Developmental changes in inhibin α and inhibin/activin βA and βB mRNA levels in the gonads during post‐hatch prepubertal development of male and female chickens

Abstract

Dimeric inhibins and activins are barely detectable in the plasma during prepubertal development of male and female chickens. This may be misconstrued to indicate that the proteins are not produced in the gonads and have no functional significance during this period. Very few studies have actually determined the mRNA expression profile of the inhibin and activin subunits in the gonads prior to puberty in order to establish their secretion at the local level and postulate potential roles for the inhibin and activins at this developmental stage. In this study, the expression of the mRNA for the alpha-, betaA-, and betaB-subunits was determined in the ovary and testis of chickens during prepubertal development. Gene expression was determined at 3, 5, 6, 8, 10, 12, 16, and 18 weeks of age by RT-PCR. Messenger RNA level was quantified by competitive RT-PCR at 3, 6, 12, and 18 weeks of age in order to detect any changes with development, suggest potential relationship to the profile of dimeric inhibins and activins reported previously and to suggest potential paracrine and endocrine roles for them. The results show that all the inhibin/activin subunit mRNAs are expressed in the testis of the chicken throughout the period of prepubertal development up to 18 weeks of age. However, in the ovary, only the betaA- and betaB-subunits were detected at all ages whereas the alpha-subunit mRNA could only be detected just before puberty. Quantification of the mRNA levels showed variation of each subunit with age. These temporal changes suggest relationship with paracrine functional role in the ovary or the testis. Quantitative changes in expression levels also suggests that there may be some relationship between mRNA levels and the type and amount of dimeric inhibins and activins produced at any developmental stage. There are major differences between the male and female gonads in the timing of the expression of different subunits. In conclusion, the expression of the mRNA subunits in the testis and ovary suggests that inhibins and activins are being produced but may be principally involved in autocrine/paracrine function within the gonads.

Secretion of Inhibin in Male Japanese Quail (<i>Coturnix japonica</i>) from One Week of Age to Sexual Maturity

“…The changing levels of each inhibin/activin subunit with age probably indicates changing functional importance during development of the gonads [1]. The pattern of expression of inhibins varies through different stages of development for the male [11][12][13].…”

“…In ducks [20], inhibin/activin subunits are present in Sertoli and Leydig cells during embryonic and newly hatched development, suggesting that monomers of these proteins play an important autocrine or paracrine role during early stages of embryo development. In the chicken [1,18,20], expression of the mRNA subunits in the testis during post-hatch prepubertal development suggests that inhibins and activins are being produced but may principally be involved in autocrine/paracrine functions within the developing gonads. Thus, our present immunohistochemical results also support the suggestion that inhibin/activin subunits from Sertoli and Leydig cells act as a paracrine or autocrine factor involved in testicular development in the Japanese quail.…”

“…In the chicken [1,18,20], expression of the mRNA subunits in the testis during post-hatch prepubertal development suggests that inhibins and activins are being produced but may principally be involved in autocrine/paracrine functions within the developing gonads. Thus, our present immunohistochemical results also support the suggestion that inhibin/activin subunits from Sertoli and Leydig cells act as a paracrine or autocrine factor involved in testicular development in the Japanese quail.The changing levels of each inhibin/activin subunit with age probably indicates changing functional importance during development of the gonads [1]. The pattern of expression of inhibins varies through different stages of development for the male [11][12][13].…”

“…54: [100][101][102][103][104][105][106] 2008) nhibins and activins are growth and differentiation factors that have been localized in both the reproductive and non-reproductive organs. They exert their effects through both endocrine and local (autocrine/paracrine) mechanisms [1]. Inhibins and activins are structurally related dimeric gonadal proteins with the ability to regulate follicle-stimulating hormone (FSH) secretion from the pituitary glands [2,3].…”

Immunolocalization of Inhibin/Activin Subunit Proteins During the Breeding Season in Testes and Scented Glands of Muskrats (Ondatra zibethicus)

“…They exert their effects through both endocrine and local (autocrine/paracrine) mechanisms [18]. Inhibins and activins are structurally related dimeric gonadal proteins with the ability to regulate follicle-stimulating hormone (FSH) secretion from the pituitary glands [26,27].…”