines, and regulations pertaining to animal experimentation. Journals were selected from nine countries (UK, US, China, Canada, India, Brazil, Germany, Japan and Australia) and seven biomedical specialties (oncology, rheumatology, surgery, pharmacology, medicine, anaesthesia and veterinary medicine). Total GTA word counts varied from 1137 to 31,609. The keyword count identified per category were expressed per myriad (10,000) of total word count. One-way analyses of variance followed by post hoc Tukey pairwise comparisons revealed greater non-neutral per myriad word counts for (a) veterinary GTAs compared with medicine, oncology, rheumatology or surgery; (b) British, compared with Australian, Canadian, German and Japanese GTAs; and (c) no differences between non-neutral categories. The English language versions of GTAs of British and veterinary medical journals contain more words associated with animal welfare, the 3Rs and the ARRIVE guidelines than those from eight other countries and six other medical specialities. The exclusion of 'national' language versions from analysis precludes attempts to identify national differences in attitudes to laboratory animal welfare.

Effects of buprenorphine on model development in an adjuvant-induced monoarthritis rat model

Complete Freund’s adjuvant (CFA)-induced arthritis in rats is a common animal model for studying chronic inflammatory pain. However, modelling of the disease is associated with unnecessary pain and impaired animal wellbeing, particularly in the immediate post-induction phase. Few attempts have been made to counteract these adverse effects with analgesics. The present study investigated the effect of buprenorphine on animal welfare, pain-related behaviour and model-specific parameters during the disease progression in a rat model of CFA-induced monoarthritis. The aim was to reduce or eliminate unnecessary pain in this model, in order to improve animal welfare and to avoid suffering, without compromising the quality of the model. Twenty-four male Sprague Dawley rats were injected with 20 μl of CFA into the left tibio-tarsal joint to induce monoarthritis. Rats were treated with either buprenorphine or carprofen for 15 days during the disease development, and were compared to a saline-treated CFA-injected group or a negative control group. Measurements of welfare, pain-related behaviour and clinical model-specific parameters were collected. The study was terminated after 3 weeks, ending with a histopathologic analysis. Regardless of treatment, CFA-injected rats displayed mechanical hyperalgesia and developed severe histopathological changes associated with arthritis. However, no severe effects on general welfare were found at any time. Buprenorphine treatment reduced facial pain expression scores, improved mobility, stance and lameness scores and it did not supress the CFA-induced ankle swelling, contrary to carprofen. Although buprenorphine failed to demonstrate a robust analgesic effect on the mechanical hyperalgesia in this study, it did not interfere with the development of the intended pathology.

Comparisons of α2-Adrenergic Agents, Medetomidine and Xylazine, with Pentobarbital for Anesthesia: Important Pitfalls in Diabetic and Nondiabetic Rats

Purpose: Anesthesia is necessary to conduct rodent electroretinograms (ERGs). We evaluated utility of the α2-agonist medetomidine versus xylazine for ERG studies in nondiabetic and diabetic rats. Pentobarbital was included as a comparator. Methods: Male Sprague-Dawley rats, with and without streptozotocin (STZ)-induced diabetes, were anesthetized with medetomidine (1 mg/kg), xylazine (10 mg/kg) (both with ketamine 75 mg/kg), or pentobarbital (70 mg/kg). The depth of anesthesia was assessed, and if adequate, scotopic ERGs were recorded. Blood glucose was monitored. Results: In nondiabetic rats, all three agents induced satisfactory anesthesia, but with differing durations: medetomidine > pentobarbital > xylazine. ERG responses were similar under medetomidine and xylazine, but relatively reduced under pentobarbital. Both α2-agonists (but not pentobarbital) elicited marked hyperglycemia (peak values 316.1 ± 42.6 and 300.3 ± 29.5 mg/dL, respectively), persisting for 12 h. In diabetic rats, elevated blood glucose concentrations were not affected by any of the agents, but the depth of anesthesia under medetomidine and xylazine was inadequate for ERG recording. Conclusions: In nondiabetic rats, medetomidine and xylazine elicited comparable effects on ERGs that differ from pentobarbital, but both perturbed glucose metabolism, potentially confounding experimental outcomes. In STZ-diabetic rats, neither α2-agent provided adequate anesthesia, while pentobarbital did so. Problems with α2-anesthetic agents, including medetomidine, must be recognized to ensure meaningful interpretation of experimental results.

Monitoring of Cardiorespiratory Parameters in Rats-Validation Based on Pharmacological Stimulation

The methods used in preclinical studies should minimize the suffering and the number of animals but still provide precise and consistent results enabling the introduction of drug candidates into the phase of clinical trials. Thus, we aimed to develop a method allowing us to perform preliminary safety and toxicity studies of candidates for human medicines, while reducing the number of animals. We have devised a method based on a combination of two devices: Plugsys (Transonics System Inc., Ithaca, NY, USA) and PhysioSuite (Kent Scientific Corporation, Torrington, CT, USA), which allow simultaneous registration of nine circulatory and respiratory parameters, and body temperature. Vehicle and adrenaline, or nitroglycerin, as reference substances were administered into the right femoral vein of Wistar rats. Physiological conditions were registered over 60 min after drug administration by measuring systolic, diastolic and mean blood pressure, heart rate (HR), blood perfusion of paw vessels, blood oxygen saturation, respiratory rate, average and peak exhaled CO₂, and body temperature. Blood pressure was measured by cannula placed in the left common carotid artery and connected to the pressure transducer (Plugsys). The other parameters were measured by the PhysioSuite. Adrenaline-induced immediate dose-related hypertension and nitroglycerin hypotension were correlated with the change in blood perfusion. They both increased HR. Adrenaline decreased blood oxygen saturation and slightly affected respiratory parameters, while nitroglycerin caused a progressive increase in respiratory rate and a decrease in the peak of exhaled CO₂. Our method may become an inseparable part of the preliminary safety and toxicity studies of tested drugs, while being an important step towards improving animal welfare.

