Experimental Animals Research Articles

Therapeutic Potential of Quercetin and their Compound Against Ovarian Cancer: New Approaches & Application

Ovarian cancer is an exceptionally perilous form of cancer as it develops within the female reproductive system. Finding effective therapy platforms for ovarian cancer has been difficult because to the diverse array of molecular pathways and genetic alterations involved in its development. Therefore, it is imperative to discover novel therapeutic methodologies and advance their development. Medicinal herbs possess the capacity to independently or in combination with other pharmaceuticals, effectively treat malignancies such as ovarian cancer. Quercetin possesses remarkable anti-inflammatory and anti-cancer properties, making it one among numerous natural compounds with such qualities. Quercetin has demonstrated cytotoxicity against ovarian cancer cells in both laboratory experiments (in vitro) and live animal tests (in vivo). The potential anti-cancer effects of quercetin, particularly in relation to ovarian cancer, have not been extensively studied in human trials, despite encouraging findings from laboratory and animal experiments. Hence, it seems that quercetin could potentially be utilized in clinical trials as a therapeutic agent, either on its own or in conjunction with other chemotherapeutic drugs. This article will outline the primary aspects of quercetin's anti-cancer characteristics and thereafter concentrate on its application in the treatment of ovarian cancer.

The development of the bone system of young Bestuzhev breed and its crossbreeds with simmentals

Relevance. As a result of morphological studies, materials were obtained characterizing the effect of genotype and castration of young cattle and the development of the bone system in the postnatal period of ontogenesis.Methodology. For the purpose of conducting the experiment, groups of experimental young animals were selected:Results. The influence of the genotype and castration of young cattle on the absolute weight and length of individual parts and the entire skeleton of gobies and castrated gobies of the Bestuzhev breed and its first-generation crossbreeds with simmentals was established. The advantage of crossbred bulls of the ½ Bestuzhevskaya × ½ simmental group II in terms of the absolute weight of both the axial and peripheral skeleton over purebred and crossbred bulls and castrated bulls of the Bestuzhevskaya breed, crossbred castrated bulls has been established. For the entire mass of the carcass skeleton, this superiority was, respectively, 12 g (2.4%), 6616 g (14.7%) and 5553 (12.0%). Similar intergroup differences were found in the length of individual parts and the entire skeleton of the carcass.

Hydrogen Sulfide in Musculoskeletal Diseases: Molecular Mechanisms and Therapeutic Opportunities.

Significance: Musculoskeletal diseases seriously affect global health, but their importance is greatly underestimated. These diseases often afflict the elderly, leading to disability, paralysis, and other complications. Hydrogen sulfide (H2S) plays an important role in the occurrence and development of musculoskeletal diseases, which may have potential therapeutic significance for these diseases. Recent Advances: Recently, it has been found that many musculoskeletal diseases, such as osteoporosis, periodontitis, muscle atrophy, muscle ischemia-reperfusion injury, muscle contraction under high fever, arthritis, and disc herniation, can be alleviated by treatment with H2S. H2S may be conducive to the development of multiple myeloma. The mechanism of action of H2S in the musculoskeletal system has been partly elucidated. A variety of H2S donors and nano-delivery systems provide promising prospects for H2S-based therapies. Critical Issues: Related research remains at the level of cell or animal experiments, but clinical research is lacking. The roles of H2S in more musculoskeletal disorders remain largely unknown. The serious consequences of musculoskeletal diseases have not been widely concerned. Targeted delivery of H2S remains a challenging task in musculoskeletal diseases. Future Directions: Develop therapeutic drugs for musculoskeletal diseases based on H2S and test their safety, efficacy, and tolerance. Explore the combination of current drugs for musculoskeletal diseases with H2S-releasing components to improve the therapeutic efficacy and avoid side effects. Carry out relevant clinical trials to verify the possibility of its widespread use. Antioxid. Redox Signal. 00, 000-000.

