Dexamethasone enhances fertility and preovulatory serum prolactin levels in eCG/hCG primed immature rats

Protective role of Allium cepa Linn (onion) juice on maternal dexamethasone induced alterations in reproductive functions of female offspring of Wistar rats

Maternal treatment with dexamethasone induces oxidative stress in the reproductive structures of offspring. Consumption of Allium cepa Linn improves antioxidant status. This study was designed to evaluate the protective role of Allium cepa Linn juice on maternal dexamethasone induced alterations in reproductive functions of the female offspring of Wistar rats. Twenty lactating dams (180-200 ​g) were randomly assigned into four groups (n ​= ​5) on the day of parturition and treated as follows during lactation for 21 days: Control (5 ​ml/kg BW distilled water); Dexamethasone (60 ​μg/kg BW); Allium cepa (5 ​ml/kg BW); Dexamethasone ​+ ​Allium cepa (60 ​μg/kg BW ​+ ​5 ​ml/kg BW). The female offspring were separated at birth. Days of vaginal opening and first oestrus cycle, length and frequency of estrous cycle as well as serum hormonal profiles were assessed as measure of reproductive functions. Ovarian superoxide dismutase (SOD) activity, catalase activity and malondialdehyde (MDA) level were measured as indices of oxidative stress. Oestrous cycle length, frequencies of diestrus as well as the Ovarian MDA were significantly increased (p ​< ​0.05) in dexamethasone (DEX) group relative to control group. Serum 17β-oestradiol and corticosterone level in addition to SOD and catalase activities were significantly reduced (p ​< ​0.05) in DEX group relative to control. Co-administration of Dex with Allium cepa Linn juice reduced the oestrous length, frequency of diestrous as well as ovarian MDA. There was also a significant increase in serum 17β-oestradiol, ovarian SOD and catalase activity. The results suggest that Allium cepa could protect against alterations in reproductive functions of offspring induced by maternal treatment with dexamethasone during lactation in Wistar rats. The flavonoid constituent of onion may also help in reducing oxidative stress in the offspring.

Cyclic changes in cortisol across the estrous cycle in parous and nulliparous Asian elephants

In the context of reproduction, glucocorticoids (GCs) are generally considered to have negative effects. However, in well-studied model species, GCs fluctuate predictability across the estrous cycles, and short-term increases promote healthy ovarian function. Reproductive challenges have plagued captive elephant populations, which are not currently self-sustaining. Efforts to understand reproductive dysfunction in elephants have focused on the suppressive effects of cortisol, but the potential permissive or stimulatory effects of cortisol are unknown. In this study, we provide a detailed examination of cortisol patterns across the estrous cycle in Asian elephants (Elephas maximus). Time series analysis was used to analyze cortisol and progesterone data for a total of 73 cycles from eight females. We also compared cortisol profiles between females that successfully conceived and females that failed to conceive despite repeated mating attempts. Our results revealed that cortisol fluctuates predictably across the estrous cycle, with a peak during the second half of the follicular phase followed by low levels throughout the luteal phase. Furthermore, this pattern was significantly altered in nulliparous females; cortisol concentrations did not decline during the luteal phase to the same extent as in parous females. This study highlights the complexity of cortisol signaling and suggests future directions for understanding the role of cortisol in reproductive dysfunction.

Use of the immature rat uterotrophic assay for specific measurements of chorionic gonadotropins and follicle-stimulating hormones in vivo bioactivities

The uterine weight growth stimulation by equine Chorionic Gonadotropin (eCG/PMSG) was found to occur at much lower eCG concentrations than ovarian growth. Human Chorionic Gonadotropin (hCG) which has only LH activity, was found to be as active as eCG in the uterotrophic assay whereas equine Luteinizing Hormone (eLH) which has dual LH+FSH activities like eCG, exhibited a much lower potency. In contrast to hCG, porcine and ovine LH as well as pFSH and oFSH exhibited no uterotrophic activity indicating that only gonadotropins with both LH activity and long half-lives are active alone in this assay. The FSH preparations were nevertheless found to trigger a dose-dependent response, but only in the presence of a subactive dose of hCG. The uterotrophic activity of hCG was found to be suppressed in ovariectomized immature rats and to be diminished after injection of GnRH antagonist suggesting an indirect pathway implicating the hypothalamo-pituitary complex. The data in this report together with the analysis of literature suggest that choriogonadotropins exert their stimulatory role on uterine growth by an indirect mechanism involving an increase in ovarian FSH receptors and FSH release by the pituitary. At the lowest concentrations of hCG, the increase in ovarian FSH receptors without endogenous FSH release is thought to be responsible for the sensitivity of the uterotrophic assay to exogenous FSHs. In conclusion, the immature rat uterotrophic assay is a sensitive and convenient assay for eCG and hCG as well as for FSHs in the presence of a sub-active dose of hCG.