Simultaneous Exposure to Noise and Toluene Induces Oxidative and Inflammatory Damage in the Heart of Wistar Rats: Therapeutic Potential of Olea europaea L. Leaf Extract

Workers in occupational settings often face simultaneous exposure to multiple risk factors, including noise and chemicals. This study aimed to investigate the effects of combined exposure to noise and toluene on the cardiac health of rats, with a focus on assessing the potential mitigating effects of Olea europaea L. (OLE) leaf extract (40 mg/kg/day). The evaluation involved scrutinizing biochemical and hematological markers, quantifying oxidative stress levels, determining proinflammatory cytokines in the serum, and conducting an in silico Docking studies. Forty-two male Wistar rats were divided into eight groups-(n = 6/group):-Control-group-(C),-OLE-group-(Rats administered OLE), NT-group (rats co-exposed to noise and toluene), NT-4 group-(rats co-exposed to noise and toluene four weeks after the exposure period), NT + OLE1-group (rats co-exposed to noise and toluene treated with OLE for one week), NT + OLE2-group-(rats co-exposed to noise and toluene treated with OLE for two weeks), NT + OLE3-group-(rats co-exposed to noise and toluene treated with OLE for three weeks), and NT + OLE4-group (rats co-exposed to noise and toluene treated with OLE for four weeks). The results revealed that combined exposure to noise and toluene led to oxidative damage and increased serum levels of proinflammatory cytokines. However, OLE treatment attenuated these effects by reducing lipid peroxidation and enhancing catalase and superoxide dismutase activities. Additionally, OLE treatment significantly decreased proinflammatory cytokine levels compared to the noise and toluene co-exposed group. The study highlighted the potential of OLE to attenuate the adverse effects of combined exposure to noise and toluene, attributed to its anti-inflammatory and antioxidant properties.

Changes in environmental stress over COVID-19 pandemic likely contributed to failure to replicate adiposity phenotype associated with Krtcap3

We previously identified keratinocyte-associated protein 3, Krtcap3, as an obesity-related gene in female rats where a whole body Krtcap3 knockout (KO) led to increased adiposity compared to wild-type (WT) controls when fed a high-fat diet (HFD). We sought to replicate this work to better understand the function of Krtcap3 but were unable to reproduce the adiposity phenotype. In the current work, WT female rats ate more compared to WT in the prior study, with corresponding increases in body weight and fat mass, while there were no changes in these measures in KO females between the studies. The prior study was conducted before the COVID-19 pandemic, while the current study started after initial lockdown orders and was completed during the pandemic in a generally less stressful environment. We hypothesize that the environmental changes impacted stress levels and may explain the failure to replicate our results. Analysis of corticosterone (CORT) at euthanasia showed a significant study-by-genotype interaction where WT had significantly higher CORT relative to KO in study 1, with no differences in study 2. These data suggest that decreasing Krtcap3 expression may alter the environmental stress response to influence adiposity. We also found that KO rats in both studies, but not WT, experienced a dramatic increase in CORT after their cage mate was removed, suggesting a separate connection to social behavioral stress. Future work is necessary to confirm and elucidate the finer mechanisms of these relationships, but these data indicate the possibility of Krtcap3 as a novel stress gene.NEW & NOTEWORTHY Obesity is linked to both genetics and environmental factors such as stress. Krtcap3 has previously been identified as a gene associated with adiposity, and our work here demonstrates that environmental stress may influence the role of Krtcap3 on both food intake and adiposity. Obesity is strongly influenced by stress in humans, so the identification of novel genes that link stress and obesity will greatly advance our understanding of the disease.

Olea europaea L. leaf extract mitigates oxidative and histological damage in rat heart tissue exposed to combined noise and toluene: An experimental study

