Creatine metabolism in the uterus: potential implications for reproductive biology

Value of serum muscular creatinine phosphokinase levels in patients with adenomyosis as a non-invasive diagnostic marker

OBJECTIVE

In the present study, we aimed to compare serum CK-MM levels in patients with and without adenomyosis and to investigate whether CK-MM level can be a non-invasive marker for myometrial damage due to adenomyosis.

MATERIALS AND METHODS

Our study was a prospective case-control study in a tertiary center and consisted of 40 patients with a clinical/ultrasonographic diagnosis of adenomyosis and 40 patients without a clinical/ultrasonographic diagnosis of adenomyosis as the control group based on recently published morphological uterus sonographic assessment (MUSA) criteria. Individuals of similar age who signed a voluntary consent form were included in our study. Demographic, clinical, and laboratory findings of the patients in both groups were recorded. Blood serum samples were used for the determination of serum CK-MM levels of the participants in our study. The samples were analyzed by using the human CK-MM enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

In our study, the mean serum CK-MM level was 16.2 ± 21.7 (ng/dL) in patients with adenomyosis and 2.6 ± 2.2 (ng/dL) in patients without adenomyosis. Serum CK-MM level was statistically significantly higher in the patient group with adenomyosis than in the control group (p < 0.001). The CK-MM threshold value of 3.43 ng/mL, with a sensitivity of 82.5% and specificity of 85%, has been found to be a valuable distinguishing level in patients with and without adenomyosis.

CONCLUSION

In this study, we demonstrated that serum CK-MM can be used as a non-invasive diagnostic method in patients with adenomyosis. As the number of studies around this subject in the literature is insufficient, larger studies are needed to use CK-MM as a diagnostic marker in adenomyosis.

Enhanced hepatic metabolic perturbation of polystyrene nanoplastics by UV irradiation-induced hydroxyl radical generation

The environmental behavior of and risks associated with nanoplastics (NPs) have attracted considerable attention. However, compared to pristine NPs, environmental factors such as ultraviolet (UV) irradiation that lead to changes in the toxicity of NPs have rarely been studied. We evaluated the changes in morphology and physicochemical properties of polystyrene (PS) NPs before and after UV irradiation, and compared their hepatotoxicity in mice. The results showed that UV irradiation caused particle size reduction and increased the carbonyl index (CI) and negative charge on the particle surface. UV-aged PS NPs (aPS NPs) could induce the generation of hydroxyl radicals (·OH), but also further promoted the generation of ·OH in the Fenton reaction system. Hepatic pathological damage was more severe in mice exposed to aPS NPs, accompanied by a large number of vacuoles and hepatocyte balloon-like changes and more marked perturbations in blood glucose and serum lipoprotein, alanine aminotransferase and aspartate aminotransferase levels. In addition, exposure to PS NPs and aPS NPs, especially aPS NPs, triggered oxidative stress and significantly damaged the antioxidant capacity of mice liver. Compared with PS NPs, exposure to aPS NPs increased the number of altered metabolites in hepatic and corresponding metabolic pathways, especially glutathione metabolism. Our research suggests that UV irradiation can disrupt the redox balance in organisms by promoting the production of ·OH, enhancing PS NPs-induced liver damage and metabolic disorders. This study will help us understand the health risks of NPs and to avoid underestimation of the risks of NPs in nature.

Proteomics approach reveals urinary markers for early pregnancy diagnosis in buffaloes