A new anesthetic protocol to medullary nerve roots access in rats

Purpose:

To describe a new anesthetic protocol medullary and nerve roots access and in Rattus norvegicus.

Methods:

Seventy female Wistar rats (n=70) were used. The animals were randomly divided into two laminectomy groups: cervical (n=40) and thoracic (n=30). In cervical group, a right posterior hemilaminectomy was performed to access the nerve roots. In thoracic group, a laminectomy of the eighth thoracic vertebra was accomplished. Thirty-five rats (20 cervical and 15 thoracic) were submitted to old anesthetic protocol (ketamine 70 mg/kg plus xylazine 10 mg/kg); and the 35 other animals (20 cervical and 15 thoracic) were submitted to a new anesthetic protocol (ketamine 60 mg/kg,xylazine 8 mg/kg and fentanyl 0.03 mg/kg).

Results:

The time to complete induction was 4.15 ±1.20 minin ketamine, xylazine and fentanyl group, and it was 4.09 ±1.47 min in the ketamine and xylazine group. There was no correlation in the time required to perform the cervical laminectomy in the old anesthetic protocol. In all groups, the animals submitted to the old anesthetic protocol had a higher level of pain on the first and third postoperative days than the animals submitted to the new anesthetic protocol.

Conclusions:

The new anesthetic protocol reduces the surgical time, allows better maintenance of the anesthetic plan, and brings more satisfactory postoperative recovery.

Evaluation of Inflammatory Response Due to Use of Controlled Release Drug Delivery System of Chitosan Hydrogel Loaded with Buprenorphine and Ketorolac in Rat with Experimental Proximal Tibial Epiphysis Defect

Aims:A controlled release drug delivery system loaded with buprenorphine and ketorolac was synthesized and used in the experimental model of bone defect and while evaluating the inflammatory response, the repair process in the defects was investigated.Materials and methods:To determine the effectiveness of the synthesized the mentioned systems, 5 groups were defined; the control group, the chitosan hydrogel receiving group (chitosan group), the ketorolac-loaded chitosan hydrogel group (ketorolac group), the buprenorphine-loaded chitosan hydrogel receiving group (buprenorphine group), and the chitosan hydrogel-loading group loaded with a combination of ketorolac and buprenorphine (ketorolac-buprenorphine group).Results:The results showed that the population of leukocytes (tWBC) and neutrophils on different days of the study in the control group compared to other groups had a significant increase (P < 0.05) while on day 7 of the study in the ketorolac group these parameters decreased significantly compared to other groups (P < 0.05). While examining the histological changes in the experimental defect created in the proximal tibia of rats at different times, some inflammatory indices such as total and differential leukocyte population, plasma concentrations of TNF-α and IL-6 were compared in different groups (P < 0.05). The various evaluated data showed that among the different groups, in the control and ketorolac-buprenorphine groups, there was the lowest and highest control of inflammatory response and bone repair, respectively.Conclusion:In the ketorolac group due to the impact of ketorolac on leukocyte populations the best bone healing can be expected among the different treatment groups.

Improving Stereotaxic Neurosurgery Techniques and Procedures Greatly Reduces the Number of Rats Used per Experimental Group-A Practice Report

Simple Summary

Stereotaxic surgery techniques are commonly used today in research laboratories by a range of students, technicians, and researchers. Over the past twenty years, technical and scientific progress has been made in neurosurgery to meet the evolving requirements imposed by international legislation, and to promote the implementation of 3R rules. These improvements were motivated by a greater awareness of animal welfare and the necessary effort in the reduction of the number of animals used in experiments. The data presented in the present study show that technical and methodological improvements brought to our surgical procedures from 1992 resulted in reproducible stereotaxic neurosurgeries and in a significant reduction in experimental errors and animal morbidity. The effects of these improvements include a decrease in the final number of animals used in our experiments as well as better management of pain during and after surgery and the use of appropriate aseptic techniques. Correct stereotaxic surgical approaches are precisely described throughout the text.

Abstract

Techniques of stereotaxic surgery are commonly used in research laboratories by a range of students, technicians, and researchers. To meet the evolving requirements imposed by international legislation, and to promote the implementation of 3R rules (replacement, reduction, and refinement) by reducing experimental error, animal morbidity, and mortality, it is essential that standard operating procedures and proper conduct following such complex surgeries be precisely described and respected. The present report shows how refinements of our own neurosurgical techniques over decades, have significantly reduced the number of animals (rats) used in experiments and improved the animals’ well-being during the post-surgical recovery period. The current pre-, per-, and post-surgical procedures used in our laboratory are detailed. We describe the practical aspects of stereotaxic neurosurgery that have been refined in our laboratory since 1992 and that cover various areas including appropriate anesthesia and pain management during and after surgery, methods to determine the stereotaxic coordinates, and the best approach to the target brain structure. The application of these optimal surgical methods that combine reliable and reproducible results with an acute awareness of ethics and animal welfare leads to a significant reduction in the number of animals included in experimental research in accordance with ethical and regulatory rules as required by the European Directive on laboratory animal welfare.

Mice Harboring a Non-Functional CILK1/ICK Allele Fail to Model the Epileptic Phenotype in Patients Carrying Variant CILK1/ICK

CILK1 (ciliogenesis associated kinase 1)/ICK (intestinal cell kinase) is a highly conserved protein kinase that regulates primary cilia structure and function. CILK1 mutations cause a wide spectrum of human diseases collectively called ciliopathies. While several CILK1 heterozygous variants have been recently linked to juvenile myoclonic epilepsy (JME), it remains unclear whether these mutations cause seizures. Herein, we investigated whether mice harboring either a heterozygous null Cilk1 (Cilk1^+/−) mutation or a heterozygous loss-of-function Cilk1 mutation (Cilk1^R272Q/+) have epilepsy. We first evaluated the spontaneous seizure phenotype of Cilk1^+/− and Cilk1^R272Q/+ mice relative to wildtype littermates. We observed no electrographic differences among the three mouse genotypes during prolonged recordings. We also evaluated electrographic and behavioral responses of mice recovering from isoflurane anesthesia, an approach recently used to measure seizure-like activity. Again, we observed no electrographic or behavioral differences in control versus Cilk1^+/− and Cilk1^R272Q/+ mice upon isoflurane recovery. These results indicate that mice bearing a non-functional copy of Cilk1 fail to produce electrographic patterns resembling those of JME patients with a variant CILK1 copy. Our findings argue against CILK1 haploinsufficiency being the mechanism that links CILK1 variants to JME.

