Defective mucosal immunity and normal systemic immunity of Mongolian gerbils,Meriones unguiculatus,to reinfection with Strongyloides venezuelensis

The systemic and local protective activity of Mongolian gerbils was examined after re-infection with Strongyloides venezuelensis. Mongolian gerbils were unable to expel S. venezuelensis adult worms from the intestine for over ten weeks after a primary infection. Therefore, immune animals were prepared by treating with mebendazole four weeks after a primary infection and then they were challenged by different maturation stages of the parasite; subcutaneous inoculation with the infective larvae ( L₃₎ obtained by faecal culture, oral administration of L3 obtained from the lungs of rats three days after a primary infection, or oral implantation of adult worms obtained from the intestines of rats seven days after a primary infection. The results show that, although immune animals were highly resistant against challenge infection by subcutaneous inoculation with cultured L₃, they were unable to expel orally administered lung-recovered L3 nor orally implanted adult worms. Although potentiated mastocytosis was induced by challenge infections with lung-recovered L₃ and adult worms, all mast cells were formalin-resistant, heparin-containing cells and never seen in the epithelial layer. In spite of the defective protective capacity at the intestinal mucosa, circulating antibody production specific to S. venezuelensis adult as well as L3 antigen was positive. Therefore, the inability of Mongolian gerbils to expel S. venezuelensis adult worms from the intestine seems to be due to the defects of effector/regulator cells, presumably mast cells, but not due to immune unresponsiveness to parasite antigen.     

二连浩特口岸地区沙鼠鼠疫自然疫源地现状分析

目的：掌握二连浩特口岸地区生物群落状况，评估动物鼠疫流行的可能性。方法：通过疫源地现场的动物流行病学调查，参考有关历史资料，进行综合分析。结果：1999～2001年由于连续3年干旱，植被稀矮，主要宿主长爪沙鼠因食源匮乏，繁殖减少，自然死亡增加，种群数量急剧下降，以鼠疫细菌学和血清学方法检验了大量宿主动物和媒介蚤类，未发现阳性材料。结论：1999～2002年动物鼠疫出现了明显间断。但随着长爪沙鼠生存条件变好，数量会迅速回升，有可能出现新的流行。二连浩特口岸地区沙鼠鼠疫自然疫源性将长期存在。     

塔里木盆地子午沙鼠对内蒙古长爪沙鼠鼠疫疫源地鼠疫菌的感受性实验

为研究塔里木盆地子午沙鼠 (Merionesmeridianus)对鼠疫菌的感受性、敏感性及仔鼠体内是否存在母系抗体 ,用分离自内蒙古长爪沙鼠体的鼠疫菌 980 0 5号 ,以 1× 10 1～ 1× 10 9个菌皮下接种从塔里木盆地捕获的子午沙鼠。其在病理改变、感受性、敏感性、二次感染后抗性增强等方面 ,与用新疆乌恰县灰旱獭体分离的 2 110 6号菌株感染子午沙鼠的结果大致相同。二次接种 1× 10 9个鼠疫菌 ,存活鼠在饲养 168d后产仔 ,从父本、母本、仔鼠体内测出鼠疫F1抗体 ,证实了子午沙鼠♀鼠抗体可通过胎盘传递。     

子午沙鼠的室内生长发育观察

目的 对驯养第4代的子午沙鼠进行生长发育和行为观察.方法 对出生至150日龄子午沙鼠进行外观形态、体质量、体长、尾长和后足长测量,测量自我体温调节能力,观察记录形态特征和行为变化.结果 0～5日龄由无毛至出现被毛,外观形态变化大;6～13日龄体毛增长,活动量逐渐增加;14日龄开始睁眼;17日龄开始取食饵料,饵料比例逐渐增加,吸乳量减少;25日龄前体温调节机制尚不成熟;30日龄雌、雄体体质量增长出现分化,雄体略大于雌体;70日龄后雌、雄体增长缓慢,基本达到体成熟.结论 依据该鼠的行为和生长发育特点,其生长发育期划分4个阶段:初生～ 24日龄为乳鼠阶段,25 ～ 40日龄为幼鼠阶段,40 ～ 70日龄为亚成体阶段,70日龄以上为成体阶段.     

