Relationship of Some Oxidative Stress Biomarkers in Jumper Horses After Regular Training Program

Relationship between Oxidative Stress and Endometritis: Exploiting Knowledge Gained in Mares and Cows

Simple Summary

Endometritis is a widespread pathology in mares and cows and one of the leading causes of reproductive efficiency decline. Although localized in the innermost layer of the uterus, this inflammation involves the release of bioactive molecules and by-products related to molecular damage. Among the bioactive substances, a primary role is played by the reactive oxygen and nitrogen species, which, while exerting an antimicrobial effect, can amplify the inflammation, sometimes causing unwanted and self-aggravating effects. Part of these substances enters the bloodstream, with implications that range from sustaining distant effects on organs and tissues to being used as diagnostic biomarkers. The research carried out on this matter in cows and mares has maintained certain independence due to its species specificity. This review aims to collect and analyze the information available in these species to enhance diagnostics and provide new insights to prevent and treat this pathology.

Abstract

The etiopathogenesis of endometritis in mares and cows differs significantly; this could depend on a different sensitivity and reactivity of the uterus but also on endocrine and rearing factors and different stress sources. In both species, microorganisms and the immune system play a primary role in the generation of this pathology. Microbiological and cytological tests support clinical examination and significantly improve diagnostic accuracy. For both species, during the inflammation, immune cells invade the endometrium and release bioactive substances to contrast primary or secondary pathogen contamination. These molecules are traceable to cytokines, chemokines, and prostaglandins as well as reactive oxygen and nitrogen species (ROS and RNS), collectively known as RONS. The RONS-mediated oxidation causes morphological and functional alterations of macromolecules, such as proteins, lipids, and nucleic acids, with the consequent production of derivative compounds capable of playing harmful effects. These bioactive molecules and by-products, which have recently become increasingly popular as diagnostic biomarkers, enter the bloodstream, influencing the functionality of organs and tissues. This review has collected and compared information obtained in cows and mares related to the diagnostic potential of these biomarkers that are assessed by using different methods in samples from either blood plasma or uterine fluid.

Assessment of total (anti)oxidant status in goat kids

The redox potential of goat serum was assessed by different spectrophotometric assays. Among them, three methods are commonly applied for the evaluation of the oxidative (reactive oxygen metabolites, ROMs, and total oxidant status, TOS) and nitrosative (NO ⚫ metabolites, NO x ) stress, and four methods for the evaluation of the antioxidant status: the total antioxidant capacity (TAC) based on the ferric reducing ability of plasma (FRAP), the total antioxidant activity (TAA) based on the reduction of the coloured ABTS ⚫ + radical cation, the free radical scavenging activity (FRSA) based on the reduction of the purple DPPH ⚫ , and the total thiol levels (TTLs) based on their interaction with DTNB to form a highly coloured anion. Besides, myeloperoxidase (MPO) and ceruloplasmin oxidase (CP) activities were also assessed. Except for TAA, analytical data showed a great inter-individual variation for both oxidant and antioxidant assays. ROMs were strongly correlated with CP, while TOS with MPO and TAC. Furthermore, a tendency between TOS and FRSA was shown. NO x was correlated with TAC and TAA, and a tendency with TOS was shown. No correlations appeared among the antioxidant assays, even if a tendency between TAC and TAA was evidenced, but TAC was correlated with MPO activity. The observed correlation between ROMs and CP is discussed as a possible analytical interference. The absence of correlation among the antioxidant biomarkers suggests the simultaneous use of a panel of tests to verify any changes in the redox balance, mainly in livestock in which reference values for each biomarker are lacking.

Relative Deficiency in Albumin Methionine Content is Associated With Decreased Antioxidant Capacity of Equine Plasma

Relative to other species, horses seem particularly susceptible to oxidative stress. Plasma albumin plays an important role in preventing oxidative damage, in part due to its methionine (MET) content. Equine albumin is highly unusual in that it contains no MET residues. Whether or not this causes deficient antioxidant capacity in equine plasma relative to that of other species has not yet been explored. The objective of this study was to compare the redox status of equine (no MET) to that of bovine (moderate amount of MET) plasma. Plasma was collected from healthy, nonpregnant Quarter Horse mares (n = 10) and adult, healthy, nonpregnant, dried Holstein cows (n = 15). Measures of total antioxidant capacity and oxidative stress were assessed for each plasma sample using multiple commercially available assays: total antioxidant capacity, thiol detection, thiobarbituric acid reactive substances, and advanced oxidation protein products. Plasma from horses had significantly (P < .05) lower thiol content and thiobarbituric and reactive substances and higher advanced oxidation protein products than plasma from cattle. A difference in total antioxidant capacity was not observed; however, our study was underpowered to establish a meaningful comparison. Based on these findings, the lack of MET in equine albumin appears to translate to a lower antioxidant capacity of equine plasma. Our findings are consistent with previous reports in other species that identify MET as having an important role in the antioxidant capacity of albumin. Our results also highlight the complex system of antioxidant defenses in plasma that counteract the harmful effects of oxidants.

Profile of Acute-Phase Proteins of Horses Submitted to Low-Level Show Jumping Classes

The objective of this study was to evaluate the serum proteinogram, identifying and quantifying the acute-phase proteins (APPs) of horses used in show jumping activity with obstacles of a meter in height. As it is an equestrian sport that involves high intensity and excessive impact, the possibility of injury is relevant. The serum of 10 horses was evaluated in a competition for beginners. The material was collected at rest (T0), immediately after exercise (T1), 30 minutes after the effort (T2), 1 hour after the effort (T3), and 24 hours after the effort. Acute-phase proteins were separated by polyacrylamide gel electrophoresis and their concentrations determined by computerized densitometry. Protein identification was performed using mass spectrometry. The data were evaluated using analysis of variance for repeated measures, considering the level of significance of P < .05. Eight APPs were identified: α2-macroglobulin (α2-macro), ceruloplasmin (Cp), transferrin (Trf), albumin (Alb), α1-antitrypsin (α1-atp), haptoglobin (Hp), acid glycoprotein (AGP), and apolipoprotein A1 (Apo A1). There was a difference in Cp, AGP, and Apo A1 between moments. As the other proteins were not influenced by exercise, they were established as a valuable resource in the monitoring of inflammatory processes and an important complementary element in controlling the impact of training on the animals, thus guaranteeing their welfare.

Evaluation of Biological Indicators of Fatigue and Muscle Damage in Arabian Horses After Race

The aim of this study was to assay changes in blood biochemical parameters that resulted from exercise-induced muscle fatigue in horses participating in the two races (1,250 and 1,400 meters). Six male Arabian horses (3 to 6 years old) were used in this study. Blood samples were collected at time intervals including 1 hour before the race, immediately after the race, 1 and 24 hours after the end of race. Catalase (CAT), superoxide dismutase, glutathione peroxidase (GPX) activities, the blood level of malondialdehyde, protein carbonyl, and total antioxidant capacity (TAC) were measured, as well as muscle damage biomarkers including aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase (CK) activities, and myoglobin were measured. The results showed that CAT activity and plasma TAC in the horse increased immediately after the race and then gradually decreased. The highest GPX activity in red blood cells was recorded 1 hour before the start of the race. Superoxide dismutase showed an incremental pattern after the race. Immediately after the race, there was a significant increase in the plasma levels of AST, which continued until 1 hour after the race. The activity of LDH and CK reached its highest value 1 hour after the race. According to our findings, it can be concluded that the horses were tired and antioxidant enzymes altered under fatigue conditions. Muscle damage biomarkers have increased, but these increases were in their natural ranges and did not indicate muscle damage in horses.