Working with laboratory rodents in Spain: a survey on welfare and wellbeing

Background

Replacement, reduction and refinement, the 3R principles, provide a framework to minimize the use and suffering of animals in science. In this context, we aimed to determine the actual perception that individuals working with laboratory rodents in biomedical research have on animal welfare and on their interaction with the animals, as well as how they perceive its impact on their social relations. To this end, we designed an anonymous on-line survey for people working with rodents, at three responsibility levels, in Spain.

Results

Of the 356 participants, 239 were women (67 %); 263 were researchers (74 %), and 93 animal facility staff (26 %), of which 55 were caretakers/technicians (15 %), and 38 welfare officer/veterinarians (11 %). Animal facility staff indicated environmental enrichment to be a universal practice. About half of the participants reported that, in their opinion, animals suffer “little to none” or “minor” stress and pain. Animal caretakers/technicians and researchers perceived higher levels of stress and pain than welfare officers/veterinarians. Participants judged decapitation the most unpleasant method to kill rodents, whereas anaesthetic overdose was the least one. A sizable proportion − 21 % of animal caretakers/technicians and 11.4 % of researchers - stated that they were never given the choice not to euthanize the rodents they work with. Overall, women reported higher interactions with animals than men. Nevertheless, we could detect a significant correlation between time spent with the animals and interaction scores. Notably, 80 % of animal facility staff and 92 % of researchers rarely talked about their work with laboratory rodents with people outside their inner social circle.

Conclusions

Overall, the participants showed high awareness and sensitivity to rodent wellbeing; animal facility staff reported a similar perception on welfare questions, independently of their category, while researchers, who spent less time with the animals, showed less awareness and manifested lower human-animal interaction and less social support. Regarding the perception on social acceptance of laboratory animal work, all groups were cautious and rarely talked about their job, suggesting that it is considered a sensitive issue in Spain.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42826-021-00098-w.

Mouse Anesthesia: The Art and Science

There is an art and science to performing mouse anesthesia, which is a significant component to animal research. Frequently, anesthesia is one vital step of many over the course of a research project spanning weeks, months, or beyond. It is critical to perform anesthesia according to the approved research protocol using appropriately handled and administered pharmaceutical-grade compounds whenever possible. Sufficient documentation of the anesthetic event and procedure should also be performed to meet the legal, ethical, and research reproducibility obligations. However, this regulatory and documentation process may lead to the use of a few possibly oversimplified anesthetic protocols used for mouse procedures and anesthesia. Although a frequently used anesthetic protocol may work perfectly for each mouse anesthetized, sometimes unexpected complications will arise, and quick adjustments to the anesthetic depth and support provided will be required. As an old saying goes, anesthesia is 99% boredom and 1% sheer terror. The purpose of this review article is to discuss the science of mouse anesthesia together with the art of applying these anesthetic techniques to provide readers with the knowledge needed for successful anesthetic procedures. The authors include experiences in mouse inhalant and injectable anesthesia, peri-anesthetic monitoring, specific procedures, and treating common complications. This article utilizes key points for easy access of important messages and authors’ recommendation based on the authors’ clinical experiences.

Long-Term Analgesia following a Single Application of Fentanyl Transdermal Solution in Pigs

INTRODUCTION

In animal research, obtaining efficient and constant pain control is regulatory but challenging. The gold standard pain management consists of opioid analgesic administration, such as buprenorphine or fentanyl extended-release patches. However, as in all drugs with a short half-life time, repeated buprenorphine administrations are needed, leading to multiple injections that affect the research protocol. On the other hand, fentanyl patch efficacy is discussed in some species. These elements highlight the need of an optimal formulation of analgesic drugs for laboratory animals. In this study, we investigated how Recuvyra®, a fentanyl transdermal solution (FTS), validated in dog perioperative pain management, could provide sustained analgesia after a single topical administration in pigs in a surgical context.

METHODS

A total of 11 minipigs were used in this study. As a preliminary experiment, two different doses were tested as a single application on five pigs: two pigs at full dose (2.6 mg/kg) and three pigs at half dose (1.3 mg/kg). Plasma fentanyl dosages were performed during 4 consecutive days, using liquid chromatography with tandem mass spectrometry detection. The efficacy of FTS was then evaluated in a perioperative period. Six minipigs benefited from a surgical intervention comprising a laparotomy. The FTS was blotted on the skin in a single application 20 min before the surgical incision and plasma fentanyl dosages, clinical examination (body weight, food intake, heart rate, and body temperature) and pain assessment were performed for 7 consecutive days.

RESULTS

During the preliminary experiment, all fentanyl concentrations reached the minimum effective concentration (MEC) extrapolated in pigs (fentanylemia ≥0.2 ng/mL) throughout the 4 days. The half dose was chosen for the next step of the study. After the surgical intervention, all plasma fentanyl concentrations remained above the MEC up to 7 days post administration. Pig clinical examinations and pain evaluations showed efficient and constant pain control at the half dose, and few adverse events were observed.

DISCUSSION AND CONCLUSION

This study confirms the pharmacological and clinical efficacy of FTS at 1.3 mg/kg in pigs throughout at least 7 postoperative days following laparotomy. The clinical analgesic effect of FTS appears more efficient and well-tolerated than the one observed with repeated injections of buprenorphine. This analgesic drug formulation could be universally used in animal research to provide optimal perioperative pain management and long-term analgesia.

