The effects of cadmium on ALA-D activity, growth and haemoglobin content in the water flea, Daphnia magna

The ALA-D activity, haemoglobin content and growth was studied in the water flea, Daphnia magna, exposed to 0, 0.1, 0.2, 0.4, 0.8 and 1.6 micrograms Cd/l. The ALA-D activity in water fleas exposed to 0.2-1.6 micrograms Cd/l fluctuated around the control value. The activity in animals exposed to 0.1 micrograms Cd/l decreased during the entire experiment. After 16 days exposure to cadmium the haemoglobin content in water fleas ranged between 80 and 31% of control value. In animals exposed to 0.8 and 1.6 micrograms Cd/l the haemoglobin content decreased progressively during the experiment. Growth was not affected by cadmium at these concentrations.     

Apoptosis and regeneration of the gastric mucosa under the action of S-phase-specific agent, hydroxyurea

The treatment of periodic injections of hydroxyurea to mice on the processes of regeneration in gastric mucosa was studied. In all experimental groups of animals dystrophic and atrophic changes of gastric mucosa could be observed. The phenomena of dystrophy were more pronounced. If the time of the experiment was not more than 4 days apoptosis bodies could be found only in the epithelium. The long-term duration of the experiment resulted in increased death of apoptosis bodies inside the glands, and development of atrophy of gastric mucosa.     

The effects of hormonal and circadian cycles, stress, and activity on levels of cyclic AMP and cyclic GMP in pituitary, hypothalamus, pineal and cerebellum of female rats

Cyclic AMP and cyclic GMP levels were measured in the anterior and posterior pituitary, hypothalamus, pineal and cerebellum of female rats sacrificed during proestrus, metestrus and diestrus. In the first experiment rats were sacrificed by microwave irradiation between 0900 and 1100, between 1600 and 1800 and between 2100 and 2300. Cyclic AMP and cyclic GMP levels did not vary in any region tested as a function of the estrous cycle except for slightly elevated cyclic GMP levels in the posterior pituitary during proestrus. However the time of day at which the animals were sacrificed affected levels of cyclic AMP in the hypothalamus and cerebellum and levels of cyclic GMP in the cerebellum. In a second experiment female rats were all sacrificed between 2130 and 2330 during proestrus and diestrus. In this experiment rats were sacrificed either immediately upon removal from the home cage or after 10 min of immobilization stress, or after 10 min of open field activity. No differences in pituitary cyclic nucleotides were seen between proestrous and diestrous animals. However, stressed animals showed large cyclic AMP increases in the pituitary, and activity increased cyclic GMP levels in the cerebellum and pineal.     

The effect of size,age, and recent egg laying on copulatory choice of the hermaphroditic mollusc Aplysia juliana

Summary

Aplysia juliana is a cross-fertilizing, simultaneous hermaphrodite. During copulation, an individual may act as either a sperm donor or a sperm recipient, or both, when a pair copulates reciprocally. Experiments were conducted with A. juliana to determine if an animal's size, age, or recent egg-laying activity influenced its choice of copulatory role. Animals were isolated except when paired during daily, half-hour trials. In the first experiment, mature animals of different size (weight) but similar age were randomly paired. Animal size had no effect on the initial copulatory role chosen. In the second experiment, young, maturing A. juliana were paired with older animals. Young animals showed no preference in initial copulatory role either as a group or individually. Older A. juliana showed no copulatory preference as a group, but over half of the individuals demonstrated a consistent choice of one role. Some individuals acted almost exclusively as sperm donors, others as sperm recipients, suggesting that as an A. juliana ages, it is likely to develop a preference for a single copulatory role. A record of daily egg mass production was kept for all animals in the second experiment. Production of an egg mass since the last copulation did not affect the copulatory role chosen in the subsequent copulation.     

Influences on the feeding behavior of three mammals in the Maruyama Zoo: bears, elephants, and chimpanzees

Modifications of feeding conditions are essential to the establishment of environmental enrichment in zoos. In this study, we attempted to increase the duration of feeding by varying feeding conditions, such as the spatial or temporal distribution of foods, while keeping the sorts and amounts of food the same. Subjects included nonhuman animals reared at the Maruyama Zoo in Sapporo, Japan: 3 bears (Ursus arctos), 2 elephants (Elephas maximus), and 5 chimpanzees (Pan troglodytes). Considering that the feeding ecologies of these animals differed a great deal from those in the wild, we used the focal animal sampling method. Consisting of the spatial dispersive and massed feeding conditions, the experiment with bears found feeding time increased more in the dispersive condition. In addition, the behavioral rhythm of alternate feeding and sleeping appeared. The experiment with elephants, consisting of the temporal dispersive and massed condition, increased feeding time under the massed condition. The experiment using chimpanzees reversed conditions used in the elephant study and increased feeding time under the dispersive condition. Results indicated that these simple modifications both influenced an increasing duration of feeding and affected behavioral patterns in a day.     

