Endotoxins in animal feedstuffs

Microbial heat stable endotoxins comprise part of most animal feedstuffs. These components have become the subject of considerable interest in later years because of the demonstration of acute toxicity, intravascular coagulation and generalized Shwartzman’s reaction in connection with intravenous injections of endotoxins (Nordstoga 1976). Endotoxins are normally present in the intestine of man and animals, but seem only to be absorbed under special conditions. Of particular interest is the “sudden infant death syndrome” which has been described for infants receiving cow milk (Di Luzio & Friedmann 1973). Absorption of endotoxins may also occur in adults e.g. in connection with γ-irradiation, immunosuppression, transplantations, severe traumatic lesions and burns (Nordstoga). It is supposed that endotoxins play an important role in the development of shock under these conditions (Nordstoga). Fine (1972) reported that exogenously administered endotoxins may break down the defence mechanisms and lead to continuous absorption of endotoxins from the intestine.     

The endocrine system and the challenge of exercise.

Fine-tuning of the response to exercise that lasts longer than a few seconds is reliant on the regulation of several key variables governing the cardiopulmonary, vascular, and metabolic response to exercise. This type of integrative response requires communication between organ systems that relies on the secretion of endocrine and paracrine substances by one tissue or organ that are transported remotely to other tissues or organs to evoke a response to adjust to the disturbance.     

Stress and the endocrine hypothalamus-pituitary-testis system: a review

Stressors generally induce a depression of the hypothalamus-pituitary-testis (HPT) system, mediated by the activated hypothalamus-pituitary-adrenocortical (HPA) system, resulting in a fall in plasma luteinising hormone (LH) and testosterone levels. Hypothalamic gonadotrophin-releasing hormone (GnRH) secretion may be suppressed by endogenous opioid peptides (EOP) and/or corticosteroids. The latter dramatically enhance the negative feedback effects of testosterone on both the hypothalamus and pituitary. Pituitary gonadotrophin secretion may be reduced by adrenocorticotrophic hormone or by EOP of hypothalamic or pituitary origin. Decreases in plasma concentrations of testosterone, independent of gonadotrophins, can be induced by corticosteroids. These hormones might reduce the number of Leydig-cell LH-receptors or occupation of LH-receptors. Testicular steroidogenesis may also be inhibited by pro-opiomelanocortin-derived (opioid) peptides secreted by the Leydig cells. There are some indications of increases in LH and testosterone during acute stress and, in dominant male animals, during the stress of social conflict. The latter finding indicates a difference in stress response between dominant and subordinate males. In subordinate males, decreased feedback sensitivity may allow hypersecretion throughout the HPA system. As a result, corticotrophin releasing hormone may induce the release of EOP from the hypothalamus, which inhibit the HPT axis. This inhibition may be enhanced by a corticosteroid-induced decrease in testosterone feedback.     

Environmental modulation of the immune system via the endocrine system

Numerous studies have demonstrated that a variety of hormones have receptors and exert biologic actions on tissues of the immune system. Conversely, cytokines exert biologic actions on the endocrine system. This bidirectional interaction is likely involved in maintenance of physiological and immunologic homeostasis. This paper summarizes a variety of actions of growth hormone (GH), prolactin (PRL), insulin-like growth factor-I (IGF-I), glucocorticoids and thyroid hormones (TH) on the immune system. It then proceeds to put these actions into a hypothetical context whereby these hormones may mediate some changes in immune system function in response to environmental stimuli such as physical and emotional stress, nutritional deprivation and environmental temperature. In the first example, it is proposed that PRL secretion in response to stress may serve an immunomodulatory role in two ways. The first is by stimulating the immune system directly and the second is by dampening or reducing the degree to which glucocorticoids are secreted in response to stress. The second example suggests that the increase in GH secretion and reduced IGF-I secretion in response to protein/energy restriction may have two potential immunomodulatory actions. One action is a direct effect of GH on several components of the immune system. The other is the partitioning of nutrient use away from skeletal muscle growth and toward tissues of higher priority such as the immune system. The third example proposes that the increased secretion of TH during cold environmental temperatures not only increases basic metabolic rate, but also directly stimulates both primary and secondary lymphoid tissues. It is suggested, therefore, that these three hormones are involved in maintaining immune system homeostasis in response to environmental change.     

The anatomy and physiology of the avian endocrine system.

