Reproductive hormones monthly variation in free‐ranging European wildcats: Lack of association with faecal marking

Spatial and temporal expression profile of sex steroid receptors and antioxidant enzymes in the maternal-fetal interface of domestic cats

Sex steroids and antioxidant enzymes modulate uterine and placental physiology. Failures in the expression, signaling, and/or secretion of these mediators are associated with female infertility and gestational problems. However, there is no data on the expression profile of receptors for sex steroids and antioxidant enzymes in the maternal-fetal interface of domestic cats. Uterus and placenta samples from non-pregnant diestrus cats and cats in mid- and late pregnancy were used to analyze the protein and gene expression of the receptors for estrogen alpha (ERα), progesterone (PR), and androgen (AR) and the antioxidant enzymes superoxide dismutase 1 (SOD1), catalase, and glutathione peroxidase 1 (GPX1) by immunohistochemistry and qPCR. Higher uterine expression of ERα, Pr, and Sod1 was observed in the pregnant cats, especially in mid-pregnancy, compared to non-pregnant diestrus cats, as well as reduced endometrial catalase immunostaining. In the placenta, the mRNA expression of Erα, Pr, Ar, and Gpx1 was higher in late pregnancy in relation to mid-pregnancy. Moreover, weak or no placental expression was observed for catalase in mid- and late pregnancy, while strong immunostaining was observed for AR in trophoblasts and decidual cells in mid-pregnancy. The findings of this study demonstrated that pregnancy in female cats increases the uterine expression of sex steroid receptors and antioxidant enzymes, and that the placental expression of these mediators varies according to gestational age.

Non-Invasive Determination of Annual Fecal Cortisol, Androstenedione, and Testosterone Variations in a Herd of Male Asian Elephants (Elephas maximus) and Their Relation to Some Climatic Variables

Simple Summary

Studies of physiology, animal welfare, and behavior in endangered species are gaining more importance with the aim of contributing to their conservation, and studies that use non-invasive methods for hormonal determinations are especially valuable. In this study, feces were used to assess whether the adrenal and gonadal hormones showed variation in male Asian elephants in a 14-month period and to evaluate whether there were any influences of climatic variables with respect to hormonal secretion. We show here that the use of non-invasive methods to measure the levels of steroid hormones in Asian elephant feces allows us to obtain useful results without having to subject the animals to stressful activity or requiring specific training to obtain the samples. Additionally, this research provides a deeper understanding of endocrine regulation in captive Asian elephants (Elephas maximus) in order to enhance reproduction programs in captivity and conserve the species.

Abstract

The measurement of stress and reproductive hormones in wild animal species by non-invasive methods is of special interest. To assess whether the adrenal and gonadal hormones show annual variations in male Asian elephants (Elephas maximus) and to evaluate whether there is any influence of climatic variables on hormonal secretion, fecal samples were taken from a herd of 7 Asian elephants over a 14-month period to subsequently determine the concentrations of testosterone (T), androstenedione (A4), and cortisol (C) by a validated immunoassay technique. Data referring to three climatic variables in the place and period of study were collected, namely monthly mean values of temperature, humidity and rainfall. Levels of T and A4 showed two major increases in July (T: 1088.35 ± 131.04 ng/g; A4: 480.40 ± 50.86 ng/g) and October (T: 825.09 ± 31.60 ng/g; A4: 319.96 ± 32.69 ng/g) (p < 0.05). Our results show a secretion of fecal androgens dependent on temperature (T and A4), and humidity (T). Male musth was detected during the initial increases of T and A4 levels. The highest concentrations of C were observed in September (156.67 ± 60.89 ng/g) (p < 0.05), probably due to the stressful fights that occurred during the musth period. The observed results of the fecal levels of T, A4 and C were similar to those obtained by invasive methods. In conclusion, fecal secretion of the three hormones in these captive male Asian elephants showed variations related in some cases to different weather factors.

Female-female reproductive suppression: impacts on signals and behavior

Female-female reproductive suppression is evident in an array of mammals, including rodents, primates, and carnivores. By suppressing others, breeding females can benefit by reducing competition from other females and their offspring. There are neuroendocrinological changes during suppression which result in altered behavior, reproductive cycling, and communication. This review, which focuses on species in Rodentia, explores the current theoretical frameworks of female-female reproductive suppression, how female presence and rank impacts reproductive suppression, and some of the proposed mechanisms of suppression. Finally, the understudied role of olfactory communication in female-female reproductive suppression is discussed to identify current gaps in our understanding of this topic.