Influences on the Feeding Behavior of Three Mammals in the Maruyama Zoo: Bears,Elephants, and Chimpanzees

Modifications of feeding conditions are essential to the establishment of environmental enrichment in zoos. In this study, we attempted to increase the duration of feeding by varying feeding conditions, such as the spatial or temporal distribution of foods, while keeping the sorts and amounts of food the same. Subjects included nonhuman animals reared at the Maruyama Zoo in Sapporo, Japan: 3 bears (Ursus arctos), 2 elephants (Elephas maximus), and 5 chimpanzees (Pan troglodytes). Considering that the feeding ecologies of these animals differed a great deal from those in the wild, we used the focal animal sampling method. Consisting of the spatial dispersive and massed feeding conditions, the experiment with bears found feeding time increased more in the dispersive condition. In addition, the behavioral rhythm of alternate feeding and sleeping appeared. The experiment with elephants, consisting of the temporal dispersive and massed condition, increased feeding time under the massed condition. The experiment using chimpanzees reversed conditions used in the elephant study and increased feeding time under the dispersive condition. Results indicated that these simple modifications both influenced an increasing duration of feeding and affected behavioral patterns in a day.     

Moderate prenatal carbon monoxide exposure produces persistent, and apparently permanent, memory deficits in rats

The effects of moderate (150 +/- 2 ppm) prenatal carbon monoxide (CO) exposure (maternal HbCO concentrations of 15.6 +/- 1.1%) on learning and memory were assessed in young and aged adult rats using a two-way active avoidance paradigm. In experiment 1, the prenatal CO-exposed rats at 120 days of age acquired a conditioned avoidance response equally well as control animals in a 100-trial session. However, following a 24-hr interval the CO-exposed rats failed to demonstrate significant retention of the task as indicated by the absence of significant improvement in performance over the indicated by the absence of significant improvement in performance over the previous day; control subjects did show significant retention. In experiment 2, in which 120-day-old animals received 50 training trials per day until a criterion of ten consecutive avoidance responses was met, the prenatal CO-exposed subjects again acquired the task as well as control animals. When tested for retention 28 days later, a significant memory impairment was again observed in terms of trials required to reattain the avoidance criterion as well as in total percent avoidance responding. In neither experiment did an analysis of initial or average latency to escape the footshock stimulus reveal any significant alterations. These latter results suggest that the observed performance impairment reflected a memory deficit and not a disruption of sensory, motor, or motivational factors. In experiment 3, prenatal CO-exposed rats approximately 1 year of age (300-360 days of age) showed impairment relative to air-exposed controls in both the original learning and retention of the two-way avoidance response. Again, however, there was no evidence for alterations in performance factors per se. Collectively these data indicate that while young adult rats prenatally exposed to 150 ppm CO demonstrate an associative deficit restricted to memory impairment, aged adults similarly exposed during the prenatal period display a more pronounced deficit similar to that recently reported for animals tested as juveniles. The importance of parametric manipulations in uncovering long-term toxicity is also discussed.     

Role of ancillary variables in the design,analysis, and interpretation of animal experiments

During the course of an experiment using animals, many variables (e.g., age, body weight at several times, food and water consumption, hematology, and clinical biochemistry) and other characteristics are often recorded in addition to the primary response variable(s) specified by the experimenter. These additional variables have an important role in the design and interpretation of the experiment. They may be formally incorporated into the design and/or analysis and thus increase precision and power. However, even if these variables are not incorporated into the primary statistical design or into the formal analysis of the experiment, they may nevertheless be used in an ancillary or exploratory way to provide valuable information about the experiment, as shown by various examples. Used in this way, ancillary variables may improve analysis and interpretation by providing an assessment of the randomization process and an approach to the identification of outliers, lead to the generation of new hypotheses, and increase generality of results or account for differences in results when compared across different experiments. Thus, appropriate use of additional variables may lead to reduction in the number of animals required to achieve the aims of the experiment and may provide additional scientific information as an extra benefit. Unfortunately, this type of information is sometimes effectively discarded because its potential value is not recognized. Guidelines for use of animals include, in addition to the obligation to follow humane procedures, the obligation to use no more animals than necessary. Ethical experimental practice thus requires that all information be properly used and reported.     

