Melatonin administration during the first half of pregnancy improves the reproductive performance of rabbits: Emphasis on ovarian and placental functions.

This study was designed to investigate the roles of melatonin administration during different sensitive windows of the first half of pregnancy in the function and gene expression of the ovary and placenta, hormone profile, and pregnancy outcomes in rabbits. Four equal experimental groups of 20 rabbits each were used. The first (FW), second (SW), and third (F + SW) groups comprised rabbits that orally received 0.7-mg melatonin/kg body weight during the first week, second weeks, and during both weeks of pregnancy; and the fourth group served as the control group (C). The total number of visible follicles significantly increased in all melatonin-treated groups compared with that in the C group. In all melatonin-treated groups, the number of absorbed fetuses was significantly reduced, whereas the weights of embryonic sacs and fetuses were higher than in the C group. The placenta efficiency was significantly increased in the F + SW group compared with that in the C group, followed by the SW group, whereas no significant difference in the placenta efficiency was found between the FW and C groups. Melatonin treatments significantly improved the expression of antioxidants, gonadotropin receptors, and cell cycle regulatory genes in the ovary, whereas only FW treatment upregulated steroidogenic acute regulatory gene. Compared with the C and FW groups, melatonin treatments during the SW and F + SW significantly upregulated the expression of most genes in the placenta. The concentrations of estradiol were significantly higher in the SW and F + SW groups than in the FW and C groups. The concentrations of progesterone were significantly increased in the FW group compared with those in the C and SW groups, whereas the F + SW group showed intermediate values. The litter size and weight at birth significantly increased in all melatonin-treated groups compared with those in the C group. The second week of pregnancy seems to be a sensitive window for melatonin actions during pregnancy. Thus, melatonin administration during the second week of pregnancy can be effective in improving pregnancy outcomes in rabbits.

Use of GnRH-Encapsulated Chitosan Nanoparticles as an Alternative to eCG for Induction of Estrus and Ovulation during Non-Breeding Season in Sheep.

This study is aimed at determining the reproductive performance of anestrous ewes treated with nanoencapsulated GnRH after a progesterone-based protocol for estrus induction was proposed as a way of replacing eCG. A total of sixty anestrous, multiparous, non-lactating Barki ewes were randomly allocated into three homogenous groups and subjected to a CIDR-based estrus induction protocol. The first group (eCG) received an intramuscular (i.m.) injection of 350 IU of eCG at CIDR removal. The second (LNGnRH) and third (HLNGnR) groups received either 25 µg or 50 µg of encapsulated GnRH nanoparticles by the i.m. route in the form of spherical GnRH-encapsulated chitosan-TPP nanoparticles (which were 490.8 nm and had a 13.6 mV positive charge) 48 h after CIDR removal. Follicular dynamics, estrous behavior, luteal activity, and pregnancy outcomes were evaluated. Three days after CIDR removal, the number of large follicles increased by similar amounts in the LNGnRH and eCG groups and were significantly higher in both groups than in the HNGnRH group. However, no differences were observed in the numbers and diameters of CLs among the experimental groups and, on the other hand, treatment with HNGnRH significantly increased blood serum progesterone levels compared with eCG and LNGnRH. Treatment with HNGnRH increased conception, lambing, and fecundity rates (p < 0.05), with the trend of a higher litter size (p = 0.081) compared with eCG, whereas LNGnRH resulted in intermediate values. In conclusion, a dose of 50 µg of GnRH encapsulated in chitosan-TPP nanoparticles can be used as an alternative to eCG in progesterone-based estrus induction protocols in sheep.