封闭群子午沙鼠的寄生虫感染及药物净化效果

目的 为建立清洁级子午沙鼠种群奠定基础,为制定子午沙鼠寄生虫检测标准提供参考依据。方法 对封闭群子午沙鼠寄生虫感染情况进行调查研究,选择胺菊·氯菊酯、吡喹酮、替硝唑三种药物,分为高、中、低剂量对子午沙鼠用药,观察子午沙鼠体内外寄生虫驱除情况。结果 在子午沙鼠体内检出鼠三毛滴虫和短膜壳绦虫两种体内寄生虫,体外寄生虫有鼠肉螨。高、中、低剂量组能不同程度杀死子午沙鼠体表食肉螨,鼠肉螨用1%的胺菊·氯菊酯药浴子午沙鼠三次即可驱除子午沙鼠体表的鼠肉螨,有螨动物只数为零。吡喹酮中剂量组（31 mg/kg）有完全杀死子午沙鼠体内短膜壳绦虫的作用,且为最佳给药剂量。替硝唑中剂量组（42 mg/kg）为净化子午沙鼠体内鼠三毛滴虫的最佳剂量。结论 现有的子午沙鼠体内有鼠三毛滴虫和短膜壳绦虫感染,体外有鼠肉螨寄生,三种抗寄生虫药物具有选择性驱除这些寄生虫的作用。     

Cellular immune response of Mastomys and gerbils in experimental filariasis

Summary
objective  To determine mitogenic and antigen-specific cellular immune responses of two species of rodents, viz . Meriones unguiculatus and Mastomys coucha to assess the usefulness of the A. viteae/Mastomys model for cellular immune studies in experimental filariasis.
methods  Lymphocyte blast transformation test (LTT) using spleen cells of normal and A. viteae infected animals.
results  The proliferative response of gerbils was much higher than that of Mastomys to both ConA and filarial antigens. Cells of both species of rodents did not respond to microfilarial (mf) antigen, however, their mitogenic response differed during infection. Some degree of nonspecific suppression was observed in gerbils during prepatent and patent stages of infection, while Mastomys revealed highest proliferation during patent microfilaraemia. Mastomys cells did not respond to adult or mf antigen,while adult-specific proliferation was detected in the case of gerbils.
conclusion  The A. viteae /gerbil model shows more similarity to human filarial infection regarding cellular immune response. Markedly low responsiveness of a high percentage of Mastomys and wide variations in the cellular response to nonspecific mitogen limit the usefulness of Mastomys coucha in immunological studies, especially cellular immunity.     

Structural and neurochemical plasticity in both supraoptic and paraventricular nuclei of hypothalamus of a desert rodent Meriones Shawi after a severe dehydration versus opposite treatment by rehydration: GFAP and vasopressin immunohistochemical study

Various lines of evidence indicate that astrocytes can undergo morphological changes that modify their relationship to adjacent neurons in response to physiological stimulation such as dehydration. Supraoptic (SON) and paraventricular (PVN) nuclei of hypothalamus represent obvious examples of activity-dependent neuro-astrocytic plasticity. In the present study, Meriones shawi is used as an animal model. Moreover, GFAP and vasopressin expressions are used as indicators successively of astrocytes and neuronal activations. In order to evaluate the reversibility of the neuro-astrocytic plasticity in SON and PVN, prolonged episode of water deprivation followed by episode of rehydration were examined. Hence, we studied the immunoreactivity in various hydration states: water ad libitum, dehydration, and rehydration of animals. Our results showed that dehydration of Meriones induced a significant decrease of GFAP immunoreactivity accompanied by a significant increase of AVP immunoreactivity, the latter concerns both cell bodies and fibers in the same hypothalamic nuclei SON and PVN. Conversely, rehydration of animals shows a reversible phenomenon leading a return of vasopressin and GFAP immunoreactivities to the control level. These results show that both astrocytes and vasopressin neurons display a remarkable structural and physiological plasticity, allowing to M. shawi, a great ability to support the hostile conditions in dry environment.     

