Physiological and pharmacokinetic effects of multilevel caging on Sprague Dawley rats under ketamine-xylazine anesthesia

Comparative study of the anti-inflammatory activity of etoricoxib and Matcha green tea against acute kidney injury induced by gamma radiation in rats

PURPOSE

The primary objective of this study was to conduct a comparative analysis of the anti-inflammatory activity between Etoricoxib (ETO) and Matcha green tea (MG) in the context of acute kidney injury (AKI) induced by ionizing gamma radiation (IR) in female rats. Furthermore, the potential impact of whole body IR exposure on the intestinal system and serum estradiol levels was investigated. Additionally, it was acknowledged that the ETO and MG treatments might have exerted favorable effects on the intestinal and hormonal responses.

MATERIALS AND METHODS

Six groups of rats were assigned to different treatments: control, ETO, MG, irradiation (IRR), ETO + IRR, and MG + IRR. The evaluation included measuring the total phenolic and flavonoid contents of ETO and MG, as well as assessing their antioxidant activity, radical scavenging capacity, reducing power, and total antioxidant capacity. Kidney function was assessed through serum creatinine and urea levels. Oxidative stress markers, including superoxide dismutase, glutathione, malondialdehyde, and catalase, were measured to evaluate the antioxidant effects of ETO and MG. The anti-inflammatory potential of the treatments was evaluated by measuring STAT-3 and interleukins (IL-6, IL-23, and IL-17) using an ELISA assay. Prostaglandin E2 receptor (PGE-2) mRNA expression, histopathological examination, and immunohistochemistry for NF-κB inhibitors were performed to investigate the underlying mechanisms in kidney tissue homogenates. Histopathological changes and DNA fragmentation in the intestinal tissues were determined, and the characterization of Matcha green tea was performed using liquid chromatography-mass spectrometry (LC-MS). This allowed for the identification and quantification of various compounds present in Matcha green tea. Furthermore, the study assessed the effect of IR and treatments on estrogen levels in female rats.

RESULTS

Data showed that both ETO and MG had the potential to mitigate the adverse effects of AKI induced by IR. Notably, MG exhibited greater efficacy in attenuating oxidative stress and inflammation associated with renal injury. These findings revealed and compared the effects of ETO and MG in alleviating AKI caused by IR. MG demonstrated greater anti-inflammatory and antioxidant properties, highlighting its potential as a natural therapeutic agent.

CONCLUSIONS

These results contribute to the growing evidence supporting the use of MG in managing IR-induced renal complications. Future studies should focus on elucidating the molecular mechanisms and optimizing the application of MG in clinical settings.

Context-Specific Tolerance and Pharmacological Changes in the Infralimbic Cortex-Nucleus Accumbens Shell Pathway Evoked by Ketamine

Like other drugs, ketamine is abused due to its ability to act as a positive reinforcer in the control of behavior, just as natural reinforcers do. Besides, through Pavlovian conditioning, tolerance to drug effects can become conditioned to specific contextual cues showing that environmental stimuli can act as powerful mediators of craving and relapse. In the present study, we shall investigate the effects of long-term ketamine administration and withdrawal on behavioral measures and emotionality, the drug-context-specific influence on the tolerance to the sedative effects of an anesthetic dose of ketamine, and the neuropharmacological events underlying this phenomenon, in rats conditioned with 10 mg/kg of ketamine and later challenged with a dose of ketamine of 80 mg/kg in a familiar and non-familiar environment. Variations in dopamine and serotonin efflux in the infralimbic cortex-nucleus accumbens shell circuitry (IL-NAcSh) was further recorded in the same conditions. Our results highlight that besides its well-known reinforcing properties, ketamine also shares the ability to induce behavioral and pharmacological conditioned tolerance, associated with increases in cortical (IL), and decreases in striatal (NAcSh) dopamine release. To our knowledge, we are presenting the first set of behavioral and neurochemical data showing that, like other drugs of abuse, ketamine can induce learned context-specific tolerance.