Lidocaine and bupivacaine as part of multimodal pain management in a C57BL/6J laparotomy mouse model

While the use of local anesthesia as part of multimodal pain management is common practice in human and veterinarian surgery, these drugs are not applied routinely in rodent surgery. Several recommendations on the use of local anesthesia exist, but systematic studies on their efficacy and side effects are lacking. In the present study, male and female C57BL/6J mice were subjected to a sham vasectomy or a sham embryo transfer, respectively. We tested whether a mixture of subcutaneously injected Lidocaine and Bupivacaine in combination with systemic Paracetamol applied via drinking water results in superior pain relief when compared to treatment with local anesthesia or Paracetamol alone. We applied a combination of methods to assess behavioral, emotional, and physiological changes indicative of pain. Voluntary Paracetamol intake via drinking water reached the target dosage of 200 mg/kg in most animals. Local anesthesia did not lead to obvious side effects such as irregular wound healing or systemic disorders. No relevant sex differences were detected in our study. Sevoflurane anesthesia and surgery affected physiological and behavioral measurements. Surprisingly, Paracetamol treatment alone significantly increased the Mouse Grimace Scale. Taken together, mice treated with a combination of local anesthesia and systemic analgesia did not show fewer signs of post-surgical pain or improved recovery compared to animals treated with either local anesthesia or Paracetamol.

Effects of Oxygen Supplementation on Injectable and Inhalant Anesthesia in C57BL/6 Mice

Oxygen supplementation is rarely considered when anesthetizing laboratory mice, despite reports that mice become profoundly hypoxic under anesthesia. Little is known about the effects of hypoxia on anesthetic performance. This article focuses on the effects of oxygen supplementation on physiologic parameters and depth of anesthesia in male and female C57BL/6 mice. Anesthesia was performed via common injectable anesthetic protocols and with isoflurane. Mice anesthetized with injectable anesthesia received one of 3 drug protocols. Low-dose ketamine/xylazine (100/8 mg/kg) was chosen to provide immobilization of mice, suitable for imaging procedures. Medium-dose ketamine/xylazine/acepromazine (100/10/1 mg/kg) was chosen as a dose that has been recommended for surgical procedures. High-dose ketamine/xylazine/acepromazine (150/12/3 mg/kg) was chosen after pilot studies to provide a long duration of a deep plane of anesthesia. We also tested the effects of oxygen supplementation on the minimum alveolar concentration (MAC) of isoflurane in mice. Mice breathed supplemental 100% oxygen, room air, or medical air with 21% oxygen. Anesthetized mice that did not receive supplemental oxygen all became hypoxic, while hypoxia was prevented in mice that received oxygen. Oxygen supplementation did not affect the MAC of isoflurane. At the high injectable dose, all mice not receiving oxygen supplementation died while all mice receiving oxygen supplementation survived. At low and medium doses, supplemental oxygen reduced the duration of the surgical plane of anesthesia (low dose with oxygen: 22 ± 14 min; low dose without supplementation: 29 ± 18 min; medium dose with oxygen: 43 ± 18 min; medium dose without supplementation: 61 ± 27 min). These results suggest that mice anesthetized with injectable and inhalant anesthesia without supplemental oxygen are routinely hypoxic. This hypoxia prolongs the duration of anesthesia with injectable drug protocols and affects survival at high doses of injectable anesthetics. Because of variable responses to injectable anesthetics in mice, oxygen supplementation is recommended for all anesthetized mice.

Electrospun PVP/PVA Nanofiber Mat as a Novel Potential Transdermal Drug-Delivery System for Buprenorphine: A Solution Needed for Pain Management

Over the past several decades, the formulation of novel nanofiber-based drug-delivery systems has been a frequent focus of scientists around the world. Aiming to introduce a novel nanofibrous transdermal drug-delivery system to treat pain, the nanofiber mats of buprenorphine-loaded poly (vinyl pyrrolidone) (Bup/PVP) and buprenorphine-loaded poly(vinyl alcohol)/poly(vinyl pyrrolidone) (Bup/PVP/PVA) were successfully fabricated by the electrospinning process for transdermal drug delivery. Similarly, PVP and PVP/PVA nanofibers were fabricated in the same conditions for comparison. The viscosity and electrical conductivity of all electrospinning solutions were measured, and nanofiber mats were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FT-IR) spectroscopy and contact angle analysis. The conductivity of PVP and PVP/PVA solutions showed a considerable increase by the addition of buprenorphine due to the polarity of buprenorphine. SEM images showed a smooth, fine and porous nanofibrous structure without any adhesion or knot for all of the samples. The contact angle analysis showed the increased hydrophilicity and wettability of PVP/PVA and Bup/PVP/PVA nanofibers compared to PVP and Bup/PVP nanofibers which can be attributed to the addition of PVA. Attenuated total reflectance (ATR) FT-IR results confirmed that the electrospinning process did not affect the chemical integrity of the drug. For the modification of the drug release rate, the cross-linking of nanofiber mats was carried out using glutaraldehyde. Drug release measurements using high-performance liquid chromatography (HPLC) analysis demonstrated that Bup/PVP/PVA nanofibers exhibited better physical and chemical properties compared to Bup/PVP. Furthermore, the cross-linking of nanofibers led to an increase in drug release time. Thus, the novel buprenorphine-loaded nanofibers can be efficient biomaterial patches for transdermal delivery against pain improving carrier retention and providing a controlled release of the drug.

