The effect of zeranol and testosterone on Merino wethers exposed to highly oestrogenic subterranean clover pasture

Groups of Merino wethers treated with 2 doses of zeranol (6 mg and 12 mg), or testosterone cyclopentyl propionate (150 mg) and untreated controls were grazed at 2 sites, one an oestrogenic subterranean clover (Trifolium subterraneum) pasture and the other a low oestrogen medic (Medicago truncatula) pasture. The influence of oestrogenic subterranean clover on these treatments was assessed by measuring changes in teat length, bulbourethral gland weight and pathology, bodyweight, carcase weight, dressing percentage and greasy and clean fleece weights. Teat lengths were increased by all treatments except 6 mg of zeranol where increases were not significant, and although increased by exposure to oestrogenic pasture this effect were not additive. Bulbourethral gland weights were increased by both of the zeranol treatments and by oestrogenic pasture, and these effects appeared to be additive. Differences observed histologically indicated that testosterone protected whereas zeranol exacerbated the influence of oestrogen. The bodyweights of all treated groups were heavier than the controls, but carcase weights were not significantly different. However an effect was seen in the group given the 6 mg dose of zeranol on the low oestrogen site, where the dressing percentage was significantly lower than in the control and testosterone treated groups. Differences in greasy and clean fleece weights were not significant except that the washing yield of the testosterone-treated group was significantly lower at the low oestrogen site.     

Hormone producing ovarian tumours in the dog

In two cases of granulosa cell tumours of the ovary in bitches there was production of sex hormones by the neoplasm. Both tumours produced oestrogens but one also produced significant concentrations of progesterone. In both bitches, the presenting sign was abnormally prolonged oestrus activity. One dog also developed a haemorrhagic diathesis as a result of endogenous oestrogen toxicity.     

Effects of endocrine disrupting compounds on the pathology and oestrogen receptor alpha and beta distribution in the uterus and cervix of ewe lambs

A number of chemicals have been classed as endocrine disrupting compounds due to their ability to mimic the actions of endogenous hormones in vivo and in vitro. The objective of this experiment was to determine the pathological changes and oestrogen receptor (ER) distribution in the cervix and uterus of prepubertal ovariectomised ewe lambs following exposure to a range of compounds with a predominantly oestrogenic effect. Lambs were exposed to diethylstilbestrol (0.175 mg/kg biweekly), bisphenol-A (3.5mg/kg biweekly) or octylphenol (3.5mg/kg biweekly) for 6 weeks. Following sacrifice, uterine and cervical tissue pathology was assessed. The endometrial and myometrial areas were quantified and the distribution of ERalpha and ERbeta assessed by immunohistochemistry. No differences were observed between control and octylphenol-exposed lambs in uterine gross pathology and histopathology. Uteri from bisphenol-A- and diethylstilbestrol-exposed lambs were heavier than both control and octylphenol-exposed lambs. In the bisphenol-A-exposed lambs, endometrial oedema accounted for a significant increase in the endometrial cross-sectional area over the other groups. Uteri from animals exposed to diethylstilbestrol showed variable pathology including oedema and cellular proliferation. Keratinisation of the cervical epithelium was observed in both bisphenol-A- and diethylstilbestrol-exposed lambs. Exposure to diethylstilbestrol and bisphenol-A was associated with a diffuse intracellular distribution of ERalpha and ERbeta in the uterine endometrium. This was in addition to the strong cytoplasmic staining of uterine epithelial cells and nuclear staining of specific sub-epithelial cells observed in all groups. We conclude that a 6-week exposure of lambs to bisphenol-A and diethylstilbestrol altered the uterocervical environment and has the potential to disrupt subsequent reproductive function. Pathological changes could not be detected in the uterus or cervix of lambs exposed to octylphenol.     