Hydrogen therapy from the initiation to its practical applications

Molecular hydrogen (H2) has emerged as a therapeutic and prophylactic agent devoid of adverse effects. H2 demonstrates multifaceted functionality across diverse cell types and organs, attributable to its interaction with oxidized hemes as a fundamental molecular mechanism. Given the abundance of various heme types both intracellularly and extracellularly, the broad-ranging effects of H2 are comprehensible. Subsequent Pathways are mediated by end-or modified- products of lipid peroxide followed by free radical chain reactions. Notably, H2 confers benefits not only to patients afflicted with diseases but also to individuals seeking to enhance health and wellness. The mission of hydrogen medicine encompasses addressing unresolved medical challenges, including cerebral infarction, post-cardiac arrest syndrome, advanced cancer, metabolic syndrome, and dementia. Transitioning from animal experiments to clinical studies is imperative to confront these formidable diseases effectively.

Mechanisms of HIF1A-mediated immune evasion in gastric cancer and the impact on therapy resistance

BackgroundThe high prevalence and detrimental effects on patient outcomes make gastric cancer (GC) a significant health issue that persists internationally. Existing treatment modalities exhibit limited efficacy, prompting the exploration of immune checkpoint inhibitors as a novel therapeutic approach. However, resistance to immunotherapy poses a significant challenge in GC management, necessitating a profound grasp of the intrinsic molecular pathways.MethodsThis study focuses on investigating the immunosuppressive mechanisms of quiescent cancer cells (QCCs) in GC, particularly their resistance to T-cell-mediated immune responses. Utilizing mouse models, gene editing techniques, and transcriptome sequencing, we aim to elucidate the interactions between QCCs, immune cells, and key regulatory factors like HIF1A. Functional enrichment analysis will further underscore the role of glycolysis-related genes in mediating immunosuppression by QCCs.ResultsThe cancer cells that survived GC treated with T-cell therapy lost their proliferative ability. QCCs, as the main resistance force to immunotherapy, exhibit stronger resistance to CD8+ T-cell attack and possess higher cancer-initiating potential. Single-cell sequencing analysis revealed that the microenvironment in the QCCs region harbors more M2-type tumor-associated macrophages and fewer T cells. This microenvironment in the QCCs region leads to the downregulation of T-cell immune activation and alters macrophage metabolic function. Transcriptome sequencing of QCCs identified upregulated genes related to chemo-resistance, hypoxia, and glycolysis. In vitro cell experiments illustrated that HIF1A promotes the transcription of glycolysis-related genes, and silencing HIF1A in QCCs enhances T-cell proliferation and activation in co-culture systems, induces apoptosis in QCCs, and increases QCCs' sensitivity to immune checkpoint inhibitors. In vivo, animal experiments showed that silencing HIF1A in QCCs can inhibit GC growth and metastasis.ConclusionUnraveling the molecular mechanisms by which QCCs resist T-cell-mediated immune responses through immunosuppression holds promising implications for refining treatment strategies and enhancing patient outcomes in GC. By delineating these intricate interactions, this study contributes crucial insights into precision medicine and improved therapeutic outcomes in GC management.

Cardioprotective effect of lithium ascorbate in an in vivo model of myocardial infarction

The aim of the work was to study the cardioprotective effect of lithium ascorbate in an in vivo model of myocardial infarction. In the course of the study, we searched for compounds promising for therapy of acute myocardial infarction.Materials and methods. Myocardial infarction was modeled in Wistar rats by ligating the left coronary artery (the duration of ischemia was 45 minutes) followed by ligature loosening and 120-minute reperfusion. All manipulations were performed under alpha-chloralose anesthesia with mechanical lung ventilation and recording heart rate, blood pressure, and ECG. Lithium ascorbate was administered intravenously at a dose of 100 mg / ml before ischemia. The area at risk (the ischemia / reperfusion zone) was detected by staining the myocardium with tightened ligature with 5% potassium permanganate. After that consecutive myocardial slices were prepared, and infarct size was determined. Differentiation of the infarct size from the area at risk was performed by staining with 1% 2,3,5-triphenyl tetrazolium chloride solution for 30 minutes at 37 ºC. The infarct size and the area at risk were determined by the planimetric method. The serum concentration of myocardial damage marker creatine kinase-MB (CK-MB) was measured using ELISA kits.Results. Lithium ascorbate reduced the infarct size / area at risk ratio by 38% and decreased the serum CPKMB level in the experimental animals by 42% compared to the control group. Lithium ascorbate did not affect hemodynamics parameters during coronary artery occlusion and reperfusion.Conclusion. The cardioprotective effect of lithium ascorbate in cardiac ischemia / reperfusion in vivo was found.

