Oxygenation through oral Ox66 in a two-hit rodent model of respiratory distress

Acute respiratory distress syndrome (ARDS) is a complication of pulmonary disease that produces life-threatening hypoxaemia. Despite ventilation and hyperoxic therapies, undetected hypoxia can manifest in capillary beds leading to multi-organ failure. Ox66™ is an ingestible, solid-state form of oxygen designed to supplement oxygen deficits. Twenty-four anaesthetized rats underwent a two-hit model of respiratory distress (ARDS), where a single dose (5 mg/kg) of lipopolysaccharide (LPS) was given intratracheally, and then the respiratory tidal volume was reduced by 40%. After 60 min, animals were randomized to receive Ox66™, or normal saline (NS; vehicle control) via gavage or supplemental inspired oxygen (40% FiO2). A second gavage was administered at 120 min. Cardiovascular function and blood oximetry/chemistry were measured alongside the peripheral spinotrapezius muscle's interstitial oxygenation (PISFO2). ARDS reduced mean arterial pressure (MAP) and PISFO2 compared to baseline (BL) for all treatment groups. Treatment with Ox66 or NS did not improve MAP, but 40% FiO2 caused a rapid return to BL. PISFO2 improved after treatment with Ox66™ and 40% FiO2 and remained elevated for both groups against NS until study conclusion. Both oxygen treatments also suppressed the inflammatory response to LPS, suggesting that Ox66™ can deliver therapeutically-impactful levels of oxygen in situations of pulmonary dysfunction.

Viral diversity in wild and urban rodents of Yunnan Province, China

Rodents represent over 40% of known mammal species and are found in various terrestrial habitats. They are significant reservoirs for zoonotic viruses, including harmful pathogens such as arenaviruses and hantaviruses, yet knowledge of their hosts and distributions is limited. Therefore, characterizing the virome profile in these animals is invaluable for outbreak preparedness, especially in potential hotspots of mammal diversity. This study included 681 organs from 124 rodents and one Chinese tree shrew collected from Yunnan Province, China, during 2020-2021. Metagenomic analysis revealed unique features of mammalian viruses in rodent organs across habitats with varying human disturbances. R. tanezumi in locations with high anthropogenic disturbance exhibited the highest mammal viral diversity, with spleen and lung samples showing the highest diversities for these viruses at the organ level. Mammal viral diversity for both commensal and non-commensal rats was identified to positively correlate with landscape disturbance. Some virus families were associated with particular organs or host species, suggesting tropism for these pathogens. Notably, known and novel viral species that are likely to infect humans were identified. R. tanezumi was identified as a reservoir and carrier for various zoonotic viruses, including porcine bocavirus, hantavirus, cardiovirus, and lyssavirus. These findings highlight the influence of rodent community composition and anthropogenic activities on diverse virome profiles, with R. tanezumi as an important reservoir for zoonotic viruses.

Harvesting decellularized liver extracellular matrix from rodents for 3D scaffold fabrication

Decellularization is a process to harvest the decellularized extra cellular matrix (dECM) that helps develop 3D scaffolds which mimic the native tissue composition. The decellularized tissues retain the structural and functional properties of the extracellular matrix (ECM) by an efficient decellularization process that retains tissue-specific biochemical and biophysical cues for tissue regeneration. In this study, we report an injection-based decellularization method, without perfusion setup. This study also compares the efficiency of the proposed protocol in the two animal models viz rat and mice. This method harvests rat and mice liver dECM using ethylenediamine tetra acetic acid (EDTA) and sodium dodecyl sulphate (SDS) within 08 h and 02 h respectively and preserved significant amount of ECM proteins. We reported that the harvested mice decellularized extracellular matrix (mdECM) and rat decellularized extracellular matrix (rdECM) had significant reduction in their DNA content (∼97%) and retained structural architecture resembling their native tissue counterparts. The total protein content retained in mdECM was ∼39% while that retained in rdECM was ∼65%. It was also found that the sGAG (sulphated glycosaminoglycan) content showed a no List of Figures.

Acute and subacute toxicological evaluation of the ethanol leaf extract of Morus mesozygia stapf. (Moraceae) in rodents

ETHNOPHARMACOLOGICAL RELEVANCE

Traditionally, the Morus mesozygia tree leaf has been used to manage maladies such as peptic ulcer, hyperglycemia, dermatitis, rheumatism, stomach-ache, arthritis, cough, malignancies, and malaria in parts of Africa.

AIM OF THE STUDY

The study aimed to evaluate the potential of ethanol leaf extract of Morus mesozygia (EEMm) to induce toxicity by employing both acute and sub-acute oral toxicity experimental models.

MATERIAL AND METHODS

The extract's cytotoxicity was studied using brine shrimps (Artemia salina) lethality assay (BSLA), while in the acute toxicity test, male and female mice were administered a single oral dose of EEMm (2000 mg/kg). Male and female Wistar rats received repeated doses of 100 or 500 mg/kg EEMm orally for 28 days in the sub-acute toxicity experiment. The phytochemical analysis of EEMm was done using the HPLC.

RESULTS

The BSLA revealed a moderate cytotoxic potential of the extract, with an LC50 of 567.13 ± 0.27 μg/mL. All the animals survived the acute toxicity test, with no significant changes in the relative organ weights, suggesting that LD50 is greater than 2000 mg/kg. The animal weights did not vary significantly in the sub-acute toxicity test neither were the alterations in biochemical and hematological tests pronounced, although the histoarchitectures of the kidney, liver and spleen indicated slight anomalies in the evaluated animals. The HPLC analysis revealed the presence of quercetin, ferulic acid, rutin, caffeic acid, morin and gallic acid.

CONCLUSIONS

Ethanol leaf extract of Morus mesozygia demonstrated a safe toxicity profile in rodents, supporting its broad folkloric use in African ethnomedicine.

Can we gain translational insights into the functional roles of cerebral cortex from acortical rodent and naturally acortical zebrafish models?

Cerebral cortex is found only in mammals and is particularly prominent and developed in humans. Various rodent models with fully or partially ablated cortex are commonly used to probe the role of cortex in brain functions and its multiple subcortical projections, including pallium, thalamus and the limbic system. Various rodent models are traditionally used to study the role of cortex in brain functions. A small teleost fish, the zebrafish (Danio rerio), has gained popularity in neuroscience research, and albeit (like other fishes) lacking cortex, its brain performs well some key functions (e.g., memory, consciousness and motivation) with complex, context-specific and well-defined behaviors. Can rodent and zebrafish models help generate insights into the role of cortex in brain functions, and dissect its cortex-specific (vs. non-cortical) functions? To address this conceptual question, here we evaluate brain functionality in intact vs. decorticated rodents and further compare it in the zebrafish, a naturally occurring acortical species. Overall, comparing cortical and acortical rodent models with naturally acortical zebrafish reveals both distinct and overlapping contributions of neocortex and 'precortical' zebrafish telencephalic regions to higher brain functions. Albeit morphologically different, mammalian neocortex and fish pallium may possess more functional similarities than it is presently recognized, calling for further integrative research utilizing both cortical and decorticated/acortical vertebrate model organisms.

Eutrichophilus cordiceps Mjöberg, 1910 (Ischnocera: Trichodectidae) in Spiny Tree Porcupines (Coendou villosus): New locality records and the first molecular evidence of association with Bartonella sp

The chewing louse genus Eutrichophilus Mjöberg has 19 species only associated with porcupines (Rodentia: Erethizontidae). Of these species, E. cercolabes, E. cordiceps, E. emersoni, E. minor, E. moojeni, and E. paraguayensis have been recorded in Brazil. In the present study, we report E. cordiceps for the first time in the São Paulo State (Bauru Municipality) and for the second time in the Santa Catarina State (Lages Municipality), providing scanning electron images and light microscopy for the eggs, as well as the first molecular data (18S rRNA) for the genus. Additionally, Bartonella sp. was detected for the first time in this chewing lice species.

Sex differences in the rodent medial prefrontal cortex - What Do and Don't we know?

The prefrontal cortex, particularly its medial subregions (mPFC), mediates critical functions such as executive control, behavioral inhibition, and memory formation, with relevance for everyday functioning and psychopathology. Despite broad characterization of the mPFC in multiple model organisms, the extent to which mPFC structure and function vary according to an individual's sex is unclear - a knowledge gap that can be attributed to a historical bias for male subjects in neuroscience research. Recent efforts to consider sex as a biological variable in basic science highlight the great need to close this gap. Here we review the knowns and unknowns about how rodents categorized as male or female compare in mPFC neuroanatomy, pharmacology, as well as in aversive, appetitive, and goal- or habit-directed behaviors that recruit the mPFC. We propose that long-standing dogmatic concepts of mPFC structure and function may not remain supported when we move beyond male-only studies, and that empirical challenges to these dogmas are warranted. Additionally, we note some common pitfalls in this work. Most preclinical studies operationalize sex as a binary categorization, and while this approach has furthered the inclusion of non-male rodents it is not as such generalizable to what we know of sex as a multidimensional, dynamic variable. Exploration of sex variability may uncover both sex differences and sex similarities, but care must be taken in their interpretation. Including females in preclinical research needs to go beyond the investigation of sex differences, improving our knowledge of how this brain region and its subregions mediate behavior and health. This article is part of the Special Issue on "PFC circuit function in psychiatric disease and relevant models".

