瘤胃代谢的神经内分泌调节

反刍动物试验证明,瘤胃液含有17β-雌二醇（E2）、孕酮（P4）和睾酮（T）。E2抑制瘤胃代谢,而P4和T则提高瘤胃代谢水平。这些甾体类激素通过与瘤胃微生物细胞的相应受体结合而直接影响瘤胃内代谢变化。瘤胃液中只发现甲状腺激素的T3,而未检出T4,T3可促进瘤胃微生物代谢活动增强。豆科牧草和大豆含有植物雌激素异黄酮,可提高瘤胃内容物的菌体蛋白、TVFA和氨氮水平。瘤胃液及唾液内发现肽类激素如胃泌素。饲料蛋白在瘤胃内降解可产生一些活性肽,如外啡肽可能起肽类激素的生理作用。半胱胺可耗竭下丘脑和肠道的生长抑素,从而提高生长激素等水平,使瘤胃内代谢及蛋白质合成显著加强。因此,初步认为,瘤胃代谢受神经内分泌的调节,但尚有若干问题有待进一步试验阐明。     

弥散神经内分泌系统研究概论

本文系统概述了弥散神经内分泌系统(DNES)概念的形成、DNES的组成及其细胞结构、功能特点和DNES细胞的鉴定方法,并简要概述了DNES与疾病及免疫的关系。指出从免疫-神经-内分泌网络的角度来揭示DNES与消化道疾病及其黏膜免疫的关系将是研究胃肠道疾病发病机理的一个新思路。     

Salmonellosis in hospitalized horses: seasonality and case fatality rates

Salmonellosis was studied during an 11-year period (July 1971 through June 1982) in 245 hospitalized horses. Ten years' data (207 cases) were analyzed in a time series study. Peak seasonality of the disease was from June through September. The cycle curve revealed 3 major outbreaks, with no apparent periodicity. Eighteen Salmonella serotypes caused clinical salmonellosis in horses, but 84% of the cases and 90% of the deaths were caused by 5 serotypes: Salmonella typhimurium, S typhimurium var copenhagen, S anatum, S kottbus, and S saint-paul. Overall, the case fatality rate was 44.9%. Excluding mixed infections, horses infected with S typhimurium and S typhimurium var copenhagen, had a significantly higher (P less than 0.001) case fatality rate (60.4%) than those infected with other Salmonella serotypes (32.3%).     

Neuroendocrine evaluation of cardiac disease.

Current evidence favors the view that regardless of etiology, there is a predictable sequence of neuroendocrine activation that operates in most dogs and cats with progressive heart disease and that it is largely, but not entirely, independent of etiology. The natriuretic peptides and sympathetic nervous system seem to be early responders to developing cardiac and hemodynamic perturbations in both species. BNP plays a particularly prominent role in cats, possibly as a reflection of disease etiology. Shortly thereafter, plasma endothelin concentrations rise, reflecting the impact of the hemodynamic alterations on the vasculature. Endothelin and the natriuretic peptides directly suppress plasma renin release but have divergent effects on aldosterone. Activation of the tissue RAAS may operate early on to further the progression of heart failure, but evidence of plasma RAAS activation occurs comparatively late and near the time of development of overt CHF. Finally, in animals with severe CHF that are prone to hypotension,vasopressin levels may also rise, contributing to the retention of free water and congestion that is refractory to diuretics. Although oversimplified, this scenario seems to be consistent with data obtained in human, canine, and feline patients. These observations provide some impetus for evaluating ACE inhibitors in cats and beta-receptor-blocking drugs in dogs and cats. Perhaps we are also a little closer to identifying useful biochemical markers that can aid in the diagnosis of heart disease, guide therapy, and improve our understanding of the biologic processes occurring in our patients.     

Neuroendocrine mechanism of seasonal reproduction in birds and mammals

In temperate zones, animals use changes in day length as a calendar to time their breeding season. However, the photoreceptive and neuroendocrine mechanisms of seasonal reproduction are considered to differ markedly between birds and mammals. This can be understood from the fact that the eye is the only photoreceptive organ, and melatonin mediates the photoperiodic information in mammals, whereas in birds, photoperiodic information is directly received by the deep brain photoreceptors and melatonin is not involved in seasonal reproduction. Recent molecular and functional genomics analysis uncovered the gene cascade regulating seasonal reproduction in birds and mammals. Long day‐induced thyroid stimulating hormone in the pars tuberalis of the pituitary gland regulates thyroid hormone catabolism within the mediobasal hypothalamus. Further, this local thyroid hormone catabolism appears to regulate seasonal gonadotropin‐releasing hormone secretion. These findings suggest that although the light input pathway is different between birds and mammals (i.e. light or melatonin), the core mechanisms are conserved in these vertebrates.     

