Zhao F Q, Moseley W M, Tucker H A, Kennelly J J
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada.
J Anim Sci. 1996 Jan;74(1):183-9. doi: 10.2527/1996.741183x.
Primiparous cows received 29 mg of bovine growth hormone (bGH)/d, or 12 mg of bovine growth hormone-releasing factor (bGHRF)/d by continuous i.v. infusion, or no treatment (controls) from 118 to 181 d postpartum. Compared with controls, bGHRF and bGH did not influence the amount of erythrocyte-type glucose transporter (GLUT1) protein in the mammary gland; however, GLUT1 mRNA was increased (P < .01) by bGHRF, but not by bGH. The insulin-responsive glucose transporter (GLUT4) mRNA in skeletal muscle was decreased by 44% (P < .05) as a result of bGH treatment, but there was no significant effect of bGHRF. The GLUT4 mRNA was barely detectable in the omental fat of control cows and became undetectable in bGH-and bGHRF-treated cows. The results of the present study indicate that bGH and bGHRF may increase glucose availability to the mammary gland by regulating glucose transporter expression in skeletal muscle and omental fat. Our data also indicate that the galactopoietic action of bGHRF may not be mediated solely through GH.
初产奶牛在产后118至181天期间，通过持续静脉输注接受29毫克/天的牛生长激素（bGH），或12毫克/天的牛生长激素释放因子（bGHRF），或不接受任何处理（对照组）。与对照组相比，bGHRF和bGH对乳腺中红细胞型葡萄糖转运蛋白（GLUT1）的蛋白量没有影响；然而，bGHRF可使GLUT1 mRNA增加（P <.01），而bGH则无此作用。由于bGH处理，骨骼肌中胰岛素反应性葡萄糖转运蛋白（GLUT4）的mRNA减少了44%（P <.05），但bGHRF没有显著影响。对照组奶牛网膜脂肪中的GLUT4 mRNA几乎检测不到，在接受bGH和bGHRF处理的奶牛中则无法检测到。本研究结果表明，bGH和bGHRF可能通过调节骨骼肌和网膜脂肪中的葡萄糖转运蛋白表达来增加乳腺的葡萄糖供应。我们的数据还表明，bGHRF的泌乳作用可能并非仅通过生长激素介导。
