Graphical abstract

13-lined ground squirrels (TLGS; Ictidomys tridecemlineatus) are small, omnivorous, fossorial, hibernating sciurids. TLGS are seasonal induced ovulators, with a ~28-day gestation period. The main goal of this study was to ascertain whether enzyme-linked immunosorbent assay (ELISA) of TLGS fecal samples can be used to non-invasively detect pregnancy. Competitive ELISAs for progestogen metabolites were conducted on feces collected from a group of (n =13) females. Feces were collected thrice weekly during the breeding season and frozen for subsequent analysis. Competitive ELISAs were run using progesterone kits ), setting data against seven different time-points between hibernation, emergence, and litter birthdate. Eleven females produced litters. ELISA data from the (n = 2) non-pregnant females demonstrated no rise in progestogen metabolites at any point over 28 days. In contrast, data from the (n = 11) pregnant females all demonstrated a pronounced rise in progestogen metabolites, with most animals displaying progesterone withdrawal in the final week of gestation. A >20-fold rise in progestogen metabolite was observed halfway through gestation (P < 005). Analysis on litter size and progestogen metabolite concentration showed no significant correlation (r₂ = −0.615). Initial correlation analysis done on sex ratio of litters vs progestogen metabolites showed no significant effect of progesterone on sex ratios (males: r₂ = −0.772, females: r₂ = 0.375). This work demonstrated that TLGS also undergo progesterone withdrawal about a week before parturition. We have ascertained that a commercially available progesterone assay kit can detect a significant elevation in progestogen metabolites in this species about halfway through gestation.

Endometriosis is a complex disease characterized by inflammation and the growth of endometrial- like glands and stroma outside the uterine cavity. The pathophysiology of endometriosis is not entirely understood, however, with a prevalence of ~10% of women in their reproductive years, the disease symptoms significantly affect the quality of life of millions of women globally. Metabolomic studies have previously identified specific metabolites that could be a signature of endometriosis. This approach could potentially be used as a non-invasive tool for early diagnosis and provide a better understanding of endometriosis pathophysiology. This review aims to provide insight as to how endometriosis affects the metabolome by reviewing different studies that have used this approach to design follow-up studies. The search query included the term 'endometriosis' in combination with 'metabolomics', 'lipidomics', or 'sphingolipidomics' published between 2012 and 2020. We included studies in humans and animal models. Most studies reported differences in the metabolome of subjects with endometriosis in comparison to healthy controls and used samples taken from serum, endometrial tissue, follicular fluid, urine, peritoneal fluid, or endometrial fluid. Statistically significant metabolites contributed to group separation between patients and healthy controls. Reported metabolites included amino acids, lipids, organic acids, and other organic compounds. Differences in methods, analytical techniques, and the presence of confounding factors can interfere with results and interpretation of data. Metabolomics seems to be a promising tool for identifying significant metabolites in patients with endometriosis. Nonetheless, more investigation is needed in order to understand the significance of the study results.

Varicocele, defined by a dilation of efferent testicular veins, is the most commonly identifiable, surgically correctable lesion associated with male-factor infertility, starts at puberty and causes a progressive decline in fertile potential. The pathophysiology of infertility caused by this disease is still poorly understood, but it is suggested that the main mechanism is oxidative stress. Therefore, the aim of this study was to verify if varicocele is associated with changes in enzymatic antioxidant mechanisms and seminal plasma lipid peroxidation levels in adolescents. We recruited 90 adolescents that were divided into control (C; n= 27); varicocele and normal semen (VNS; n=46); varicocele and altered semen (VAS; n=17). Seminal and serum levels of lipid peroxidation were quantified by thiobarbituric acid reactive substances (TBARS). Seminal plasma antioxidant profile was evaluated by the activities of catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD). The VAS group had increased lipid peroxidation levels when compared to the other groups. The levels of serum lipid peroxidation and activities of the enzymes SOD and GPx did not differ between groups. CAT was undetectable by the method used. In conclusion, in adolescents with varicocele and altered semen analysis, there is an increase in seminal lipid peroxidation levels compared to adolescents with varicocele and without seminal change and adolescents without evident varicocele. However, the observed oxidative stress is not caused by a decrease in superoxide dismutase and glutathione peroxidase activities, which did not differ between adolescents with and without evident varicocele.