The endocrine system of birds is comparable to that of mammals, although there are many unique aspects to consider when studying the anatomy, physiology, and biochemistry. Avian endocrinology is a field of veterinary medicine that is unfamiliar to many practitioners; however, it is important to have a comprehensive understanding when evaluating companion birds in clinical practice. This article covers the anatomy and physiology of the normal avian, and readers are referred to other articles for a more detailed explanation of altered physiology and pathology.     

头孢喹肟注射液的细菌内毒素检查

参照《中国兽药典》2000年版一部附录细菌内毒素检查法进行试验,研究了头孢喹肟注射液细菌内毒素检查法的干扰情况。结果表明,供试品在0.78125 mg/mL稀释液的浓度下对细菌内毒素无干扰作用。通过实验研究,建立了该品种的细菌内毒素限量检查法。     

超早期断奶应激对仔猪内分泌的影响

为研究超早期断奶应激对仔猪内分泌的影响,试 验从２ 窝１４ 日龄杜大长三元杂交商 品猪中各选体重相似公猪２ 头,其中１ 头分至断奶组,另１ 头留为哺乳组,每组２ 个重复（ 栏） , 每重复１ 头猪,试验共用猪４ 头。分别于断奶当天（１４ 日龄） 及断奶后连续９ 天 内早上８ ：００ ,对试猪前腔静 脉采血,采用放免法测定血清皮质醇、 Ｔ３ 、 Ｔ４ 浓度。试验结 果表明,在断奶后１ ～４ 天内,与哺乳仔猪相比, 断奶应激使断奶仔猪血清皮质醇浓度降低, Ｔ４ 浓度升高, Ｔ３ 浓度接近哺乳仔猪,且表现出 Ｔ４ 较 Ｔ３ 更能反映应激效应。在断奶第４ 天以后,皮质醇浓度呈不规则变化, Ｔ３ 、 Ｔ４ 浓度下降,至断奶后第９ 天, Ｔ４ 浓度上升。     

Presence and distribution of neuroendocrine cells in the gastroenteropancreatic endocrine system of fallow deer foetuses

The gastroenteropancreatic endocrine system was studied in 11- and 17-week-old fallow deer foetuses using an immunocytochemical technique. In the gastrointestinal tract, gastrin-, serotonin-, somatostatin- and cholecystokinin-containing cells were found: their frequency and distribution were also determined. Anti-glucagon and anti-insulin antibodies did not stain any cells along the gut. In the pancreas, somatostatin-, pancreatic polypeptide-, insulin- and glucagon-immunoreactive cells were detected. The different distribution and number of neuroendocrine cells, in the two investigated stages of foetal life, are discussed. Data obtained in this study were compared with those published in a previous study on the gastrointestinal system of the adult fallow deer.     

油剂普鲁卡因青霉素注射液细菌内毒素检查方法的研究

对油剂普鲁卡因青霉素注射液细菌内毒素检查方法进行了研究,在样品中加入适量的无菌、无内毒素的０．１ｍｏｌ／Ｌ氢氧化钠％吐温－８０溶液;并用０．１ｍｏｌ／Ｌ盐酸调节样品液的ＰＨ值,解决了样品的溶解方法,。用稀释法排除样品对细菌内毒素检查的干扰。实验结果表明,选用鲎试剂灵敏度为０．５ＥＵ／ｍｌ将样品稀释 １２５００ｕ／ｍｌ的溶液后可消除其干扰作用,因此,用细菌内毒素检查法作为该药品的热原物质检查是可行持     

玉米赤霉烯酮通过干扰内分泌系统造成性成熟雄性大鼠生殖损伤

玉米赤霉烯酮(ZEA),作为一种环境类雌激素物,其对动物及人体健康具有潜在的危害。尤其是,ZEA可能会导致人类不孕不育症。本试验中,给予性成熟的雄性SD大鼠每公斤单次腹腔注射5 mg/kg的ZEA,在随后的48 h内观察检测。可见大鼠血清睾酮(T)和促黄体生成素(LH)在6 h极显著降低,而血清LH在随后12 h又极其显著升高;睾丸环腺苷酸(cAMP)在6 h同样显著下降;同时,睾丸LHR,Star,p450scc,3β-hsd-1 mRNA表达水平在注射ZEA后6 h显著下调。总之,本研究可以得出单次腹腔注射ZEA可能通过扰乱内分泌系统,影响胆固醇合成中关键酶的基因表达,进而抑制睾酮生成,最终造成生殖系统短暂性的损伤。     