Comparison of the effects of Lactobacillus plantarum versus imipenem on infected burn wound healing

Background: Infection of burn wounds is one of the most important problems in the world. Lactobacillus plantarum is known for burn wound healing because of the immunomodulatory and anti-microbial roles. This study was performed to compare the effects of L. plantarum and imipenem - alone and in combination - on infected burn wound healing. Methods: Burn wounds were experimentally induced on 50 rats in three test groups (germ and supernatant of L. plantarum ) and two control groups (n=10 each) and were inoculated with Pseudomonas aeruginosa. During a 14-day period, wounds in all groups were daily treated topically. The data were analyzed using one-way analysis of variance followed by Tukey-Kramer and LSD. A p-value of < 0.05 was considered as statistically significant. Results: The mean size of the wound on day 14 after the treatment in the probiotic group was significantly lower than the control and the supernatant treated groups (p<0.05). The percentage of wound healing was significantly higher in the probiotic pellet treated group compared to the imipenem and the supernatant groups (by Anova test: 69.58%, p=0.022). The mean leukocyte count in the probiotic pellet group (12110) and supernatant group (13650) was significantly higher than the imipenem group (7670) (p=0.002 and 0.001, respectively). Wound cultures revealed that the percentage of cases where the pathogens had no growth was significantly different among the comparison groups. In all three test groups, P. aeruginosa was completely eliminated in comparison to the positive control group (p<0.05). Conclusion: The results of our study showed that L. plantarum and its by-products promote wound healing and can be used as an alternative to antibiotics to treat ulcer infections caused by resistant bacteria.

The paradox of dipeptidyl peptidase IV inhibition in enterocytic differentiation and epithelial-mesenchymal transition in rat cholestatic sepsis

Proper enterocytic proliferation/differentiation, besides providing adequate adherens junctions (AJ) integrity, are responsible for strengthening of the gut barrier that acts as a first line defense against endotoxemia. However, the preferential role of the underlying PI3K/Akt (PKB) axis in triggering enterocytic proliferation/differentiation signaling and AJ assembly is still obscure in sepsis. Additionally, the potential involvement of dipeptidyl peptidase (DPP)-IV in cholestatic sepsis has not yet been reported. Common bile duct ligation (CBDL) insult was performed in adult male Sprague-Dawley rats except for sham operated animals; three doses of vildagliptin (VLD3, 10 and 30 mg/kg/d; p.o) were administered for 10 consecutive days post CBDL. VLD3/10/30 dose-dependently decreased DPP-IV and elevated GLP-1, IGF-1, PI3K, pS473-Akt (PKB), pS9-GSK-3β, pS133-CREB and cyclin-D1. VLD3/10 reduced fever, portal/aortic endotoxin and IgG, body weight loss as well as ileal NF-κB, TNF-α, MPO, TBARS, subepithelial/pericryptal and submucosal collagen deposition, vimentin immunoreactivity, N-cadherin, Zeb1 and pY654-β-catenin but increased E-cadherin, NPSH and colon/spleen indices - effects that were quite the opposite of VLD30. Accordingly, maintaining proper enterocytic proliferation/differentiation and phosphorylation inputs consequent to adequate DPP-IV inhibition is integral to AJ assembly in cholestatic sepsis; however, perturbed signals by excessive suppression of the enzyme activity induce toxic effects manifested as AJ disassembly and EMT, hence gut leakage and overt endotoxemia.

Oxygen inhalation improves postoperative survival in ketamine-xylazine anaesthetised rats: An observational study

OBJECTIVE

A simple but reliable and safe anaesthetic procedure is required for surgical interventions in small rodents. Combined ketamine and xylazine injections are often used in rats for less invasive surgery, possibly with spontaneous breathing and without airway management. However, there are important pitfalls to be avoided by special precautions and monitoring, as shown subsequently.

STUDY DESIGN

Observational study.

ANIMALS

Twenty-four anaesthetic procedures for bile duct ligation, sham operation or carotid artery dilatation in 20 male Sprague-Dawley rats, preoperatively weighing between 440 and 550 g.

