Secretion of Inhibin by Chicken Granulosa Cells in Vitro

Abstract. The present study was undertaken to compare the changes in circulating levels of inhibin-B, prolactin, follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol-17β, progesterone and testosterone during the different reproductive states of turkey hens. Blood samples were collected during different reproductive states, at laying, incubating and out of lay. Inhibin-B was measured by ELISA, while other hormones were determined by Chemiluminescent Microparticle Immunoassay (CMIA). The results revealed highly significant differences among the hen's states for all serum hormone concentrations. The highest levels of inhibin-B and prolactin were observed in incubating hens, while the lowest values were observed in laying hens. In contrast, the highest levels of FSH, LH, estradiol-17β, progesterone and testosterone were found in the laying group, while the lowest values were found in the incubating group. The progesterone level was higher in the laying group compared with the other groups. These results clearly demonstrate that negative correlation was found between both the inhibin-B and prolactin levels and the gonadotropin and steroid hormone concentrations during the different reproductive states of the turkey hens. In addition, the results suggest that inhibin-B may be involved in control of FSH and LH secretion. . The existence of bioactive inhibin in testis preparations [3,4] and ovarian granulosa cells [5,6] has been reported. The effect of induction of ovarian regression and removal of ovarian follicles on plasma inhibin indicate that the ovary is the major source of inhibin in the hen [7,8]. Prolactin secretion from the avian anterior pituitary gland is principally maintained by tonic stimulation from hypothalamic prolactinreleasing factors [9]. Prolactin secretion markedly changes during the reproductive cycle of the turkey hen. The hyperprolactinemia associated with incubation behavior (broodiness) induces ovarian regression, resulting in a substantial loss of egg production in commercial breeder flocks [10]. Administration of exogenous prolactin suppresses plasma gonadotropins necessary for egg production in domestic fowl [11]. However, there is additional evidence that suppression of gonadotropin secretion in incubating birds also involves a mechanism independent of increased prolactin secretion [12,13]. In turkey hens, the changes in the concentrations of inhibin-B, prolactin, gonadotropins and progesterone have been poorly documented. Therefore, in the present study, we investigated the changes in inhibin-B, prolactin, FSH, luteinizing hormone (LH), estradiol-17β, progesterone and testosterone hormones during the different reproductive states. Materials and Methods Animals and experimental designDomestic turkey hens (local Egyptian strain) were used in the present study. The turkeys were in the first year of production. The hens received a stimulatory photoperiod of 14 h of light:10 h of dark throughout the experimental period and were maintained in floor pens with trap nests. They...

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confidence: 99%

Comparative Changes in the Serum Concentrations of Inhibin-B, Prolactin, Gonadotropins and Steroid Hormones at Different Reproductive States in Domestic Turkey Hens

Khalil

Hanafy

Saleh

et al. 2009

“…Early studies [10,11] demonstrated that granulosa cell condition [12] provided direct evidence that the granulosa cells of the four largest follicles of laying hen are the primary source of inhibin in the chicken. Our findings that the plasma FSH peak occurred 12 h before ovulation are in agreement with the reports of Scanes et al [6], and in contrast to the report of Vanmonfort et al [7].…”

Section: Discussionmentioning

confidence: 99%

“…The existence of bioactive inhibin in testis preparations [9] and ovarian granulosa cells [10,11] has been observed. The effect of induction of ovarian regression [12] and removal of ovarian follicles [8] on plasma irinhibin indicate that the ovary is the major source of inhibin in the hen.…”

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confidence: 98%

Plasma Concentrations of Immunoreactive (ir)-Inhibin, Gonadotropins and Steroid Hormones during the Ovulatory Cycle of the Duck