Formulation development, characterization, and evaluation of sorafenib-loaded PLGA-chitosan nanoparticles.

The basic purpose of this work was to develop environmentally friendly, biodegradable, and biocompatible polymeric nanoparticles of sorafenib that can effectively release the desired drug in a customized and controlled manner for targeting hepatocellular carcinoma. The solvent evaporation technique was employed for the synthesis of sorafenib-loaded PLGA-chitosan nanoparticles, followed by various experimental specifications and compatibility studies using poloxamer 407 as the stabilizer. The best nanoparticles thus synthesized were selected to be used for cytotoxicity investigations through in vitro and in vivo assessments. For the in vitro drug release tests, the dialysis bag diffusion technique was used. For both chitosan nanoparticles and PLGA loaded with sorafenib, a biphasic release pattern was found, exhibiting a protracted release lasting 10 days after a 24-h burst release. As experimental animals, rabbits were utilized to evaluate different in vivo pharmacokinetic properties of the selected formulations. Plasma samples were extracted with acetonitrile and analyzed through the developed HPLC method. Pharmacokinetic parameters such as AUC0-t, Cmax MRT, Vd, and half-life (t1/2) were enhanced significantly (p ≤ 0.001), while clearance was considerably decreased (p ≤ 0.001) for the chosen synthesized nanoparticles in contrast to the commercially accessible sorafenib formulation (Nexavar®). The cytotoxicity of the reference drug and sorafenib-loaded PLGA and chitosan nanoparticles was calculated by performing an MTT assay against HepG2 cell lines. The developed polymeric sorafenib nanoformulations possess the appropriate physicochemical properties, better targeting, surface morphology, and prolonged release kinetics. The pharmacokinetic parameters were improved significantly when the results were compared with commercially available sorafenib formulations.

Cardiac Histomorphological Alterations in Adult Wistar Rats Following Exposure to 3,4- Methylenedioxymethamphetamine (MDMA) Pills

The Ecstasy pill sold with the trade name ‘molly’ which has 3,4-methylenedioxymethamphetamine (MDMA) as the active component, is one of the most popular recreational drugs in parts of Africa. This study was carried out to determine the histomorphological effects of molly on the heart using adult wistar rats as the mammalian model. The study was done on twenty-five adult albino wistar rats which were sacrificed after 21 days of molly administration, the rats were put under light chloroform anesthesia and the Heart harvested for histological processing. The experimental animals were separated into five groups. Each group contained five rats each using 5 big cages to house them. The administration of molly was given orally as follows: Group A (Control) received only normal feed (growers’ mash) and distilled water daily for 21days. Group B-E (Test groups) received growers mash and graded quantities of molly (B, 0.12 mg/kg body weight each; C, 0.18 mg/kg body weight each; D, 0.32 mg/kg body weight each and E, 0.4 mg/kg body weight each) and water was given ad libitum for 21 days. Heart sections were obtained from the rats and processed histologically. The results showed that the weight of the control increased during the period of the study. The mean weight of rats in all groups before the period of molly administration were significantly increased. Group A (Control), group B and C showed normal cardiac muscle, while Group D and E showed section of cardiac muscle showing fragmented myocytes with karyolysis of nuclei surrounded by eosinophilic cytoplasm and features of Myolysis. This study revealed that consumption of molly could result in the distortion and disruption of the microanatomy of the cardiac muscle showing fragmented myocytes with karyolysis of nuclei surrounded by eosinophilic cytoplasm. Molly consumption may be the cause of the various deleterious distortions which occurred in the heart and a necessary reduction in its consumption is required to avoid these effects.

