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The studies on leptin, an endocrine factor secreted from adipose tissue, in domestic animals

瘦素（脂肪组织分泌的一种内分泌因子）在家畜中的研究

基本信息

批准号：
09460126
负责人：
YANO Hideo
金额：
$ 8.19万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09460126/
关键词：
Leptin Sheep Cattle Feed intake Cortisol Fattening Carcass traits Adipocyte 脂肪交雑飼料摂取脂肪組織ヒツジ

项目摘要

It has been known that the increase in body fat mass stimulated leptin secretion from adipocytes in rats and humans. Leptin suppressed food intake and increased basal metabolic rate in these animals. However, the action of leptin and the regulation of leptin secretion did not clarified in ruminants. In the first experiment, we intracerebroventricularly injected mouse leptin into sheep. The administration of leptin reduced feed intake and body weight and increased body temperature in sheep, which suggests that leptin suppresses food intake and increases basal metabolic rate in sheep. In the second experiment, we collected blood from sheep at 15-minutes intervals for 24 hours and plasma leptin concentration was determined. Similar to humans, plasma leptin level showed pulsatility in sheep. However, feeding and lightening condition did not affect plasma leptin level. Additionally, plasma leptin level was not affected by plasma cortisol. We suggest that ruminants do not show diurnal rhythms of plasma leptin because postprandial changes in blood glucose and insulin was slight in ruminants. In the third experiment, we collected blood in fattening beef cattle and serum leptin concentrations were determined. Serum leptin level was increased during fattening periods. There was a positive correlation between serum leptin level and marbling score. However the relationship between plasma leptin and subcutaneous fat thickness was not found. These results suggest that leptin adversely affects productivity of beef cattle during late fattening period but beef marbling may be estimated by plasma leptin level in fattening cattle. In the fourth experiment, we tried to manipulate leptin secretion by a dietary factor using isolated rat adipocyte. Vanadium increased leptin secretion from adipocyte. Additionally, the action of vanadium on leptin secretion was additive to the action of insulin, which suggests that vanadium enhances insulin-inducing leptin secretion.

已经知道，在大鼠和人类中，体脂肪量的增加刺激脂肪细胞分泌瘦素。瘦素抑制这些动物的食物摄入并增加基础代谢率。然而，在反刍动物中瘦素的作用和对瘦素分泌的调控尚不清楚。在第一个实验中，我们将小鼠瘦素注入绵羊脑室内。瘦素的施用降低了绵羊的采食量和体重，并增加了体温，这表明瘦素抑制了绵羊的采食量并提高了基础代谢率。在第二个实验中，我们以15分钟的间隔从绵羊中采集血液，持续24小时，并测定血浆瘦素浓度。与人类相似，绵羊血浆瘦素水平呈脉动性。然而，喂养和光照条件不影响血浆瘦素水平。此外，血浆瘦素水平不受血浆皮质醇的影响。我们认为反刍动物血浆瘦素没有昼夜节律，因为反刍动物餐后血糖和胰岛素的变化是轻微的。第三个试验是对育肥肉牛进行采血，测定血清瘦素浓度。血清瘦素水平在肥育期间呈上升趋势。血清瘦素水平与大理石纹评分呈正相关。这些结果表明，瘦素对肥育后期肉牛的生产性能有不利影响，但可以通过肥育后期血浆瘦素水平来评价牛肉大理石花纹。在第四个实验中，我们试图通过一个饮食因素来操纵离体大鼠脂肪细胞的瘦素分泌。万古霉素增加脂肪细胞分泌瘦素。此外，钒对瘦素分泌的作用与胰岛素的作用是相加的，这表明钒增强胰岛素诱导的瘦素分泌。