A possible role of central serotonin in L-tryptophan-induced GH secretion in cattle
A possible role of central serotonin in L-tryptophan-induced GH secretion in cattle
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DOI：
10.1111/j.1740-0929.2010.00747.x
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发表时间：
2010-01-01
影响因子：
2
通讯作者：
Sutoh, Madoka
中科院分区：
文献类型：
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作者：
Kasuya, Etsuko;Yayou, Ken-ichi;Sutoh, Madoka
为阐明5-羟色胺（5-HT）在色氨酸（TRP）诱导牛生长激素（GH）分泌的调节机制中的作用，同时测定了外周静脉输注TRP前后第三脑室（3V）脑脊液（CSF）中5-HT和血浆中GH浓度的变化。TRP对GH从分散的垂体前叶细胞释放的直接影响也进行了评估。通过立体定位手术将慢性插管置于3V中，然后在生理条件下抽取CSF和血液。从12：00至14：00通过静脉导管输注TRP（38.5 mg/kg BW），从11：00至18：00以1 h间隔采集CSF和血液样本。采用高效液相色谱-电化学检测法测定脑脊液中5-HT的浓度。采用放射免疫法和酶免疫法测定GH、褪黑素（MEL）和皮质醇（CORT）浓度。5-HT浓度增加TRP输注。TRP输注显著增加GH释放。另一方面，TRP不刺激牛垂体细胞的GH释放。MEL和CORT浓度不改变TRP输注。这些结果表明，TRP诱导GH的释放通过激活牛的β-肾上腺素能神经元。
To clarify the role of serotonin (5-HT) in the regulatory mechanism of L-tryptophan (TRP)-induced growth hormone (GH) secretion in cattle, changes in 5-HT concentrations in the cerebrospinal fluid (CSF) in the third ventricle (3V) and GH in plasma before and after the peripheral infusion of TRP were determined simultaneously. The direct effect of TRP on GH release from the dispersed anterior pituitary cells was also assessed. A chronic cannula was placed in 3V by stereotaxic surgery, then CSF and blood were withdrawn under physiological conditions. TRP (38.5 mg/kg BW) was infused through an intravenous catheter from 12.00 to 14.00 hours and CSF and blood sampling were performed from 11.00 to 18.00 hours at 1-h intervals. The concentration of 5-HT in CSF was determined by high-performance liquid chromatography with electrochemical detection. GH, melatonin (MEL), and cortisol (CORT) concentrations were measured by radio-immunoassay and enzyme-immunoassay. Concentrations of 5-HT were increased by TRP infusion. The TRP infusion significantly increased GH release. On the other hand, TRP did not stimulate GH release from the bovine pituitary cells. MEL and CORT concentrations were not altered by TRP infusion. These results suggest that TRP induced GH release via the activation of serotonergic neurons in cattle.