【作者】 刘华珍；

【导师】 彭克美；

【作者基本信息】 华中农业大学 ， 动物遗传育种与繁殖， 2005， 博士

【摘要】 摄食是一种复杂的行为活动,是多种神经递质和调质在下丘脑的广泛区域互作的结果。5-HT是一种经典的神经递质,具有广泛的生物学功能,参与对摄食等功能的调节。有关5-HT的摄食调节作用,在哺乳动物中有一些报道,但在禽类中的报道较少。本研究以樱桃谷鸭为试验动物,采用免疫组化SABC法,从形态学上探讨了5-HT对鸭的摄食调节作用机理。主要研究工作和结果如下: 1 能量条件对鸭下丘脑中5-HT、NPY能神经元的影响 为了探讨5-HT是否也参与禽类的摄食和能量代谢的调节,以及5-HT和NPY对摄食调节的相互作用,本研究选用来自同一父母代的1日龄健康樱桃谷鸭60羽为试验动物,将其随机分为两组,分别饲喂高能和低能日粮,饲养5w后,开始处理动物。将鸭灌流固定后,取下丘脑制作石蜡连续横切片(厚6μm)。采用免疫组化链霉亲和素-生物素-过氧化物酶复合物法(Streptavidin-biotin-peroxidase complexmethod,SABC)进行染色,并用图像分析系统进行半定量分析。结果显示:高能组室旁核(17.73±1.41个/19.46×10~3μm~2)及腹内侧核(15.80±1.71个/19.46×10~3μm~2)有大量的5-HT阳性胞体,低能组外侧区(11.25±1.53个/19.46×10~3μm2)也有大量的5-HT阳性胞体;高能组和低能组下丘脑室旁核、视上核及外侧区均有NPY能阳性神经元分布,低能组下丘脑外侧区和视上核的阳性神经元的平均积分光度显著高于高能组(p<0.01),室旁核中阳性神经元的平均积分光度差异不显著。这一研究结果表明:禽类下丘脑中5-HT能神经元参与摄食和能量代谢的调节;禽类下丘脑中NPY对摄食调节作用部位可能位于下丘脑外侧区与视上核,与哺乳动物的摄食调节通路存在差异;5-HT可能通过抑制下丘脑外侧区NPY的功能而发挥抑制摄食作用。 2 色氨酸对鸭摄食的影响 色氨酸是机体的必需氨基酸,同时也是5-HT合成的前体物质。为了探讨过量的色氨酸是否对鸭产生抑制摄食作用,本研究选用健康樱桃谷鸭为试验动物,禁食更多还原

