Kisspeptin-10 Improves Testicular Redox Status but Does Not Alter the Unfolded Protein Response (UPR) That Is Downregulated by Hypothyroidism in a Rat Model

Hypothyroidism compromises the testicular redox status and is associated with reduced sperm quality and infertility in men. In this regard, studies have demonstrated the antioxidant potential of kisspeptin in reproductive and metabolic diseases. In this study, we evaluate the effects of kisspeptin-10 (Kp10) on the testicular redox, as well as mediators of the unfolded protein response (UPR) in adult rats with hypothyroidism. Adult male Wistar rats were randomly separated into the Control (n = 15), Hypo (n = 13) and Hypo + Kp10 (n = 14) groups, and hypothyroidism was induced with 6-propyl-2-thiouracil (PTU) for three months. In the last month, half of the hypothyroid animals received Kp10. Testis samples were collected for enzymatic, immunohistochemical and/or gene evaluation of mediators of oxidative stress (TBARs, lipid hydroperoxides (LOOH), ROS, peroxynitrite, SOD, CAT and GPX), endoplasmic reticulum stress (GRP78, ATF6, PERK, CHOP, HO-1 and sXBP1) and antiapoptocytes (BCL-2). Hypothyroidism increased apoptosis index, TBARS and LOOH concentrations, and reduced testicular gene expression of Sod1, Sod2 and Gpx1, as well as the expression of Grp78, Atf6, Ho1 and Chop. Treatment with Kp10, in turn, reduced testicular apoptosis and the production of peroxynitrite, while increased SOD1 and GPX ½ expression, and enzymatic activity of CAT, but did not affect the lower expression of UPR mediators caused by hypothyroidism. This study demonstrated that hypothyroidism causes oxidative stress and dysregulated the UPR pathway in rat testes and that, although Kp10 does not influence the low expression of UPR mediators, it improves the testicular redox status, configuring it as an important antioxidant factor in situations of thyroid dysfunction.

Pyometra alters the redox status and expression of estrogen and progesterone receptors in the uterus of domestic cats

OBJECTIVES

The aim of this study was to evaluate the expression profile of sex steroid receptors and redox mediators in the uterus of domestic cats with pyometra.

METHODS

Twelve cats were used and divided into groups: (1) non-gestational healthy diestrus (n = 7) and (2) pyometra (n = 5). The plasma profiles of estradiol and progesterone (P4) as well as uterine expression levels of estradiol alpha (ERα), progesterone (PR) and androgen (AR) receptors, of the antioxidant enzymes superoxide dismutase 1 (SOD1), catalase and glutathione peroxidase 1 (GPX1), and of the oxidative damage marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) were evaluated.

RESULTS

Cats with pyometra showed higher plasma P4 levels and increased uterine messenger RNA (mRNA) and protein expression of ERα and PR, mainly in the glandular epithelium for ERα and in stromal and myometrial cells for PR. In addition, there was an increase in 8-OHdG immunostaining and GPX1 mRNA and protein expression in cats with pyometra compared with those in non-gestational diestrus, while catalase showed a reduction in endometrial immunostaining in cats with pyometra. There were no differences in uterine AR and SOD1 expression between the groups.

CONCLUSION AND RELEVANCE

The findings of this study showed that pyometra is associated with oxidative stress in the uterus of domestic cats and alterations of the profile of sex steroid receptors, especially ERα and PR, and of antioxidant enzymes, suggesting that changes in these mediators may play a role with the etiopathogenesis of this disease.

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.

Kisspeptin treatment reverses high prolactin levels and improves gonadal function in hypothyroid male rats

We evaluated whether the administration of kisspeptin-10 (Kp10) is capable of restoring gonadal function in hypothyroid male rats. Hypothyroidism was induced with 6-propyl-2-thiouracil (PTU) for three months. In the last month, half of the hypothyroid animals were treated with Kp10. Hypothyroidism reduced testicular and sex gland mass, decreased the proliferation of the seminiferous epithelium, and compromised sperm morphology, motility, and vigor. A decrease in plasma LH and testosterone levels and an increase in prolactin secretion were observed in the hypothyroid rats. Hypothyroidism reduced Kiss1 and Kiss1r protein and gene expression and Star and Cyp11a1 mRNA levels in the testis. Furthermore, it reduced Lhb, Prl, and Drd2 and increased Tshb and Gnrhr expression in the pituitary. In the hypothalamus, hypothyroidism increased Pdyn and Kiss1r while reducing Gnrh1. Kp10 treatment in hypothyroid rats restored testicular and seminal vesicle morphology, improved sperm morphology and motility, reversed high prolactin levels, and increased LH and testosterone levels. In addition, Kp10 increased testicular expression of Kiss1, Kiss1r, Fshr, and Nr5a1 and pituitary Kiss1 expression. Our findings describe the inhibitory effects of hypothyroidism on the male gonadal axis and sperm quality and demonstrate that Kp10 treatment reverses high prolactin levels and improves gonadal function and sperm quality in hypothyroid rats.

Estrogen and progesterone receptors and antioxidant enzymes are expressed differently in the uterus of domestic cats during the estrous cycle

Sex steroids and antioxidant enzymes are important in female sexual development and adequate modulation of the estrous cycle, pregnancy, and fetal development. Therefore, modifications in its signaling or expression in the genital system are associated with reproductive dysfunctions. However, the spatial-temporal expression profile of receptors for sex steroids and antioxidant enzymes in the uterus of domestic cats throughout the estrous cycle needs to be studied. Cats in proestrus/estrus (N = 6), diestrus, (N = 7), and anestrus (N = 6) were used to evaluate the uterine expression of estrogen alpha (ERα), progesterone (PR), and androgen (AR) receptors and of the antioxidant enzymes superoxide dismutase 1 (SOD1), catalase and glutathione peroxidase 1 (GPX1) by immunohistochemistry and qPCR. The uterus of cats in diestrus showed lower protein and mRNA expression of ERα and PR compared to proestrus/estrus and anestrus, mainly in the luminal and glandular epithelium and myometrium, different from catalase and SOD1, which showed higher expression in diestrus in relation to other phases of the cycle. GPX1, on the other hand, showed lower uterine gene expression in diestrus compared to proestrus/estrus and anestrus. No significant differences in AR expression were observed. In conclusion, ERα and PR sex steroid receptors and antioxidant enzymes are expressed differently in the uterus of domestic cats during the estrous cycle.