Effects of Rodiola extract on the cytotoxic activity of natural killer cells of the liver, spleen, lungs and small intestine in rats after partial hepatectomy

In experiments on Wistar rats the cytotoxic activity of NK on the 1, 2, 10 days after partial hepatectomy (PH) and the application of Rodiola extract (RE) was studied. After 5 injections of RE the NK activity in gut increased by 112%, and after 12 ones (towards the end of experiment) by 222% in the spleen. The decreasing of this index in a first day after PH in lung, liver and gut was shown to restore in these tissues to the end of experiment. The absence of NK cytotoxicity diminishing just after PH in all the tissues was shown in operated animals, receiving RE and the decreasing of this index was found only in the lungs (by 335%).     

Responsiveness to “social” releasers in cattle. II. Relation between social status and responsiveness,and possible effect of previous familiarization with the test conditions

The data of two previous experiments, investigating the effects of social releasers in Friesian-Dutch heifers were analysed in order to verify whether the frequency of approach responses to models and calls of conspecifics was modified by pre-experimental factors. First, responsiveness was correlated to the social status of individuals; a social hierarchy was assessed on the basis of agonistic interactions recorded for a 2-month period prior to the experiments with models. A significant positive correlation was found between the total number of responses and the total number of escape-avoidance reactions to aggressive acts. The same result was found when individual ranks were assessed on a hierarchy re-presenting a dominance order established on the basis of the number of aggressive acts causing escape-avoidance reactions. In this case, also, animals with highest ranks presented a significantly higher number of responses to models than animals with lowest ranks. In our second experiment, a significant positive correlation was found between all criteria used to assess individual ranks in a hierarchy, while this result was not found necessarily in the first experiment.The other pre-experimental factor under consideration was a possible familiarization with the testing conditions (models/calls of conspecifics, handling, and other procedures); some of the group-members tested during the second experiment had already been tested in the first one, carried out a year before. Many results demonstrated that the frequency of responses to social releasers was significantly lower for the previously tested subjects than for the animals tested for the first time.     

One brief exposure to a psychological stressor induces long-lasting, time-dependent sensitization of both the cataleptic and neurochemical responses to haloperidol.

Rats were exposed for 10 minutes to one of several enclosures graded in novelty. In one experiment they were then simply sacrificed and plasma corticosterone determinations made in order to obtain an index of the relative stressfulness of these enclosures. In a second experiment the animals received haloperidol and were tested for catalepsy, 2 hours or two weeks following the novel experience. The most novel experience, exposure to a black box, resulted in the highest corticosterone levels and was the only one of our pre-treatments to induce significant enhancement of catalepsy as well as alteration of nucleus accumbens dopamine levels, 2 weeks--but not 2 hours--later. These findings indicate that brief exposure of adult animals to a psychological stressor can induce a long-term alteration in both behavioral and neurochemical responses to a drug and that this effect requires a minimum level of stress to get started and once triggered gets stronger with the passage of time.     

复合微量元素缓释丸对放牧反刍动物Cu、Co、Se营养价值的研究

从放牧生态环境大群的大别山黄牛和英山白山羊中选择年龄,体重相近的２０头牛和２０头羊,各随机分为两组,每组１０头,雌、雄均匀配,以复合微量元素缓释丸为试验材料,、每Ⅰ组投丸为试验组,每Ⅱ组不投丸为对照组,牛的两组每组以５头补料,５头不补料,试验期１３５ｄ。羊的两组均不补料,为全放牧方式,试验期６０ｄ,试验结束对羊Ⅰ、Ⅱ组各随机抽取３头屠宰,取样测定肝、肾、脾、肌肉、心、血和瘤胃内容物测定Ｃｕ、Ｃｏ和     

Characterization of thymosin alpha 1 and beta 4 during the bovine estrual period: effects of elevated estradiol and progestin