浅析反刍动物胃肠道微生物通过肠道－脑轴对宿主的影响

反刍动物胃肠道中存在着众多微生物,如细菌、真菌、原虫和古细菌等。胃肠道微生物对于动物的能量代谢发挥着重要作用,同时对于动物的中枢神经正常功能的发挥也扮演着重要角色。肠道微生物可以与肠道细胞直接接触,不仅产生激活内源性中枢神经系统信号传导机制的代谢物,还可以独立地产生或促成许多神经活性分子的产生。微生物代谢产物和神经活性分子通过神经信号通路、胃肠道内分泌信号通路、免疫系统等关键途径共同形成一个复杂的反射网络,即胃肠道微生物与代谢产物通过传入神经元将信号传导至中枢神经系统。胃肠道微生物与宿主之间通过主要的信号通路相互作用,影响机体胃肠道屏障、营养代谢、免疫应答等生理机能和摄食行为。作者主要从反刍动物胃肠道微生物的种类、微生物通过肠道-脑轴的"自下而上"的传导途径、微生物及其代谢产物通过肠道-脑轴对宿主疾病和行为起到的作用、胃肠道微生物-肠道-脑轴可能的影响因素进行浅析,并对反刍动物胃肠道微生物-肠道-脑轴的研究进行了展望。     

Lectin binding patterns in hyperplastic and metaplastic bullock prostate tissues after diethylstilbestrol administration

Hyperplasia and squamous metaplasia of the prostatic epithelium are conditions induced by oestrogens. Diethylstilbestrol (DES) has been banned from cattle used for beef production because of the health risks. The potential use of molecular markers for the detection of illegal oestrogen administration was evaluated by taking samples of prostatic tissue from control bullocks, bullocks which had been treated with oestrogens, and bullocks sacrificed 21 and 90 days after a single dose of DES. The expression of the glycoconjugates was examined by lectinhistochemistry and the lectin binding pattern was characterised in epithelium and connective tissue. In the animals sacrificed after 21 days there was an increase in the binding of one lectin (JAC) and there was an increase in the binding of one of the other lectins (DBA) in the animals sacrificed after 90 days. An increase in SWGA lectin staining was observed in the bullocks that had probably been treated with oestrogen and in the animals sacrificed 90 days after the inoculation with DES. There were also differences between the binding of SWGA in the control bullocks and the other groups.     

Importance of estrogens and estrogen-active compounds for udder health in cattle. A review

High oestrogen concentrations in blood or high intake of oestrogen-active compounds with forage can be associated with an enhanced occurrence of udder diseases. Mean somatic cell count (MSCC) can increase and milk yield can decrease. Subclinically infected udder quarters can develop clinical mastitis and the rate of new infections can be high. This review describes concentrations of oestrogens in peripheral blood plasma in cattle and occurrence of oestrogen-active compounds in forage. Relationships between oestrogens or oestrogen-active compounds and udder health are presented. The possible mechanisms of enhanced susceptibility of the udder to infection under the influence of oestrogens are discussed.     

Expression of aromatase and oestrogen receptors in reproductive tissues of the stallion and a single cryptorchid visualised by means of immunohistochemistry

Androgen metabolism may proceed to amplify the action of testosterone by its aromatisation to oestradiol. Recently, a growing body of evidence suggests a role of oestrogens in the male reproductive tract via their specific oestrogen receptors (ERs). In order to check whether androgens are converted to oestrogens in the testis, epididymis and prostate of the stallion, the expression of aromatase was visualised by means of immunohistochemistry. Moreover, to show the cellular targets for oestrogens the presence of oestrogen receptor alpha (ERalpha) and oestrogen receptor beta (ERbeta) was demonstrated in these tissues. Finally, to show whether naturally occurring cryptorchidism has any influence on the localisation of aromatase and distribution of ERs, the reproductive tissues of a single horse, bilaterally cryptorchid, were also taken for this study. The results demonstrated that aromatase and ERs are ubiquitously distributed throughout the male reproductive tract, what indicates a putative role of oestrogens in modulating the function of the reproductive tissues of the stallion. In the cryptorchid horse the increase in conversion of androgen to oestrogen was observed as manifested by aromatase overexpression. This is the first report showing the cellular site of oestrogen biosynthesis not only in the testis but also in the epididymis and prostate of sexually mature stallion and a single, adult cryptorchid.     