Proopiomelanocortin in the arcuate nucleus of the rodent Meriones shawi: Effects of dehydration

Proopiomelanocortin (POMC) is a 36 kDa glycoprotein implicated in homeostatic balance. We used in situ hybridization histochemistry coupled with quantitative autoradiography to determine the anatomical distribution of POMC mRNA-expressing neurons in the arcuate nucleus (AN) and to examine the effects of prolonged dehydration on POMC gene expression in a semi-desert rodent, Meriones shawi (Shaw’s Jird). In the hypothalamus of control animals, POMC mRNA-expressing neurons were exclusively localized in the AN and they showed a differential distribution and density along its rostro-caudal subdivisions. In dehydrated animals, water deprivation caused a decrease in POMC mRNA labeling in the AN. These results suggest that dehydration stress can induce negative regulation of POMC gene expression in this species. A comparative study of weight variation between control and dehydrated animals showed a weight loss followed by stabilization of weight during prolonged dehydration.     

西伯利亚棘球绦虫和多房棘球绦虫泡状蚴在长爪沙鼠体内发育的比较

从内蒙古呼伦贝尔草原捕获的沙狐（Vulpes corsac)小肠中收集到的西伯利亚棘球绦虫（Echinococcus sibiricensis)和多房棘球绦虫（Echinococcus multilocularis）的成虫,经人工感染实验小白鼠,用在小白鼠体内发育的两种泡状蚴（Alveolar echinococcus)的微量物质,分别经腹腔接种到实验室饲养的长爪沙鼠（Meriomes unguiculatus),结果再次证实此两种棘球绦虫具有完全不同发生形式的泡状蚴和不同的宿主反应以及西伯利亚棘球绦虫种的独立性。     

Antifilarial activity in vitro and in vivo of some flavonoids tested against Brugia malayi

We evaluated the antifilarial activity of 6 flavonoids against the human lymphatic filarial parasite Brugia malayi using an in vitro motility assay with adult worms and microfilariae, a biochemical test for viability (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT)-reduction assay), and two animal models, Meriones unguiculatus (implanted adult worms) and Mastomys coucha (natural infections). In vitro, naringenin and hesperetin killed the adult worms and inhibited (>60%) MTT-reduction at 7.8 and 31.2 μg/ml concentration, respectively. Microfilariae (mf) were killed at 250-500 μg/ml. The half maximal inhibitory concentration (IC₅₀) of naringenin for motility of adult females was 2.5 μg/ml. Flavone immobilized female adult worms at 31.2 μg/ml (MTT > 80%) and microfilariae at 62.5 μg/ml. Rutin killed microfilariae at 125 μg/ml and inhibited MTT-reduction in female worms for >65% at 500 μg/ml. Naringin had adulticidal effects at 125 μg/ml while chrysin killed microfilariae at 250 μg/ml. In vivo, 50 mg/kg of naringenin elimiated 73% of transplanted adult worms in the Meriones model, but had no effect on the microfilariae in their peritoneal cavity. In Mastomys, the same drug was less effective, killing only 31% of the naturally acquired adult worms, but 51%, when the dose was doubled. Still, effects on the microfilariae in the blood were hardly detectable, even at the highest dose. In summary, all 6 flavonoids showed antifilarial activity in vitro, which can be classed, in a decreasing order: naringenin > flavone = hesperetin > rutin > naringin > chrysin. In jirds, naringenin and flavone killed or sterilized adult worms at 50 mg/kg dose, but in Mastomys, where the parasite produces a patent infection, only naringenin was filaricidal. Thus naringenin and flavone may provide a lead for design and development of new antifilarial agent(s). This is the first report on antifilarial efficacy of flavonoids.