Rodent maze studies: from following simple rules to complex map learning

More than 100 years since the first maze designed for rodent research, researchers now have the choice of a variety of mazes that come in many different shapes and sizes. Still old designs get modified and new designs are introduced to fit new research questions. Yet, which maze is the most optimal to use or which training paradigm should be applied, remains up for debate. In this review, we not only provide a historical overview of maze designs and usages in rodent learning and memory research, but also discuss the possible navigational strategies the animals can use to solve each maze. Furthermore, we summarize the different phases of learning that take place when a maze is used as the experimental task. At last, we delve into how training and maze design can affect what the rodents are actually learning in a spatial task.

A method for studying escape behavior to terrestrial threats in rodents

BACKGROUND

Escape is one of the most essential behaviors for an animal's survival because it could be a matter of life and death. Much of our current understanding of the neural mechanisms underlying escape is derived from the looming paradigm, which mimics a diving aerial predator. Yet, the idea of the looming paradigm does not account for all types of threats like lions hunting antelopes or cats stalking mice. Escape responses to such terrestrial threats may require different strategies and neural mechanisms.

NEW METHODS

Here, we developed a real-time interactive platform to study escape behavior to terrestrial threats in mice. A closed-loop controlled robot was magnetically pulled to mimic a terrestrial threat that chases a mouse. By using strong magnets and high-precision servo motors, the robot is capable of moving precisely with a high spatial-temporal resolution. Different algorithms can be used to achieve single approach or persistent approach.

RESULTS

Animal experiments showed that mice exhibited consistent escape behavior when exposed to an approaching robotic predator. When presented with a persistently approaching predator, the mice were able to rapidly adapt their behavior, as evidenced by a decrease in startle responses and changes in movement patterns.

COMPARISON WITH EXISTING METHODS

In comparison to existing methods for studying escape behavior, such as the looming paradigm, this approach is more suitable for investigating animal behavior in response to sustained threats.

CONCLUSION

In conclusion, we have developed a flexible platform to study escape behavior to terrestrial threats in mice.

Gene delivery followed by ex vivo lung perfusion using an adeno-associated viral vector in a rodent lung transplant model

OBJECTIVE

Ex vivo lung perfusion has emerged as a platform for organ preservation, evaluation, and restoration. Gene delivery using a clinically relevant adeno-associated vector during ex vivo lung perfusion may be useful in optimizing donor allografts while the graft is maintained physiologically active. We evaluated the feasibility of adeno-associated vector-mediated gene delivery during ex vivo lung perfusion in a rat transplant model. Additionally, we assessed off-target effects and explored different routes of delivery.

METHODS

Rat heart-lung blocks were procured and underwent 1-hour ex vivo lung perfusion. Before ex vivo lung perfusion, 4e11 viral genome luciferase encoding adeno-associated vector 9 was administered via the left bronchus (Br group, n = 4), via the left pulmonary artery (PA group, n = 3), or directly into the circuit (Circuit group, n = 3). Donor lungs in the Control group (n = 3) underwent ex vivo lung perfusion without adeno-associated vector 9. Only the left lung was transplanted. Animals underwent bioluminescence imaging weekly before being killed at 2 weeks. Tissues were collected for luciferase activity measurement.

RESULTS

All recipients tolerated the transplant well. At 2 weeks post-transplant, luciferase activity in the transplanted lung was significantly higher among animals in the Br group compared with the other 3 groups (Br: 1.1 × 106 RLU/g, PA: 8.3 × 104 RLU/g, Circuit: 3.8 × 103 RLU/g, Control: 2.5 × 103 RLU/g, P = .0003). No off-target transgene expression was observed.

CONCLUSIONS

In this work, we demonstrate that a clinically relevant adeno-associated vector 9 vector mediates gene transduction during ex vivo lung perfusion in rat lung grafts when administered via the airway and potentially the pulmonary artery. Our preliminary results suggest a higher transduction efficiency when adeno-associated vector 9 was delivered via the airway, and delivery during ex vivo lung perfusion reduces off-target effects after graft implant.

Meta-analysis and machine learning reveal the antiobesity effects of melatonin on obese rodents

Melatonin appears to be a promising supplement for obesity treatment. The antiobesity effects of melatonin on obese rodents are influenced by various factors, including the species, sex, the dosage of melatonin, treatment duration, administration via, daily treatment time, and initial body weight (IBW). Therefore, we conducted a meta-analysis and machine learning study to evaluate the antiobesity effect of melatonin on obese mice or rats from 31 publications. The results showed that melatonin significantly reduced body weight, serum glucose (GLU), triglycerides (TGs), low-density lipoprotein (LDL), and cholesterol (TC) levels in obese mice or rats but increased high-density lipoprotein (HDL) levels. Melatonin showed a slight positive effect on clock-related genes, although the number of studies was limited. Meta-regression analysis and machine learning indicated that the dosage of melatonin was the primary factor influencing body weight, with higher melatonin dosages leading to a stronger weight reduction effect. Together, male obese C57BL/6 mice and Sprague-Dawley rats with an IBW of 100-200 g showed better body weight reduction when supplemented with a dose of 10-30 mg/kg melatonin administered at night via injection for 5-8 weeks.

Transmembrane pH gradient imaging in rodent glioma models

A unique feature of the tumor microenvironment is extracellular acidosis in relation to intracellular milieu. Metabolic reprogramming in tumors results in overproduction of H+ ions (and lactate), which are extruded from the cells to support tumor survival and progression. As a result, the transmembrane pH gradient (ΔpH), representing the difference between intracellular pH (pHi) and extracellular pH (pHe), is posited to be larger in tumors compared with normal tissue. Controlling the transmembrane pH difference has promise as a potential therapeutic target in cancer as it plays an important role in regulating drug delivery into cells. The current study shows successful development of an MRI/MRSI-based technique that provides ΔpH imaging at submillimeter resolution. We applied this technique to image ΔpH in rat brains with RG2 and U87 gliomas, as well as in mouse brains with GL261 gliomas. pHi was measured with Amine and Amide Concentration-Independent Detection (AACID), while pHe was measured with Biosensor Imaging of Redundant Deviation in Shifts (BIRDS). The results indicate that pHi was slightly higher in tumors (7.40-7.43 in rats, 7.39-7.47 in mice) compared with normal brain (7.30-7.38 in rats, 7.32-7.36 in mice), while pHe was significantly lower in tumors (6.62-6.76 in rats, 6.74-6.84 in mice) compared with normal tissue (7.17-7.22 in rats, 7.20-7.21 in mice). As a result, ΔpH was higher in tumors (0.64-0.81 in rats, 0.62-0.65 in mice) compared with normal brain (0.13-0.16 in rats, 0.13-0.16 in mice). This work establishes an MRI/MRSI-based platform for ΔpH imaging at submillimeter resolution in gliomas.

Peripheral direct current reduces naturally evoked nociceptive activity at the spinal cord in rodent models of pain

Objective.Electrical neuromodulation is an established non-pharmacological treatment for chronic pain. However, existing devices using pulsatile stimulation typically inhibit pain pathways indirectly and are not suitable for all types of chronic pain. Direct current (DC) stimulation is a recently developed technology which affects small-diameter fibres more strongly than pulsatile stimulation. Since nociceptors are predominantly small-diameter Aδand C fibres, we investigated if this property could be applied to preferentially reduce nociceptive signalling.Approach.We applied a DC waveform to the sciatic nerve in rats of both sexes and recorded multi-unit spinal activity evoked at the hindpaw using various natural stimuli corresponding to different sensory modalities rather than broad-spectrum electrical stimulus. To determine if DC neuromodulation is effective across different types of chronic pain, tests were performed in models of neuropathic and inflammatory pain.Main results.We found that in both pain models tested, DC application reduced responses evoked by noxious stimuli, as well as tactile-evoked responses which we suggest may be involved in allodynia. Different spinal activity of different modalities were reduced in naïve animals compared to the pain models, indicating that physiological changes such as those mediated by disease states could play a larger role than previously thought in determining neuromodulation outcomes.Significance.Our findings support the continued development of DC neuromodulation as a method for reduction of nociceptive signalling, and suggests that it may be effective at treating a broader range of aberrant pain conditions than existing devices.