An Anglocentric History of Anaesthetics and Analgesics in the Refinement of Animal Experiments

Previous histories of animal experimentation, e.g., Franco (2013) have focused on ethics, the law and the personalities involved, but not on the involvement of anaesthetics or analgesics. Given that these were major subjects of (UK) Parliamentary debates on vivisection in the mid-19th century and viewed as "indisputable refinements in animal experimentation" (Russell and Burch 1959), it seemed that an analysis of their role was overdue. This commentary has, in interweaving the history of animal experimentation in the UK with the evolution of anaesthesia, attempted to: (1) clarify the evidence for Russell and Burch's view; and (2) evaluate anaesthesia's ongoing contribution to experimental refinement. The history that emerges reveals that the withholding or misuse of anaesthetics and, or analgesics from laboratory animals in the UK has had a profound effect on scientists and indirectly on the attitudes of the British public in general, becoming a major driver for the establishment of the anti-vivisection movement and subsequently, the Cruelty to Animals Act (1876)-the world's first legislation for the regulation of animal experimentation. In 1902, the mismanaged anaesthetic of a dog in the Department of Physiology, University College London resulted in numerous events of public disorder initiated by medical students against the police and a political coalition of anti-vivisectionists, trade unionists, socialists, Marxists, liberals and suffragettes. The importance of anaesthesia in animal experiments was sustained over the following 150 years as small mammalian species gradually replaced dogs and cats as the principle subjects for vivisection. In discussing experimental refinement in their 1959 report, "The Principles of Humane Experimental Technique" Russell and Burch described anaesthetics as "… the greatest single advance in humane technique, (which) has at the same time been virtually indispensable for the advance of experimental biology". Since then, the role of anaesthetics and in particular analgesics has become an unavoidable consideration whenever animal experiments are planned and conducted. This has been accompanied by a proliferation of training and educational programmes in laboratory animal anaesthesia.

Duration of thermal support for preventing hypothermia induced by anesthesia with medetomidine-midazolam-butorphanol in mice

Hypothermia during anesthetic events is a common adverse effect of anesthesia in laboratory animals. In particular, small rodents such as mice is susceptible to hypothermia during anesthetic events. Therefore, the animals will need additional thermal support by external heating devices during and after anesthesia. In general, the time of recovery from anesthesia is typically longer in case of injectable anesthesia rather than inhalant anesthesia. However, the durations of thermal support have been almost limited to 1 hr from administration of anesthesia in general. Our study objectives are two-fold: 1) to compare the levels of hypothermia induced by injectable anesthesia with medetomidine-midazolam-butorphanol (MMB) and inhalant anesthesia with isoflurane (ISO); 2) to find the adequate durations of thermal support for preventing hypothermia induced by their anesthesia in mice. Adult male ICR mice were anesthetized during 40 min without and with the thermal support for 1 (both anesthetic groups), 2, 3, and 5 hr (in MMB group). Without thermal support, the decrease of body temperature in MMB group were more severe than that in ISO group. The durations of thermal support completely prevented hypothermia at 5 hr-support in MMB group and that at 1 hr-support in ISO group. However, the other short durations did not prevent hypothermia at 1, 2 and 3 hr-support in MMB group. These results suggest that the mice should be received thermal support over 5 hr after injection of MMB anesthesia to prevent hypothermia.

Design and in vivo evaluation of a microparticulate depot formulation of buprenorphine for veterinary use

Buprenorphine is a frequently used analgetic agent in veterinary medicine. A major drawback, however, is the short duration of action requiring several daily administrations. We therefore designed a poly-lactic-co-glycolic acid (PLGA) based microparticulate drug formulation for sustained parenteral drug release. Particles were designed to allow for a fast onset of action and a duration of the analgesic effect of at least two days in laboratory mice. Microparticles were produced using a solvent evaporation technique. Release rate was dependent on polymer type and particle size. Spherical particles used for subsequent animal studies had a mean size of 50 µm and contained 4.5% of buprenorphine. Drug release was characterized by an initial burst release of 30% followed by complete release over seven days. In vivo pharmacokinetic experiments in female C57BL/6 J mice confirmed prolonged exposure in plasma and brain tissue and correlated with the pharmacological effect in the hot plate assay or after minor abdominal surgery. No adverse side effects with respect to food and water intake, body weight, local tolerability, or nesting behavior were observed. Our formulation is an attractive alternative to established immediate release formulations. A use for prolonged pain management in laboratory animals is proposed.

A Comparison of Ketamine or Etomidate Combined with Xylazine for Intraperitoneal Anesthesia in Four Mouse Strains

Intraperitoneal (IP) injection is a common route of anesthetic administration in mice. Ketamine-xylazine (KX) anesthesia is one of the most widely used IP protocols, but has limitations. Etomidate is an alternative to ketamine that has been used in both human and veterinary medicine yet has not been widely studied in mice. The purpose of this study was to evaluate etomidate-xylazine (EX) anesthesia as an alternative to KX. We hypothesized that EX would be as safe and effective as KX, with both sex- and strain-dependent differences. Male and female Crl:CD1(ICR), C57BL/6NCrl, BALB/cJ and NU/J mice were given a single IP dose of ketamine 100 mg/kg and xylazine 10 mg/kg or etomidate 20 mg/kg and xylazine 10 mg/kg. Sedation times were similar between KX and EX, with CD1 mice exhibiting shorter sedation times. Surgical anesthesia was achieved in 44% of EX mice, compared with 4% of KX mice. C57BL/6NCrl mice were significantly more likely to achieve surgical anesthesia when given EX (94%) or KX (18%) than were other strains. In all strains except C57BL/6NCrl mice, females were more likely to reach surgical anesthesia than males. Several mice experienced an adverse hyperexcitement response during induction, with BALB/cJ (79%) and NU/J (87%) mice given EX significantly more likely than other strains to experience hyperexcitement. EX and KX protocols had no overall differences in lowest respiration rate, lowest systolic blood pressure, lowest rectal temperature, or levels of acidosis, although the lowest heart rates were significantly higher with EX, indicating that EX and KX have similar safety profiles. Thus, EX and KX administration were associated with several significant physiologic differences when comparing sexes or individual strains. Our results indicate that EX is an equally effective sedative and a more effective surgical anesthetic than KX; however, EX is only recommended for invasive procedures in C57BL/6 mice due to the high rate of hyper-excitement and inconsistent surgical depth seen in other strains. Further study is needed to optimize EX for use in multiple mouse strains.