In many occupational settings, workers are frequently exposed to toluene and noise. However, the individual and combined effects of these exposures on the cardiovascular system have not been fully elucidated. Therefore, this study aimed to investigate the impact of simultaneous exposure to toluene and noise on the rat heart, while also evaluating the potential preventive effect of olive leaf extract (OLE). Forty-eight male Wistar rats were randomly assigned to eight groups (n = 6/group): control group (C), control group that received OLE (C + OLE), group exposed to noise (N), group exposed to noise and receiving OLE (N + OLE), group exposed to toluene (T), group exposed to toluene and receiving OLE (T + OLE), group co-exposed to noise and toluene (NT), and group co-exposed to noise and toluene and receiving OLE (NT + OLE). The rats in this study were subjected to simultaneous exposure to toluene and noise for a duration of six weeks, within a custom-built plexiglass chamber. Toluene was administered at a concentration of 300 ppm, while the noise level was set to 85 dB(A). The exposure chamber was equipped with a generation system, an exposure system, and a monitoring system, ensuring precise and accurate exposure conditions. After the six-week period, heart and blood samples were collected from the rats for subsequent analysis. Plasma levels of cholesterol (CHOL), triglycerides (TG), lactate dehydrogenase (LDH), and creatine kinase (CK) were measured, and histopathological investigation was conducted using HE staining. Additionally, superoxide dismutase (SOD) and catalase (CAT) activities, as well as malondialdehyde (MDA) levels in heart tissue were measured. Our results showed that simultaneous exposure to noise and toluene altered CHOL, TG, LDH, and CK levels, and also caused an increase in lipid peroxidation levels and superoxide dismutase activity, along with a decrease in catalase activity in the heart. A significant alteration in the myocardium was also observed. However, treatment with OLE was found to modulate these oxidative and histological changes, ultimately correcting the deleterious effects induced by the combined exposure to noise and toluene. Therefore, our study suggests that OLE could be a potential preventive measure for individuals exposed to toluene and noise in industrial settings.

Changes in Environmental Stress over COVID-19 Pandemic Likely Contributed to Failure to Replicate Adiposity Phenotype Associated with Krtcap3

We previously identified Keratinocyte-associated protein 3, Krtcap3, as an obesity-related gene in female rats where a whole-body Krtcap3 knock-out (KO) led to increased adiposity compared to wild-type (WT) controls when fed a high-fat diet (HFD). We sought to replicate this work to better understand the function of Krtcap3 but were unable to reproduce the adiposity phenotype. In the current work, WT female rats ate more compared to WT in the prior study, with corresponding increases in body weight and fat mass, while there were no changes in these measures in KO females between the studies. The prior study was conducted before the COVID-19 pandemic, while the current study started after initial lock-down orders and was completed during the pandemic with a generally less stressful environment. We hypothesize that the environmental changes impacted stress levels and may explain the failure to replicate our results. Analysis of corticosterone (CORT) at euthanasia showed a significant study by genotype interaction where WT had significantly higher CORT relative to KO in Study 1, with no differences in Study 2. These data suggest that decreasing Krtcap3 expression may alter the environmental stress response to influence adiposity. We also found that KO rats in both studies, but not WT, experienced a dramatic increase in CORT after their cage mate was removed, suggesting a separate connection to social behavioral stress. Future work is necessary to confirm and elucidate the finer mechanisms of these relationships, but these data indicate the possibility of Krtcap3 as a novel stress gene.

Viscoelastic Coagulation Testing in Exotic Animals

Whole blood viscoelastic coagulation testing (VCT) allows global assessment of hemostasis and fibrinolysis. Although not widely used in exotic animal practice, VCT has been used in exotic animal research settings. Differences in patient demographics and analytical variables can result in dramatically different results with the same analyzer. To improve the utility of VCT in exotic animal medicine, standardization of protocols is necessary to facilitate the establishment of reference intervals. Despite these challenges, the quantitative/qualitative nature of VCT has already proved its real-world value to some clinicians.

The Impact of Acute Loud Noise on the Behavior of Laboratory Birds

Husbandry procedures and facility settings, such as low-frequency fire alarms, can produce noises in a laboratory environment that cause stress to animals used in research. However, most of the data demonstrating harmful effects that have, consequently, led to adaptations to management, have largely come from laboratory rodents with little known of the impacts on avian behavior and physiology. Here we examined whether exposure to a routine laboratory noise, a low-frequency fire alarm test, induced behavioral changes in laboratory zebra finches (Taeniopygia guttata). Twenty-four breeding pairs of zebra finches were randomly selected and exposed to the low-frequency fire alarm (sounding for 10-20 s) or no noise (control) on separate test days. All birds were filmed before and after the alarm sounded and on a control day (without the alarm). The zebra finches decreased their general activity and increased stationary and social behaviors after exposure to the alarm. Brief exposure to a low-frequency alarm disrupted the birds' behavior for at least 15 min. The induction of this behavioral stress response suggests that low-frequency sound alarms in laboratory facilities have the potential to compromise the welfare of laboratory birds.

