Smith L A, Thompson D L, French D D, Leise B S
Department of Animal Science, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge 70803, USA.
J Anim Sci. 1999 Jul;77(7):1815-22. doi: 10.2527/1999.7771815x.
The primary purpose of this experiment was to assess the possible beneficial effects of recombinant equine somatotropin (reST) administration on wound healing in adult geldings. The effects of the 21-d reST treatment on carbohydrate and lipid metabolism and on endogenous ST characteristics were monitored as well. Single, full-thickness skin incisions (7.62 x 7.62 cm) were made in the pectoral region of all geldings on d 0. Treated geldings received reST at 20 microg/kg BW i.m., and control geldings received vehicle (10 mM sodium borate) at equivalent volumes daily from d 0 (immediately after surgery) through d 20. Tracings of the wounds were made with acetate transparencies, and wound areas were calculated via a digital analyzer. In addition to once-daily blood samples collected at specified days throughout the treatment period, an i.v. glucose tolerance test was performed on d 16, and three assessments of endogenous ST secretion were performed in the 2 d immediately following the end of treatment: epinephrine administration during the morning of d 21, an exercise test during the afternoon of d 21, and i.v. aspartic acid infusion on d 22. There was no effect (P > . 1) of reST treatment on wound healing as assessed by changes in wound areas. Daily plasma ST, IGF-I, glucose, and insulin concentrations were higher (P < .05) and urea-nitrogen concentrations were lower (P < .001) in geldings receiving reST relative to controls. Glucose, NEFA, and insulin concentrations were all higher (P < .01) in reST-treated geldings before glucose infusion on d 16, and the responses to glucose were greater (P < .05) as well. Epinephrine administration increased (P < .02) ST concentrations in control geldings on d 21 but not in reST-treated geldings; a similar suppressive effect of reST treatment was observed for the ST response to exercise (P < .001). After aspartic acid infusion on d 22, reST-treated geldings had a much smaller (P < .001) ST response than did control geldings. In conclusion, reST administered to geldings at 20 microg/kg BW i.m. caused hyperglycemia, hyperinsulinemia, insulin insensitivity, mobilization of fatty acids, and an apparent negative feedback on the pituitary's ST response to various stimuli known to induce ST secretion. However, there was no beneficial effect of reST treatment with the wound model used in this experiment.
本实验的主要目的是评估注射重组马生长激素（reST）对成年去势雄马伤口愈合可能产生的有益效果。同时还监测了21天reST治疗对碳水化合物和脂质代谢以及内源性生长激素特征的影响。在第0天，对所有去势雄马的胸部区域进行单次全层皮肤切口（7.62×7.62厘米）。治疗组去势雄马以20微克/千克体重的剂量肌肉注射reST，对照组去势雄马从第0天（手术后立即）至第20天每天接受等量的赋形剂（10毫摩尔硼酸钠）。用醋酸透明片对伤口进行描记，并通过数字分析仪计算伤口面积。除了在整个治疗期间特定日期每天采集一次血样外，在第16天进行了静脉葡萄糖耐量试验，并在治疗结束后的紧接着的2天内对内源性生长激素分泌进行了三次评估：在第21天上午注射肾上腺素，在第21天下午进行运动试验，以及在第22天静脉输注天冬氨酸。通过伤口面积变化评估，reST治疗对伤口愈合没有影响（P>.1）。与对照组相比，接受reST的去势雄马每日血浆生长激素、胰岛素样生长因子-I、葡萄糖和胰岛素浓度较高（P<.05），而尿素氮浓度较低（P<.001）。在第16天葡萄糖输注前，接受reST治疗的去势雄马的葡萄糖、非酯化脂肪酸和胰岛素浓度均较高（P<.01），并且对葡萄糖的反应也更大（P<.05）。在第21天注射肾上腺素后，对照组去势雄马的生长激素浓度升高（P<.02），而接受reST治疗的去势雄马则没有升高；对于运动引起的生长激素反应，reST治疗也有类似的抑制作用（P<.001）。在第22天输注天冬氨酸后，接受reST治疗的去势雄马的生长激素反应比对照组小得多（P<.001）。总之，以20微克/千克体重的剂量肌肉注射reST给去势雄马会导致高血糖、高胰岛素血症、胰岛素不敏感、脂肪酸动员以及对垂体生长激素对各种已知诱导生长激素分泌的刺激的反应产生明显的负反馈。然而，在本实验所使用的伤口模型中，reST治疗没有产生有益效果。