Reproductive seasonality in the mare: neuroendocrine basis and pharmacologic control

Reproductive seasonality in the mare is characterized by a marked decline in adenohypophyseal synthesis and secretion of LH beginning near the autumnal equinox. Thus, ovarian cycles have ceased in most mares by the time of the winter solstice. Endogenous reproductive rhythms in seasonal species are entrained or synchronized as a result of periodic environmental cues. In the horse, this cue is primarily day length. Hence, supplemental lighting schemes have been used managerially for decades to modify the annual timing of reproduction in the mare. Although a full characterization of the cellular and molecular bases of seasonal rhythms has not been realized in any species, many of their synaptic and humoral signaling pathways have been defined. In the mare, neuroendocrine-related studies have focused primarily on the roles of GnRH and interneuronal signaling pathways that subserve the GnRH system in the regulatory cascade. Recent studies have considered the role of a newly discovered neuropeptide, RF-related peptide 3 that could function to inhibit GnRH secretion or gonadotrope responsiveness. Although results that used native peptide sequences have been negative in the mare and mixed in all mammalian females, new studies that used an RFRP3 antagonist (RF9) in sheep are encouraging. Importantly, despite continuing deficits in some fundamental areas, the knowledge required to control seasonal anovulation pharmacologically has been available for >20 yr. Specifically, the continuous infusion of native GnRH is both reliable and efficient for accelerating reproductive transition and is uniquely applicable to the horse. However, its practical exploitation continues to await the development of a commercially acceptable delivery vehicle.     

Reproductive seasonality in Saanen goats kept under tropical conditions

Tropical Animal Health and Production - This study aimed to verify the reproductive seasonality in Saanen goats from distinct parity orders (nulliparous, primiparous, and pluriparous) throughout an...     

Neuroendocrine control of reproductive function in ruminants

Gonadotropin‐releasing hormone (GnRH) is a key molecule in the control of reproduction in mammals. It is generally thought that the secretion of GnRH into the pituitary portal vessels is governed by two distinct neural mechanisms: the pulsatile and surge mode centers. The former is called the GnRH pulse generator, and this neural substrate plays a role as the master regulator of the reproductive function. An electrophysiological technique for monitoring the neural activity of the GnRH pulse generator has been established in the Shiba goat. The central actions of several neuropeptides have been assessed using this system. Results suggest that several neuropeptides including neuropeptide Y, cholecystokinin‐octapeptide and melanocortins are involved in the regulation of the GnRH pulse generator activity in the goat. Each input of those neuropeptides likely represents a unique mechanism conveying specific information about changes in the internal and external environments such as olfactory signals, nutrition, stress, and steroidal milieu, to the GnRH pulse generator. Further elucidations of actions of neurotransmitters on the GnRH pulse generator may serve for better understanding of the neuroendocrine control of reproduction in the ruminant.     

Neuroendocrine carcinoma of the gallbladder in a dog

A 9-year-old Bullmastiff with hematemesis was determined to have primary neuroendocrine carcinoma of the gallbladder. Despite the dismal prognosis when these unusual tumors are located in the liver, the hematemesis resolved, and there was no obvious tumor regrowth in this dog 10 months after cholecystectomy.     

Neuroendocrine carcinoma of the nasopharynx in a dog

Neuroendocrine carcinoma of the nasopharynx was diagnosed in a 9-year-old male Golden Retriever. The mass was identified by computed tomography of the nasal cavity and nasopharyngoscopy, and it was surgically excised. Histologic, cytochemical, and electromicroscopic examination of specimens confirmed the type of tumor. The dog was clincally improved for 150 days but was then reexamined because of respiratory difficulty and poor appetite. Thoracic radiographs revealed multiple nodules in all lung lobes, and ultrasonography revealed a mass in the spleen. The dog died the next day.     

饲粮中添加半纤维素酶对生长猪的促生长作用及其内分泌机制

以“长嘉”二元生长猪为试验对象 ,研究了在稻谷基础饲粮中添加 0 .2 %半纤维素酶对其的促生长作用及内分泌机制。结果表明 ,饲粮中添加半纤维素酶 ,(1)可使生长猪日增重提高 8.78%(P<0 .0 5 ) ,饲料转化率提高 9.42 %(P<0 .0 5 ) ,与玉米饲粮组相比无差异 ;(2 )血清尿素氮水平降低 15 .0 5 %(P<0 .0 5 ) ,胆固醇、甘油三酯、血糖水平分别升高15 .2 1%(P<0 .0 5 )、16 2 .2 2 %(P<0 .0 1)和 32 .6 6 %(P<0 .0 1) ;与玉米饲粮组相比 ,甘油三酯水平升高 40 .48%(P<0 .0 1) ,其他指标则无显著差异 (P>0 .0 5 ) ;(3)血清中胃泌素、胰岛素、T3 、TSH水平分别升高 44 .2 7%(P<0 .0 1)、85 .48%(P<0 .0 5 )、47.0 6 %(P<0 .0 1)和 114.75 %(P<0 .0 5 ) ,对 T4和生长激素的影响不显著 (P>0 .0 5 ) ,与玉米饲粮组相比均差异不显著 (P>0 .0 5 )     