The development and use of facial grimace scales for pain measurement in animals

The measurement of pain in animals is surprisingly complex, and remains a critical issue in veterinary care and biomedical research. Based on the known utility of pain measurement via facial expression in verbal and especially non-verbal human populations, "grimace scales" were first developed a decade ago for use in rodents and now exist for 10 different mammalian species. This review details the background context, historical development, features (including duration), psychometric properties, modulatory factors, and impact of animal grimace scales for pain.

Thyroidectomy induces thyroglobulin formation by parotid salivary glands in rats

Structural changes in parotid gland (PG) were previously reported following ablation of thyroid gland. However, the functional alterations (especially for proteins) have not been elucidated yet. Herein, we investigated the effect of rat thyroidectomy on PG structure and protein content and studied the ability of thyroxin-supplementation to alleviate the associated structural and functional changes. Male young adult 4-month old albino rats (n = 48) were allocated equally into 4 groups (control, sham-operated, thyroidectomized, and thyroxin-supplemented). PGs were examined histologically, and their proteins expression and localization were analyzed using western blot (WB) and immunohistochemistry (IHC), respectively at 3 w and 5 w post-surgery. Functionally, PGs of thyroidectomized rats formed a newly expressed 300 KDa protein, which was confirmed to be thyroglobulin (TG) by WB and IHC, with higher expression at 5 w. TG was localized in the interstitium, within capillaries, in the cytoplasm of the intralobular ductal cells, in the secretory products within the ductal lumen, and in the cytoplasm of individual small cells at the periphery of the acini. This functional change accompanied by structural changes in PGs (presence of dark and light acinar cells, TG-like colloid material, and high periductal vasculature). Noteworthy, PG of the thyroxin-supplemented depicted vanishment of TG. From these data, it could be concluded that thyroidectomy could alter the morphology and function of the parotid that induce a thyroid-like reprogramming of the parotid to secrete TG and thyroxin supplementation could alleviate this effect.

The Effect of Anesthetic Regimens on Intestinal Absorption of Passively Absorbed Drugs in Rats

PURPOSE

Different anesthetic regimens are used during single pass intestinal perfusion (SPIP) experiments for the study of intestinal drug absorption in rats. We examined the ketamine/xylazine anesthetic combination to evaluate its influence on drug absorption compared to older regimens. Additionally, we examined whether supplementary analgesia has any effect on drug absorption and the effect of the different anesthetic regimens on induction time and stress response.

METHODS

Rats were anesthetized using four different anesthetic regimens; ketamine/midazolam, pentobarbital, ketamine/xylazine and ketamine/xylazine/butorphanol. Three model drugs were administered to rat intestines and P_eff was calculated. Stress response was evaluated by quantifying blood corticosterone levels and induction time was recorded.

RESULTS

We found absorption under pentobarbital to be higher or similar to absorption under ketamine/midazolam. These results partly correlate with past literature data. Ketamine/xylazine was found to give similar or higher P_eff compared to pentobarbital and ketamine/midazolam. Addition of butorphanol did not affect absorption and reduced induction time and stress.

CONCLUSIONS

In studies of intestinal drug absorption, the ketamine/xylazine combination is superior to other anesthetic regimens as it is more convenient and seems to affect absorption to a lesser extent. Addition of butorphanol is highly recommended as it did not affect absorption but led to a more effective and less stress inducing experiment.

Chemopreventive activity of Tualang honey against oral squamous cell carcinoma-in vivo

OBJECTIVE

The aim of this study was to evaluate the chemopreventive activity of Malaysian jungle Tualang honey (TH) after oral carcinogenesis induced with 4-nitroquinoline 1-oxide (4 NQO).

STUDY DESIGN

A total of 28 male Sprague-Dawley (SD) rats were distributed into 4 groups as follows: group 1 (nontreated group); group 2 (control), which received 4 NQO during 8 weeks in drinking water only; and groups 3 and 4, which received 4 NQO for 8 weeks in drinking water and treated with TH 1000 mg/kg and 2000 mg/kg by oral gavage for 10 weeks. All rats from all experiments were sacrificed after 22 weeks, and the incidence of oral neoplasms and histopathologic changes were microscopically evaluated. Moreover, immunohistochemical expression was analyzed in tongue specimens by using image analysis software. The expression of particular genes associated with oral cancer were assessed by using RT² Profiler PCR Array (Qiagen, Germantown, MD).

RESULTS

TH significantly reduced the incidence of oral squamous cell carcinoma (OSCC) and suppressed cancer cell proliferation via diminishing the expression of CCND1, EGFR, and COX-2. Furthermore, TH preserved cellular adhesion (epithelial polarity) through overexpression of β-catenin and e-cadherin and inhibited the OSCC aggressiveness by downregulating TWIST1 and RAC1.

CONCLUSIONS

Our data suggest that TH exerts chemopreventive activity in an animal model in which oral cancer was induced by using 4 NQO.

Antitumor Activity of Ficus deltoidea Extract on Oral Cancer: An In Vivo Study

Background

The aim of this study is to evaluate the chemopreventive and chemotherapeutic activities of Ficus deltoidea (FD) in an animal model induced for oral cancer using 4-nitroquinoline-1-oxide (4NQO).

Methods

Male Sprague-Dawley (SD) rats were randomized into six groups (n = 7 per group): Group 1 (untreated group); Group 2 (control cancer group) received 4NQO only for 8 weeks in their drinking water; Groups 3 and 4 (chemopreventive) received 4NQO for 8 weeks and were simultaneously treated with FD extract at 250 and 500 mg/kg, respectively, by oral gavage; Groups 5 and 6 (chemotherapeutic) received 4NQO for 8 weeks followed by the administration of FD extract at 250 and 500 mg/kg, respectively, for another 10 weeks. The incidence of oral cancer was microscopically evaluated. Moreover, immunohistochemical expression was analysed in tongue specimens using an image analyser computer system, while the RT² profiler PCR array method was employed for gene expression analysis.

