Changes in the suppressive effects of recombinant inhibin A on FSH secretion in ram lambs during sexual maturation: evidence for alterations in the clearance rate of inhibin

Tilbrook, Alan John; Kretser, David M de; Clarke, Iain J.

doi:10.1677/joe.0.1610219

Cited by 17 publications

(5 citation statements)

References 49 publications

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“…One possible explanation is that the clearance rate of ir-inhibin might be low during this infant period and ir-inhibin might be accumulated in the plasma. A progressive c l e a r a n c e r a t e o f i n h i b i n w i t h a g e w a s demonstrated in a previous study of developing ram lambs [21]. Another possible explanation is that there might be sources of ir-inhibin other than the testis and the extragonadal tissues might secrete high amounts of inhibin in the early infant stage.…”

Section: Discussionmentioning

confidence: 79%

Developmental Changes in Testicular Function and Inhibin Secretion of Golden Hamsters (<i>Mesocricetus auratus</i>)

Itoh

Kishi

Ohshima

et al. 2002

Journal of Reproduction and Development

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Abstract. We studied developmental reproduction of male golden hamsters (Mesocricetus auratus) by determining hormone secretion, observing morphological changes including distribution of immunoexpression of inhibin α subunit, 3β-hydroxysteroid dehydrogenase (HSD), and investigating sperm head count from birth to adulthood. Immunoexpression of inhibin α subunit was found in interstitial cells of not well organized testes of neonatal animals, and positive staining was also found in Sertoli cells in developing animals. However, the intensity of immunostaining in Sertoli cells varied when the spematogenic cycle of the seminiferous epithelium began. Testosterone levels in the plasma and testicular contents of testosterone and immunoreactive (ir)-inhibin increased from around 25 days of age, about 10 days before the presence of the first sperm in the testis. On the other hand, plasma concentrations of ir-inhibin progressively increased from birth to 10 days of age, when it reached peak levels. A reciprocal pattern of change between plasma concentrations of ir-inhibin and FSH was found from 10 days of age. Plasma concentrations and pituitary contents of LH increased from 15 days of age and reached adult levels about 40 days of age. The present results suggest that inhibin is an important factor in the regulation of FSH secretion even in infant male golden hamsters, and the regulated FSH may control the increasing the number of germ cells. Inhibin might be not the only endocrine factor as the regulator of FSH secretion, but also a paracrine or autocrine factor which is involved in spermatogenesis in the golden hamster. Key words: Inhibin, Hamster, Development, Testis (J. Reprod. Dev. 48: [343][344][345][346][347][348][349][350][351][352][353] 2002) arly 20 th century experiments, which were the initial proposal for the existence of inhibin, showed that destruction of the germinal epithelium by irradiation caused hyperfunction in the absence of atrophy of the second sex glands [1], and that injection of aqueous testicular extracts to castrated rats prevented the appearance of enlarged "castration cells" in the pituitary [2,3]. These

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Section: Discussionmentioning

confidence: 79%

Developmental Changes in Testicular Function and Inhibin Secretion of Golden Hamsters (<i>Mesocricetus auratus</i>)

Itoh

Kishi

Ohshima

et al. 2002

Journal of Reproduction and Development

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“…Although GnRH induces the release of FSH, other gonadal factors, including testicular inhibin, can also modulate FSH secretion (Kaneko et al. 1993; Tilbrook et al. 1999).…”

Section: Discussionmentioning

confidence: 99%

Lamprey GnRH‐III Releases Luteinizing Hormone but not Follicle Stimulating Hormone in Pigs