Sildenafil, alone and in combination with imipramine or escitalopram, display antidepressant-like effects in an adrenocorticotropic hormone-induced (ACTH) rodent model of treatment-resistant depression

BACKGROUND

Major depressive disorder (MDD) represents a challenge with high prevalence and limited effectiveness of existing treatments, particularly in cases of treatment-resistant depression (TRD). Innovative strategies and alternative drug targets are therefore necessary. Sildenafil, a selective phosphodiesterase type 5 (PDE5) inhibitor, is known to exert neuroplastic, anti-inflammatory, and antioxidant properties, and is a promising antidepressant drug candidate.

AIM

To investigate whether sildenafil monotherapy or in combination with a known antidepressant, can elicit antidepressant-like effects in an adrenocorticotropic hormone (ACTH)-induced rodent model of TRD.

METHODS

ACTH-naïve and ACTH-treated male Sprague-Dawley (SD) rats received various sub-acute drug treatments, followed by behavioural tests and biochemical analyses conversant with antidepressant actions.

RESULTS

Sub-chronic ACTH treatment induced significant depressive-like behaviour in rats, evidenced by increased immobility during the forced swim test (FST). Sub-acute sildenafil (10 mg/kg) (SIL-10) (but not SIL-3), and combinations of imipramine (15 mg/kg) (IMI-15) and sildenafil (3 mg/kg) (SIL-3) or escitalopram (15 mg/kg) (ESC-15) and SIL-3, exhibited significant antidepressant-like effects. ACTH treatment significantly elevated hippocampal levels of brain-derived neurotrophic factor (BDNF), serotonin, norepinephrine, kynurenic acid (KYNUA), quinolinic acid (QUINA), and glutathione. The various mono- and combined treatments significantly reversed some of these changes, whereas IMI-15 + SIL-10 significantly increased glutathione disulfide levels. ESC-15 + SIL-3 significantly reduced plasma corticosterone levels.

CONCLUSION

This study suggests that sildenafil shows promise as a treatment for TRD, either as a stand-alone therapy or in combination with a traditional antidepressant. The neurobiological mechanism underlying the antidepressant-like effects of the different sildenafil mono- and combination therapies reflects a multimodal action and cannot be explained in full by changes in the individually measured biomarker levels.

Systematic review of rodent studies of deep brain stimulation for the treatment of neurological, developmental and neuropsychiatric disorders

Deep brain stimulation (DBS) modulates local and widespread connectivity in dysfunctional networks. Positive results are observed in several patient populations; however, the precise mechanisms underlying treatment remain unknown. Translational DBS studies aim to answer these questions and provide knowledge for advancing the field. Here, we systematically review the literature on DBS studies involving models of neurological, developmental and neuropsychiatric disorders to provide a synthesis of the current scientific landscape surrounding this topic. A systematic analysis of the literature was performed following PRISMA guidelines. 407 original articles were included. Data extraction focused on study characteristics, including stimulation protocol, behavioural outcomes, and mechanisms of action. The number of articles published increased over the years, including 16 rat models and 13 mouse models of transgenic or healthy animals exposed to external factors to induce symptoms. Most studies targeted telencephalic structures with varying stimulation settings. Positive behavioural outcomes were reported in 85.8% of the included studies. In models of psychiatric and neurodevelopmental disorders, DBS-induced effects were associated with changes in monoamines and neuronal activity along the mesocorticolimbic circuit. For movement disorders, DBS improves symptoms via modulation of the striatal dopaminergic system. In dementia and epilepsy models, changes to cellular and molecular aspects of the hippocampus were shown to underlie symptom improvement. Despite limitations in translating findings from preclinical to clinical settings, rodent studies have contributed substantially to our current knowledge of the pathophysiology of disease and DBS mechanisms. Direct inhibition/excitation of neural activity, whereby DBS modulates pathological oscillatory activity within brain networks, is among the major theories of its mechanism. However, there remain fundamental questions on mechanisms, optimal targets and parameters that need to be better understood to improve this therapy and provide more individualized treatment according to the patient's predominant symptoms.

Substantial viral diversity in bats and rodents from East Africa: insights into evolution, recombination, and cocirculation

BACKGROUND

Zoonotic viruses cause substantial public health and socioeconomic problems worldwide. Understanding how viruses evolve and spread within and among wildlife species is a critical step when aiming for proactive identification of viral threats to prevent future pandemics. Despite the many proposed factors influencing viral diversity, the genomic diversity and structure of viral communities in East Africa are largely unknown.

RESULTS

Using 38.3 Tb of metatranscriptomic data obtained via ultradeep sequencing, we screened vertebrate-associated viromes from 844 bats and 250 rodents from Kenya and Uganda collected from the wild. The 251 vertebrate-associated viral genomes of bats (212) and rodents (39) revealed the vast diversity, host-related variability, and high geographic specificity of viruses in East Africa. Among the surveyed viral families, Coronaviridae and Circoviridae showed low host specificity, high conservation of replication-associated proteins, high divergence among viral entry proteins, and frequent recombination. Despite major dispersal limitations, recurrent mutations, cocirculation, and occasional gene flow contribute to the high local diversity of viral genomes.

CONCLUSIONS

The present study not only shows the landscape of bat and rodent viromes in this zoonotic hotspot but also reveals genomic signatures driven by the evolution and dispersal of the viral community, laying solid groundwork for future proactive surveillance of emerging zoonotic pathogens in wildlife. Video Abstract.

Prevalence, genetic diversity and eco-epidemiology of pathogenic Leptospira species in small mammal communities in urban parks Lyon city, France

Rodents are recognized as the main reservoirs of Leptospira spp. Rats, in particular, serve as hosts for the widely predominant Leptospira interrogans serovar Icterohaemorrhagiae, found worldwide. Several studies have shown the importance of other reservoirs, such as mice or hedgehogs, which harbor other leptospires' serovars. Nevertheless, our knowledge of circulating Leptospira spp. in reservoirs other than rats remains limited. In this context, we proposed an eco-health approach to assess the health hazard associated with leptospires in urban green spaces, where contacts between human/small mammals and domestic animals are likely. We studied the prevalence, the diversity of circulating strains, and epidemiology of pathogenic Leptospira species in small terrestrial mammal communities (rodents and shrews), between 2020-2022, in two parks in Lyon metropolis, France. Our study showed a significant carriage of Leptospira spp. in small terrestrial mammals in these parks and unveiled a global prevalence rate of 11.4%. Significant variations of prevalence were observed among the small mammal species (from 0 to 26.1%), with Rattus norvegicus exhibiting the highest infection levels (26.1%). We also observed strong spatio-temporal variations in Leptospira spp. circulation in its reservoirs. Prevalence seems to be higher in the peri-urban park and in autumn in 2021 and 2022. This is potentially due to differences in landscape, abiotic conditions and small mammal communities' composition. Our study suggests an important public health relevance of rats and in a lesser extent of other rodents (Apodemus spp., Clethrionomys glareolus and Mus musculus) as reservoirs of L. interrogans, with rodent species carrying specific serogroups/serovars. We also emphasize the potential hazard associated between the shrew Crocidura russula and L. kirschneri. Altogether, these results improve our knowledge about the prevalence of leptospirosis in an urban environment, which is an essential prerequisite for the implementation of prevention of associated risks.

Space wandering in the rodent default mode network

The default mode network (DMN) is a large-scale brain network known to be suppressed during a wide range of cognitive tasks. However, our comprehension of its role in naturalistic and unconstrained behaviors has remained elusive because most research on the DMN has been conducted within the restrictive confines of MRI scanners. Here, we use multisite GCaMP (a genetically encoded calcium indicator) fiber photometry with simultaneous videography to probe DMN function in awake, freely exploring rats. We examined neural dynamics in three core DMN nodes-the retrosplenial cortex, cingulate cortex, and prelimbic cortex-as well as the anterior insula node of the salience network, and their association with the rats' spatial exploration behaviors. We found that DMN nodes displayed a hierarchical functional organization during spatial exploration, characterized by stronger coupling with each other than with the anterior insula. Crucially, these DMN nodes encoded the kinematics of spatial exploration, including linear and angular velocity. Additionally, we identified latent brain states that encoded distinct patterns of time-varying exploration behaviors and found that higher linear velocity was associated with enhanced DMN activity, heightened synchronization among DMN nodes, and increased anticorrelation between the DMN and anterior insula. Our findings highlight the involvement of the DMN in collectively and dynamically encoding spatial exploration in a real-world setting. Our findings challenge the notion that the DMN is primarily a "task-negative" network disengaged from the external world. By illuminating the DMN's role in naturalistic behaviors, our study underscores the importance of investigating brain network function in ecologically valid contexts.