Results

The results of the present study showed a beneficial regression effect of the FD extract on tumor progression. The FD extract significantly reduced the incidence of oral squamous cell carcinoma (OSCC) from 100% to 14.3% in the high-dose groups. The immunohistochemical analysis showed that the FD extract had significantly decreased the expression of the key tumor marker cyclin D1 and had significantly increased the expression of the β-catenin and e-cadherin antibodies that are associated with enhanced cellular adhesion. Based on the gene expression analysis, FD extract had reduced the expression of the TWIST1 and RAC1 genes associated with epithelial-mesenchymal transition (EMT) and had significantly downregulated the COX-2 and EGFR genes associated with cancer angiogenesis, metastasis, and chemoresistance. Our data suggest that the FD extract exerts chemopreventive and chemotherapeutic activities in an animal model induced for oral cancer using 4NQO, thus having the potential to be developed as chemopreventive and chemotherapeutic agents.β-catenin and e-cadherin antibodies that are associated with enhanced cellular adhesion. Based on the gene expression analysis, FD extract had reduced the expression of the TWIST1 and RAC1 genes associated with epithelial-mesenchymal transition (EMT) and had significantly downregulated the COX-2 and EGFR genes associated with cancer angiogenesis, metastasis, and chemoresistance. Our data suggest that the FD extract exerts chemopreventive and chemotherapeutic activities in an animal model induced for oral cancer using 4NQO, thus having the potential to be developed as chemopreventive and chemotherapeutic agents.TWIST1 and RAC1 genes associated with epithelial-mesenchymal transition (EMT) and had significantly downregulated the COX-2 and EGFR genes associated with cancer angiogenesis, metastasis, and chemoresistance. Our data suggest that the FD extract exerts chemopreventive and chemotherapeutic activities in an animal model induced for oral cancer using 4NQO, thus having the potential to be developed as chemopreventive and chemotherapeutic agents.RAC1 genes associated with epithelial-mesenchymal transition (EMT) and had significantly downregulated the COX-2 and EGFR genes associated with cancer angiogenesis, metastasis, and chemoresistance. Our data suggest that the FD extract exerts chemopreventive and chemotherapeutic activities in an animal model induced for oral cancer using 4NQO, thus having the potential to be developed as chemopreventive and chemotherapeutic agents.COX-2 and EGFR genes associated with cancer angiogenesis, metastasis, and chemoresistance. Our data suggest that the FD extract exerts chemopreventive and chemotherapeutic activities in an animal model induced for oral cancer using 4NQO, thus having the potential to be developed as chemopreventive and chemotherapeutic agents.EGFR genes associated with cancer angiogenesis, metastasis, and chemoresistance. Our data suggest that the FD extract exerts chemopreventive and chemotherapeutic activities in an animal model induced for oral cancer using 4NQO, thus having the potential to be developed as chemopreventive and chemotherapeutic agents.

An inter-laboratory trial as a tool to increase rabies diagnostic capabilities of Sub-Saharan African Veterinary laboratories

To achieve the goal of eliminating dog-mediated human rabies deaths by 2030, many African countries have agreed to list rabies as a priority zoonotic disease and to undertake both short and long-term control programs. Within this context, reliable local diagnosis is essential for the success of field surveillance systems. However, a harmonized, sustainable and supportive diagnostic offer has yet to be achieved in the continent. We herewith describe the organization and outcome of a proficiency test (PT) for the post-mortem diagnosis of rabies in animals, involving thirteen veterinary laboratories and one public health laboratory in Africa. Participants were invited to assess both the performance of the Direct Fluorescent Antibody (DFA) test and of a conventional RT-PCR. From the submitted results, while thirteen laboratories proved to be able to test the samples through DFA test, eleven performed the RT-PCR method; ten applied both techniques. Of note, the number of laboratories able to apply rabies RT-PCR had increased from four to ten after the exercise. Importantly, results showed a higher proficiency in applying the molecular test compared to the DFA test (concordance, sensitivity and specificity: 98.2%, 96.97% and 100% for RT-PCR; 87.69%, 89.23% and 86.15% for DFA test), indicating the feasibility of molecular methods to diagnose animal pathogens in Africa. Another positive outcome of this approach was that negative and positive controls were made available for further in-house validation of new techniques; in addition, a detailed questionnaire was provided to collect useful and relevant information on the diagnostic procedures and biosafety measures applied at laboratory level.

Clinical Management of Pain in Rodents

The use of effective regimens for mitigating pain remain underutilized in research rodents despite the general acceptance of both the ethical imperative and regulatory requirements intended to maximize animal welfare. Factors contributing to this gap between the need for and the actual use of analgesia include lack of sufficient evidence-based data on effective regimens, under-dosing due to labor required to dose analgesics at appropriate intervals, concerns that the use of analgesics may impact study outcomes, and beliefs that rodents recover quickly from invasive procedures and as such do not need analgesics. Fundamentally, any discussion of clinical management of pain in rodents must recognize that nociceptive pathways and pain signaling mechanisms are highly conserved across mammalian species, and that central processing of pain is largely equivalent in rodents and other larger research species such as dogs, cats, or primates. Other obstacles to effective pain management in rodents have been the lack of objective, science-driven data on pain assessment, and the availability of appropriate pharmacological tools for pain mitigation. To address this deficit, we have reviewed and summarized the available publications on pain management in rats, mice and guinea pigs. Different drug classes and specific pharmacokinetic profiles, recommended dosages, and routes of administration are discussed, and updated recommendations are provided. Nonpharmacologic tools for increasing the comfort and wellbeing of research animals are also discussed. The potential adverse effects of analgesics are also reviewed. While gaps still exist in our understanding of clinical pain management in rodents, effective pharmacologic and nonpharmacologic strategies are available that can and should be used to provide analgesia while minimizing adverse effects. The key to effective clinical management of pain is thoughtful planning that incorporates study needs and veterinary guidance, knowledge of the pharmacokinetics and mechanisms of action of drugs being considered, careful attention to individual differences, and establishing an institutional culture that commits to pain management for all species as a central component of animal welfare.