Micro-arc oxidation for balancing antibacterial activity and bone formation on titanium surface

Ti surfaces must balance bone formation and antibacterial activity to achieve bone reconstruction and prevent infections. In this study, a Ti surface was electrochemically modified via micro-arc oxidation in an electrolyte containing calcium ions, phosphate ions, and either Ag, or Cu ions to form an antibacterial porous oxide layer on Ti surface. The resultant porous oxide layers consisted of both electrolyte and substrate elements. The Ag- and Cu-incorporated porous oxide layers exhibited antibacterial activity against methicillin-resistant Staphylococcus aureus. Furthermore, animal experiments were performed to reveal the bone-formation on the Ag- and Cu-incorporated porous oxide layers. Both porous oxide layers promoted bone formation more effectively than untreated Ti. Thus, the Ag- and Cu-incorporated porous oxide layers formed on the Ti surface by micro-arc oxidation balanced bone formation and antibacterial activity owing to their structural and compositional features. Our findings will be useful for the surface design of Ti-based medical devices and can provide a simple electrochemical treatment to form porous surfaces to balance antibacterial activity and bone formation on Ti surfaces.

Challenges and opportunities of poly(amino acid) nanomedicines in cancer therapy.

Poly(amino acid) nanomedicines hold significant promise for cancer therapy. However, their clinical translation has not matched the extensive efforts of scientists or the burgeoning body of research. The therapeutic outcomes with most nanomedicines often fall short of the promising results observed in animal experiments. This review explores the challenges faced in cancer therapy using poly(amino acid) nanomedicines, particularly addressing the controversies surrounding the enhanced permeability and retention effect and the lack of methods for controlled and reproducible mass production of poly(amino acid) nanomedicines. Furthermore, this review examines the opportunities emerging in this field due to the rapid advancements in artificial intelligence.

Otolithiasis in the Animal Kingdom: A Retrospective Analysis.

If otolithiasis can be demonstrated to affect multiple species, it may be possible to identify an experimental animal for prospective study of this entity. Otolithiasis refers to dislodged otolithic matter within the confines of the membranous labyrinth that has the potential to cause clinical symptoms. The mechanism involves separation of free-floating otoconia that can affect the hearing and balance functions of the ear. While this process is known to occur in humans, it is uncertain if other species are affected. The published images of 37 whole-mount specimens of mammalian labyrinths were identified for retrospective examination. These were evaluated stereographically for the presence of calcareous material in abnormal locations within the membranous labyrinth. Thirty normal labyrinth specimens were found, exemplified by that of the Cape sea lion. Seven pathologic specimens were found, including a human, a black ape, a yellow-faced baboon, a hocheur monkey, a collie dog, a common sheep, and a common hare. Abnormal accumulations of calcareous material were found at one or more sites, more frequently in the utricle and canal system and less frequently in the endolymphatic and cochlea ducts. Otolithiasis appears to occur in other animal species besides the human. Abnormal calcareous material was found in various locations within the membranous labyrinth of affected animals. One or more of these might serve as an animal model to prospectively study the phenomenon of otolithiasis.

GROWTH PERFORMANCE AND SEMEN CHARACTERISTICS OF MONGREL RABBIT BUCKS FED DIETARY LEVELS OF GARLIC (ALLUM SATIVUM) MEAL

This study was designed to evaluate the effect of garlic meal supplementation on growth performance and semen characteristics in rabbit bucks. Twenty-four (24) mixed breed rabbit bucks were used for this study. The bucks were allowed to acclimatize for two weeks before the commencement of the study, during this period, they were fed formulated diet and Calopogonium ad-libitum. Feed and clean drinking water were offered ad libitum to the experimental animals. Four different experimental diets were formulated with varying levels of 0.00, 0.50, 1.00 and 1.50% garlic meal as supplement and were coded as T1, T2, T3 and T4 respectively, with as control. The 24 bucks were weighed and randomly allotted into the four experimental treatments and replicated thrice with two rabbit bucks per replicate in a complete randomized design (CRD) for a period of 8 weeks. At the end of the feeding period, semen collection was done using a specially designed artificial vagina for rabbits. The data obtained were subjected to one-way analysis of variance (ANOVA) procedure using IBM Statistical Package for Social Science (SPSS) version 21. The result showed that garlic meal had significant effect (P<0.05) on final weight, total and daily feed intake. Garlic significantly influenced (p<0.05) sperm volume, motility, concentration and total cells per ejaculate however, did not affect sperm morphology. In conclusion, garlic meal supplementation at 1.0% (10g/kg) can improve some growth and seminal parameters in male rabbits.