METHODS

Intolerable high mortality rates occurred in the first 7 postoperative days while establishing a new experimental model in rats using ketamine-xylazine anaesthesia. Rats were spontaneously breathing ambient air during the first 12 surgeries without airway management. An observed high mortality rate in these animals led to a change in the trial protocol: the insufflation of 2 litres of oxygen per minute via nose cone during the following 12 rat surgeries. Retrospective comparison of the outcome (without oxygen vs. with oxygen insufflation) was conducted.

RESULTS

The perioperative mortality rate could be significantly reduced from 58% (7/12) to 17% (2/12) (p = 0.036) by oxygen insufflation via nose cone. Significantly different levels of intraoperative oxygen saturation (SpO2; 89 ± 4% [without oxygen] vs. 97 ± 0.5% [with oxygen], p < 0.0001), but no significant differences in heart rate (HR; 267 ± 7 beats minute-1 [bpm] [without oxygen] vs. 266 ± 6 bpm [with oxygen], p = 0.955) were observed.

CONCLUSIONS AND CLINICAL RELEVANCE

In summary, rats under ketamine-xylazine anaesthesia are susceptible to hypoxia. This may lead to increased delayed mortality related to hypoxia induced lung failure. Apparently, this is an underestimated problem. We highly recommend using additional oxygen insufflation in spontaneously breathing rats under ketamine-xylazine anaesthesia with basic monitoring such as measurement of oxygen saturation.

Applying the 3Rs: A Case Study on Evidence and Perceptions Relating to Rat Cage Height in the UK

This article investigates the barriers to implementing higher caging in animal research establishments in the UK. The use of animals in research and testing in the UK is regulated by the Animals (Scientific Procedures) Act 1986, which sets out how animal experiments must be licensed and regulated. Within this, the Code of Practice currently allows laboratory rats to be housed in cages that are 20 cm high, even though adults can rear up to 30 cm. Most adult rats therefore cannot stand upright in 'standard' cages. We found that the main factors hindering the implementation of higher caging were classified into five different groups; health and safety, financial, animal welfare, scientific, and 'human'. Suggestions to overcome these barriers are provided, as well as alternative animal welfare changes that can be put into place. We conclude that much of the desired evidence for moving to higher cages is already available, and therefore the focus should be on education and improving access to the existing evidence, in order to encourage facilities to work around existing financial and health and safety concerns.

Sex-dependent changes in ketamine-induced locomotor activity and ketamine pharmacokinetics in preweanling, adolescent, and adult rats

Although ketamine has long been known to increase locomotor activity, only recently was it realized that this behavioral effect varies according to both sex and age. The purpose of the present study was threefold: first, to measure the locomotor activating effects of ketamine in male and female rats across early ontogeny and into adulthood; second, to assess ketamine and norketamine pharmacokinetics in the dorsal striatum and hippocampus of the same age groups; and, third, to use curvilinear regression to determine the relationship between locomotor activity and dorsal striatal concentrations of ketamine and norketamine. A high dose of ketamine (80 mg/kg, i.p.) was administered in order to examine the complete cycle of locomotor responsiveness across a 280-min testing session. In separate groups of rats, the dorsal striata and hippocampi were removed at 10 time points (0-360 min) after ketamine administration and samples were assayed for ketamine, norketamine, and dopamine using HPLC. In female rats, ketamine produced high levels of locomotor activity that varied only slightly among age groups. Male preweanling rats responded like females, but adolescent and adult male rats exhibited lesser amounts of ketamine-induced locomotor activity. Ketamine and norketamine pharmacokinetics, especially peak values and area under the curve, generally mirrored age- and sex-dependent differences in locomotor activity. Among male rats and younger female rats, dorsal striatal ketamine and norketamine levels accounted for a large proportion of the variance in locomotor activity. In adult female rats, however, an additional factor, perhaps involving other ketamine and norketamine metabolites, was influencing locomotor activity.