Ibrutinib disrupts blood-tumor barrier integrity and prolongs survival in rodent glioma model

In malignant glioma, cytotoxic drugs are often inhibited from accessing the tumor site due to the blood-tumor barrier (BTB). Ibrutinib, FDA-approved lymphoma agent, inhibits Bruton tyrosine kinase (BTK) and has previously been shown to independently impair aortic endothelial adhesion and increase rodent glioma model survival in combination with cytotoxic therapy. Yet additional research is required to understand ibrutinib's effect on BTB function. In this study, we detail baseline BTK expression in glioma cells and its surrounding vasculature, then measure endothelial junctional expression/function changes with varied ibrutinib doses in vitro. Rat glioma cells and rodent glioma models were treated with ibrutinib alone (1-10 µM and 25 mg/kg) and in combination with doxil (10-100 µM and 3 mg/kg) to assess additive effects on viability, drug concentrations, tumor volume, endothelial junctional expression and survival. We found that ibrutinib, in a dose-dependent manner, decreased brain endothelial cell-cell adhesion over 24 h, without affecting endothelial cell viability (p < 0.005). Expression of tight junction gene and protein expression was decreased maximally 4 h after administration, along with inhibition of efflux transporter, ABCB1, activity. We demonstrated an additive effect of ibrutinib with doxil on rat glioma cells, as seen by a significant reduction in cell viability (p < 0.001) and increased CNS doxil concentration in the brain (56 ng/mL doxil alone vs. 74.6 ng/mL combination, p < 0.05). Finally, Ibrutinib, combined with doxil, prolonged median survival in rodent glioma models (27 vs. 16 days, p < 0.0001) with brain imaging showing a - 53% versus - 75% volume change with doxil alone versus combination therapy (p < 0.05). These findings indicate ibrutinib's ability to increase brain endothelial permeability via junctional disruption and efflux inhibition, to increase BTB drug entry and prolong rodent glioma model survival. Our results motivate the need to identify other BTB modifiers, all with the intent of improving survival and reducing systemic toxicities.

Beyond hippocampus: Thalamic and prefrontal contributions to an evolving memory

The hippocampus has long been at the center of memory research, and rightfully so. However, with emerging technological capabilities, we can increasingly appreciate memory as a more dynamic and brain-wide process. In this perspective, our goal is to begin developing models to understand the gradual evolution, reorganization, and stabilization of memories across the brain after their initial formation in the hippocampus. By synthesizing studies across the rodent and human literature, we suggest that as memory representations initially form in hippocampus, parallel traces emerge in frontal cortex that cue memory recall, and as they mature, with sustained support initially from limbic then diencephalic then cortical circuits, they become progressively independent of hippocampus and dependent on a mature cortical representation. A key feature of this model is that, as time progresses, memory representations are passed on to distinct circuits with progressively longer time constants, providing the opportunity to filter, forget, update, or reorganize memories in the process of committing to long-term storage.

Restorative effects of (+)-epicatechin in a rodent model of aging induced muscle atrophy: underlying mechanisms

Sarcopenia is a progressive and generalized age-related skeletal muscle (SkM) disorder characterized by the accelerated loss of muscle mass (atrophy) and function. SkM atrophy is associated with increased incidence of falls, functional decline, frailty and mortality. In its early stage, SkM atrophy is associated with increased pro-inflammatory cytokine levels and proteasome-mediated protein degradation. These processes also link to the activation of atrophy associated factors and signaling pathways for which, there is a lack of approved pharmacotherapies. The objective of this study, was to characterize the capacity of the flavanol (+)-epicatechin (+Epi) to favorably modulate SkM mass and function in a rat model of aging induced sarcopenia and profile candidate mechanisms. Using 23 month old male Sprague-Dawley rats, an 8 weeks oral administration of the +Epi (1 mg per kg per day in water by gavage) was implemented while control rats only received water. SkM strength (grip), treadmill endurance, muscle mass, myofiber area, creatine kinase, lactate dehydrogenase, troponin, α-actin, tumor necrosis factor (TNF)-α and atrophy related endpoints (follistatin, myostatin, NFκB, MuRF 1, atrogin 1) were quantified in plasma and/or gastrocnemius. We also evaluated effects on insulin growth factor (IGF)-1 levels and downstream signaling (AKT/mTORC1). Treatment of aged rats with +Epi, led to significant increases in front paw grip strength, treadmill time and SkM mass vs. controls as well as beneficial changes in makers of myofiber integrity. Treatment significantly reversed adverse changes in plasma and/or SkM TNF-α, IGF-1, atrophy and protein synthesis related endpoints vs. controls. In conclusion, +Epi has the capacity to reverse sarcopenia associated detrimental changes in regulatory pathways leading to improved SkM mass and function. Given these results and its recognized safety and tolerance profile, +Epi warrants consideration for clinical trials.

Health of Holochilus chacarius (Rodentia: Cricetidae) in rice agroecosystem in a neotropical wetland assessed by histopathology

Small mammals have a short lifetime and are strictly associated with their environment. This work aimed to use histopathology to assess the health of Holochilus chacarius in a rice agroecosystem in the Pantanal of Mato Grosso do Sul. During necropsy, fragments of the lung, kidney, skin, liver, and reproductive system of 33 animals were collected and submitted to histological processing. Tissue damages were evaluated as mild, moderate, and severe and arranged in a matrix for further statistical analysis. Furthermore, we used generalized linear models to verify the influence of tissue changes on the body condition, obtained by a regression between body mass and length. In the lungs, we found an intense inflammatory infiltrate associated with anthracosis that had a negative influence on the body's condition. Also, we observed degenerative and inflammatory changes in the liver, kidneys, skin, and reproductive system that ranged from mild to moderate. The histopathological lesions observed in this study may be associated with environmental alterations of anthropic origin such as the exposure to soot from wildfires and heavy metals, evidenced by lesions in the lung, kidney, and liver. The present study provided a histopathological matrix as a new approach that allows to classify and quantify the tissue alterations. Tissue changes when associated with body condition demonstrated to be an effective tool to assess the health of small free-living mammals, showing that these animals can be used as bioindicators of environmental condition.

Functional convergence in gastric lysozymes of foregut-fermenting rodents, ruminants, and primates is not attributed to convergent molecular evolution

Convergent evolution is a widespread phenomenon. While there are many examples of convergent evolution at the phenotypic scale, convergence at the molecular level has been more difficult to identify. A classic example of convergent evolution across scales is that of the digestive lysozyme found in ruminants and Colobine monkeys. These herbivorous species rely on foregut fermentation, which has evolved to function more optimally under acidic conditions. Here, we explored if rodents with similar dietary strategies and digestive morphologies have convergently evolved a lysozyme with digestive functions. At the phenotypic level, we find that rodents with bilocular stomach morphologies exhibited a lysozyme that maintained higher relative activities at low pH values, similar to the lysozymes of ruminants and Colobine monkeys. Additionally, the lysozyme of Peromyscus leucopus shared a similar predicted protonation state as that observed in previously identified digestive lysozymes. However, we found limited evidence of positive selection acting on the lysozyme gene in foregut-fermenting species and did not identify patterns of convergent molecular evolution in this gene. This study emphasizes that phenotypic convergence need not be the result of convergent genetic modifications, and we encourage further exploration into the mechanisms regulating convergence across biological scales.

Gastrointestinal dysmotility in rodent models of Parkinson's disease

Multiple studies describe prodromal, nonmotor dysfunctions that affect the quality of life of patients who subsequently develop Parkinson's disease (PD). These prodromal dysfunctions comprise a wide array of autonomic issues, including severe gastrointestinal (GI) motility disorders such as dysphagia, delayed gastric emptying, and chronic constipation. Indeed, strong evidence from studies in humans and animal models suggests that the GI tract and its neural, mainly vagal, connection to the central nervous system (CNS) could have a major role in the etiology of PD. In fact, misfolded α-synuclein aggregates that form Lewy bodies and neurites, i.e., the histological hallmarks of PD, are detected in the enteric nervous system (ENS) before clinical diagnosis of PD. The aim of the present review is to provide novel insights into the pathogenesis of GI dysmotility in PD, focusing our attention on functional, neurochemical, and molecular alterations in animal models.

Natural infection of free-ranging capybaras (Hydrochoerus hydrochaeris) with Anaplasmataecea and Rickettsiaceae bacteria in the Iberá wetlands ecoregion, Argentina

The current work assessed the infection with Ehrlichia and Anaplasma species, and exposure to Rickettsia spp. in free-ranging capybaras in the Iberá wetlands ecoregion in Argentina. By indirect immunofluorescence assay, 37 out of 51 (73%) capybara sera were seropositive to Rickettsia spp., with 23.5% and 4% samples considered homologous to Rickettsia parkeri and Rickettsia bellii, respectively (or very closely related serotypes). Anaplasmataceae DNA was found to be highly prevalent in capybaras, with 33 out of 62 samples positive for Anaplasma sp. with Ct values of 28.64 ± 0.35 (average ± standard error), and 12 samples positive for Ehrlichia sp. with Ct values of 31.74 ± 0.87. Anaplasma sp. from capybaras was closely related to Anaplasma sp. reported to infect Amblyomma dubitatum in Iberá wetlands and to Anaplasma odocoilei, while the detected Ehrlichia sp. was closely related to "Candidatus Ehrlichia hydrochoerus" previously reported to infect capybaras in Brazil and A. dubitatum in Iberá wetlands. Structures compatible with Anaplasma morulae were observed in the cytoplasm of platelets from Anaplasma-positive capybaras. Our findings show that capybaras from the Iberá wetlands were exposed to Rickettsia species related to R. bellii and to the pathogen R. parkeri, and were infected with "Ca. Ehrlichia hydrochoerus" and a novel Anaplasma species, herein named "Candidatus Anaplasma capybara".

