Growth hormone (GH) is an essential factor in enhancing the productivity of animals. In ruminants, L-aspartate (L-Asp) stimulates the secretion of GH; however, the effect of D-Asp on GH remains unknown. Here, we examined the effect of D-Asp on GH secretion in wethers. Blood GH, insulin, adrenaline, noradrenaline, non-esterified fatty acid (NEFA), and glucose concentrations were evaluated in response to the intravenous infusion of a high-dose (0.1 mmol/kg/min) of D-Asp for 20 min. Further, concentrations of these biomolecules were evaluated when a low-dose (0.05 mmol/kg/min) of D-Asp was continuously infused intravenously for 20 min. Finally, the direct effect of D-Asp on GH secretion was determined using cultured sections of the anterior pituitary tissue from wethers. Infusion of the high-dose of D-Asp markedly increased blood GH concentrations (P < 0.05), resulting in an increase in the area under the curve (AUC). Plasma GH concentrations and AUC also increased in response to infusion of a low D-Asp dose. Infusion of a high and low D-Asp dose caused a prolonged reduction in plasma insulin concentrations, and the AUC was lower (P < 0.05). Plasma NEFA concentrations gradually increased after the end of D-Asp infusion, with a low D-Asp dose infusion resulting in significantly higher concentrations at 90 min (P < 0.05). Plasma adrenaline, noradrenaline, and glucose concentrations did not show significant changes despite differences in the dose of D-Asp. Although D-Asp treatments stimulated GH secretion in the cultured sections of pituitary tissues, the effect was not significant. These results suggest that D-Asp stimulates the secretion of GH in wethers through not only a direct action on the pituitary gland but also through another pathway of GH stimulation.

中文翻译：

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D-天冬氨酸刺激生长激素分泌。


生长激素 （GH） 是提高动物生产力的重要因素。在反刍动物中，L-天冬氨酸 （L-Asp） 刺激 GH 的分泌;然而，D-Asp 对 GH 的影响仍然未知。在这里，我们检查了 D-Asp 对 wethers 中 GH 分泌的影响。评估静脉输注高剂量 （0.1 mmol/kg/min） D-Asp 20 min 的反应后血液 GH 、胰岛素、肾上腺素、去甲肾上腺素、非酯化脂肪酸 （NEFA） 和葡萄糖浓度。此外，当连续静脉输注低剂量 （0.05 mmol/kg/min） D-Asp 20 分钟时，评估这些生物分子的浓度。最后，使用来自垂体前叶组织的培养切片确定 D-Asp 对 GH 分泌的直接影响。输注高剂量 D-Asp 显着增加血液 GH 浓度 （P < 0.05），导致曲线下面积 （AUC） 增加。血浆 GH 浓度和 AUC 也因输注低剂量 D-Asp 而增加。输注高剂量和低剂量 D-Asp 导致血浆胰岛素浓度长期降低，AUC 较低 （P < 0.05）。D-Asp 输注结束后血浆 NEFA 浓度逐渐增加，低 D-Asp 剂量输注导致 90 分钟时浓度显着升高 （P < 0.05）。尽管 D-Asp 的剂量存在差异，但血浆肾上腺素、去甲肾上腺素和葡萄糖浓度未显示显着变化。尽管 D-Asp 治疗刺激了垂体组织培养切片中的 GH 分泌，但效果并不显着。这些结果表明，D-Asp 不仅通过直接作用于垂体，而且通过另一种 GH 刺激途径刺激 GH 在体内的分泌。