A biomimetic fruit fly robot for studying the neuromechanics of legged locomotion

For decades, the field of biologically inspired robotics has leveraged insights from animal locomotion to improve the walking ability of legged robots. Recently, 'biomimetic' robots have been developed to model how specific animals walk. By prioritizing biological accuracy to the target organism rather than the application of general principles from biology, these robots can be used to develop detailed biological hypotheses for animal experiments, ultimately improving our understanding of the biological control of legs while improving technical solutions. In this work, we report the development and validation of the robot Drosophibot II, a meso-scale robotic model of an adult fruit fly,Drosophila melanogaster. This robot is novel for its close attention to the kinematics and dynamics ofDrosophila, an increasingly important model of legged locomotion. Each leg's proportions and degrees of freedom have been modeled afterDrosophila3D pose estimation data. We developed a program to automatically solve the inverse kinematics necessary for walking and solve the inverse dynamics necessary for mechatronic design. By applying this solver to a fly-scale body structure, we demonstrate that the robot's dynamics fit those modeled for the fly. We validate the robot's ability to walk forward and backward via open-loop straight line walking with biologically inspired foot trajectories. This robot will be used to test biologically inspired walking controllers informed by the morphology and dynamics of the insect nervous system, which will increase our understanding of how the nervous system controls legged locomotion.

Role of Ferroptosis in ALD: Focusing on Hepcidin and Besides Hepcidin.

Ascending incidence and poor outcomes make Alcoholic Liver Disease (ALD) a considerable public health concern. This review concluded the iron metabolism under physiology conditions and alcohol disturbance (leading to ferroptosis in ALD) and summarized the novel treatment, diagnosis, and prognosis of ferroptosis for ALD. ALD is characterized by alcohol-induced chronic metabolism disorder, peroxidation damage, and dysfunction of the anti-oxidant system. Current animal experiments and clinical studies identified ferroptosis as a new form of regulated cell death involved in ALD. One strong evidence is that the key iron regulatory hormone, hepcidin, is downgraded in ALD through NF-κB/IL-6/STAT3, BMP/SMAD, and Jak/STAT3 pathways, which would impair iron hemostasis and induce ferroptosis in ALD. Also, imbalance metabolism and other pathological responses in ALD induce and regulate ferroptosis, which proves ferroptosis participates in the pathophysiology of ALD via oxidative stress, steatosis, and fibrosis. Inhibition of ferroptosis via regulating hepcidin expression and metabolism impairment may provide new therapies for ALD.

Design, construction, and use of a tapered-spiral, quadrature 1H/23Na double-tuned coil for in ovo MRI at 7 T.

In ovo MR presents a promising and viable alternative to traditional in vivo small animal experiments. Sodium MRI complements proton MRI by providing potential access to tissue cellular metabolism. Despite its abundance, sodium MRI is challenged by lower MR sensitivity and faster relaxation times compared to proton MRI. Ensuring a high signal-to-noise ratio and effective B0 shimming is essential. Double-tuned coils combining 23Na and 1H are frequently employed to achieve structural imaging and efficient shim adjustment. This study introduces a novel, highly optimized, double-tuned coil design, specifically for MR scans of chick embryos. A tapered-spiral, double-tuned coil was designed and constructed following careful consideration of design parameters. The performance of the coil was rigorously assessed through bench tests, and final validation was conducted on a 7 T MRI scanner using a chick embryo. Bench tests demonstrated that the return losses for both 1H and 23Na coils were better than -30dB, and isolation factors were better than -21dB, indicating that the double-tuned coil was well-set, with negligible coupling between channels. MR images of chick embryos, obtained using the coil, validated the feasibility of utilizing the design concept for in ovo applications. The innovative design of the proposed double-tuned coil, characterized by its unique arrangement, offers improved performance. This design has the potential to significantly enhance the quality of in ovo 1H and 23Na measurements.

