Modulation of ovarian function by steroid and inhibin immunization

Terqui, M.; Wrathall, J. H. M.; Driancourt, Marc Antoine; Knight, P. G.

doi:10.1016/0301-6226(95)00019-h

Cited by 8 publications

(6 citation statements)

References 72 publications

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“…Although the mean FSH levels in IMM birds were numerically higher than in control birds at all times throughout the study, this included the preimmunization period, and overall, there was no significant effect of IMM. This result is in contrast to observations in sexually mature mammals that active immunization against inhibin ␣-subunit increased plasma FSH [2,4]. However, active immunization of 3-wk-old lambs against inhibin ␣-subunit had no significant effect on plasma FSH concentrations [42].…”

Section: Fig 5 Concentrations (Ng Per Mg Dna) Of A) Inhibin a And Bcontrasting

confidence: 92%

“…It was hypothesized that interference with this negative feedback action would result in a corresponding increase in FSH leading to enhanced follicular development and an increased ovulation rate. This has been demonstrated in sheep and cattle by passive or active immunization against inhibin [3,4]. However, raised circulating FSH concentrations were not always observed following inhibin immunization (IMM) even when follicle development and/or ovulation rates were enhanced [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Changes in Plasma Inhibin A Levels During Sexual Maturation in the Female Chicken and the Effects of Active Immunization Against Inhibin α-Subunit on Reproductive Hormone Profiles and Ovarian Function1

Lovell

Knight

Groome

et al. 2001

Biology of Reproduction

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Inhibins and activins are firmly implicated in the control of pituitary FSH secretion and ovarian follicular development in mammals. As in mammals, inhibin A and activin A are expressed in the preovulatory follicles of birds, and a defined ovulation cycle for inhibin A has recently been demonstrated in the laying hen. To investigate further the role of inhibin-related proteins in developing pullets, circulating concentrations of inhibin A, inhibin B, total immunoreactive inhibin alpha-subunit (ir-alpha), activin A, LH, FSH, and progesterone were measured from the juvenile state through to sexual maturity in 22 birds. In the 11 birds assigned to control groups, plasma inhibin A levels were low from 7 to 13 wk of age rising about threefold to a peak at Week 19 after which levels fell slightly to a plateau level characteristic of adult hens. Plasma inhibin A levels were negatively correlated with FSH (r = -0. 33; P: < 0.001) and positively correlated with progesterone (r = 0. 67; P: < 0.001) and ir-alpha (r = 0.53; P: < 0.001). Plasma ir-alpha levels were much higher than inhibin A levels although the relative differences varied with age. Plasma levels of inhibin B and activin A were below assay detection limits at all times. The remaining group of 11 birds was actively immunized (IMM) against a synthetic chicken inhibin alpha-subunit peptide (amino acids 1-26). The IMM generated circulating antibodies that bound native bovine inhibin A but altered neither plasma FSH nor progesterone levels relative to control birds at any stage of development nor the timing of first oviposition in week 19. Apart from a transient decline 1 wk after primary IMM, plasma LH concentrations did not differ from controls. Comparison of the numbers and size-class distribution of ovarian follicles at 29 wk showed an approximate twofold increase in the number of 8- to 9.9-mm-diameter follicles (control; 1.82 +/- 0.44 vs. IMM; 3.91 +/- 0.89; P: < 0.05), a size class that corresponds to follicles that have just joined the preovulatory hierarchy. The numbers of growing follicles in other size-classes and the sizes of hierarchical F(1)-F(7) follicles were not altered by IMM. However, the number of postovulatory follicles increased (control 3.73 +/- 0. 20 vs. IMM 5.55 +/- 0.28; P: < 0.01), and significantly more (P: < 0. 02) immunized hens laid two eggs within a 24-h period on at least one occasion (control 1 of 11 vs. IMM 9 of 11). The IMM increased (P: < 0.05) activin A content of F(1) and F(2) theca layers and decreased (P: < 0.05) activin A content in F(3) and F(4) granulosa layers, raising the possibility of a local intraovarian role of activin in mediating the response to IMM. These findings support a role for inhibin A in regulating the entry of follicles into the preovulatory hierarchy in the chicken, although further studies are required to establish the mechanism by which inhibin IMM increases the rate of follicle selection and ovulation without raising plasma FSH.

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Section: Fig 5 Concentrations (Ng Per Mg Dna) Of A) Inhibin a And Bcontrasting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Changes in Plasma Inhibin A Levels During Sexual Maturation in the Female Chicken and the Effects of Active Immunization Against Inhibin α-Subunit on Reproductive Hormone Profiles and Ovarian Function1

Lovell

Knight

Groome

et al. 2001

Biology of Reproduction

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“…Immunoneutralization experiments involving either active or passive immunization have provided good evidence that ovarian inhibin contributes to the negative feedback regulation of follicle-stimulating hormone (FSH) secretion in the ewe (for reviews see Findlay et al 1993, Terqui et al 1995. Various immunogens have been used to generate antibodies against inhibin, including partially purified follicular fluid (FF) preparations, recombinant inhibin subunits and chemically synthesized inhibin fragments.…”

Section: Introductionmentioning

confidence: 99%

“…There is good agreement that active immunization of sheep using any of these different immunogens can increase the ovulation rate. However, the expected rise in circulating FSH levels has not been a consistent finding raising doubts about the mechanism through which active inhibin immunization enhances follicle development and ovulation rate (Findlay et al 1993, Terqui et al 1995.…”