Social environment and anogenital distance length phenotype interact to explain testosterone levels in a communally rearing rodent: Part 1: The male side

In vertebrates, male testosterone levels vary across the year being generally higher during the mating season relative to the offspring rearing season. However, male testosterone levels may also be associated with male anogenital distance (AGD) length (a proxy of prenatal androgen exposition), and influenced by the social group environment. In social species, it has been proposed that high levels of testosterone could be incompatible with the development of an amicable social environment. Thus, in these species, it is predicted that males have relatively low levels of testosterone. Our goal was to examine the potential association between male serum testosterone levels, season, male AGD length, and the social environment in the rodent Octodon degus under natural conditions. We quantified male serum testosterone levels during the mating and offspring rearing seasons, and we determined the number of females and males in each social group, as well as the composition of groups, in terms of the AGD length of the female and male group mates, from 2009 to 2019. Our results revealed that male testosterone levels covary with season, being highest during the offspring rearing season. Additionally, male testosterone levels vary with male AGD length, and female and male social group environments. More importantly, male degus exhibit low levels of testosterone that are indistinguishable from female levels during offspring rearing season. Similar to other highly social mammals, where males and females live together year-round, male amicable behavior could be the best male mating strategy, thus leading to a reduction in circulating testosterone levels.

Recreational hazard: Vegetation and host habitat use correlate with changes in tick-borne disease hazard at infrastructure within forest stands

Studies on density and pathogen prevalence of Ixodes ricinus indicate that vegetation and local host community drive much of their variation between green spaces. Contrarily, micro-geographic variation is understudied, although its understanding could reduce disease risk. We studied the density of infectious nymphal Ixodes sp. ("DIN", proxy for disease hazard), density of questing nymphs ("DON") and nymphal infection prevalence ("NIP") near recreational forest infrastructure. Drag sampling within forest stands and at adjacent benches and trails was combined with vegetation surveys, camera trapping hosts and pathogen screening of ticks. We analysed Borrelia burgdorferi s.l. and its genospecies, with complementary analyses on Rickettsia sp., Anaplasma phagocytophilum, Neoehrlichia mikurensis and Borrelia miyamotoi. DIN was highest in forest interior and at trails enclosed by forest. Lower disease hazard was observed at benches and trails at forest edges. This infrastructure effect can be attributed to variation in vegetation characteristics and the habitat use of tick hosts, specifically roe deer, rodents and songbirds. DON is the main driver of DIN at micro-geographic scale and negatively affected by infrastructure and forest edges. A positive association with vegetation cover in understorey and canopy was observed, as were positive trends for local rodent and songbird abundance. NIP of different pathogens was affected by different drivers. Lower B. burgdorferi s.l. prevalence in the interior of forest stands, driven by its most prevalent genospecies B. afzelii, points towards higher density of uninfected hosts there. B. afzelii was positively associated with understorey containing tall species and with high canopy cover, whereas local bird community composition predicts B. garinii prevalence. A positive effect of songbird abundance and a negative effect of pigeons were observed. Our findings support amplification and inhibition mechanisms within forest stands and highlight that the effect of established drivers of DIN may differ based on the considered spatial scale.

The effects of melatonin supplementation on neurobehavioral outcomes and clinical severity in rodent models of multiple sclerosis; a systematic review and meta-analysis

BACKGROUND

Through the antioxidant and anti-inflammation pathways, melatonin is proposed as a safe and effective intervention in neurological diseases. This study aims to evaluate the effects of melatonin supplementation on the neurobehavioral and clinical outcomes in animal models of multiple sclerosis (MS).

METHODS

This study was conducted following the PRISMA statement. Animal studies that reported the effects of melatonin in preclinical MS models, including the experimental autoimmune encephalomyelitis (EAE) and cuprizone model for demyelination are included in this study. A systematic search in PubMed, Web of Science, Embase, and Scopus up was conducted in April 2023. The collaborative Approach to Meta-Analysis and Review of Animal Experimental Studies (CAMARADES) critical appraisal tool was used for the quality assessment of the studies and the quantitative synthetizes were conducted using the comprehensive meta-analysis software.

RESULTS

Out of 542 studies, finally 21 studies, including 14 studies in the EAE model and 7 studies of the toxic demyelination method with cuprizone were included. The route of administration was intraperitoneal in 18 studies, oral in 2 studies, and subcutaneous in 1 study. The quantitative synthesis of the EAE clinical severity scale was associated with significant differences (standardized mean difference [SDM]: - 2.52; - 3.61 to - 1.42; p value < 0.01). In subgroup analyses, the difference was statistically significant in the mouse subgroup (SMD: - 2.60; - 3.74 to - 1.46; p value < 0.01).

DISCUSSION

This study encountered that melatonin may be associated with improved behavioral and cognitive outcomes of preclinical models of MS with acceptable safety profiles.

FUNDING

The research was supported by the Student Research Committee, Tabriz University of Medical Sciences (grant number: 71005).

Fatal leptospirosis in endangered Barbary macaques (Macaca sylvanus) kept in captivity: Assessing the role of sympatric rodents

Between December 2020 and January 2021, an outbreak of acute mortality in endangered Barbary macaques (Macaca sylvanus) kept in captivity was detected in a zoo in Spain. The main findings observed in the two fatally affected animals at post-mortem evaluation were jaundice, renal tubular necrosis and interstitial nephritis. Leptospira spp. infection was confirmed by real time PCR (qPCR) in different tissues in both individuals. Analyses of secY gene from a positive individual showed 100% homology with a previously published sequence corresponding to Leptospira interrogans serovar Copenhageni. Free-living sympatric brown rats (Rattus norvegicus) from the affected zoo were also analyzed, and showed a prevalence and seroprevalence of Leptospira spp. of 18.2% (4/22; 95% CI: 2.1-34.3) and 41.9% (26/62; 95% CI: 29.7-54.2), respectively. We detected seropositive sera to five different serovars of Leptospira spp. (Copenhageni, Grippotyphosa, Pomona, Canicola and Hardjo) in the rodent population, with L. Copenhageni being the predominant one. This study describes for first time an outbreak of fatal leptospirosis in captive non-human primates in Europe. Our results show that Barbary macaques, an endangered species, are highly susceptible to Leptospira spp. infection, with sympatric wild rodents being the most likely reservoir animals involved in transmission in this outbreak. Our results suggest that rodent control could be an effective measure for minimizing exposure to Leptospira spp. in zoological collections. Given the potential implications for conservation, animal and public health, non-human primates and rodents should be included in surveillance programs for Leptospira spp. in zoos.

The infection of Cysticercus fasciolaris in natural rats (Rattus species) residing in human residence areas, Nakhon Si Thammarat, Thailand

Cysticercus fasciolaris (C. fasciolaris) is the larval stage of a cestode parasite named Taenia taeniaeformis (T. taeniaeformis). C. fasiolaris is found in small rodents, especially rats. Rattus species are listed as intermediate hosts of this parasite, and cats are the main definitive host of C. fasiolaris. The objective of this study was to study the pathological, microscopic, and molecular aspects of C. fasciolaris in rodents residing in human residence areas. One hundred and two rodents were trapped in human settlements and dissected for larva-containing cyst examinations in the body cavity. The larvae of C. fasciolaris were investigated using histopathological examination, microscopic observations under a stereomicroscope and scanning electron microscope, and molecular detection using polymerase chain reaction. The prevalence of hepatic cysts containing larvae was 8.91% (95% CI = 4.16-16.24). In addition, the older larvae also had longer micropapillae. Histopathological investigation revealed normal hepatic tissue containing larvae and a scanty fluid cyst. The cyst capsule contains mostly mononuclear cells and spindle cells in all infected rats. The molecular detection using two primer sets revealed the amplicons were similar to the clade of C. fasciolaris. In the future, more investigation is necessary to fully understand the parasite's molecular pathogenesis and virulent molecules, which are less obvious.

The prenatal use of agmatine prevents social behavior deficits in VPA-exposed mice by activating the ERK/CREB/BDNF signaling pathway

BACKGROUND

According to reports, prenatal exposure to valproic acid can induce autism spectrum disorder (ASD)-like symptoms in both humans and rodents. However, the exact cause and therapeutic method of ASD is not fully understood. Agmatine (AGM) is known for its neuroprotective effects, and this study aims to explore whether giving agmatine hydrochloride before birth can prevent autism-like behaviors in mouse offspring exposed prenatally to valproic acid.

