Changes of Hypothalamic GnRH-I, POMC and NPY mRNA Expression and Serum IGF-I and Leptin Concentrations during Maturation of Shaoxing Ducks (Anas platyrhynchos)

Y Ni,L Lu,R Zhao,J Chen

doi:10.5713/ajas.2011.11024

Y Ni, L Lu + Show 2 more

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https://doi.org/10.5713/ajas.2011.11024

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Abstract

Sexual maturity in poultry is controlled by a complex neural circuit located in the basal forebrain, which integrates the central and peripheral signals to activate hypothalamic gonadotrophin-releasing hormone (GnRH) secretion. This study demonstrated the changes of GnRH-I, POMC and NPY mRNA transcription in hypothalamus and IGF-I and leptin levels in serum of Shaoxing ducks during puberty. Body weight increased progressively from d30 to d120 and at d120 the flock reached 5% of laying rate. A significant up- regulation of hypothalamic GnRH-I mRNA expression was observed from d60, reaching the peak at d120. POMC and NPY mRNA expression in hypothalamus showed a similar pattern, which increased from d30 to d60, followed by a significant decrease towards sexual maturity. Serum IGF-I levels exhibited two peaks at d30 and d120, respectively. Serum leptin displayed a single peak at d90. The results indicate that the down-regulation of POMC and NPY genes in hypothalamus coincides with the up-regulation of GnRH-I gene to initiate sexual maturation in ducks. In addition, peripheral IGF-I and leptin may relay the peripheral metabolic status to the central system and contribute to the initiation of the reproductive function in ducks. (Key Words : GnRH-I, POMC, NPY, Leptin, IGF-1, Sexual Maturity, Duck)

Highlights

The acceleration of hypothalamic gonadotrophin-releasing hormone (GnRH) neurons is regarded as the proximal signal for the activation of the pituitary-gonadal axis at the initiation of reproduction (Ebling, 2005)
Hypothalamic GnRH-I mRNA expression did not show a significant change from d30 to d60
A significant up-regulation of hypothalamic GnRH-I mRNA expression was observed after d60, reaching a peak at d120 when the flock had reached 5% of laying rate (Figure 1)

Summary

Introduction

The acceleration of hypothalamic GnRH neurons is regarded as the proximal signal for the activation of the pituitary-gonadal axis at the initiation of reproduction (Ebling, 2005). Till studies on the profile of hypothalamic GnRH-I mRNA expression from earlier growth stage to sexual maturity have not been reported in domestic birds. In order to better The avian myeloblastosis virus (AMV) reverse understand the effects of NPY and beta-endorphin on transcriptase, Taq DNA polymerase and other related regulating GnRH-I synthesis during sexual maturity in birds, reagents were products of Promega, USA.

Results

Conclusion