Toxicity of hexachlorobenzene in Meriones unguiculatus: effects on thyroid and liver

The effect of in vivo administered hexachlorobenzene (HCB) on liver and thyroid was studied on Meriones unguiculatus. HCB (1.6, 4, and 16 mg/kg of body weight) has been administered orally to meriones for 30 days. At the end of the experiment, the body weight of the animals did not show significant change. However, the higher dose of HCB treatment led to a pronounced hepatic hypertrophy comparatively to controls. Histological observations revealed many cytomorphological alterations. Cellular necrosis, periportal, and centrolobular vein congestion and cytoplasmic vacuolisation were noted and correlated with the administered doses of HCB. The higher dose of HCB induced modifications in the activities of hepatic transaminases and on thyroid hormones levels: ALAT activity level was more pronounced in males (170+/-24.7 U/l vs. 52.66+/-8.29 U/l in controls) than in females (120+/-12.47 U/l vs. 56+/-5 U/l in controls). However, ASAT activity increased significantly only in females (259+/-29 U/l vs. 244.66+/-18 U/l in controls). Plasma total triiodothyronine (TT3) and total thyroxine (TT4) levels seemed to be sex-dependent in intoxicated animals, since TT4 decreased significantly in males (21.95+/-7.46 nmol/l vs. 40.59+/-1.08 nmol/l in controls) and TT3 in females (1.42+/-0.11 nmol/l vs. 3.96+/-0.48 nmol/l in controls).     

剥夺食物对雄性长爪沙鼠贮食行为的影响

禁食导致一些啮齿动物的贮食量增加,但禁食处理后雄性长爪沙鼠贮食行为的变化则不一致。每天禁食22 h,长爪沙鼠的一些个体表现出高水平的贮食行为(禁食贮食组),而另一些个体则没有表现出贮食行为(禁食无贮食组)。延长禁食(22 h)持续的时间(连续重复3 d 和20 d)和增加禁食时间(禁食48 h),都没有使禁食无贮食组的动物表现出贮食行为。同样在自由取食条件下,长爪沙鼠的贮食行为也表现为二型性。在自由取食和禁食条件下,贮食量与体重、体脂含量和瘦素的浓度之间无明显相关关系。研究结果表明,禁食是诱导雄性长爪沙鼠贮食行为发生的一个重要条件,但增加禁食的程度并不改变其贮食行为的表现。     

Discrimination of individuals by odor in male Mongolian gerbils, Meriones unguiculatus

The ability to discriminate among individuals plays a fundamental role in the establishment of social relationships in animals. We examined how Mongolian gerbils (Meriones unguiculatus) discriminate among individuals using odor. In the first experiment, the ability of male gerbils to discriminate among five odor sources from different individuals was investigated using a habituation-dishabituation paradigm. After male gerbils had been habituated to a scent from one individual, they were exposed to familiar and unfamiliar scents from different donors simultaneously. Where urine and ventral gland secretions were used, the subjects spent more time investigating novel odors than familiar ones, suggesting that they were able to discriminate individual differences in these odor sources. However, with the scents of feces and saliva, they could detect, but could not discriminate individual differences; with scent from inside the pinnae, they could not even detect. In the second experiment, we tested whether cross-habituation occurred between the scents of urine and ventral gland secretions. A male was exposed repeatedly to urine from one of two familiar donor males during four habituation trials, and was then exposed to the ventral gland secretions from two donors simultaneously. The subject males spent more time investigating scents of ventral gland secretions, but there was no difference in the investigation time between ventral gland scents from the two donors. These results suggest that male gerbils discriminate among individuals using odors from urine and ventral gland secretions and that cross-habituation may not occur between these scents during social-memory formation.     

食物蛋白含量对雄性长爪沙鼠社会行为和某些生理特征的影响

为确定食物蛋白对长爪沙鼠行为和生理特征的影响,我们采用两种不同蛋白含量(9% 和27% )的食物饲喂不同年龄的雄性长爪沙鼠,测定了不同食物条件下长爪沙鼠的体重、睾丸重、脾脏重、血清抗体、社会行为和气味吸引力等指标。结果发现,食物蛋白含量没有影响长爪沙鼠的社会行为、生理特征及幼体气味的选择,但对成体气味的被选择程度影响显著,提示食物质量与其配偶选择过程相关联。     

Effects of quinestrol and levonorgestrel on prolactin serum concentration in lactating Mongolian gerbils (Meriones unguiculatus) and reproductive parameters of their offspring