Yang

Medan

Arai

et al. 2005

Abstract. The present study was undertaken to determine changes in circulating levels of immunoreactive (ir)-inhibin, FSH, LH, estradiol-17β, progesterone, and testosterone during the ovulatory cycle of Shao ducks. Serial blood samples were taken from two groups of laying ducks for measurement of ir-inhibin, gonadotropins, and steroid hormones at 2 h intervals for 24 h. Plasma concentrations of ir-inhibin did not change significantly during the ovulatory cycle. The highest level of plasma ir-inhibin was observed 6 h prior to ovulation, which coincided with a decreased level of plasma FSH. One FSH surge was found 12 h after ovulation. Estradiol-17β, progesterone, and testosterone were also determined during the ovulatory cycle. Two peak values were detected for estradiol-17β 8 h before ovulation and 4 h after ovulation, while progesterone started to increase 4 h before ovulation and reached a peak at ovulation. The highest level of plasma testosterone was detected around the time of ovulation. These results suggest that inhibin may be involved in the control of FSH secretion during the ovulatory cycle. In addition, both LH and progesterone are of importance in the ovulation process of Shao ducks.

“…Inhibins selectively suppress [7][8][9][10][11][12] while activins stimulate [11][12][13][14][15] the release of FSH. Previous studies have shown that the avian ovary also produces inhibins, which plays important roles in the regulation of pituitary FSH [16][17][18][19][20][21]. However, the roles of inhibins have received little attention in quail.…”

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confidence: 99%

Secretion of Inhibin in Female Japanese Quails (Coturnix japonica) from Hatch to Sexual Maturity

Sedqyar

Wang

Watanabe

et al. 2008

Abstract.To clarify the cellular source and secretory pattern of inhibin in the Japanese quail during follicular development, the plasma concentrations of immunoreactive (ir) inhibin were measured from 1 to 7 weeks after hatching. Localization of the inhibin/activin α, βA and βB subunts was investigated by immunohistochemistry. To monitor development of the pituitary and ovarian functions, the plasma luteinizing hormone (LH) and progesterone concentrations were also measured. Ovarian weight increased gradually until 6 weeks of age and then abruptly increased at 7 weeks of age just at the onset of egg production. Plasma concentrations of LH increased significantly at 6 weeks of age. The plasma concentrations of ir-inhibin and progesterone and the pituitary contents of LH also increased significantly at 7 weeks of age. Immunohistochemically, the inhibin/activin α, βA and βB subunts were localized in the granulosa cells of all follicles during different stages of development from 1 to 7 weeks after hatching. The inhibin α, βA and βB subunts were also found in the interstitial cells but not theca cells of all follicles. These results demonstrated that the plasma concentrations of ir-inhibin of the female Japanese quails rose with ovarian development. The immunohistochemical results suggested that granulosa and interstitial cells are the major source of ovarian inhibins in female Japanese quails. Key words: Development, Female quail, Inhibin, Luteinizing hormone (LH), Progesterone (J. Reprod. Dev. 54: [52][53][54][55][56][57] 2008) nhibins and activins are structurally related dimeric gonadal proteins with the ability to regulate follicle-stimulating hormone (FSH) secretion from pituitary glands in mammals [1,2]. Inhibin consists of an α subunit linked by a disulfide bridge to one of the 2 highly homologous β subunits (βA and βB) to form inhibin A (α and βA) or inhibin B (α and βB) [3]. Apart from their action on FSH secretion, inhibins and activins have been shown to exert paracrine/autocrine effects within the gonads [4,5] and other tissues [6]. In mammalian females, the roles played by inhibin/ activin in modulating FSH secretion by the pituitary gland in vivo and in vitro have been well documented. Inhibins selectively suppress [7-12] while activins stimulate [11][12][13][14][15] the release of FSH. Previous studies have shown that the avian ovary also produces inhibins, which plays important roles in the regulation of pituitary FSH [16][17][18][19][20][21]. However, the roles of inhibins have received little attention in quail. As a laboratory animal, the female Japanese quail has been extensively used in reproductive research, because of its adaptability to battery breeding cages, small body size, early sexual maturation, short generation interval, regular egg laying and high egg production. However, studies on the reproductive endocrinology of quails are scarce. Specifically, no research results have been published concerning the secretion of inhibins in female quails. In order to clarify the possible endoc...