This study aimed to compare urine proteomics from non- and pregnant buffaloes in order to identify potential biomarkers of early pregnancy. Forty-four females underwent hormonal ovulation synchronization and were randomly divided into two experimental groups: inseminated (n = 30) and non-inseminated (n = 14). The pregnant females were further divided into two groups: pregnant at Day 12 (P12; n = 8) and at Day 18 (P18; n = 8) post-ovulation. The non-pregnant group was also subdivided into two groups: non-pregnant at Day 12 (NP12; n = 7) and at Day 18 (NP18; n = 7). Urine was collected from all females on Days 12 or 18. The samples were processed for proteomics. A total of 798 proteins were reported in the urine considering all groups. The differential proteins play essential roles during pregnancy, acting in cellular transport and metabolism, endometrial remodeling, embryonic protection, and degradation of defective proteins. We suggest that some proteins from our study can be considered biomarkers for early pregnancy diagnosis, since they were increased in pregnant buffaloes. SIGNIFICANCE: Macromolecules have been studied for early pregnancy diagnosis, aiming to increase reproductive efficiency in cattle and buffaloes. Direct methods such as rectal palpation and ultrasonography have been considered late. Thus, this study aimed to compare urine proteomics from non- and pregnant buffaloes to identify potential biomarkers of early pregnancy. The differential proteins found in our study play essential roles during pregnancy, acting in cellular transport and metabolism, endometrial remodeling, embryonic protection, and degradation of defective proteins. We suggest that these proteins can be considered possible biomarkers for early pregnancy diagnosis since they were increased in the pregnant buffaloes.

Creatine metabolism at the uterine-placental interface throughout gestation in sheep†

The placenta requires high levels of adenosine triphosphate to maintain a metabolically active state throughout gestation. The creatine-creatine kinase-phosphocreatine system is known to buffer adenosine triphosphate levels; however, the role(s) creatine-creatine kinase-phosphocreatine system plays in uterine and placental metabolism throughout gestation is poorly understood. In this study, Suffolk ewes were ovariohysterectomized on Days 30, 50, 70, 90, 110 and 125 of gestation (n = 3-5 ewes/per day, except n = 2 on Day 50) and uterine and placental tissues subjected to analyses to measure metabolites, mRNAs, and proteins related to the creatine-creatine kinase-phosphocreatine system. Day of gestation affected concentrations and total amounts of guanidinoacetate and creatine in maternal plasma, amniotic fluid and allantoic fluid (P < 0.05). Expression of mRNAs for arginine:glycine amidinotransferase, guanidinoacetate methyltransferase, creatine kinase B, and solute carrier 16A12 in endometria and for arginine:glycine amidinotransferase and creatine kinase B in placentomes changed significantly across days of gestation (P < 0.05). The arginine:glycine amidinotransferase protein was more abundant in uterine luminal epithelium on Days 90 and 125 compared to Days 30 and 50 (P < 0.01). The chorionic epithelium of placentomes expressed guanidinoacetate methyltransferase and solute carrier 6A13 throughout gestation. Creatine transporter (solute carrier 6A8) was expressed by the uterine luminal epithelium and trophectoderm of placentomes throughout gestation. Creatine kinase (creatine kinase B and CKMT1) proteins were localized primarily to the uterine luminal epithelium and to the placental chorionic epithelium of placentomes throughout gestation. Collectively, these results demonstrate cell-specific and temporal regulation of components of the creatine-creatine kinase-phosphocreatine system that likely influence energy homeostasis for fetal-placental development.

Metabolic signature of cervical mucus in ewe breeds with divergent cervical sperm transport: a focus on metabolites involved in amino acid metabolism

INTRODUCTION

Cervical artificial insemination (AI) with frozen-thawed semen in sheep has yielded unacceptably low pregnancy rates. The exception is in Norway where vaginal AI yields non-return rates in excess of 60%, which has been attributed to the ewe breed used.

OBJECTIVES AND METHODS

This study aimed to characterise, for the first time, the ovine follicular phase cervical mucus metabolome, with a focus on the amino acid profile. Cervical mucus was collected from four European ewe breeds with known differences in pregnancy rates following cervical AI with frozen-thawed semen. These were Suffolk (low fertility), Belclare (medium fertility), Norwegian White Sheep (NWS) and Fur (both high fertility).

RESULTS

A total of 689 metabolites were identified in the cervical mucus of all the four ewe breeds. Of these, 458 metabolites were altered by ewe breed, which had the greatest effect in the dataset (P < 0.05). We detected 194 metabolites involved in the amino acid pathway, of which 133, 56 and 63 were affected by ewe breed, type of cycle and their interaction, respectively (P < 0.05). N-methylhydantoin and N-carbamoylsarcosine (degradation products of creatinine pathway) exhibited the greatest fold change decrease in the Suffolk breed compared to Fur and NWS (P < 0.001). Oxidized metabolites were also decreased in Suffolk compared to high fertility breeds (P < 0.05). In contrast, other metabolites such as 3-indoxyl-sulfate, putrescine, cadaverine were significantly increased in Suffolk at the synchronised cycle.