At present, there is a renewed interest in thymic function and its secretions in relation to endocrine control and reproductive function. In an initial experiment, 60 crossbred heifers (18-20 mo) were detected in estrus and assigned to control or FSH superovulatory groups. On Days 7-14 of the subsequent estrous cycle, FSH was administered for 5 days and prostaglandin F2 alpha (PGF2 alpha) was administered at 48 and 60 h after the initial FSH injection. Control animals received only PGF2 alpha injections between Days 9 and 15 of the cycle. Blood samples were collected from all animals at the time of PGF2 alpha injection and every 12 h thereafter to 72 h post PGF2 alpha injection. In a subsequent experiment, 103 crossbred heifers (16-18 mo) were superovulated with FSH and synchronized to estrus with PGF2 alpha administered 60 h after the initial FSH injection. Twenty-eight of the heifers received Norgestomet implants 12 h prior to the initial PGF2 alpha injection to inhibit the LH surge. Blood samples were collected from animals at 12-h intervals until the PGF2 alpha injection and every 6 h thereafter until 108 h post PGF2 alpha treatment. Although thymosin beta 4 concentrations did change over the estrual period, no differences were noted between control and superovulatory animals in the initial experiment even though estradiol concentrations were increased tenfold from the FSH stimulated ovary. In the second experiment, thymosin beta 4 and alpha 1 increased as the estrual period progressed and decreased (p less than 0.05) subsequent to the LH surge. (ABSTRACT TRUNCATED AT 250 WORDS)     

Susceptibility and sensitivity of the Siberian lemming and Middendorff's vole to leptospirae of the grippotyphosa serogroup]

Siberian lemmings and Middendorf's voles were found to be susceptible to infection caused by Leptospira of the Grippotyphosa serogroup after the intraperitoneal injection of Leptospira culture, the application of the culture or infected urine to the skin, as well as after Leptospira-carrying animals were placed together with the animals to be infected. The infectious sensitivity of these animals to Leptospira was not high: leptospiruria was observed for 1-3 weeks; in some of the voles leptospiruria was slightly pronounced, whereas other voles had a great number of Leptospira in urine. Antibodies appeared in the blood on day 5 after infection, and their titers increased till days 61-63. In no case could Leptospira be isolated from the kidneys of the animals killed on days 61-83 of the experiment.     

Decrease of mu opioid receptors in the brain and in the hypothalamus of the aged male rat

Experiments have been designed in order to analyze whether the binding capability of mu opioid receptors in the brain of the male rat is modified by age. In a first experiment, the number of receptors (Bmax) and the constant of affinity (Ka) for the mu ligand 3H-dihydromorphine (3H-DHM) have been measured in the whole brain of male rats of 2, 15 and 22 months of age. In a second experiment the Bmax and the Ka for 3H-DHM have been evaluated in the hypothalamus of male rats of 2 and 22 months of age. In this experiment it was also investigated whether the administration of exogenous testosterone modifies the number and/or the affinity of the hypothalamic mu receptors. Serum levels of LH, FSH, prolactin and testosterone have been measured by specific RIAs. The results obtained show that: serum testosterone levels are significantly decreased in aged rats, while serum LH and FSH show only a small decline; serum prolactin is higher in old than in young animals; the number of mu receptors in the whole brain of 15 and 22 month old animals and in the hypothalamus of 22 month old rats is significantly lower than in the same tissues of young animals; the administration to old animals of testosterone, in doses able to bring back towards normal serum levels of testosterone, induces a decrease of LH and FSH, but has no effect on serum prolactin titers. Testosterone administration does not modify the number of hypothalamic mu opioid receptors, indicating that the decline of brain mu receptors in old animals is not the consequence of the physiological decline of testosterone secretion; in no instance the Ka for the mu ligand is significantly affected.     

Growth,reproductive function,and tolerance to load tests in rats under repetitive adverse conditions

Wistar rats were subjected to a 3.5-day water deprivation once a month in the period of 1 to 10 months of age. The rats' adaptive abilities proved sufficient for compensation of adverse effects, the rats preserved their normal motor activity, emotionality, and orienting behaviour in the intervals between the effects. In the reproductive period, the males manifested a normal sexual behaviour and fertilizing capacity of their spermatozoids. In the end of the experiment, the experimental animals did not differ from the control animals.     

