Necessity for LH in selection and continued growth of the bovine dominant follicle

Abstract

Previous research demonstrated that acute treatment with GnRH antagonist, Acyline, allowed follicle growth until ~8.5 mm and no dominant follicle was selected. This study evaluated whether deficient LH was the underlying mechanism for Acyline effects by replacing LH action, using human chorionic gonadotropin (hCG), during Acyline treatment. Holstein heifers (n = 24) during first follicular wave were evaluated by ultrasound and randomized into one of three treatments: Control (saline treatments), Acyline (5 µg/kg Acyline), or Acyline+hCG (Acyline plus 50 IU of hCG at start then 100 IU every 12 h). Pulses of LH were present in Control heifers (9 Pulses/10 h) but not during Acyline treatment. Data were normalized to the transition to diameter deviation (day 0; F1 ~7.5 mm). Diameter deviation of the largest (F1) and the second largest (F2) follicle was not observed in Acyline-treated heifers, whereas control heifers had decreased growth of F2 at F1 ~7.5 mm, indicating deviation. Selection of a single dominant follicle was restored by providing LH activity in Acyline+hCG heifers, as evidenced by F1 and F2 deviation, continued growth of F1, and elevated circulating estradiol. Separation of F1 and F2 occurred 12 h (~7.0 mm) earlier in Acyline+hCG heifers than Controls. Circulating FSH was greater in Acyline than Controls, but lower in Acyline+hCG than Controls after day 1.5. In conclusion, dominant follicle selection and growth after follicle deviation is due to LH action as shown by inhibition of this process during ablation of GnRH-stimulated LH pulses with Acyline and restoration of it after replacement of LH action by hCG treatment.

Letrozole cotreatment with progestin-primed ovarian stimulation in women with polycystic ovary syndrome undergoing IVF treatment

“…The "freeze all" strategy in our study reduced the exposure of gametes and the endometrium to supraphysiological levels of progesterone (Yang et al, 2019). Another reason was that letrozole promotes the selection of dominant follicles, and embryos obtained from dominant follicles may be associated with improved implantation potential (Giorgetti et al, 1995;Hugues et al, 2005;Mermillod et al, 2008;Rosen et al, 2008;Gomez-Leon et al, 2020). Letrozole coadministration increases the secretion of LH by inhibiting the synthesis of oestrogen (Requena et al, 2008).…”

“…Letrozole coadministration increases the secretion of LH by inhibiting the synthesis of oestrogen (Requena et al, 2008). Higher LH levels could probably advance the dominant follicle selection and drive growth of the dominant follicle after the beginning of diameter deviation (Hugues et al, 2005;Gomez-Leon et al, 2020). These fully developed preovulatory-stage follicles are more likely to yield high-quality oocytes (Rosen et al, 2008) and thus viable embryos (Mermillod et al, 2008).…”

Mechanism of LH release after peripheral administration of kisspeptin in cattle

“…Interestingly, the dominant follicle of all animals entered the regression phase by 72 hours after kisspeptin and GnRH antagonist treatment. A possible reason for the regression may be altered gene expression [47] and estradiol production by the dominant follicle [48] due to LH suppression [49].…”

Comparison between Iraqi Jenoubi heifers and bulls fed on date palm pollen to accelerate puberty and sexual maturit

“…Advanced puberty and maturity: In heifers the overall Dramatic increase in the absorption of trace minerals in the liver, heart, kidneys, spleen and lungs led to advance puberty and sexual maturity. Gomez-León et al (2020), Handcock et al (2020) mentioned increase in the hormone concentrations in the blood plasma and a high rate of BCS and weight are all factors that advance the age of puberty and sexual maturity in cows. Li et al (2019) reported the biofeedback episode causes the hypothalamus and thyroid gland to release a series of youth-promoting hormones such as growth hormone, estrogen and testosterone, as well as hormones that stimulate the adrenal gland and thyroid gland, leading lead to precocious puberty and sexual maturity.…”