Abstract:

【Objective】 The aim of the experiment was to investigate the change of growth hormone (GH) and insulin (INS) in development of dairy goat mammary gland, and the expression of growth hormone receptor (GHR) and insulin receptor (INSR) in the same periods. 【Method】The mammary glands of Chinese Guanzhong dairy goats based on the development character were divided into 4 periods, virgin, pregnancy, lactation and involution. The levels of GH and INS in serum were measured by radioimmunoassay (RIA), and the expressions of GHR and INSR in tissue were measured by immunofluorescence (IF).【Result】 No remarkable difference in GH changes (P＞0.05) in serum was observed, but in mammary gland the level of GH reached the peak in late pregnancy (2.599±0.459 ng•mL-1, P＜0.01). The level of INS in serum had no significant difference in virgin (P＞0.05) and in early pregnancy it reached 31.664±6.416 µIU•mL-1 (P＜0.01). In mammary gland INS began to increase after pregnancy and maintained to lactation. The expression of GHR in pregnancy was higher than in virgin and in early metaphase of lactation, and reached maximum at the late of lactation. INSR increased slowly from virgin and reached the top after the lactogenesis. 【Conclusion】 In the development of mammary gland, GH not changed obviously in serum and mammary gland. The content of serum INS gradually reduced during the pregnancy period. While in mammary gland it got down gradually in the lactogenesis. GHR expressed higher in pregnancy, the later lactation and the early involution periods. The expression of INSR maintained at a high level during the pregnant and lactation periods.

Key words: dairy goat')">dairy goat, mammary gland, GH, INS, GHR, INSR