METHODS

In this study, we investigated the effects of AGM prenatally on valproate (VPA)-exposed mice. We established a mouse model of ASD by prenatally administering VPA. From birth to weaning, we evaluated mouse behavior using the marble burying test, open-field test, and three-chamber social interaction test on male offspring.

RESULTS

The results showed prenatal use of AGM relieved anxiety and hyperactivity behaviors as well as ameliorated sociability of VPA-exposed mice in the marble burying test, open-field test, and three-chamber social interaction test, and this protective effect might be attributed to the activation of the ERK/CREB/BDNF signaling pathway.

CONCLUSION

Therefore, AGM can effectively reduce the likelihood of offspring developing autism to a certain extent when exposed to VPA during pregnancy, serving as a potential therapeutic drug.

Erinacine S, a small active component derived from Hericium erinaceus, protects oligodendrocytes and alleviates mood abnormalities in cuprizone-exposed rodents

Hericium erinaceus mycelium extract (HEM), containing erinacine A (HeA) and erinacine S (HeS), has shown promise in promoting the differentiation of oligodendrocyte precursor cells (OPCs) into mature oligodendrocytes (OLs), crucial for myelin production in the central nervous system (CNS). The main aim of this study was to characterize the protective effects of HEM and its components on OLs and myelin in demyelinating rodents by exposure to cuprizone (CPZ), a copper chelating agent commonly used to induce demyelination in the corpus callosum of the brain. Rats were fed by CPZ-containing diet and simultaneously orally administered HEM, HeA, or HeS on a daily basis for three weeks. We found that HEM and HeS preserved myelin and OLs in the corpus callosum of CPZ-fed rats, along with reduced microglia and astrocyte activation, and downregulated IL-1β expression. Furthermore, post-treatment with HeS, in mouse models with acute (6 weeks) or chronic (12 weeks) CPZ-induced demyelination demonstrated oral administration during the final 4 weeks (HeS4/6 or HeS4/12) effectively preserved myelin in the corpus callosum. Additionally, HeS4/6 and HeS4/12 inhibited anxious and depressive-like behaviors in CPZ-fed mice. In summary, simultaneous administration of HEM and HeS in rats during short-term CPZ intoxication preserved OLs and myelin. Furthermore, post-administration of HeS not only inhibited demyelination and gliosis but also alleviated anxiety and depression in both acute and chronic CPZ-fed mice. This study presents compelling evidence supporting the potential of HeS as a promising small active compound for protecting OLs and preserving myelin in demyelinating diseases associated with emotional disorders.

Social environment and anogenital distance length phenotype interact to explain testosterone levels in a communally rearing rodent: Part 2: The female side

Testosterone is known as a "male" hormone; however, females also synthetize testosterone, which influences female sexual and aggressive behavior. In female vertebrates, as in males, testosterone levels can vary seasonally. However, female testosterone levels may also be related with female anogenital distance (AGD) length phenotype (a proxy of prenatal androgen exposure), and the social group environment. We used data from a long-term rodent study (2009-2019) in a natural population of degus (Octodon degus) to examine the potential associations between female serum testosterone levels, season, female AGD phenotype, and social group composition. We quantified female serum testosterone levels during the mating and offspring rearing seasons, and we determined the number of females and males in social groups, as well the composition of groups, in terms of the AGD of the female and male group mates. Our results indicate that female testosterone levels vary with season, being highest during the offspring rearing season. Additionally, female testosterone levels were associated with the number of male group-members and the AGD of male group-members but were not associated with female social environment and focal female AGD phenotype. Together, our results suggest that female testosterone levels are sensitive to intersexual interactions. Our results also reveal that female and male testosterone levels do not differ between the sexes, a finding previously reported only in rock hyraxes. We discuss how the complex social system of degus could be driving this physiological similarity between the sexes.

Microbiome diversity and zoonotic bacterial pathogen prevalence in Peromyscus mice from agricultural landscapes and synanthropic habitat

Rodents are key reservoirs of zoonotic pathogens and play an important role in disease transmission to humans. Importantly, anthropogenic land-use change has been found to increase the abundance of rodents that thrive in human-built environments (synanthropic rodents), particularly rodent reservoirs of zoonotic disease. Anthropogenic environments also affect the microbiome of synanthropic wildlife, influencing wildlife health and potentially introducing novel pathogens. Our objective was to examine the effect of agricultural development and synanthropic habitat on microbiome diversity and the prevalence of zoonotic bacterial pathogens in wild Peromyscus mice to better understand the role of these rodents in pathogen maintenance and transmission. We conducted 16S amplicon sequencing on faecal samples using long-read nanopore sequencing technology to characterize the rodent microbiome. We compared microbiome diversity and composition between forest and synanthropic habitats in agricultural and undeveloped landscapes and screened for putative pathogenic bacteria. Microbiome richness, diversity, and evenness were higher in the agricultural landscape and synanthropic habitat compared to undeveloped-forest habitat. Microbiome composition also differed significantly between agricultural and undeveloped landscapes and forest and synanthropic habitats. We detected overall low diversity and abundance of putative pathogenic bacteria, though putative pathogens were more likely to be found in mice from the agricultural landscape. Our findings show that landscape- and habitat-level anthropogenic factors affect Peromyscus microbiomes and suggest that landscape-level agricultural development may be important to predict zoonotic pathogen prevalence. Ultimately, understanding how anthropogenic land-use change and synanthropy affect rodent microbiomes and pathogen prevalence is important to managing transmission of rodent-borne zoonotic diseases to humans.

Luminal Delivery of Pectin-Modified Oxygen Microbubbles Mitigates Rodent Experimental Intestinal Ischemia

INTRODUCTION

Ischemic gut injury is common in the intensive care unit, impairs gut barrier function, and contributes to multiorgan dysfunction. One novel intervention to mitigate ischemic gut injury is the direct luminal delivery of oxygen microbubbles (OMB). Formulations of OMB can be modified to control the rate of oxygen delivery. This project examined whether luminal delivery of pectin-modified OMB (OMBp5) can reduce ischemic gut injury in a rodent model.

METHODS

The OMBp5 formulation was adapted to improve delivery of oxygen along the length of small intestine. Adult Sprague-Dawley rats (n = 24) were randomly allocated to three groups: sham-surgery (SS), intestinal ischemia (II), and intestinal ischemia plus luminal delivery of OMBp5 (II + O). Ischemia-reperfusion injury was induced by superior mesenteric artery occlusion for 45 min followed by reperfusion for 30 min. Outcome data included macroscopic score of mucosal injury, the histological score of gut injury, and plasma biomarkers of intestinal injury.

RESULTS

Macroscopic, microscopic data, and intestinal injury biomarker results demonstrated minimal intestinal damage in the SS group and constant damage in the II group. II + O group had a significantly improved macroscopic score throughout the gut mucosa (P = 0.04) than the II. The mean histological score of gut injury for the II + O group was significantly improved on the II group (P ≤ 0.01) in the proximal intestine only, within 30 cm of delivery. No differences were observed in plasma biomarkers of intestinal injury following OMBp5 treatment.

CONCLUSIONS

This proof-of-concept study has demonstrated that luminal OMBp5 decreases ischemic injury to the proximal small intestine. There is a need to improve oxygen delivery over the full length of the intestine. These findings support further studies with clinically relevant end points, such as systemic inflammation and vital organ dysfunction.

Leveraging the unique social organization of California mice to study circuit-specific effects of oxytocin on behavior

Oxytocin is a versatile neuropeptide that modulates many different forms of social behavior. Recent hypotheses pose that oxytocin enhances the salience of rewarding and aversive social experiences, and the field has been working to identify mechanisms that allow oxytocin to have diverse effects on behavior. Here we review studies conducted on the California mouse (Peromyscus californicus) that shed light on how oxytocin modulates social behavior following stressful experiences. In this species, both males and females exhibit high levels of aggression, which has facilitated the study of how social stress impacts both sexes. We review findings of short- and long-term effects of social stress on the reactivity of oxytocin neurons. We also consider the results of pharmacological studies which show that oxytocin receptors in the bed nucleus of the stria terminalis and nucleus accumbens have distinct but overlapping effects on social approach behaviors. These findings help explain how social stress can have different behavioral effects in males and females, and how oxytocin can have such divergent effects on behavior. Finally, we consider how new technological developments and innovative research programs take advantage of the unique social organization of California mice to address questions that can be difficult to study in conventional rodent model species. These new methods and questions have opened new avenues for studying the neurobiology of social behavior.