The effects of the two sterilants, quinestrol (QE) and levonorgestrel (LNG) on serum prolactin (PRL) level in lactating Mongolian gerbils and reproductive parameters of their offspring were examined in the study. Both sterilants increased the serum PRL level in lactating gerbils. The body weight as well as weights of the ovary, testis, epididymides, and seminal vesicles were lower, whereas that of the uterus was higher in the pups originating from QE-treated mothers in comparison to controls. Histological ovarian sections of the offspring from QE-treated mothers contained only growing follicles, whereas their uterine sections showed a thinner endometrium, thicker myometrium, and greater epithelial-cell height than in controls. The histometrical testis characteristics as well as sperm concentration and motility of male pups from QE-treated mothers were lower compared to those of the control group. The serum gonadotropin levels of female pups from mothers treated with QE were lower, whereas the serum estradiol (E₂) and progesterone (P₄) levels were higher than in control gerbils. In contrast, serum gonadotropin and testosterone (T) levels of male pups from QE-treated mothers were lower compared to controls. LNG did not affect the examined parameters of the offspring. The offspring from QE-treated mothers was infertile, whereas the offspring from LNG-treated mothers was fertile. In summary, QE and LNG have a stimulatory effect on PRL level in lactating gerbils. It also appears that QE administered via milk to mothers affects reproductive processes of their offspring.     

多巴胺对长爪沙鼠 贮食行为的影响

长爪沙鼠的贮食行为具有高低二型性。禁食诱导的贮食行为可能与中脑多巴胺系统（Dopamine,DA）有关,但尚乏证据。本文通过Fos标记相关脑区的活性,酪氨酸羟化酶（TH）标记DA神经元,以免疫组化方法观察高贮食组沙鼠腹腔注射DA拮抗剂haloperidol （1 mg/kg）和对低贮食组沙鼠腹腔注射DA激动剂apomorphine（0.3 mg/kg）的行为和神经变化,验证中枢DA对贮食行为的调节。结果显示,haloperidol抑制了禁食诱导的沙鼠的贮食行为,这种抑制刺激了伏隔核和尾壳核Fos-ir阳性细胞表达,但却降低了黑质区Fos-ir和Fos-ir/TH-ir的细胞表达。Apomorphine增加了禁食诱导的沙鼠的贮食行为,且降低伏隔核和尾壳核Fos-ir阳性细胞表达。这些结果表明,中脑DA系统参与调节了禁食条件下长爪沙鼠的贮食行为。     

Effect of tamoxifen citrate on reproductive parameters of male dogs

Tamoxifen is a synthetic, nonsteroidal Type I antiestrogenic compound that competitively blocks estrogen receptors with a mixed antagonist-agonist effect. The manifestation of these different actions depends on each species, organ, tissue and cell type considered. Very little is known about the effect of antiestrogens in dogs. The objectives of this study were to determine the effects of tamoxifen citrate on some testis, prostate, hormone, and semen parameters in seven Beagle dogs with uncomplicated spontaneous benign prostatic hyperplasia. Two dogs were normospermic, four were oligozoospermic, and one was azoospermic. The dogs were allocated to a control pre-treatment period, followed by a treatment period, and five post-treatment periods (the duration of each period was 4 weeks). During the treatment period, 2.5mg tamoxifen citrate was given p.o. daily for 28 days to all the dogs. Maximum scrotal width, testicular consistency, libido semen parameters, prostatic volume, serum testosterone concentrations, and side effects were assessed. Tamoxifen negatively affected testis size and libido (P<0.01), and decreased prostatic volume (P<0.01) and testosterone concentrations during treatment. Semen quality deteriorated to nadir values (P<0.01) approximately one spermatic cycle after treatment and returned to pre-treatment values on the second cycle after treatment in all the dogs, except one young oligoazoospermic dog, in which the sperm count was higher ( P<0.01 ) at that time. No side effects were observed and fertility was conserved at the end of the study. Tamoxifen acted more like an agonist than antagonist on the gonadal axis and, therefore, upon both the prostate and testis. Therefore, tamoxifen may have therapeutic applications in dogs.     

Effects of androgen on fighting behavior in male and female Mongolian gerbils (Meriones unguiculatus)

Contrary to the results of most other mammalian species studied thus far, castration in infancy or adulthood has been shown to increase the display of intermale aggression in gerbils tested as adults in dyadic encounters. Males castrated in adulthood were divided into two groups: one that received testosterone propionate (TP) treatment and one that did not. A third group of adult males were sham-operated. Infant subjects were either sham-operated or castrated and tested once without and once with TP. Both infant and adult castrates that received no TP treatment demonstrated significantly more fighting behavior than did sham-operates. Adult subjects treated with TP show significantly less aggression than castrates that did not receive TP. Ovariectomized females were also divided into a TP and no-TP group. Females treated with TP showed significantly less aggression than those that had no treatment showing that TP inhibits aggression in both males and females gonadectomized in adulthood. The results are assessed in terms of the importance of perinatal androgen to “organize” adult behavior patterns.     

