子午沙鼠的室内繁殖特征

目的了解和掌握子午沙鼠在实验室内繁殖特征。方法根据1996~2002年实验室饲养的子午沙鼠记录数据,推导雌雄体的性成熟期和雌体妊娠期,统计分析不同胎次和月份每窝产仔数、离乳数、成活率和性比结果。结果雌雄体的性成熟期分别为(109.3±21.0)d和(106.3±21.7)d,妊娠期为(21.3±1.4)d;1~7胎各胎次之间出生数和离乳数差异不显著(P0.05),而第4胎和第6胎的成活率低于平均胎仔数,但差异无显著性(P0.05);1~7胎之间雌雄百分比差异没有显著性(P0.05),各胎次平均雌雄比例为1.4∶1.0。在12个月份中,9月-11月停止繁殖,其它各月份之间每窝出生数之间差异不显著(P0.05),每窝离乳数和成活率在部分月份之间差异有显著性(P0.05)。结论与野生子午沙鼠繁殖数据比较,实验室驯化对子午沙鼠繁殖有影响,主要为季节繁殖提前到12月,繁殖窝数增加1~2窝。本结果为该鼠种实验动物化研究提供参考。     

Evidence that short photoperiod-induced gonadal regression in the Mongolian gerbil is mediated by the action of melatonin in the medial hypothalamus

The present study was undertaken to examine the effects of exposure to short photoperiod (SD) and treatment with subcutaneous (s.c.) or intrahypothalamic melatonin-containing beeswax implants on reproduction in the Mongolian gerbil Meriones unguiculatus. Exposure of adult female gerbils to SD (8 h light:16 h dark) causeda significant decrease in weight of the reproductive tract (ovaries, oviducts, uterus and vagina; RTW) compared to animals maintained under stimulatory photoperiod (12 h light:12 h dark;81.4± 8.0mg vs151.8 ± 16.0mg, respectively (P < 0.01)). Treatments with two large s.c, implants, each containing 3 3 mg melatonin, mimicked the antigonadal effect of SD (68.7 ± 3.9g vs118.1 ± 19.5m for the blank (melatonin-free) implant controls P < 0.05). Gerbils with a small melatonin-beeswax pellet (containing 0.2 mg melatonin) in the anterior hypothalamus (AH) underwent a significant reduction in RTW compared to gerbils with a blank intrahypothalamic implant (73.0±5.7mg vs 134.6 ± 14.5mg, respectively; P < 0.01). Melatonin pellets in the mediobasal hypothalamus (MBH) also induced gonadal regression, but toa lesser degree (88.7. ± 12.6mg; P < 0.05 vs blank controls). Small melatonin pellests placed elsewhere in the hypothalamus or s.c. had little effect on RTW (143.4 ± 20.9mg and129.2 ± 19.7mg, respectively). Only 25% of the gerbils with a melatonin pellet in the AH or MBH had a corpus luteum compared to 73% of the blank controls (P < 0.01). Melatonin-treated gerbils had fewer preovulatory follicles (1.2 ± 0.4) than did the blank controls (2.8 ± 0.4; P < 0.05). These results were evidence that adult female Mongolian gerbils are responsive to the antigonadal action of SD, and that this effect may be mediated via the action of melatonin on neurons in the medial AH, and possibly the MBH.     

Immunity to a challenge infection of Strongyloides stercoralis third-stage larvae in the jird

Jirds support the entire life-cycle of Strongyloides stercoralis. We therefore used this host as a model to define the mechanism of the immune response to a challenge infection, as well as the parasite stage effected by the response. Jirds given a primary infection of S. stercoralis are resistant to re-infection. The use of implanted diffusion chambers containing larvae showed that the immune response killed the third-stage larvae, and this was confirmed by subcutaneous infections. The larvae of a challenge infection are killed within 48 h, a time period too short to allow for the development of L4 and adult worms. The immune response is dependent on both a serum factor and cells, suggestive of an ADCC type response.     

杀鼠新灭长爪沙鼠的试验研究

本文报道辽宁化工研究院新近合成的茚满二酮类抗凝血灭鼠剂──杀鼠新对长爪沙鼠的毒力测定、适口性观察及现场杀灭效果试验结果，用孙瑞元（１９６３）简化概率单位法计算，该药对长爪沙鼠的急性口服ＬＤ５０及９５％可信限为２．８２５５±１．７６７４ｍｇ／ｋｇ，ＳＥ５０＝０．１３９０，直线回归方程Ｙ＝３．４３１７＋３．４７６６Ｘ．有选择对比试验，采用敌鼠钠盐毒饵；无选择对比试验，采用无毒饵，摄食系数均大于０．３．用２５、５０、１００ｐｐｍ杀鼠新毒饵进行现场灭效测试，对长爪沙鼠的灭洞率分别为９７．９８％、１００％、１００％，此药在我国广阔的北方沙鼠鼠疫自然疫源地有较大的推广价值     

我国不同流行区周期型马来丝虫动物模型的建立

1985—1988年,在我们实验室建成了安徽泾县、福建建阳、贵州独山、贵州荔波、湖北谷城、四川乐山和浙江安吉七个丝虫病流行区周期型马来丝虫长爪沙鼠模型。上述各地区马来丝虫在沙鼠体内分别传至4、5、5、4、2、3和2代,接种沙鼠的微丝蚴腹腔液症阳性率分别平均为68.33％、51.30％、63.16％、50.00％、62.79％、71.43％和64.10％,各区马来丝虫感染沙鼠的阳性率之间无显著性差异(P>0.05)。     