Section: Introductionmentioning

confidence: 99%

Effects of active immunization of sheep against an amino terminal peptide of the inhibin alpha C subunit on intrafollicular levels of activin A, inhibin A and follistatin

Tannetta

Feist²,

Bleach³

et al. 1998

Journal of Endocrinology

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Active immunization of ewes against inhibin (IMM) consistently increases ovulation rate but this response is not always accompanied by the expected rise in plasma FSH. Inhibin-related molecules also have local auto/paracrine effects within the ovary and the ovulatory response to IMM could be due to neutralization of one of these effects, independent of changing FSH levels. To investigate this, ovaries were collected from long-term IMM (n=6) and control (CON; n=8) ewes killed 48 h after progestagen withdrawal (late follicular phase) and all follicles _3 mm were recovered to determine intrafollicular levels of inhibin A, activin A and follistatin by specific two-site immunoassay and oestradiol and testosterone by radioimmunoassay. Blood samples were collected to assess plasma FSH, oestradiol and inhibin antibody titres. Although plasma FSH levels were similar in IMM and CON ewes, IMM ewes had 3-fold more follicles _3 mm (P<0·0001) and 3-fold more oestrogenic follicles (P<0·001) than CON ewes. Compared with CON ewes, follicles from IMM ewes had much higher concentrations of activin A (6-fold; P<0·001) and inhibin A (3-fold; P<0·001) but only slightly more follistatin (1·4-fold; not significant). The activin A:follistatin ratio in follicles from IMM ewes (1:1) was significantly higher (P<0·001) than in follicles from CON ewes (0·3:1). Levels of inhibin antibody measured in follicular fluid (FF) from IMM ewes were similar to plasma levels. Given that activin A has been shown previously to up-regulate FSH receptors and aromatase activity in rat granulosa cells, the increase in intrafollicular activin A, unaccompanied by a rise in the concentration of its binding protein (follistatin), could explain how long-term IMM enhances follicle development and ovulation rate without necessarily promoting a sustained increase in FSH secretion.

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“…Experiments involving passive or active immunization against inhibin, oestradiol, androstenedione or testosterone have provided valuable insights into the complexity of this feedback system , Terqui et al 1995. For instance, passive immunization of ewes against inhibin during the luteal phase of the oestrous cycle raises plasma concentration of FSH without modifying LH concentration (Mann et al 1989) and increases ovulation rate (Wheaton et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Anastomosis of the ovarian vein to the hepatic portal vein in sheep induces ovarian hyperstimulation associated with increased LH pulsatility, but only in the absence of the contralateral ovary

Garcés¹,

Mariana²,

Blanc³

et al. 2000

Journal of Endocrinology

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In this study, two experiments were performed, the first of which examined the ovarian response in ewes that were subject to unilateral ovariectomy (ULO) at different intervals (0-14 days) after surgical anastomosis (AN) of the ovarian vein to the mesenteric vein (n=7 ewes), or sham operation (SO; n=4 ewes). Hypertrophy and development of multiple follicular and luteal structures on AN ovaries were observed after ULO, while SO ovaries remained of normal size and appearance after ULO. The second experiment involving 11 ewes (five AN; six SO) aimed to clarify the mechanism by which AN following ULO-induced ovarian hypertrophy and increased follicle development. The results confirmed that there were more large (>5 mm) follicles on AN compared with SO ovaries; however, their rate of atresia was similar. Oestradiol and progesterone concentrations in follicular fluid of class 1 follicles (5-9 mm) were higher in AN ovaries than those in control follicles of the same size collected in the late follicular phase of an induced oestrous cycle. In AN ewes, intrafollicular progesterone concentrations increased while follicular aromatase activity and intrafollicular oestradiol, inhibin A, follistatin and activin A concentrations all decreased as follicle size increased. Oestradiol and progesterone concentrations were substantially higher in ovarian venous blood than in hepatic venous blood, both in AN and SO ewes, whereas inhibin A levels were not significantly modified by passage through the liver in either group. Mean plasma LH concentration, and LH pulse frequency and amplitude increased markedly after AN but were not affected by SO. Plasma FSH showed only a small transient increase after AN, presumably due to the maintenance of inhibin feedback. Injection of prostaglandin F 2 4 days later did not further modify LH or FSH secretion in either group. Full ovariectomy (FO) 9-14 days after AN or SO increased LH secretion markedly in SO ewes but to a lesser degree in AN ewes; FO induced a large and rapid increase in FSH levels in both groups. In conclusion, AN of the ovary to the liver via the mesenteric vein provides a useful model for studying the feedback between the ovary and the hypothalamo-pituitary system and the mechanisms controlling follicle development. The present results indicate that the pattern of LH secretion is an important factor controlling the terminal phase of follicle development in the ewe.

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Modulation of ovarian function by steroid and inhibin immunization

Cited by 8 publications

References 72 publications

Changes in Plasma Inhibin A Levels During Sexual Maturation in the Female Chicken and the Effects of Active Immunization Against Inhibin α-Subunit on Reproductive Hormone Profiles and Ovarian Function1

Changes in Plasma Inhibin A Levels During Sexual Maturation in the Female Chicken and the Effects of Active Immunization Against Inhibin α-Subunit on Reproductive Hormone Profiles and Ovarian Function1

Effects of active immunization of sheep against an amino terminal peptide of the inhibin alpha C subunit on intrafollicular levels of activin A, inhibin A and follistatin

Anastomosis of the ovarian vein to the hepatic portal vein in sheep induces ovarian hyperstimulation associated with increased LH pulsatility, but only in the absence of the contralateral ovary

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