Christensenellaceae minuta modulates epithelial healing via PI3K-AKT pathway and macrophage differentiation in the colitis

Ulcerative colitis (UC) is a chronic inflammatory disorder with an unsatisfactory cure rate and mucosal healing is a key treatment objective. Christensenellaceae minuta (C. minuta) has emerged as a next-generation of probiotic for maintaining intestinal health. We investigated the therapeutic efficacy of C. minuta in dextran sulfate sodium (DSS)-induced colitis, focusing on mucosal healing and the underlying mechanisms. C. minuta effectively alleviated colitis and promoted the regeneration of intestinal epithelial cells (IECs). Using 16S rRNA sequencing and metabolomics, we found that C. minuta administration increased beneficial bacteria, decreased pathogenic bacteria, and significantly elevated propionic acid levels. Additionally, C. minuta activated the PI3K-AKT pathway by upregulating systemic and local IGF-1 expression. Inhibiting the PI3K-AKT pathway reduced the therapeutic effects of C. minuta and impaired IEC regeneration. Furthermore, C. minuta promoted macrophage differentiation into the M2 phenotype and decreased proinflammatory factors. We propose that C. minuta alleviates colitis by regulating the gut microbiota, modulating macrophage differentiation, and enhancing mucosal healing by activating the PI3K-AKT pathway via IGF-1 secretion induced by short-chain fatty acids. Our findings provide evidence from animal experiments to support future clinical trials and the therapeutic translation of C. minuta.

Application of 3D Printing to Design and Manufacture Pancreatic Duct Stent and Animal Experiments.

Objective: Postoperative pancreatic fistula (POPF) is a common and challenging complication following pancreaticoduodenectomy (PD), occurring in 2% to 46% of cases. Despite various pancreaticojejunostomy techniques, an effective method to prevent POPF has not been established. This study aimed to develop and evaluate a novel 3D-printed biodegradable pancreatic duct stent to simplify the surgical process of pancreaticojejunostomy, reduce anastomotic complexity, and minimize postoperative complications. Methods: Data from 32 patients undergoing total laparoscopic pancreaticoduodenectomy were utilized. Preoperative CT scans were transformed into 3D reconstructions to guide the design and printing of customized stents using polylactic acid (PLA). The stents were assessed for mechanical integrity, surface texture, and thermal stability. Animal experiments were conducted on 16 mini pigs, with the experimental group receiving the novel stent and the control group receiving traditional silicone stents. Results: The 3D-printed stents demonstrated accurate dimensional replication and mechanical reliability. In the animal experiments, the experimental group showed no significant difference in postoperative complications compared to the control group. At 4 weeks post-surgery, CT scans revealed well-healed anastomoses in both groups, with no significant inflammation or other complications. Histological examination and 3D reconstruction models confirmed good healing and device positioning in the experimental group. Conclusion: The 3D-printed biodegradable pancreatic duct stent offers a promising solution for pancreaticojejunostomy, with comparable safety and efficacy to traditional methods. Further research is needed to validate its clinical application.

Photoactivated Hydrogel Therapeutic System with MXene-Based Nanoarchitectonics Potentiates Endogenous Bone Repair Through Reshaping the Osteo-Vascularization Network.