细菌内毒素对鸡NLRC5受体及IFN基因转录的影响

本研究旨在探讨鸡NLRC5受体及IFN基因对不同细菌内毒素的诱导表达变化,为禽类NLRC5受体的分子功能及其参与先天免疫调控的作用机制提供理论依据.用不同浓度的(0、0.1、1.0、10.0 μg·mL-1)来自致病性大肠杆菌(E.coli,EC)和肠炎沙门氏菌(S.enteriditis,SE)的2种内毒素(LPS)分别刺激鸡天然巨噬细胞系(HD11)2、4和6h,在不同的时间点收集细胞,提取总RNA,并设计相关引物,利用荧光定量PCR分析鸡NLRC5受体以及下游功能基因IFNA和IFNB的转录量变化,探讨HD11细胞对不同来源的细菌内毒素的免疫反应.研究表明:与对照组相比,1.0和10.0μg·mL-1的EC-LPS、SE-LPS均能诱导HD11细胞产生免疫应答,但0.1μg·mL-1组未能诱导成功;不同细菌LPS诱导的免疫应答时间不一致,经EC-LPS诱导的NLRC5和IFNB基因均在刺激后6h达到转录高峰,与2、4h差异显著(P＜0.05),与对照组差异极显著(P＜0.01);但IFNA基因在2、6h达到高峰,而在4h下降,呈“V”型转录趋势.SE-LPS诱导的NLRC5和IFNA、IFNB转录量随时间均保持一直上升的趋势,在6h达到高峰,且与对照组及2、4h差异显著(P＜0.05).结果表明NLRC5受体与IFNA和IFNs共同参与了细胞对细菌内毒素的免疫应答,NLRC5基因可能对鸡先天免疫功能具有调节作用.     

Some Reproductive and Clinical Aspects of Endotoxins in Cows with Special Emphasis on The Role of Prostaglandins

Endotoxin from Salmonella typhimurium was administered intravenously to 3 cows. It produced an immediate increase in blood prostaglandin metabolite levels causing either luteolysis or a temporary drop in progesterone concentrations depending on the degree of prostaglandin synthesis. The clinical effects on heart rate, respiratory rate, ruminai contraction rate, body temperature and other general signs were studied. The cows showed a transient increase in heart and respiratory rate and a decrease in ruminai activity. The temperature responded by a small initial decrease and a secondary increase. Other symptoms included muscular weakness and shivering, excessive salivation and diarrhoea. Plasma Ca levels showed a direct decrease and then slowly increased to initial levels in the course of several days. The role of endotoxins in Gram-negative infections and their mode of action on the body are discussed with special emphasis on the role of prostaglandins on reproductive function.     

Cross-talk between the immune and endocrine systems

Significant advances have been made in the field of immunophysiology since Selye discovered that acute stressors reduce the size of lymphoid organs. It is known that a variety of hormones other than glucocorticoids affect functional activities of lymphoid cells and macrophages. This paper summarizes recent findings of the effects of glucocorticoids and other hormones on lymphoid cells of domestic animals. Glucocorticoid and beta-adrenergic receptors are up-regulated on activated lymphoid cells. Classic pituitary hormones are synthesized by lymphoid cells, and both growth hormone and prolactin appear to have distinct roles as immunomodulators. In addition, certain activities of lymphoid cells may be behaviorally conditioned. These findings support the hypothesis that changes in the endocrine system affect lymphoid cells. They also suggest that products of the immune system affect the endocrine system. These findings provide a firm functional basis for the possibility of cross-talk between these two physiological systems.     

The biomarker and endocrine disruptors in mammals

The compounds that bind steroid hormone receptors including estrogen receptors (ERs), progesterone receptor (PR) or androgen receptor (AR), and induce or modulate a steroid hormone receptor-mediated response could be defined as endocrine disruptors (EDs). Currently, there are no standard methods to determine whether a chemical is an endocrine disruptor or not. Most results of in vitro and in vivo data are derived from assays that measure estrogenic activity, thus fewer data are available from assays that measure androgenic and progestogenic activities. In this review, we introduce a novel in vivo model to detect EDs using immature rats in the induction of Calbindin-D(9k) (CaBP-9k) mRNA and protein by estrogenic compounds. In addition, we summarize other biomarkers and screening methods for EDs in mammals to describe the usefulness of indicated biomarkers, although mammalian models are very few based on experimental findings.