CONCLUSION

The suboptimal amino acid profile in the cervical mucus of the low fertility Suffolk breed may have negative consequences for sperm transport.

The Effectiveness of L-arginine in Clinical Conditions Associated with Hypoxia

The review summarises the data of the last 50 years on the effectiveness of the amino acid L-arginine in therapeutic practice in conditions accompanied by different-origin hypoxia. The aim of this review was to analyse the literature and our research data on the role of nitric oxide in the modulation of individual physiological reactivity to hypoxia. The review considers the possibility of eliminating methodological conflicts in the case of L-arginine, which can be solved by taking into account individual physiological reactivity (or the hypoxia resistance factor). Considerable attention is paid to genetic and epigenetic mechanisms of adaptation to hypoxia and conditions of adaptation in different models. The article presents data on the clinical effectiveness of L-arginine in cardiovascular system diseases (hypertension, atherosclerosis, coronary heart disease, etc.) and stress disorders associated with these diseases. The review presents a generalised analysis of techniques, data on L-arginine use by athletes, and the ambiguous role of NO in the physiology and pathology of hypoxic states shown via nitric oxide synthesis. Data on the protective effects of adaptation in the formation of individual high reactivity in sportsmen are demonstrated. The review demonstrates a favourable effect of supplementation with L-arginine and its application depending on mitochondrial oxidative phosphorylation processes and biochemical indices in groups of individuals with low and high capacity of adaptation to hypoxia. In individuals with high initial anti-hypoxic reserves, these favourable effects are achieved by the blockade of NO-dependent biosynthesis pathways. Therefore, the methodological tasks of physiological experiments and the therapeutic consequences of treatment should include a component depending on the basic level of physiological reactivity.

Short term exposure to polystyrene nanoplastics in mice evokes self-regulation of glycolipid metabolism

With the detection of nano-plastics (NPs) in daily essentials and drinking water, the potential harm of NPs to human health has become the focus of global attention. Studies have shown that long term exposure to NPs can lead to disorders of glucose and lipid metabolism in organisms, while the effects of short term exposure are rarely reported. Moreover, environmental factors cause the aging of NPs, and it is unclear whether this has an effect on their toxicity. In this study, we use 100 nm polystyrene (PS) NPs and ultraviolet (UV) aging PS (aPS) NPs to gavage mice for 7 days at an exposure dose of 50 mg/kg/day. To evaluate the effects of exposure on mice hepatic glucose lipid metabolism, we performed blood biochemical, pathological and metabolomic analyses. The results showed that exposure to PS NPs and aPS NPs increased serum glucose, disrupted serum lipoprotein levels, and up-regulated the expression levels of phosphatidylinositol 3-kinase (PI3K)/ phosphoprotein kinase B (p-AKT)/Glucose transporter 4 (GLUT4) proteins in the glucose metabolism pathway. The expression levels of key proteins sterol regulatory element binding protein-1 (SREBP-1)/peroxisome proliferator-activated receptor-γ (PPARγ)/adipose triglyceride lipase (ATGL) in the lipid metabolism signaling pathway were significantly increased. These findings suggest that short term exposure to PS NPs and aPS NPs induces glycolipid metabolism disturbance in mice, which may subsequently awaken the mice to self-regulate the serum levels of various lipoproteins and the expression of related key proteins. Compared with PS NPs, the aPS NPs interfered more strongly with glucose metabolism, and the corresponding self-regulation in mice was also more obvious. These findings not only provide a basis for environmental factors to increase the health risk of NPs but also provided a reference for the selection of test substances for further studies on the toxicity of NPs.