Specific and rapid guanidinium CEST imaging using double saturation power and QUASS analysis in a rodent model of global ischemia

PURPOSE

Guanidinium CEST is sensitive to metabolic changes and pH variation in ischemia, and it can offer advantages over conventional pH-sensitive amide proton transfer (APT) imaging by providing hyperintense contrast in stroke lesions. However, quantifying guanidinium CEST is challenging due to multiple overlapping components and a close frequency offset from water. This study aims to evaluate the applicability of a new rapid and model-free CEST quantification method using double saturation power, termed DSP-CEST, for isolating the guanidinium CEST effect from confounding factors in ischemia. To further reduce acquisition time, the DSP-CEST was combined with a quasi-steady state (QUASS) CEST technique to process non-steady-state CEST signals.

METHODS

The specificity and accuracy of the DSP-CEST method in quantifying the guanidinium CEST effect were assessed by comparing simulated CEST signals with/without the contribution from confounding factors. The feasibility of this method for quantifying guanidinium CEST was evaluated in a rat model of global ischemia induced by cardiac arrest and compared to a conventional multiple-pool Lorentzian fit method.

RESULTS

The DSP-CEST method was successful in removing all confounding components and quantifying the guanidinium CEST signal increase in ischemia. This suggests that the DSP-CEST has the potential to provide hyperintense contrast in stroke lesions. Additionally, the DSP-CEST was shown to be a rapid method that does not require the acquisition of the entire or a portion of the CEST Z-spectrum that is required in conventional model-based fitting approaches.

CONCLUSION

This study highlights the potential of DSP-CEST as a valuable tool for rapid and specific detection of viable tissues.

High diversity, novel genotypes, and vertical transmission of hemotropic Mycoplasma in micromammals

Hemotropic mycoplasmas (hemoplasmas) are emerging zoonotic pathogens. Micromammals have received little attention as hosts for hemoplasmas despite their ubiquitous presence, high population abundances, and close association with humans. A PCR protocol targeting a fragment of the 16 S rRNA gene and direct sequencing in blood samples of 189 adult specimens and 35 fetuses belonging to three species of Eulipotyphla (shrews) and seven species of Rodentia, captured in three ecologically diverse habitats in North-Eastern Spain (Steppe, High Mountain, Mediterranean) yielded and occurrence of 26%, including 36% of 39 shrews and 23% of 150 rodents. Sequencing revealed the presence of 14 nucleotide sequence types (ntST) among the 56 readable sequences. In general, each ntST was associated with a given host species, although in some cases, the same ntST was sequenced in different species (chiefly rodents). Most ntST were closely related to rodent and/or bat hemoplasmas, but one was identical with Mycoplasma haemocanis/haemofelis, and others can be considered novel genotypes. High sequence diversity was detected in rodents, whereas in the white-toothed shrew (Crocidura russula), 9/11 sequences from two distant areas were identical. Phylogenetic and network analyses classified our sequences in different clades including hemoplasmas of rodents, carnivores, bats, and humans. Twelve of the fetuses (34.2%) of 9/12 litters (75.0%) of shrews and rodents were hemoplasma-positive, indicating frequent vertical transmission. Our study contributes to expanding our knowledge about the distribution, diversity, and transmission of hemoplasmas.

The A2 haplotype of Echinococcus multilocularis is the predominant variant infecting humans and dogs in Yili Prefecture, Xinjiang

Alveolar echinococcosis (AE), caused by Echinococcus multilocularis, is an important zoonotic disease. Yili Prefecture in Xinjiang is endemic for AE, however the molecular variability of E. multilocularis in this region is poorly understood. In this study, 127 samples were used for haplotypes analysis, including 79 tissues from humans, 43 liver tissues from small rodents, and 5 fecal samples from dogs. Genetic variability in E. multilocularis was studied using complete sequences of the mitochondrial (mt) genes of cytochrome b (cob), NADH dehydrogenase subunit 2 (nad2), and cytochrome c oxidase subunit 1 (cox1), using a total of 3558 bp per sample. The Asia haplotype 2 (A2) was the dominant haplotype, with 72.15% (57/79) prevalence in humans, 2.33% (1/43) in small rodents, and 80.00% (4/5) in dogs, followed by A5, the second most common haplotype, which infected 27.91% (12/43) small rodents. Haplotype network analysis showed that all haplotypes clustered together with the Asian group. Pairwise fixation index (FST) values showed lower level of genetic differentiation between different regions within the country. Compared with the sequences of E. multilocularis from North America and Europe, all concatenated sequences isolated from Yili Prefecture were highly differentiated and formed a single population. The A2 haplotype, analyzed using the cob, nad2, and cox1 genes of E. multilocularis, is the predominant variant in humans and dogs in Yili Prefecture.

Hemotropic Mycoplasmas (Hemoplasmas) in Free-Ranging Azara's Agoutis (Dasyprocta azarae) from an Urban Area of Southern Brazil

Hemotropic mycoplasmas (hemoplasmas) are opportunistic bacteria that attach to the erythrocyte surface, causing infectious anemia in several mammalian species, including rodents. Studies surveying native Azara's agoutis (Dasyprocta azarae) in Brazil are lacking. Accordingly, the present study aimed to assess hemoplasmas infection in free-ranging agoutis from an urban environmental conservation area in Curitiba, southern Brazil. Overall, 11/35 (31.43%) agoutis were positive to hemoplasmas by quantitative PCR (cycle threshold≤34.4). Sequencing of the 16S ribosomal RNA gene indicated Mycoplasma haemomuris infection, closely related to M. haemomuris subsp. ratti, suggesting hemoplasma transmission from urban rats to agoutis. Because the main route of M. haemomuris transmission has been direct rodent-to-rodent infection, the relatively lower positivity that we detected may be the result of low intraspecies contact due to the smaller social units of agoutis, generally consisting of two to four individuals, and low interspecies contact due to only sporadic agouti-rat interactions in urban settings, compared with other rodent species interactions. Further studies should be conducted to determine whether the hemoplasma infection that we found can cause clinical onset and life-threatening anemia in agoutis.

No evidence tube entrapment distresses rodents in typical empathy tests

In the first two experiments an empty tube open at one end was placed in different locations. Male hamsters, tested one at a time, tended to stay close to the tube or in it. During the first minute of the first 4 sessions of Experiment 3, the hamster was unrestrained. If it entered the tube, it was locked within the tube. If it did not enter the tube during the first min, it was placed in it, and the tube was locked. Fifteen min later, the tube was opened, and the hamster was unrestrained for a further 20 min. The tube remained open during Session 5. Hamsters spent more time near the tube than predicted by chance and continued to enter the tube although tube-occupancy duration did not differ from chance levels. In Experiment 4, male rats were tested in two groups: rats in one group had been previously trapped in a tube and rats in the other group allowed to freely explore the test space. For the first two min of each of four 20-min sessions, trapped-group subjects were permitted to move about the chamber unless they entered the tube. In that case, they were locked in for the remainder of the session. If, after two min, they did not enter the tube, they were locked in it for the remaining 18 min. Free rats were unrestricted in all sessions. In Session 5, when both groups were permitted to move freely in the chamber, trapped and free rats spent more time in and near the tube than predicted by chance. These data show tube restraint does not seem to distress either hamsters or rats.

Brain-implanted conductors amplify radiofrequency fields in rodents: Advantages and risks

Over the past few decades, daily exposure to radiofrequency (RF) fields has been increasing due to the rapid development of wireless and medical imaging technologies. Under extreme circumstances, exposure to very strong RF energy can lead to heating of body tissue, even resulting in tissue injury. The presence of implanted devices, moreover, can amplify RF effects on surrounding tissue. Therefore, it is important to understand the interactions of RF fields with tissue in the presence of implants, in order to establish appropriate wireless safety protocols, and also to extend the benefits of medical imaging to increasing numbers of people with implanted medical devices. This study explored the neurological effects of RF exposure in rodents implanted with neuronal recording electrodes. We exposed freely moving and anesthetized rats and mice to 950 MHz RF energy while monitoring their brain activity, temperature, and behavior. We found that RF exposure could induce fast onset firing of single neurons without heat injury. In addition, brain implants enhanced the effect of RF stimulation resulting in reversible behavioral changes. Using an optical temperature measurement system, we found greater than tenfold increase in brain temperature in the vicinity of the implant. On the one hand, our results underline the importance of careful safety assessment for brain-implanted devices, but on the other hand, we also show that metal implants may be used for neurostimulation if brain temperature can be kept within safe limits.

Rodent models of AKI and AKI-CKD transition: an update in 2024

Despite known drawbacks, rodent models are essential tools in the research of renal development, physiology, and pathogenesis. In the past decade, rodent models have been developed and used to mimic different etiologies of acute kidney injury (AKI), AKI to chronic kidney disease (CKD) transition or progression, and AKI with comorbidities. These models have been applied for both mechanistic research and preclinical drug development. However, current rodent models have their limitations, especially since they often do not fully recapitulate the pathophysiology of AKI in human patients, and thus need further refinement. Here, we discuss the present status of these rodent models, including the pathophysiologic compatibility, clinical translational significance, key factors affecting model consistency, and their main limitations. Future efforts should focus on establishing robust models that simulate the major clinical and molecular phenotypes of human AKI and its progression.