Expression of GPR30 and GPR43 in oral tissues: deriving new hypotheses on the role of diet in animal physiology and the development of oral cancers

Food components and salivary hormones modulate the function of various tissues in the oral cavity. However, the mechanisms underlying such interactions are poorly understood. This study aimed at the detection of GPR30 and GPR43 in oral epithelia. Although unknown yet, the expression of these receptors is hypothesized to be fundamental for the actions of salivary oestrogens, dietary isoflavones and short chain fatty acids (SCFA) in the oral environment. Either immunoblotting or RT-PCR techniques were used for receptor detection in bovine and primate oral tissues. Here we show for the first time that mRNA of the G-protein-coupled oestrogen receptor, GPR30, and the short chain fatty acid receptor, GPR43, are expressed in bovine parotid glands. Furthermore, GPR30 protein is expressed in bovine parotid gland and the tongue of the primate Theropithecus gelada. With GPR30 being a target for dietary isoflavones and GPR43 being a suggested target for short chain fatty acids, we propose new hypotheses concerning the receptors' roles in salivary gland physiology and pathology. Our findings may trigger more detailed studies on GPRs to unravel their role in regulatory mechanisms in the oral cavity as well as in cancer development in relation to diets or biologically active compounds like soy isoflavones.     

Localization of Oestrogen Receptors in the Epididymis During Sexual Maturation of the Domestic Cat

Oestrogens are involved in regulation of spermatogenesis and sperm maturation and are essential for male fertility. To study the role of oestrogens on epididymal function in the domestic cat, we analyzed the localization patterns of oestrogen receptors (ERs) within the epididymis of juvenile, pubertal and adults using immunohistochemistry. Cat epididymal tissues obtained during routine castrations were fixed in chilled Bouin's solution and processed for immunohistochemistry with ER-specific antibodies. For a certain receptor type, ER localization was influenced by donor age. In the juvenile epididymis, ERα was localized in the nuclei of epithelial cells of efferent ducts and undifferentiated epithelium of the ductus epididymis. During puberty, ERα localization in the undifferentiated epithelium of the epididymis shifted from the nuclei to the cytoplasm and plasma membrane. Oestrogen receptor-α level was highest in the pubertal and adult epididymis, especially within the cytoplasm and in plasma membranes of caput epithelial cells. This finding was suggestive of a role in fluid reabsorption within the efferent ducts and the epididymis. In corpus and cauda regions, ERα was less abundant, suggesting a minor role for oestrogens in sperm storage areas. Interestingly, localization of ERβ was neither influenced by age nor location within the epididymis and was ubiquitous throughout. Results demonstrate that oestrogen actions within the epididymis may be predominantly mediated through ERα during sexual maturation in the domestic cat.     

Seasonal Profiles of Ovarian Activity in Iberian lynx (Lynx pardinus) Based on Urinary Hormone Metabolite Analyses

The Iberian Lynx Ex-Situ Conservation Programme is an essential part of a co-ordinated action plan to conserve the most endangered felid species of the world. Successful captive breeding demands reliable methods for reproduction monitoring including reliable non-invasive pregnancy diagnosis. During a 3-year study, urine samples from six captive Iberian lynx females were obtained (one non-pregnant, one pseudo-pregnant and 11 pregnant cycles). Progesterone, pregnanediol and oestradiol were determined in urinary extracts and relevant urinary oestrogen metabolites were characterized by high-performance liquid chromatography (HPLC). Urinary progestins did not follow the typical pregnancy-related course of felids. In the lynx, we failed to demonstrate an urinary progestin elevation during pregnancy. In contrast, urinary oestrogens increased from 3.8 ± 0.6 to 8.6 ± 0.5 ng/mg creatinine (p < 0.001) during the pregnancy. A comparison of pseudo-pregnant with pregnant cycles revealed a further increase of oestrogens caused by implantation (p < 0.05). In one female, which refused to mate, no difference was estimated between oestrogens levels during the breeding and non-breeding seasons. Almost 10-fold higher oestrogen concentrations were measured in urines of females that shared enclosures with males. HPLC analysis of oestrogens in urine samples collected from Iberian lynx during the pregnancy revealed that lynx urine is composed of two polar oestrogen metabolites in addition to oestrone and minor amounts of oestradiol. Oestrone was detectable in all urinary extracts (8–12% of metabolites), whereas oestradiol was elevated only during late pregnancy (18%). Thus, seasonal luteal activity in Iberian lynx can be monitored by urinary oestrogens. The increase of urinary oestradiol during late pregnancy might indicate an oestradiol secretion by the lynx placenta.     

MASCULINISATION OF THE EXTERNAL GENITALIA IN EWES WITH CLOVER DISEASE

Prolonged exposure of ewes to oestrogenic pasture resulted in partial fusion of the labia of the vulva and hypertrophy of the clitoris. Partial fusion of the labia was also seen in ewes which had grazed oestrogenic pastures on normal commercial properties, and was related to the amount of histological change in the cervix. This lesion may be useful as a screening test for previous exposure to oestrogenic pasture.     