【Abstract】 The regulation of food intake and energy metabolism involves the interaction of several neurotransmitters and neuromodulators at multiple hypothalamic areas. Serotonin (5-hydroxytryptamine, 5-HT), a classical neurotransmitter, has multiple physiological functions. 5-HT has been suggested to play a modulatory role in the regulation of both central sympathetic and feeding pathways. Although there are some studies on the food intake regulation of serotonin in mammals, few studies have been reported in birds.So in the present study, healthy Cherry Valley Ducks were used to morphologically investigate the mechanism of food intake regulation of serotonin by SABC method. The present study includes four parts:1 The effect of energy on serotonergic and neuropeptide Y neurons in duck hypothalamusIn order to study whether 5-HT participates in food intake regulation in birds and whether there is interaction between 5-HT and NPY in food intake regulation. Sixty healthy Cherry Valley Ducks from the same parents (1 day old) were obtained in the present study. They were divided into two groups at random and fed with high energy feed and low energy feed respectively. After 5 weeks of feeding, they were anaesthetized deeply and men were perfused. The hypothalamus was removed to make serial traverse paraffin sections (6μm thick). The immunohistochemical method streptavidin-biotin-peroxidase complex (SABC) was used to examine the distribution of serotonergic and neuropeptide Y neurons in hypothalamus. All films were analysed by using a computer-assisted image analysis system. The results are as follows: in high energy group, serotonin positive cells are widely distributed in paraventricular nucleus(PVN, 17.73 ± 1.41 neurons/19.46 × 103 μm2) and nucleus ventromedial hypothalamus (VMH, 15.80 ± 1.71 neurons/19.46 × 103 μm2), labeled cells are widely distributed in lateral hypothalamus(LH, 11.25 ± 1.53 neurons/ 19.46 × 103 μ m2) in low energy group;neuropeptide Y neurons are distributed in PVN, supraoptic nucleus(SON) and LH, there is a significant difference when the optical density averages of NPY neurons in SON and LH in low energy group were compared with the high energy group(p<0.01). There is no significant difference in PVN. These results indicate that serotonergic neurons in duck hypothalamus are involved in the regulation of food intake and energy metabolism; the action sites of food intake regulation of hypothalamic NPY are possibly localized in SON and LH, which is different from the food intake regulation pathway of mammals; serotonin inhibits food intake maybe through inhibiting NPY in lateral hypothalamus.2 The effect of tryptophan on duck food intakeTryptophan, an essential amino acid, is the precursor of serotonin. In order to investigate whether excessive tryptophan has inhibition effect on duck food intake, the healthy Cherry Valley Ducks were used in the present study. They were given 12h/12h linght/dark cycle (8:00pm-8:00am light cycle), free standard feeds and water, and housed individually. On the experiment day, they were fasted 4h later (8:00am-12:00am), and different doses of tryptophan were injected intraperitoneally to them. One hour later, preweighed food was introduced into the cages. The amounts of food consumed after 1h, 2h and 4h were determined. The amounts of the food intake were 67.20±0.91 g/kg, 80.74±2.92 g/kg and 87.15±2.53 g/kg 1h, 2h and 4h later respectively in control group. The food intake dose-dependently decreased in experimental groups, and there is a statistically significant diferrence (p<0.01) when compared with the control group. The results indicate that tryptophan peripherally injected dose-dependently inhibited the food intak of ducks.3 The effect of tryptophan on serotonergic and neuropeptide Y neurons in duck brainstemIn order to study the mechanism of food intake inhibition of excessive tryptophan and provide morphological evidence for mechanism of food intake regulation of serotonin,the healthy Cherry Valley Ducks were used in the present study. Different doses of tryptophan were injected intraperitoneally to them, and the SABC method was used to study the distribution of serotonin and NPY in the brainstem. All films were analysed by using a computer-assisted image analysis system. The results are as follows: The serotonin neurons are localized in PVN, mesencephalic lineal nucleus (ML), interpeduncular nucleus(IP), nucleus nervi trochlearis(NIV), tegmental ventral nucleus (TV), nucleus locus ceruleus(LoC), pontine medial nucleus (PM), pontine lateral nucleus (PL) , pontine raphe nuclei(R), nucleus motorius nervi vagi (NX), nucleus nervi hypoglossi(NXn), ambiguus nucleus and reticular nucleus in different groups. The optical density averages of 5-HT in ML, IP, R, PM, PL and LoC in 200 mg / kg and 100 mg / kg group are significantly higher than that of 0 mg / kg group(p<0.01). NPY neurons are distributed in PVN, SON, LH, LoC, R, PM, PL, reticular nucleus and NX. The optical density averages of NPY in PVN and R in 100 mg / kg group and 200 mg/kg group are significantly higher than that of 0 mg / kg group(p<0.01), and the optical density averages of NPY in LoC and LH in 0 mg / kg group are significantly higher than that of 100mg / kg and 200mg/kg group(p<0.01). The results suggest that tryptophan may be absorbed by LoC, R, IP, PM and PL to accelerate the biosynthesis of 5-HT, which has effect on NPY and other factors through the extensive connections with other regions to modulate food intake.4 The effect of tryptophan on serotonergic and neuropeptide Y neurons in duck cerebellumIt has been reported that rat cerebellum participates not only in the regulation of motor but also in the modulation of food intake. In order to investigate whether duck cerebellum is concerned with food intake behaviour, healthy Cherry Valley Ducks were used in the present study. Different doses of tryptophan were injected intraperitoneally to them, and the SABC method was used to study the distribution of serotonin and NPY in the cerebellum. All films were analysed by using a computer-assisted image analysis system. Serotonergic neurons are localized in Purkinje cell layer, and the optical densityaverages of 5-HT in 200 mg / kg group are significantly higher than that of 100 mg / kg and 0 mg / kg group(p<0.01). NPY neurons are distributed in Purkinje cell layer, and the optical density averages of NPY in 0 mg / kg group are significantly higher than that of 100 mg / kg and 200 mg / kg group(p<0.01). These results show that excessive tryptophan can affect the content of 5-HT and NPY in cerebellum; 5-HT in cerebellum is possible to inhibit the expression of NPY; duck cerebellum maybe participates in the regulation of food intake and energy metabolism.更多还原