The repair and reconstruction of large-scale bone defects face enormous challenges because of the failure to reconstruct the osteo-vascularization network. Herein, a near-infrared (NIR) light-responsive hydrogel system is reported to achieve programmed tissue repair and regeneration through the synergetic effects of on-demand drug delivery and mild heat stimulation. The spatiotemporal hydrogel system (HG/MPa) composed of polydopamine-coated Ti3C2Tx MXene (MP) nanosheets decorated with acidic fibroblast growth factor (aFGF, a potent angiogenic drug) and hydroxypropyl chitosan/gelatin (HG) hydrogel is developed to orchestrate the reconstruction of the osteo-vascularization network and boost bone regeneration. Upon exposure to NIR light irradiation, the engineered HG/MPa hydrogel can achieve the initial complete release of aFGF to induce rapid angiogenesis and provide sufficient blood supply, maximizing its biofunction in the defect area. This integrated hydrogel system demonstrated good therapeutic efficacy in promoting cell adhesion, proliferation, migration, angiogenesis, and osteogenic differentiation through periodic NIR irradiation. In vivo, animal experiments further revealed that the spatiotemporalized hydrogel platform synergized with mild photothermal treatment significantly accelerated critical-sized bone defect healing by increasing the osteo-vascularization network density, recruiting endogenous stem cells, and facilitating the production of osteogenesis/angiogenesis-related factors. Overall, smart-responsive hydrogel couldenhance the reconstruction of the osteo-vascularization network in bone regeneration.

The Neuroprotective Effect of Calotropis procera Against Toxicity of Mercury Chloride

Background: Central nervous system intoxication can result from exposure to various toxins, including mercury chloride. Although several chelating agents are available for mercury chloride detoxification, their efficacy can diminish over time. Calotropis procera, a medicinal plant, has shown potential as a protective agent against mercury chloride-induced brain damage. This study aims to evaluate the protective effects of Calotropis procera in mitigating mercury chloride toxicity. Experimental animal design: This study investigates the protective effects of Calotropis procera against mercury chloride toxicity in Wistar albino rats. A total of 36 rats, comprising both males and females, were housed under controlled laboratory conditions and divided into two main groups based on five animals. Each group was further subdivided into five subgroups: a control group, a group treated with Calotropis procera, a group treated with mercury chloride, a group treated with both mercury chloride and Calotropis procera and a group receiving Calotropis procera alongside mercury chloride. Treatments were administered for 20 days. After the treatment period, the rats were euthanised, and brain tissues were collected for histopathological analysis. After the brain tissues were fixed in 10% saline-buffered formalin, they were processed through a series of ascending grades of ethanol to dehydrate them. The tissues were then cleared in xylene and embedded in paraffin. The paraffin-embedded brains were treated three times with pure paraffin to ensure proper infiltration and were subsequently moulded into blocks. Sections of 5 µm thickness were prepared using a Leica microtome and stained with Haematoxylin and Eosin (H&E) for histopathological examination. The study adhered to ethical guidelines and was approved by the relevant regulatory body. The results of this study demonstrated that mercury chloride caused significant cerebral toxicity, manifesting as inflammation and pyknosis of the nuclei. Calotropis procera reduced mercury toxicity and preserved the nuclei in male rats. In female rats, Calotropis procera completely preserved the brain tissue.

Decision trees for determining the fate of laboratory animals.

Facilities involved in laboratory animal research often face ethical challenges such as: what should I do with the animals that are no longer suitable for experimental purposes? One of the common answers to this question is to kill them. And while numerous scientifically justifiable reasons exist for killing laboratory animals, we must not overlook our ethical responsibility towards these sentient beings. Animal facility managers and scientists frequently find themselves in a moral dilemma, torn between furthering their research and addressing the well-being of experimental animals required for their studies. We elaborated a concept consisting of six decision trees and recommendations for making informed decisions about the need to kill laboratory animals in research facilities, considering legal and ethical considerations. The concept is based on the German regulatory perspective. However, the measures and decisions for animal welfare can be implemented in all laboratory animal facilities. These recommendations suggest several courses of action, including implementing consistent breeding plans, exploring alternative uses, reassigning surplus animals and their organs, and establishing appropriate housing capacity limits that ensure species-appropriate care. We encourage scientists and animal facility managers to develop and implement decision-making frameworks and procedures tailored to their specific facilities, in the hope that this work will promote a thoughtful and responsible approach to the complex challenges associated with the killing of laboratory animals, advancing scientific progress and the humane treatment of these animals.