Chromogranin- and Somatostatin-containing Neuroendocrine Cells in the Porcine Uterus An Immunocytochemical Study

Endocrine cells scattered in organic mucosae were defined "Neuroendocrine" (NE) cells because they constitute a section of the Diffuse Neuroendocrine System (DNES). Such cells have never been evidentiated in the normal endometrium. By means of histochemical and immunohistochemical techniques, NE cells, some of which contain the hormone somatostatin, are described in the glandular epithelium of the uterine horn in non-pregnant, non-castrated, young and adult sows. As is known, the uterine horn is the organ of pregnancy in the pig. The localization, distribution and morphology of the uterine NE and somatostatin-containing cells are reported and the importance of their function, in the pregnant and non-pregnant porcine uterus, is discussed.     

Neuroendocrine Cells in the Gastrointestinal Tract of Wild Boar

The presence and the distribution of neuroendocrine cells in the gastrointestinal tract of adult wild boar were investigated. The endocrine cells have been identified by means of immunocytochemical techniques using antibodies against serotonin, gastrin, somatostatin, cholecystokinin (CCK), met-enkephalin (MET-ENK), gastric-inhibitory peptide (GIP) and glucagon. The number of positive cells for each antiserum in each region was evaluated. Results were compared with data present in the literature and obtained previously by us and other authors in swine and domestic mammals (Ceccarelli et al., 1985, 1987, 1990, 1991, 1995; Capella and Solcia, 1972; Domeneghini and Castaldo, 1981; Peranzi and Lehy, 1984; Krause et al., 1985).     

Neuroendocrine Regulation of Growth Hormone and Luteinizing Hormone in Fetal and Neonatal Pig

Ontogeny of the production and the regulation of growth hormone and Luteinizing hormone is studied in a series of experiments utilizing male and female pigs at different fetal and neonatal stages. Growth hormone mRNA is detectable in both sexes as early as d. 50 p.c. The mRNA levels increase to reach the maximum levels at d. 95–110 p.c. Plasma levels of GH follow the developmental patterns of GH mRNA. A sex difference is evident around d. 80–90 p.c. with males having higher GH levels than females. The stimulatory but not the inhibitory mechanisms of GH secretion are fully functioning in the pig fetus. LHβ mRNA is detectable earlier in females (d. 50 p.c.) than in males (d. 65 p.c.). Plasma concentrations of LH increase with fetal age in female fetuses, but in male fetuses there is no distinct developmental pattern evident. Basal LH secretion achieves maximum levels in both sexes after birth. Opioids do modulate fetal LH secretion, however, the mode of their action is age-dependent.     

Hosts, seasonality and geographic distribution of the South African tortoise tick, Amblyomma marmoreum

The tortoise tick Amblyomma marmoreum was collected from large numbers of reptiles and other animals during the course of numerous surveys conducted in South Africa. A total of 1229 ticks, of which 550 were adults, were recovered from 309 reptiles belonging to 13 species, with leopard tortoises, Geochelone pardalis being the most heavily infested. The 269 birds sampled harboured 4901 larvae, 217 nymphs and no adult ticks, and the prevalence of infestation was greatest on helmeted guineafowls, Numida meleagris. Only two larvae were recovered from 610 rodents, including 31 spring hares, Pedetes capensis, whereas 1144 other small mammals yielded 1835 immature ticks, of which 1655 were collected from 623 scrub hares, Lepus saxatilis. The 213 carnivores examined harboured 2459 ticks of which none were adult. A single adult tick and 6684 larvae and 62 nymphs were recovered from 656 large herbivores, and a total of 4081 immature ticks and three adults were collected from 1543 domestic animals and 194 humans. Adult male and female A. marmoreum were most numerous on reptiles during January and February, and larvae during March. The largest numbers of larvae were present on domestic cattle and helmeted guineafowls in the Eastern Cape Province during March or April respectively, whereas larvae were most numerous on helmeted guineafowls, scrub hares and the vegetation in north-eastern Mpumalanga Province during May. In both provinces nymphs were most numerous between October and December. Amblyomma marmoreum appears to be most prevalent in the western regions of the Western and Eastern Cape and Free State provinces, and the north-eastern regions of the Northern Cape, KwaZulu-Natal, Mpumulanga and Limpopo provinces.