A refinement approach in a mouse model of rehabilitation research. Analgesia strategy, reduction approach and infrared thermography in spinal cord injury

The principles of Refinement, Replacement and Reduction (3R’s) should be taken into account when animals must be used for scientific purpose. Here, a Reduction / Refinement approach was applied to the procedure of spinal cord injury (SCI), an animal model used in rehabilitation medicine research, in order to improve the quality of experiments, avoiding unnecessary suffering. The aims of this investigation were 1- to assess acute surgical pain in mice subjected to SCI, 2- to compare the efficacy of commonly used analgesia (three buprenorphine subcutaneous injection in 48 hours, 0,15 mg/kg each) with a combination of opioid and NSAID (one subcutaneous injection of 5 mg/kg carprofen before surgery followed by three buprenorphine subcutaneous injection in 48 hours, 0,15 mg/kg each) and 3- to test if Infrared Thermography (IRT) could be a potential new Refinement method to easily assess thermoregulation, an important metabolic parameter. Finally, we aimed to achieve these goals without recruiting animals on purpose, but using mice already scheduled for studies on SCI. By using behaviours analysis, we found that, despite being commonly used, buprenorphine does not completely relieve acute surgical pain, whereas the combination of buprenorphine and carprofen significantly decreases pain signs by 80%. IRT technology turned out to be a very useful Refinement tool being a non invasive methods to measure animal temperature, particularly useful when rectal probe cannot be used, as in the case of SCI. We could find that temperatures constantly and significantly increased until 7 days after surgery and then slowly decreased and, finally, we could observe that in the buprenorphine and carprofen treated group, temperatures were statistically lower than in the buprenorphine-alone treated mice. To our knowledge this is the first work providing an analgesic Refinement and a description of thermoregulatory response using the IRT technology, in mice subjected to SCI.

Influence of Pain and Analgesia on Orthopedic and Wound-healing Models in Rats and Mice

The surgical stress response and resulting physiologic changes can lead to postoperative complications and negatively impact animal welfare. Although appropriate pain management is crucial to reduce the pain and stress response to surgery, analgesic choice can significantly affect bone and wound healing. This review aims to summarize data from rat and mouse studies and to provide recommendations for integrating analgesia into orthopedic and wound healing models in these species. Data from other species, such as humans, rabbits and other rodents, is included, where available. From these data, we conclude that for orthopedic surgical models, opioids, local anesthetics and dissociative agents have minimal impact on fracture healing; cyclooxygenase 2 (COX2) selective nonsteroidal antiinflammatory drugs (NSAID) may be used in the shortterm; and steroids should be avoided. For wound healing models, short-term systemic or topical opioids have negligible impact on wound healing; NSAID or local anesthetics may be used short-term; and systemic steroids should be avoided. Alternative analgesics such as tramadol, gabapentin, ketamine, and acetaminophen warrant consideration and further evaluation for both orthopedic and wound healing models. In all cases, researchers and veterinarians should work together to determine the appropriate analgesic plan to minimize pain, as well as to minimize unwanted effects on the orthopedic and wound healing models themselves.

Minimum Information in In Vivo Research

Data quality, reproducibility and reliability are a matter of concern in many scientific fields including biomedical research. Robust, reproducible data and scientific rigour form the foundation on which future studies are built and determine the pace of knowledge gain and the time needed to develop new and innovative drugs that provide benefit to patients. Critical to the attainment of this is the precise and transparent reporting of data. In the current chapter, we will describe literature highlighting factors that constitute the minimum information that is needed to be included in the reporting of in vivo research. The main part of the chapter will focus on the minimum information that is essential for reporting in a scientific publication. In addition, we will present a table distinguishing information necessary to be recorded in a laboratory notebook or another form of internal protocols versus information that should be reported in a paper. We will use examples from the behavioural literature, in vivo studies where the use of anaesthetics and analgesics are used and finally ex vivo studies including histological evaluations and biochemical assays.

Analgesic treatment limits surrogate parameters for early stress and pain response after experimental subarachnoid hemorrhage

Background

In animal research, authorities require a classification of anticipated pain levels and a perioperative analgesia protocol prior to approval of the experiments. However, data on this topic is rare and so is the reported use of analgesics. We determined surrogate parameters of pain and general well-being after subarachnoid hemorrhage (SAH), as well as the potential for improvement by different systemic analgesia paradigms. Brain injury was induced by filament perforation to mimic SAH. Sham-operated mice were included as surgical control groups with either neck or no-neck preparation. Mice with controlled cortical impact (CCI) injury were included as a control group with traumatic brain injury (TBI), but without neck preparation. Mice were randomized to buprenorphine, carprofen, meloxicam, or vehicle treatment. 24 h after SAH, CCI or sham surgery, pain and stress levels were assessed with a visual assessment score and the amount of food intake was recorded.

Results

Neck preparation, which is required to expose the surgical field for SAH induction, already increased pain/stress levels and sham surgeries for both CCI and SAH reduced food intake. Pain/stress levels were higher and food intake was lower after SAH compared with CCI. Pain/stress levels after CCI without analgesic treatment were similar to levels after SAH sham surgery. Pain treatment with buprenorphine was effective to reduce pain after SAH, whereas lower pain/stress intensity levels after CCI were not improved.

Conclusion

This study emphasizes the importance of pain and stress assessment after surgeries and the efficacy of buprenorphine to improve pain and comfort levels after experimental SAH.