脱氧雪腐镰刀菌烯醇导致厌食和呕吐的机制研究进展

由镰刀菌产生的脱氧雪腐镰刀菌烯醇(DON)广泛存在于谷物及其加工产品中,对动物和人类健康有着潜在的危害。DON具有多方面的毒性作用,而厌食和呕吐是机体摄入DON后出现的最典型症状,厌食和呕吐的产生主要归因于DON对中枢神经系统和胃肠道食欲因子的影响。DON可直接作用于中枢神经系统的呕吐中枢产生呕吐反射,同时激活下丘脑神经元分泌食欲调节因子影响采食;DON可诱导肠内分泌细胞分泌肽YY、胆囊收缩素等食欲调节因子从而引发厌食;DON对中枢神经系统和胃肠道分泌的影响又可通过肠-脑轴产生关联;此外,细胞因子及肠道微生物也部分参与了反应的介导。本文综述了DON诱发机体出现厌食和呕吐的可能机制,以期为找到相应解决措施提供理论指导。     

The effects of ergosterol on the response of female chicks to oral oestrogens and progestogens.

The chick-oviduct assay was used to investigate the effects of dietary ergosterol on the response to oral progestogens and oestrogens. 2. Progestogens alone had no effect on the oviduct but the hypertrophy due to oestrogen was greatly enhanced by simultaneous treatment with progestogen at all dose levels tested. 3. Ergosterol had no effect on any of the responses of the oviduct studied.     

Effects of soya milk on reproductive hormones during puberty in male Wistar rats

Puberty is considered a critical period on development that involved sexual maturation and morphological changes. Isoflavones have been described as endocrine disruptors in male rats. Therefore, the present study attempt to evaluate the effect that daily intake of low and high doses of isoflavones exert into the hormonal regulation that take place during puberty by analyzing the levels of serum and testes steroid and pituitary hormones. 108 male pre‐puberal Wistar rats (30 days old) were randomly divided into three groups; control, low and high doses of isoflavones. Experimental animals were daily dosed orally with low and high doses of a mixture of two soy isoflavones (genistein and daidzein) during 6 weeks. An EIA was performed in serum and testes homogenates for analyzing FSH, LH, P5, P4, DHEA, A4, T, DHT, SO4E1 and E2 hormone concentrations. Results revealed a decrease of an oestrogen environment in testes stimulates the secretion of FSH and LH leading to the production of androgens in the testes at the onset of puberty. Low doses of isoflavones resulted in a significant increase of testes oestrogens that consequently produced a delay on the onset of puberty; however at high doses of isoflavones the maintained oestrogenic environment in the testes prevent the stimulation of the secretion of pituitary hormones and the production of T abolishing the onset of puberty. These results clarify the hormonal mechanisms that take place on puberty and determine the effect of high and low doses of isoflavones at the onset of puberty.     

The molecular basis for bidirectional communication between the immune and neuroendocrine systems

IL-2 has analgesic effects in both central and peripheral nervous systems. There are two distinct domains in IL-2 molecule mediating immunologic and analgesic activity, respectively. The analgesic domain of IL-2 may be composed of the 44th Phe, 45th Tyr, 107th Tyr, and 117th Phe residues that are located closely in the tertiary structure of IL-2. The analgesic activity may be mediated through the analgesic domain interaction with opioid receptor.In addition to peptides, cytokines may directly bind to peptide receptors, other than their specific cytokine receptors themselves. Conversely, peptides may also interact with cytokine receptors. Thus, peptide neurotransmitters and hormones may serve as endogenous regulators of the immune system, and cytokines may also serve as neurotransmitters. Multiple actions might be mediated by interactions between distinct domains of bioactive molecules with different receptors.     

Androgen and oestrogen response to a single injection of hCG in cryptorchid horses

Androgen (testosterone and androstenedione) and oestrogen (oestradiol -17 beta and oestrone) concentrations were measured by radio-immunoassay in the peripheral plasma of two geldings (five-years-old), three bilateral cryptorchids (two, two and a half, and five-years-old) and three normal intact stallions (four, five and five and a half-years-old) before and after a single injection of 10,000 iu human chorionic gonadotrophin (hCG). In the stallions, hCG administration resulted in an immediate sharp increase of conjugated oestrogens and a more gradual increase of unconjugated androgens. In the cryptorchids, the unconjugated androgens increased following a similar pattern to that observed in the stallions, but reached lower peak values, whereas the conjugated oestrogens showed only a very slight increase. In the stallions and cryptorchids, the maximum oestrogen levels were reached two days after injection, whereas the maximal levels for androgens were reached a day later. In the geldings, hCG injection had no effect on plasma steroid levels. It is suggested that the measurement of unconjugated androgens (testosterone or/and androstenedione) before and three days after intravenous injection of 10,000 iu hCG may prove useful for the diagnosis of cryptorchidism or exploration of testicular function in stallions.     