Barretero-Hernandez

Vizcarra

Bowen

et al. 2010

Reprod Domestic Animals

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The effect of exogenous administration of lamprey GnRH-III (IGnRH-III) on gonadotropin secretion was evaluated in pigs. Six crossbred barrows (82.4 ± 3.5 kg body weight) were assigned randomly to a replicated 3 × 3 Latin square design to evaluate the effect of 0.1, 1.0 or 10.0 μg/kg body weight of exogenous IGnRH-III on LH and FSH secretion. To facilitate blood collection and infusion of IGnRH-III, barrows were catheterized in the jugular vein 1 day before initiation of experiments. Blood samples were taken at 10-min intervals for 6 h, starting 2 h before treatments were applied. Relative concentrations of LH and FSH were calculated by obtaining the ratio of the average concentration of each hormone 2 h after infusion divided by the average concentration during the 2 h before infusion. Relative concentrations of FSH after IGnRH-III infusion did not influence mean concentration of FSH at any of the doses; yet 10.0 μg/kg body weight had a significant effect on LH secretion (p < 0.01). Relative concentrations of LH averaged 1.2, 1.0 and 3.0 ng/ml (for doses of 0.1, 1.0 and 10.0 μg/kg body weight of IGnRH-III respectively). Only a dose of 10 μg/kg body weight elicited a significant LH increase that was associated with exogenous IGnRH-III infusion. We conclude that IGnRH-III is a weak GnRH agonist and at high doses, IGnRH-III has the ability to release LH but not FSH in barrows.

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“…However, peaks in FSH concentrations and associated follicular waves in sheep have been observed during both the breeding and nonbreeding seasons [1,9,10,[60][61][62]. The studies showing a negative effect of inhibin on FSH secretion have used various preparations such as follicular fluid (crude inhibin) [63] or human recombinant inhibin A [64], or passive immunization against inhibin [23]. It appears there are no negative relationships between circulating concentrations of inhibin and FSH in physiologically uncompromised ewes [3,10].…”

Section: Discussionmentioning

confidence: 99%

The Effect of the Manipulation of Follicle-Stimulating Hormone (FSH)-Peak Characteristics on Follicular Wave Dynamics in Sheep: Does an Ovarian-Independent Endogenous Rhythm in FSH Secretion Exist?1

Duggavathi

Bartlewski

Agg

et al. 2005

Biology of Reproduction

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We designed three experiments to investigate the relationship between FSH peaks and ovarian follicular waves and to examine whether an endogenous rhythm of FSH peaks exists in sheep. In experiment 1, anestrous ewes were treated with ovine FSH (oFSH) or vehicle (6 ewes per group) at the expected time of an endogenous FSH peak, to double the FSH-peak amplitude in treated ewes. In experiment 2, anestrous ewes were treated with either oFSH or vehicle (6 ewes per group) at the expected time of two consecutive interpeak nadirs, such that the treated ewes had 5 FSH peaks in the time frame of 3 FSH peaks in control ewes. In experiment 3, to measure FSH concentrations, daily blood samples were collected from 5 cyclic ewes for a control period during the estrous cycle and then for three 17-day periods after ovariectomy. Daily blood samples were collected from another group of 8 ovariectomized ewes that were treated with estradiol-releasing implants and intravaginal progestogen sponges. Doubling the FSH-peak amplitude did not alter the characteristics of the following follicular wave. Increasing the frequency of FSH peaks stimulated the emergence of additional follicular waves, but did not alter the rhythmic occurrence of FSH peaks and follicular wave emergence. Endogenous follicular waves in oFSH-treated ewes emerged and grew in the presence of the growing largest follicle of the induced follicular waves. Finally, based on the observation of serum FSH concentrations in ovariectomized ewes, it appears that there exists an endogenous rhythm for peaks in daily serum FSH concentrations, which is, at least in part, independent of regulation by ovarian follicular growth patterns.

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Changes in the suppressive effects of recombinant inhibin A on FSH secretion in ram lambs during sexual maturation: evidence for alterations in the clearance rate of inhibin

Cited by 17 publications

References 49 publications

Developmental Changes in Testicular Function and Inhibin Secretion of Golden Hamsters (<i>Mesocricetus auratus</i>)

Developmental Changes in Testicular Function and Inhibin Secretion of Golden Hamsters (<i>Mesocricetus auratus</i>)

Lamprey GnRH‐III Releases Luteinizing Hormone but not Follicle Stimulating Hormone in Pigs

The Effect of the Manipulation of Follicle-Stimulating Hormone (FSH)-Peak Characteristics on Follicular Wave Dynamics in Sheep: Does an Ovarian-Independent Endogenous Rhythm in FSH Secretion Exist?1

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