Plasma homoarginine concentrations in ewe's pregnancy and association with the number of fetuses

A striking increase in homoarginine concentrations, about more than 100-fold that observed in humans, was recently reported during pregnancy in a nutritionally induced model of intra-uterine growth restriction in ewes. To determine whether this phenomenon is at least partially related to the nutritional regimen, estrus synchronization, or analytical method, thirty-four one-year-old primiparous, non-synchronized, and well-fed Sarda breed ewes were exposed to fertile rams allowing those who came into estrus to naturally mate. Plasma arginine, homoarginine, asymmetric dimethylarginine, symmetric dimethylarginine, mono methylarginine, and citrulline concentrations were measured in each sample using LC-MS/MS. Homoarginine concentrations showed a 44-fold variation between the highest and the lowest values while the fluctuations of arginine and its analogues and metabolites were much smaller, between 1.1 and 1.6-fold. Repeated-measures correlation analysis showed a significant negative correlation between homoarginine/arginine and arginine/asymmetric dimethylarginine ratios (Rm = -0.40; P < 0.000001). Furthermore, median homoarginine concentrations significantly increased with the number of fetuses. The marked increase in homoarginine concentrations with advancing gestational age is genuine and independent of mating, feeding, diet, and hormone treatment. The higher homoarginine concentrations found in ewes bearing multiple fetuses suggest the presence of a physiological link between this arginine analog and energy metabolism in pregnancy that warrants further investigation.

Metabolic Basis of Creatine in Health and Disease: A Bioinformatics-Assisted Review

Creatine (Cr) is a ubiquitous molecule that is synthesized mainly in the liver, kidneys, and pancreas. Most of the Cr pool is found in tissues with high-energy demands. Cr enters target cells through a specific symporter called Na⁺/Cl⁻-dependent Cr transporter (CRT). Once within cells, creatine kinase (CK) catalyzes the reversible transphosphorylation reaction between [Mg²⁺:ATP⁴⁻]²⁻ and Cr to produce phosphocreatine (PCr) and [Mg²⁺:ADP³⁻]⁻. We aimed to perform a comprehensive and bioinformatics-assisted review of the most recent research findings regarding Cr metabolism. Specifically, several public databases, repositories, and bioinformatics tools were utilized for this endeavor. Topics of biological complexity ranging from structural biology to cellular dynamics were addressed herein. In this sense, we sought to address certain pre-specified questions including: (i) What happens when creatine is transported into cells? (ii) How is the CK/PCr system involved in cellular bioenergetics? (iii) How is the CK/PCr system compartmentalized throughout the cell? (iv) What is the role of creatine amongst different tissues? and (v) What is the basis of creatine transport? Under the cellular allostasis paradigm, the CK/PCr system is physiologically essential for life (cell survival, growth, proliferation, differentiation, and migration/motility) by providing an evolutionary advantage for rapid, local, and temporal support of energy- and mechanical-dependent processes. Thus, we suggest the CK/PCr system acts as a dynamic biosensor based on chemo-mechanical energy transduction, which might explain why dysregulation in Cr metabolism contributes to a wide range of diseases besides the mitigating effect that Cr supplementation may have in some of these disease states.

Creatine Metabolism in Female Reproduction, Pregnancy and Newborn Health

Creatine metabolism is an important component of cellular energy homeostasis. Via the creatine kinase circuit, creatine derived from our diet or synthesized endogenously provides spatial and temporal maintenance of intracellular adenosine triphosphate (ATP) production; this is particularly important for cells with high or fluctuating energy demands. The use of this circuit by tissues within the female reproductive system, as well as the placenta and the developing fetus during pregnancy is apparent throughout the literature, with some studies linking perturbations in creatine metabolism to reduced fertility and poor pregnancy outcomes. Maternal dietary creatine supplementation during pregnancy as a safeguard against hypoxia-induced perinatal injury, particularly that of the brain, has also been widely studied in pre-clinical in vitro and small animal models. However, there is still no consensus on whether creatine is essential for successful reproduction. This review consolidates the available literature on creatine metabolism in female reproduction, pregnancy and the early neonatal period. Creatine metabolism is discussed in relation to cellular bioenergetics and de novo synthesis, as well as the potential to use dietary creatine in a reproductive setting. We highlight the apparent knowledge gaps and the research “road forward” to understand, and then utilize, creatine to improve reproductive health and perinatal outcomes.