Estrogen determination in the urine of heifers during natural and CAP-affected sexual cycle]

With all differences due to environmental effects and individuality, oestrogen secretion actually follows a typical line of dynamics during one normal sexual cycle. Oestrogen curves were found to rise on the seventh and ninth days of the sexual cycle and to reach a maximum level on the last day. Cycle-depending differences between oestrogen concentrations were found to be leveled on the eighth day, when the oestrus had been synchronised by means of CAP. Oestrogens then went down, in response to synchronisation, up to the 15th day. Both the curve proper and the amount of oestrogens in the given cycle, following synchronised oestrus in heifer, practically were congruent with the values recordable from a normal sexual cycle. Two daily CAP doses of 10 mg per individual did synchronise oestrus in heifer and had no side effects on ovarian function over the following sexual cycle.     

Effects of anabolic implants of oestradiol alone or in combination with trenbolone acetate on the ultrastructure of mammary glands in female lambs regarding their interference in prolactin secretion

The side-effects of anabolic steroid implants on mammary gland ultrastructure were evaluated in female lambs treated with oestradiol (n = 10) and with oestradiol plus trenbolone acetate (n = 10). Ten non-implanted lambs were used as controls. Apart from the ultrastructural study of the mammary gland, an assessment of the prolactin pituitary cell population was carried out by immunological methods. Our results showed that oestrogenic implants exert stimulating effects on mammary gland development, both by activating the synthesis process at mammary gland cell levels and by increasing prolactin pituitary production. Nevertheless, there was no evidence of secretory products in the lumen of the gland. Implants containing trenbolone acetate counteracted the mammary stimulus of oestrogens showing ultrastructural images of cell autolysis and necrosis.     

Making Sense of the Metaphor: How Acupuncture Works Neurophysiologically

Dropping the veil of mystery surrounding acupuncture's effects exposes the compelling and vibrant inner workings of acupuncture based on anatomy and physiology. Shining the light on the mechanisms of acupuncture with a methodical, scientific, and evidence-based approach to equine acupuncture holds the promise of improving treatment consistency and effectiveness. Disentangling acupuncture actions from arcane notions of body function that originated millennia ago requires in-depth study of the nervous system and modern scientific evidence. Abundant information exists concerning the connections between acupuncture anatomy, nerve stimulation, and neuromodulation of the peripheral, central, and autonomic nervous systems. This body of evidence can assist equine practitioners and researchers in approaching acupuncture from a scientific, rather than a metaphorical, platform.     

In utero programming of sexually differentiated gonadotrophin releasing hormone (GnRH) secretion

It has long been recognised that steroids can have both organisational and activational effects on the reproductive neuroendocrine axis of many species, including the sheep. Specifically, if the ovine foetus is exposed to testosterone during a relatively short 'window' of in utero development (from approximately day 30-90 of a 147 day pregnancy) the neural mechanisms regulating gonadotrophin releasing hormone (GnRH) secretion become organised in a male-specific manner. In post-natal life the consequences of foetal androgen exposure are sexually differentiated responses of the GnRH neuronal network to activation by factors such as photoperiod and ovarian steroid hormones. Studies in the gonadectomized lamb have demonstrated that elevated concentrations of oestrogen (E) are unable to trigger a preovulatory-like GnRH surge in the male and the androgenized ewe lamb. Further, these animals have markedly reduced sensitivity to the inhibitory actions of progesterone on tonic GnRH release compared with normal ewes. The reasons for these abnormal steroid feedback mechanisms may reside in sexually dimorphic inputs to the GnRH neurone, including those from oestrogen-receptive neurones in the arcuate nucleus that synthetize the neuropeptide, neurokinin B (NKB). The consequences of in utero androgen exposure are reflected in a progressive and dramatic impairment of fertility in the ovary-intact ewe.