Using Tiletamine-Zolazepam-Xylazine Anesthesia Compared to CO2-inhalation for Terminal Clinical Chemistry, Hematology, and Coagulation Analysis in Mice

INTRODUCTION

It is important that the method of anesthesia of mice does not considerably alter the animal's physiological and metabolic status before terminal blood sampling taken in order to analyze clinical pathology parameters.

METHODS

Hematology, hemostasis, and clinical chemistry parameters were compared in male and female BALB/c mice exposed to either tiletamine-zolazepam-xylazine (TZX) anesthesia or euthanasia in carbon dioxide (CO₂₎ chamber to reveal an alternative method of anesthesia vs. the recommended CO₂ inhalation. Blood samples were taken from the inferior vena cava.

RESULTS

Clinical blood parameters in mice exposed to CO₂ inhalation or TZX anesthesia proved to be substantially different. The TZX group had lower activated partial thromboplastin time (APTT) and fibrinogen (statistically in males and tending in females) and lower platelets (PLT), red blood cells (RBC), hemoglobin (HGB), and white blood cells (WBC) in both sexes. TZX anesthesia resulted in lower blood serum concentrations of total protein, albumin and globulins, creatinine in males (higher in females); cholesterol, triglycerides, alanine aminotransferase (АLT) and alkaline phosphatase (AP) in both sexes, and bilirubin in males. The calcium level decreased in TZX-anesthetized males and females while the phosphates decreased only in females. The volume of serum obtained from females of TZX group was approximately two times higher than in the CO₂-anesthetized group, with the degree of hemolysis tending to decrease.

DISCUSSION

The studied method of mouse anesthesia, followed by terminal blood sampling and analysis of clinical pathology parameters, suggests that TZX is a good alternative to CO₂ inhalation in toxicological and other nonclinical studies. The differences in hemostasis, hematology, and clinical chemistry parameters between these groups are supposedly associated with alterations in physiological and metabolic status of mice under conditions of increasing hypoxia, respiratory standstill, and circulatory arrest after CO₂ inhalation.

Chronic stress impacts the cardiovascular system: animal models and clinical outcomes

Psychological stresses are associated with cardiovascular diseases to the extent that cardiovascular diseases are among the most important group of psychosomatic diseases. The longstanding association between stress and cardiovascular disease exists despite a large ambiguity about the underlying mechanisms. An array of possibilities have been proposed including overactivity of the autonomic nervous system and humoral changes, which then converge on endothelial dysfunction that initiates unwanted cardiovascular consequences. We review some of the features of the two most important stress-activated systems, i.e., the humoral and nervous systems, and focus on alterations in endothelial function that could ensue as a result of these changes. Cardiac and hematologic consequences of stress are also addressed briefly. It is likely that activation of the inflammatory cascade in association with oxidative imbalance represents key pathophysiological components of stress-induced cardiovascular changes. We also review some of the commonly used animal models of stress and discuss the cardiovascular outcomes reported in these models of stress. The unique ability of animals for adaptation under stressful conditions lessens the extrapolation of laboratory findings to conditions of human stress. An animal model of unpredictable chronic stress, which applies various stress modules in a random fashion, might be a useful solution to this predicament. The use of stress markers as indicators of stress intensity is also discussed in various models of animal stress and in clinical studies.

Thromboelastographic Study of Psychophysiological Stress: A Review

Thromboelastography (TEG) is drawing more attention for clinical and laboratory studies of hemostasis. It has been applied to evaluate the effects of both psychological and physiological stress on whole blood coagulation from the onset of the coagulation cascade through clot formation, to the end with fibrinolysis. We conducted a comprehensive review on the applications of TEG for assessment of different stressors, ranging from physical exercise to emotional situations. The methodology is unique in terms of instrumentation, the methods to activate blood coagulation, the type of blood (citrated vs fresh blood), and study settings (in vitro vs in vivo vs clinical trials). Thromboelastography has most often been used to study the effects of physiological stress. The author's own work and future directions are discussed as well. The review would facilitate future development of TEG for evaluating hemostasis and potential pathological pathways in response to various forms of stress.