Expression Of Receptors For GH/IGF-I And Estrogen In Shell Gland Of Laying Hens

The effects of GH/IGF-I and estrogen on shell gland of laying hens were investigated. Developmental changes of shell gland ER-α, GHR and IGF-IR mRNA expression levels were detected by semi-quantitative RT-PCR. Further studies were conducted to determine the changes of shell gland ER-α, GHR and IGF-IR mRNA expression in shell gland after diet supplementation of CT2000 and daidzein feeding to laying hens at the late stage of egg production cycle. In addition, the in vitro effect of daidzein on proliferation and gene expression of shell gland mucosal cells was studied.The present study includes two parts as follows:1. Expression of receptors for GH/IGF-I and estrogen in shell gland of laying hensThe abundances of ER- a , GHR, IGF-IR mRNA in the shell gland were detected by RT-PCR at 105, 209, 385 and 500 day-old laying hens. The results suggested that:The relative oviduct weights at D209 and D385 were significantly (P<0.01, n=10) higher than that at D105, while relative oviduct weight at D500 was reduced compared to that at and D209 and D385 (P<0.05, n=10).The relative abundances of shell gland ER- a mRNA at D209 and D385 was reduced by 54.37% (P<0.05, n=6) and 55.25% (P<0.05, n=6), respectively, comprare to that at D105. No significant differences among age groups were found in mRNA expression of GHR and IGF-IR.2. The effects of CT2000 and daidzein on expression of receptors for GH/IGF-I and estrogen in shell gland of laying hens at the late stage of egg production cycle1) In vivo effect of CT2000 on shell gland gene expression448-day-old laying chickens were divided into control, CT2000-treated anddaidzein-treated groups. CT2000 and daidzein-treated groups were supplemented with 400 ppm CT2000 and 10 ppm daidzein in their basal diet, respectively. Oviduct weight and shell gland ER- a , GHR and IGF-IR mRNA expression levels were measured. The results showed that:Compared to the control, relative oviduct weights in CT2000 and daidzein-treated groups were increased significantly (P<0.05, n=15), suggesting that diet supplementation of CT2000 and daidzein can improve oviduct growth in laying hens.The relative abundance of shell gland ER- a mRNA in CT2000-treated group was reduced by 33.20% (P<0.05, n=9), while the relative abundances of shell gland GHR and IGF-IR mRNA in daidzein-treated were reduced by 47.19% (P<0.05, n=9) and 37.18% (P<0.05, n=9), respectively. The results indicate that CT2000 and daidzein can regulate shell gland growth by reducing ER- a , GHR and IGF-IR mRNA expression,2) In vitro effect of daidzein on mucosal cell proliferation and gene expression of shell gland500-day-old laying hens were selected, and their shell glands were collected to isolate mucosal cells with colloganase. Cultured cells were treated with daidzein at the doses of 10*6M, 10'7M and 10"8M for 24h. Cell proliferation and IGF-IR mRNA level were measured via MTT and RT-PCR. The result showed that daidzein at the dose of 10'6M had significant effect on mucosal cell proliferation (P<0.05, n=ll). An trend of increase (P=0.095, n=5) in expression of IGF-IR mRNA was observed.