Harderian letdown in male mongolian gerbils (Meriones unguiculatus) contributes to proceptive behavior

Adult female gerbils in estrus, like other female rodents, tend to engage in proceptive displays toward conspecific males. The displays, which may be interspersed with the more usual female agonistic activity, if the males are strangers, are preceded by female olfactory investigation of those head areas in the male gerbil where Harderian letdown accumulates most densely. This study explored the possibility that the male Harderian glands are a source of olfactory signals which promote proceptive behavior but suppress female agonistic behavior. Female gerbils in estrus were found to display significantly less than normal rates of proceptive behavior toward Harderianectomized males. The proceptive activity which was observed appeared to be slowed, but the typical pattern was retained. Female aggression, however, was not affected by their estrous condition or by the Harderian state of the males. Possibly Harderian letdown in male gerbils may inform females as to the reproductive competence of the males.     

长爪沙鼠体质量生长模式特征

通过Gompertz方程拟合分析了野外围栏条件下当年春季出生的长爪沙鼠(Merioties unguiculatus)体质量生长模式.结果表明:雌、雄鼠体质量生长系数相近,该结果支持生长系数具有种的特异性,反映物种固有特征的结论;但雄鼠的当年稳定体质量和体质量日瞬时增长率高于雌鼠,雄鼠的体质量增长的拐点时间、生长速率降低到起始值的时间以及达到稳定体质量90%的时间均较雌鼠的晚,这些指标呈现的性别差异提示了长爪沙鼠婚配策略中的多配倾向.     

长爪沙鼠贮食习性的研究

在内蒙古地区,由于野外食物条件的季节变化极为明显,许多种鼠类,特别是不冬眠鼠类,都形成了贮食习惯。对于长爪沙鼠（Ｍｅｒｉｏｎｅｓｕｎｇｕｉｃｕｌａｔｕｓ,简称沙鼠）,夏武平等介绍了内蒙古宝昌县的田间沙鼠洞穴贮粮情况［１］,赵肯堂描述过土默特旗田间沙鼠...     

Effects of aggressive encounters on pineal melatonin formation in male gerbils (Meriones unguiculatus,Cricetidae)

Summary Pineal N-acetyl-transferase activity and radioimmunoassayable melatonin levels were determined in adult male gerbils subjected to aggressive encounters using the intruder-model. In the first experiment, a single encounter of 3 min was applied in the afternoon to intact and to animals with sympathetically denervated pineal organs. Compared with controls, both stressed groups demonstrated a drastic decrease in N-acetyl-transferase activity followed by a slow recovery. In both groups there also occurred a marked change in pineal melatonin content: in intact animals pineal melatonin levels were elevated immediately after the encounter; thereafter, melatonin values decreased. In animals bearing denervated pineal organs melatonin levels fell as a consequence of the encounter. In a second experiment, intact gerbils experienced four daily encounters of 1 min for one week. Thereafter the nocturnal formation of melatonin was studied. In comparison with untreated controls, the repeatedly stressed animals demonstrated a temporal delay in the rise of both N-acetyl-transferase activity and melatonin. Since the pineal organ is able to transduce events of the social environment into an endocrine message — as set forth by both our experiments — the pineal organ might play an important role within central processing of social stress.Abbreviations NAT N-acetyl-transferase - HIOMT Hydroxy-indole-o-methyl-transferase - SCGX Superior cervical ganglion-ectomy     

Developmental changes in several parameters of ultrasonic calling by young Mongolian gerbils (Meriones unguiculatus)

Mongolian gerbils were isolated for one minute on each of the first 14 days of life. The ultrasounds which they produced were displayed on a recorder which allowed measurement of the sound level, duration, shape and temporal patterning of the calls. These components of the pup's response changed with age in various ways. Most of the ultrasounds produced occurred in bouts of regularly spaced calls. The bout length was longest on day 4, and then decreased, but the rate of calling within bouts increased with age. The mean sound level of the calls reached a peak on day 6 and then declined, but one or more pups at each age could produce loud calls. The total rate of production of single calls changed little with age, but production of multiple calls reached a peak on days 4 and 5, and then declined. It seems that the ability of pups to call rapidly and to produce a series of loud, complex calls increases with age. As calling declined, scrabbling movements with the legs increased. Temperature regulation and motor ability are improving during this time. These changes in calling are related to changes in maternal behaviour, especially nest building, which peaked on day 6 in another study. Observations on control litters suggested that daily handling and testing increased the rate of calling on day 5.     