清洁级长爪沙鼠正常血液生化值

测定了近４００只清洁级长爪沙鼠清蛋白等１５项血液生化值，其甘油三酯（ＴＧ）、尿素氮（ＢＵＮ）、磷（Ｐ）、Ｋ＾＋、Ｎａ＾＋、Ｃｌ＾－略高于人体正常参考值，总蛋白（ＴＰ）、总胆固醇（ＴＣＨＯ）、Ｃａ＾２＋、葡萄糖（ＧＬｕ）、肌酐（ＣＲＥ）、尿酸（ＵＲＡ）结果与人接近；与金黄仓鼠的ＴＰ、ＴＣＨＯ、ＧＬＵ、ＴＧ、ＵＲＡ、ＣＲＥ、Ｃａ＾２＋、Ｐ值接近，ＢＵＮ、Ｃｌ＾－、Ｋ＾＋、Ｎａ＾＋值略高；与豚鼠大鼠的Ｕ     

长爪沙鼠脑缺血模型的建立及脑组织中超氧歧化酶和丙二醛含量的测定

目的建立长爪沙鼠脑缺血模型，用脑含水量对该模型进行评价，并对脑组织中SOD和MDA的含量进行检测，探讨两种物质在脑缺血时的变化规律。方法本实验选用72只成年长爪沙鼠，用单侧结扎颈总动脉的方法制备了长爪沙鼠半脑缺血模型，用脑的含水量对该模型进行了评价，并检测了脑组织中超氧化物歧化酶（SOD）和丙二醛（MDA）的含量。结果用单侧结扎颈总动脉的方法制备长爪沙鼠脑缺血模型时出现临床症状的动物数占总数的为37．5％。与正常组和假手术组相比，脑缺血长爪沙鼠的脑含水量增加，脑组织中SOD活力和MDA的含量均上升。结论用单侧结扎颈总动脉的方法可以建立稳定的长爪沙鼠脑缺血模型，但成模率较低，本实验中脑缺血动物脑组织中SOD活力和MDA含量的变化规律与缺血再灌注模型中所得的结果不尽相同。     

子午沙鼠种群数量动态分析

目的研究引起子午沙鼠种群数量变动的影响因子。方法1991～1998年每年4～10月中旬利用直线夹151法，在达拉特旗沙地草场不同生境内进行数量调查，捕获鼠按常规称重、测量后解剖，详细记录繁殖情况，对有关数据进行分析。结果8年共捕鼠10种8434只，其中三趾跳鼠、小毛足鼠、子午沙鼠和黑线仓鼠数量均超过鼠类群落组成的10％，子午沙鼠位居第3位。子午沙鼠种群数量随季节和年际变化明显，年际数量变动受怀孕率、二次怀孕率、繁殖指数、月捕获率及其他3种鼠数量变化等因素的影响。结论了解子午沙鼠种群数量变化因子及其相互关系，可为预测预报和鼠类防制提供依据。     

Hepatotoxicity and lethality of halomethanes in Mongolian gerbils pretreated with chlordecone,phenobarbital or mirex

The hepatotoxic and lethal effects of CBrCl₃, CCl₄ and CHCl₃ were investigated in gerbils with or without prior exposure to dietary chlordecone (CD), phenobarbital (PB) and mirex (MX) at 10, 225 and 10 ppm, respectively, for 15 days. Gerbils were quite sensitive to these halomethanes (48 h LD₅₀: 20, 80 and 400 l/kg, respectively). CD, known to potentiate hepatotoxic and lethal effects of halomethanes in rats, failed to potentiate the toxic effects of any of these three halomethanes in gerbils. PB and MX were also ineffective. Since stimulation of early hepatocellular regeneration has been shown to be responsible for the recovery from the toxicity of a low dose of CCl₄, liver cell regeneration and tissue repair were studied in gerbils after CCl₄ administration. The objectives of these studies were to investigate the possible reasons for the high sensitivity of gerbils to halomethane toxicity and to investigate the mechanism for their refractoriness to CD-potentiated halomethane toxicity. A low and a high dose of CCl₄ (15 and 80 l/kg, i.p. respectively) were used to study the time-course of liver injury in gerbils pretreated with or without CD. The low dose of CCl₄ stimulated cellular regeneration as indicated by the increase of³H-thymidine (³H-T) incorporation in hepatic nuclear DNA. The cellular regeneration and tissue repair activities resulted in complete recovery from the limited liver injury in both CD-pretreated and control gerbils. In contrast to rats, however, the process of cell division in gerbils occurred much later, 2 days after CCl₄ administration. Evidence from histomorphometric studies was consistent with serum enzyme and³H-T incorporation data. Significant increase in hepatocyte mitosis did not occur until 42 h after CCl₄ administration. Hepatic injury assessed as hepatocellular necrosis and lipid accumulation was evident as early as 24 h after CCl₄ injection and was maximal at 42 and 72 h after CCl₄ in CD-pretreated and control gerbils, respectively. Administration of a high dose of CCl₄ alone significantly impeded tissue repair. More than 65% of the hepatocytes were necrotic in both CD-pretreated and control gerbils 24 h after the administration of a LD₅₀ dose of CCl₄.³H-T incorporation did not increase up to 48 h after CCl₄ in either group. These findings suggest that the absence of early stimulation of hepatocellular division and tissue repair might be responsible for the very high toxicity of a low dose of CCl₄ in gerbils. Since there is no early tissue proliferative response in gerbils after CCl₄ administration, CD+CCl₄ interactive ablation of liver proliferative response cannot occur, making gerbils refractory to CD-potentiation of CCl₄ toxicity.A preliminary report of these findings was presented at the 29th Annual Meeting of the Society of Toxicology at Miami, Florida. Toxicologist (1990) 10: 209Recipient of the 1988 Burroughs Wellcome Toxicology Scholar Award.