Rumsey T S, Kahl S, Norton S A, Eisemann J, Elsasser T H, Hammond A C, Tyrrell H F, Bitman J
US Department of Agriculture, Livestock and Poultry Sciences Institute, Beltsville, MD 20705.
Domest Anim Endocrinol. 1990 Apr;7(2):125-34. doi: 10.1016/0739-7240(90)90019-v.
This study examined the influence of bovine growth hormone (bGH) on liver and kidney thyroxine-5'-monodeiodinase activity (TMA) in growing beef cattle. In a preliminary trial (trial 1), tissue samples were obtained at slaughter from two placebo-injected and two bGH-injected (29.2 IU/day for 14 days before slaughter) Hereford heifers (398 kg avg slaughter wt), with one heifer on each treatment fed at either 1.0 or 2.0 times maintenance energy requirement. In a second trial, tissue and plasma samples were obtained from six placebo-injected and six bGH-injected (29.2 IU/day for 19 days) Hereford steers (331 kg avg slaughter wt) fed at 1.8 times maintenance energy requirement. In a third trial, liver tissue and plasma samples were obtained from 14 Angus X Hereford steers (270 kg avg wt) fed either an 8% protein, 1.96 Mcal-metabolizable energy/kg diet (8 steers) or a 14% protein, 2.67 Mcal-metabolizable energy/kg diet (6 steers) in association with acute administration of bGH. Half the steers in each group were given two injections per steer of either placebo or 37.8 IU bGH at 24-hr intervals and slaughtered 24 hr after the second injection. Units of tissue TMA in all trials were measured at slaughter; one unit defined as 1 ng T3 generated/hr/mg protein during incubation with T4 (1.3 fM). In trial 1, TMA in liver and kidney was 2.86 and 1.21 times greater, respectively, for bGH than for placebo treatments. In trial 2, units of TMA in liver homogenates were higher (P less than .05) for bGH (4.14) than for placebo (2.83) treatments and higher (P less than .02) in liver microsomal preparations for bGH (32.7) than for placebo (27.3) treatments. Units of TMA in kidney homogenates were also higher (P less than .10) for bGH (1.48) than for placebo (.87) treatments and higher (P less than .02) in kidney microsomal preparations for bGH (23.0) than for placebo (16.4) treatments. Following acute injection of bGH (trial 3), units of TMA in liver homogenates were higher (P less than .01) for bGH (2.5) than for placebo (1.8) treatments. Plasma T4 (70.0 vs 73.5 ng/ml) and T3 (1.08 vs 1.18 ng/ml) concentrations appeared slightly higher in bGH-treated steers (trial 2) and increased by 20 and .5 ng/ml, respectively, (P less than .01) within 6 to 12 h after acute injection of bGH (trial 3). Concurrently, plasma TSH concentration increased following acute GH injection (trial 3).(ABSTRACT TRUNCATED AT 400 WORDS)
本研究考察了牛生长激素（bGH）对生长肉牛肝脏和肾脏甲状腺素-5'-单脱碘酶活性（TMA）的影响。在初步试验（试验1）中，从两头注射安慰剂和两头注射bGH（屠宰前14天每天注射29.2国际单位）的赫里福德小母牛（平均屠宰体重398千克）身上获取组织样本，每种处理的一头小母牛按维持能量需求的1.0倍或2.0倍饲养。在第二项试验中，从六头注射安慰剂和六头注射bGH（每天注射29.2国际单位，共19天）的赫里福德阉牛（平均屠宰体重331千克）身上获取组织和血浆样本，这些阉牛按维持能量需求的1.8倍饲养。在第三项试验中，从14头安格斯×赫里福德阉牛（平均体重270千克）身上获取肝脏组织和血浆样本，这些阉牛分别饲喂含8%蛋白质、1.96兆卡代谢能/千克的日粮（8头阉牛）或含14%蛋白质、2.67兆卡代谢能/千克的日粮（6头阉牛），同时急性注射bGH。每组一半的阉牛每头每隔24小时注射两次安慰剂或37.8国际单位的bGH，并在第二次注射后24小时屠宰。在所有试验中，屠宰时测量组织TMA单位；一个单位定义为与T4（1.3飞摩尔）孵育期间每小时每毫克蛋白质产生1纳克T3。在试验1中，bGH处理组肝脏和肾脏中的TMA分别比安慰剂处理组高2.86倍和1.21倍。在试验2中，bGH处理组（4.14）肝脏匀浆中的TMA单位高于安慰剂处理组（2.83）（P<0.05），bGH处理组（32.7）肝脏微粒体制剂中的TMA单位高于安慰剂处理组（27.3）（P<0.02）。bGH处理组（1.48）肾脏匀浆中的TMA单位也高于安慰剂处理组（0.87）（P<0.10），bGH处理组（23.0）肾脏微粒体制剂中的TMA单位高于安慰剂处理组（16.4）（P<0.02）。急性注射bGH后（试验3），bGH处理组（2.5）肝脏匀浆中的TMA单位高于安慰剂处理组（1.8）（P<0.01）。bGH处理的阉牛（试验2）血浆T4（70.0对73.5纳克/毫升）和T3（1.08对1.18纳克/毫升）浓度似乎略高，急性注射bGH后（试验3），在6至12小时内分别升高20和0.5纳克/毫升（P<0.01）。同时，急性注射生长激素后（试验3）血浆促甲状腺激素浓度升高。（摘要截选至400字）
