Law And Role Of Hormones And Their Receptors In Development Of Dairy Goat Mammary Gland

The development of mammal mammary gland is different with other organs, mainly was in the pregnant period. The mammary gland epithelial cell multiplicated and differentiated in this time, and becomed the mature secretion gland, then experience the processes from lactating to involution. Many factors such as hormones regulated its growth, lactation and involution,. The experiments had proven that the progesterone can promote the gland alveolus to grow, the estrogen can be able to promote the ductus to extent, the prolactin played an important part in lactogenesis and lactating, the growth hormone affected mammary gland' through regulation outside and inside the nutrition competition, and can coordinate the estrogen to promote the mammary gland ductus growth.This research taked the diary goats as the object. Using RIA studyed the contents of estrogen, progesterone, prolactin, growth hormone and insulin in the development of mammary gland. Their's receptors were measured by IF and real-time the PCR. From these dates, we can analyze the relationships between hormones, rich the mammary gland growth regulation theory, also provide systemic theory basis for the diary goat industry's development. The results are as follows:The content of E₂ in serum increased significantly from virgin stage to pregnancy stage. And the highest content of E₂ was observed in the late pregnancy (154.385±31.915 pg/ml, P<0.01); In the pregnancy period, the content of P continued to elevate, before the parturition, it arrived to the peak (15.895±2.619 ng/ml, P<0.01). PRL content rised in the pregnancy period, and achieved to the peak in lactogenesis (19.025±4.354 ng/ml, P<0.01). The content of GH showed no significant differences during mammogenesis, lactogenesis, lactation and involution (P>0.05). During the pregnancy period, the content of INS gradually reduced (31.664±6.416 IU/ml, P<0.01).The content of E₂ in mammary gland increased from virgin period to pregnancy period. And the highest content of E₂ was observed in the late pregnancy (285.631±46.506 pg/ml, P<0.01). During the pregnancy stage, the content of P continued to elevate, before the parturition, it got to the peak (8.382±0.920 ng/ml, P<0.01). The content of PRL rised obviously, and reached to the peak in the pregnancy period (20.112±1.319ng/ml, P<0.01); GH didn't change obviously during mammogenesis, lactogenesis and lactation (P>0.05). The content of INS got down gradually (11.670±2.987μIU/ml, P<0.01) in the lactogenesis.The content of E₂ in milk at the lactogenesis was high (585.913±26.659 pg/ml), then droped. The P and PRL contents in milk didn't change obviously in every period (P>0.05). After lactation 1 day, the content of GH in milk dropped (P<0.05). The content of INS didn't began to drop until peak lactation (P<0.01).The expression of ERαwhich was in the mammary gland epithelial cell and the matrix achieved to the peak at the later pregnancy. The expression of PR which was located in the mammary gland EPCs was high during the virgin. In the pregnancy period, it expressed at a low level. GHR expressed in the mammary gland epithelial cell and the matrix, and it's expression reached to higher in the pregnant stage, the later lactation and the earlier involution period. IR mainly located in the mammary gland cell membrane, maintaining at a high level during the pregnant period and the lactation period. The expression of PRLR elevated from the virgin to lactation period, in lactogenesis and lactation the expression of PRLR to be low. In the involution time, the expression of PRLR achieved to the peak.