Biochemical properties and biological potential of Syzygium heyneanum with antiparkinson's activity in paraquat induced rodent model

Syzygium heyneanum is a valuable source of flavonoids and phenols, known for their antioxidant and neuroprotective properties. This research aimed to explore the potential of Syzygium heyneanum ethanol extract (SHE) in countering Parkinson's disease. The presence of phenols and flavonoids results in SHE displaying an IC50 value of 42.13 when assessed in the DPPH scavenging assay. Rats' vital organs (lungs, heart, spleen, liver, and kidney) histopathology reveals little or almost no harmful effect. The study hypothesized that SHE possesses antioxidants that could mitigate Parkinson's symptoms by influencing α-synuclein, acetylcholinesterase (AChE), TNF-α, and IL-1β. Both in silico and in vivo investigations were conducted. The Parkinson's rat model was established using paraquat (1 mg/kg, i.p.), with rats divided into control, disease control, standard, and SHE-treated groups (150, 300, and 600 mg/kg) for 21 days. According to the ELISA statistics, the SHE treated group had lowers levels of IL-6 and TNF-α than the disease control group, which is a sign of neuroprotection. Behavioral and biochemical assessments were performed, alongside mRNA expression analyses using RT-PCR to assess SHE's impact on α-synuclein, AChE, TNF-α, and interleukins in brain homogenates. Behavioral observations demonstrated dose-dependent improvements in rats treated with SHE (600 > 300 > 150 mg/kg). Antioxidant enzyme levels (catalase, superoxide dismutase, glutathione) were significantly restored, particularly at a high dose, with notable reduction in malondialdehyde. The high dose of SHE notably lowered acetylcholinesterase levels. qRT-PCR results indicated reduced mRNA expression of IL-1β, α-synuclein, TNF-α, and AChE in SHE-treated groups compared to disease controls, suggesting neuroprotection. In conclusion, this study highlights Syzygium heyneanum potential to alleviate Parkinson's disease symptoms through its antioxidant and modulatory effects on relevant biomarkers.

Behavioral effects of 6-hydroxydopamine-induced damage to nigro-striatal pathway and Locus coeruleus as a rodent model of Parkinson's disease

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the Substantia nigra pars compacta (SNpc), which leads to motor and non-motor symptoms (NMS). NMS can appear many years before the classical motor symptoms and are associated with the neurodegeneration of several nuclei; in this work, we highlight the neurodegeneration of Locus coeruleus (LC) in PD. The aim was to investigate the effects of depleting SNpc and LC catecholaminergic neurons on behavioral and neurobiological endpoints. Here we used 6-hydroxydopamine (6-OHDA) in order to induced neurotoxic damage in three independent experimental groups: SNpc lesion group, which 6-OHDA was injected into CPu (CPu-6-OHDA), LC lesion group, which 6-OHDA was injected directly on LC to selectively caused a damage on this nucleus (LC-6-OHDA), and the combined SNpc and LC lesion group (CL-6-OHDA). Next, the behavioral studies were performed using the Morris water maze (MWM), open field (OF), and elevated plus maze (EPM). After stereotaxic surgeries, the animals showed a loss of 67% and 77% of Tyrosine hydroxylase (TH) reactive neurons in the SNpc and LC, respectively. The behavioral analysis showed the anxiety-like behavior in CL-6-OHDA group in the EPM test; in the MWM test, the combined lesions (CL-6-OHDA) showed an impairment in memory acquisition and spatial memory; and no changes were observed in locomotor activity in all the tests. Furthermore, our investigation demonstrating the effects of depleting SN and LC catecholaminergic neurons on behavioral and neurobiological parameters. All these data together lead us to believe that a bilateral PD model including a LC bilateral degeneration is potentially a more accurate model to evaluate the NMS in the pathological development of the disease in rodents.

Phylogenetic analysis and antimony resistance of Leishmania major isolated from humans and rodents

Cutaneous Leishmaniasis (CL) is one of the world's neglected diseases which is caused by Leishmania spp. The aim of this study was to assess molecular profile and antimony resistance of Leishmania isolated from human and rodent hosts. Samples were collected from suspected CL patients referred to health centres and wild rodent's traps in Gonbad-e-Qabus region, north-eastern Iran. Smears were subjected to PCR-RFLP to identify Leishmania species. In addition, ITS1-PCR products were sequenced for phylogenetic analysis. Clinical isolates and rodent samples were subjected to MTT assay to determine IC50 values and in vitro susceptibilities. Expression levels of antimony resistance-related genes were determined in CL isolates. Out of 1,949 suspected patients with CL and 148 rodents, 1,704 (87.4%) and 6 (4.05%) were positive with direct smear, respectively. Digestion patterns of BusRI (HaeIII) endonuclease enzyme were similar to what expected for Leishmania major. Phylogenetic analysis revealed that the highest interspecies similarity was found between current L. major sequences with L. major obtained from Russia and Uzbekistan. Out of 20 L. major samples tested, 13 (65%) were resistant to meglumine antimoniate (MA) treatment, with an activity index (AI) exceeding 4. The remaining 7 samples (35%) responded to MA treatment and were classified as sensitive isolates, with a confirmed sensitive phenotype based on their AI values. The comparison expression analysis of three major antimony resistance-associated genes in unresponsive clinical isolates demonstrated significant fold changes for TDR1 (4.78-fold), AQP1 (1.3-fold), and γ-GCS (1.17-fold) genes (P < 0.05). Herein, we demonstrate genetic diversity and antimony resistance of L. major isolated from human and reservoir hosts in north-eastern Iran, which could be the basis for planning future control strategies.

Diversity of Trichinella species in carnivores from Bosnia and Herzegovina

BACKGROUND

In Bosnia and Herzegovina, domestic and wild carnivores represent a significant driver for the transmission and ecology of zoonotic pathogens, especially those of parasitic aetiology. Nevertheless, there is no systematic research of Trichinella species in animals that have been conducted in Bosnia and Herzegovina, even though trichinellosis is considered the most important parasitic zoonosis. The available results of the few studies carried out in Bosnia and Herzegovina are mainly related to the confirmation of parasitic larvae in the musculature of domestic pigs and wild boars or data related to trichinellosis in humans. The objective of our study was to present the findings of a comprehensive investigation into the species composition of Trichinella among 11 carnivorous species within the territory of Bosnia and Herzegovina, as follows: red fox (Vulpes vulpes), grey wolf (Canis lupus), brown bear (Ursus arctos), wildcat (Felis silvestris), pine marten (Martes martes), European badger (Meles meles), weasel (Mustela nivalis), European polecat (Mustela putorius), Eurasian lynx (Lynx lynx), but also dog (Canis lupus familiaris) and cat (Felis catus).

RESULTS

In the period 2013-2023, carnivore musculature samples (n = 629), each consisting of 10 g of muscle tissue, were taken post-mortem and individually examined using the artificial digestion method. In the positive samples (n = 128), molecular genotyping and identification of parasitic larvae of Trichinella spp. were performed using a PCR-based technique up to the species/genotype level. Positive samples were used for basic PCR detection of the genus Trichinella (rrnS rt-PCR technique) and genotyping (rrnl-EVS rt-PCR technique). The Trichinella infection was documented for the first time in Bosnia and Herzegovina among red foxes, grey wolves, brown bears, dogs, badgers and Eurasian lynx, with a frequency rate of 20.3%. Additionally, the presence of T. britovi infection was newly confirmed in Bosnia and Herzegovina, marking the initial documented cases. Furthermore, both T. britovi and T. pseudospiralis infections were observed in the wildcat population, whereas T. britovi and T. spiralis infections were detected in pine martens. Consistent with previous research, our findings align particularly regarding carnivores, with data from other countries such as Germany, Finland, Romania, Poland and Spain, where T. britovi exhibits a wider distribution (62.5-100%) compared to T. spiralis (0.0-37.5%). T. britovi is more common among sylvatic carnivores (89.0%), while T. spiralis prevails in wild boars (62.0%), domestic swine (82.0%) and rodents (75.0%).

CONCLUSION

The results of our study represent the first molecular identification of species of the genus Trichinella in Bosnia and Herzegovina. Additionally, our findings underscore the necessity for targeted epidemiological studies to thoroughly assess trichinellosis prevalence across diverse animal populations. Considering the relatively high frequency of trichinellosis infection in investigated animal species and its public health implications, there is an evident need for establishing an effective trichinellosis surveillance system in Bosnia and Herzegovina.

Rodent tests for psychiatric drugs get a rethink

Under pressure to ditch a controversial swim test for depression, scientists look for more precise measures.