Patterns of folliculogenesis in ducks following the administration of a gonadotropin-releasing hormone 1 (GnRH) analogue

Abstract

The efficacy of synthetic gonadotrophin-releasing hormone (GnRH) analogue in improving the folliculogenesis of ducks has not been established. The aim of the study was to investigate the effect of oral administration of GnRH analogue as luteinizing hormone releasing hormone A 2 (LHRH-A 2 ) on expression of relevant genes, egg production, changes of hormone levels and an ovarian follicle development in ducks. Five hundred ducks at 220 days old were randomly allotted to five groups, where each bird received daily in food 0, 5, 10, 15, or 20 lg LHRH-A 2 for 60 days. In all treated groups, a non-significant increase in the level of GnRH receptor was noticed as compared to the corresponding control. Interestingly, the egg product in the 10 and 15 lg LHRH-A 2 groups was profoundly increased (P < 0.05) if compared to 0 and 5 lg LHRH-A 2 groups or control. A reduction in circulating prolactin (PRL) levels occurs concurrently with an increase in progesterone (P 4 ) and estradiol (E 2 ) particularly in 5, 10 and 15 lg LHRH-A 2 groups. Maximal apoptotic percentage for the granulosa cells was obtained in 20 lg LHRH-A 2 group as compared to control or 5, 10 and 15 lg treatment groups. Finally, these data suggest that the oral administration of 10 and 15 lg LHRH-A 2 may induce ovarian cycle and play vital gonadotrope role during the folliculogenesis process in ducks. This study also demonstrated a need to concentrate further research on the potential effect of GnRH during the early period to improve the reproductive performance.

Polymorphism analysis and expression profile of the estrogen receptor 2 gene in Leizhou black duck

“…GnRH is released from the hypothalamus into the pituitary to excite the production and discharge of gonadotropins, FSH and LH. The gonadotropins then stimulate the growth of follicles and estrogen production by the granulosa cells in the ovary ( Szenci et al, 2006 ; Zoheir and Ahmed, 2012 ; Shimizu, 2016 ).…”

“…The functional unit of the ovary is the follicles made up of germ cells (oocytes) and somatic cells (granulosa cells and theca cells) ( Charlier et al, 2012 ; Luderer, 2014 ). The growth of the follicles is regulated by the hypothalamic ( GnRH ) and pituitary (follicle-stimulating hormone, FSH and luteinizing hormone, LH ) hormones which promote the production of estradiol (main estrogen) by the granulosa cells to enhance the follicle development ( Szenci et al, 2006 ; Zoheir and Ahmed, 2012 ; Shimizu, 2016 ).…”

Polymorphism Analysis and Expression Profile of the Estrogen Receptor 2 Gene in Leizhou Black Duck

“…GnRH is released from the hypothalamus into the pituitary to excite the production and discharge of gonadotropins; FSH and LH. The gonadotropins then stimulate the growth of follicles and the production of estrogen by the granulosa cells in the ovary (13,22,23).…”

“…The functional unit of the ovary is the follicles made up of germ cells (oocytes) and somatic cells (granulosa cells and theca cells) (12,21). The growth of the follicles is regulated by the hypothalamic (GnRH) and pituitary (follicle-stimulating hormone, FSH and luteinizing hormone, LH) hormones which promote the production of estradiol (main estrogen) by the granulosa cells to enhance the follicle development (13,22,23).…”

Immunohistochemistry and Expression Profile of Estrogen Receptor 2 Gene in Different Grade Size Ovarian Follicles of Leizhou Black Ducks

“…Granulosa cells differentiate into cumulus and mural cells (20,22,30). The hypothalamic, pituitary and gonadal (HPG) axis regulate follicle development and ovulation by synthesizing gonadotropin hormones (follicle-stimulating hormones, FSH and luteinizing hormone, LH) which coordinate to stimulate the synthesis and discharge of estrogen and progesterone in the somatic cells whose increase may have positive feedback on the HPG axis and gonadotropin hormones to coordinate the development, maturation, and oviposition of follicles (Figure 2) (24,(33)(34)(35)(36)(37)(38).…”