禁食时间对雌性长爪沙鼠免疫功能的影响

动物的免疫系统是防御细菌、病毒等病原体侵害的重要途径,对其生存很重要,而食物短缺是影响动物免疫的重要因素。前期研究发现,禁食3天可抑制雌性长爪沙鼠T细胞介导的免疫功能,而禁食时长可能在影响动物免疫中起重要作用。为此,本实验主要测定不同的禁食时间如何影响雌性长爪沙鼠的免疫功能,该问题的解决有助于理解它们在野外面临食物短缺时的生存状况。将55只成年雌鼠随机分为8组,分别禁食1 d、2 d 、3 d和自由取食,每种处理又分别注射磷酸缓冲液和植物血凝素（PHA）。结果发现,随禁食时间的延长,PHA反应（指示T细胞介导的免疫功能）逐渐受到抑制,胸腺和脾脏逐渐萎缩,表明禁食时间对长爪沙鼠的免疫功能影响显著。同样,随饥饿时间增加,长爪沙鼠的体脂、血糖和血清瘦素水平逐渐下降,并且与PHA反应呈正相关,但白细胞总数和皮质酮水平不受禁食时间的影响。结果表明,禁食时间长短能显著影响雌性长爪沙鼠的免疫功能,随禁食时间的延长,长爪沙鼠T细胞介导的免疫功能逐渐受抑制,这可能与体脂和葡萄糖含量下降有关,血清瘦素逐渐降低也可能是其免疫受抑制的原因。     

自愿转轮运动对雄性长爪沙鼠体重和能量代谢的影响

运动是影响动物能量平衡和体重变化的重要因素之一。为研究自愿转轮运动对体重和能量代谢的影响,我们监测了8 周自愿转轮运动过程中,雄性长爪沙鼠的体重、能量摄入、消化率、静止代谢率(RMR) 和非颤抖性产热(NST)的变化,以及8 周后的体脂含量、血清甲状腺激素(T3、T4 )和瘦素(leptin)水平的变化等。结果发现,8 周自愿转轮运动增加了长爪沙鼠的体重和能量摄入以及血清瘦素水平(血清瘦素浓度比对照组高27% ),但对消化率、RMR 和褐色脂肪组织的线粒体蛋白浓度等没有明显影响。尽管体脂含量和血清T₃ 和T₄ 没有显著差异,但运动组体脂含量比对照组高33%,血清T₃ 和T₄ 水平分别比对照组低10% 和38%。血清瘦素浓度与体脂重量呈正相关。因此,自动转轮运动并没有降低动物的体重和体脂含量,但瘦素和甲状腺素在雄性长爪沙鼠能量代谢和能量平衡中的作用尚需进一步确定。     

Effect of selenium supplementation on some blood biochemical parameters in male rats

The long-term effect of selenium supplementation on blood glutathione peroxidase (GSH-Px) activity and plasma TBARS’ production (as an index of peroxidation) was evaluated in 15-mo-old male rats fed a diet supplemented with 0.25 or 0.50 ppm selenium, for 12 mo. A group of nonsupplemented age-matched rats was the control. In addition, triglycerides, phospholipids, total and free cholesterol, HDL-cholesterol, and HDL-phospholipid levels were measured in plasma. Plasma testosterone levels were also determined in order to control the aging process in these animals. The GSH-Px activity and the peroxidation level were unchanged in all the groups. However, concerning the lipid parameters, a decrease in triglycerides concentration was observed in both treated groups (p<0.05). Therefore, in these experimental conditions, despite no observed changes in parameters related to lipid peroxidation, selenium seems to be involved with triglycerides metabolism, eventually improving the triglycerides status of aged animals.     

雷公藤制剂对雄性长爪沙鼠繁殖功能的影响

为了检测雷公藤制剂对长爪沙鼠繁殖功能的影响,根据预实验结果,将40只雄性长爪沙鼠分为40 mg/kg连续用药4周组(n=16)、100 mg/kg一次给药组(n=10)和1%CMC灌胃对照组(n=14)处理,6周后剖检,比较睾丸、附睾的脏器系数、精子密度、精子活力、精子形态和繁殖率等指标.结果表明40 mg/kg连续用药组鼠的睾丸、附睾脏器系数与对照组比较差异显著;精子密度、精子活力和活精子百分率显著下降;精子畸形率显著上升;繁殖率显著下降(df=1,P<0.05).100 mg/kg一次给药组除附睾脏器系数显著下降、精子畸形率显著上升外,其它指标与对照组无明显差异.该药对长爪沙鼠连续作用4周后不育效果明显,并且具有致畸性,在药物有效范围内,高浓度一次性给药方式不如较低浓度连续多次给药效果显著.