Effects of hyperoxia and allergic airway inflammation on cough reflex intensity in guinea pigs

Toxic influence of high oxygen concentration on pulmonary function and structures has been known for many years. However, the influence of high oxygen concentration breathing on defensive respiratory reflexes is still not clear. In our previous experiments, we found an inhibitory effect of 100 % oxygen breathing on cough reflex intensity in healthy guinea pigs. The present study was designed to detect the effects of hyperoxia on cough reflex in guinea pigs with allergic airway inflammation. In the first phase of our experiment, the animals were sensitized with ovalbumin. Thirty-two sensitized animals were used in two separate experiments according to oxygen concentration breathing: 100 % or 50 % oxygen for 60 h continuously. In each experiment, one group of animals was exposed to hyperoxia, another to ambient air. The cough reflex was induced both by aerosol of citric acid before sensitization, then in sensitized animals at 24 h and 60 h of exposition to oxygen/air in awake animals, and by mechanical stimulation of airway mucosa in anesthetized animals just after the end of the experiment. In contrast to 50 % oxygen, 100 % oxygen breathing leads to significant decrease in chemically induced cough in guinea pigs with allergic inflammation. No significant changes were present in cough induced by mechanical stimulation of airways.     

The reactions of cats to species-specific acoustic signals during electrical stimulation of the hypothalamus before and after the removal of the sensorimotor area of the cortex

In conditions of chronic experiment cats reactions were studied to species-specific acoustic signals (SAS) presented separately and against the background of the electric stimulation of the hypothalamus before and after partial bilateral ablation of the sensorimotor area of the cortex (SMC). It was shown that separately presented SAS caused in animals motor reactions, mainly orienting and negative. Ablation of SMC (field 4,6) caused an increase of positive reactions to sound, including also orienting reactions. A selective character of the reaction to SAS of agonistic type was revealed in animals with "true" aggression to combined (acoustic and subthreshold electric) stimulation. In animals with "false" aggression the combined stimulation caused only nonspecific elements of motor reactions and agonistic vocalizations. SMC ablation caused an increase of aggressive reactions to combined stimulation, revealed in the form of tendency for all animals. In this case in animals with "true" aggression after operation the probability increased of the appearance of motor reactions of aggressive type in comparison with agonistic vocalizations.     

Bombesin reduces food intake of normal and hypothalamically obese rats and lowers body weight when given chronically

Bombesin is a peptide hormone reported to reduce meal size when administered in rats. In the first experiment, synthetic bombesin was injected subcutaneously into normal rats and obese rats with lesions of the ventromedial hypothalamus just prior to the presentation of food. A dose-dependent suppression of meal size occurred for both groups, showing that the peptide has this action in obese as well as normal animals. In a second experiment, a conditioned taste aversion was not formed with a dose of bombesin which suppressed meal size by approximately 50% while the animals did develop an aversion with a dose of LiCl reported to reduce meal size equivalently. In a third experiment, rats were placed on a feeding schedule where they received three 30-min meals each day. After weights had stabilized under this paradigm, bombesin was administered just prior to each meal for six days. The bombesin caused a consistent suppression of meal size when the animals were allowed 30-min meals such that the rats lost weight over the six-day period. When this experiment was repeated with 60-min meals apparent tolerance developed to these actions of bombesin.     

Effect of thermal stress on physiological parameters, feed intake and plasma thyroid hormones concentration in Alentejana, Mertolenga, Frisian and Limousine cattle breeds

The aim of the present study was to assess the heat tolerance of animals of two Portuguese (Alentejana and Mertolenga) and two exotic (Frisian and Limousine) cattle breeds, through the monitoring of physiological acclimatization reactions in different thermal situations characterized by alternate periods of thermoneutrality and heat stress simulated in climatic chambers. In the experiment, six heifers of the Alentejana, Frisian and Mertolenga breeds and four heifers of the Limousine breed were used. The increase in chamber temperatures had different consequences on the animals of each breed. When submitted to heat stress, the Frisian animals developed high thermal polypnea (more than 105 breath movements per minute), which did not prevent an increase in the rectal temperature (from 38.7°C to 40.0°C). However, only a slight depression in food intake and in blood thyroid hormone concentrations was observed under thermal stressful conditions. Under the thermal stressful conditions, Limousine animals decreased food intake by 11.4% and blood triiodothyronine (T3) hormone concentration decreased to 76% of the level observed in thermoneutral conditions. Alentejana animals had similar reactions. The Mertolenga cattle exhibited the highest capacity for maintaining homeothermy: under heat stressful conditions, the mean thermal polypnea increased twofold, but mean rectal temperature did not increase. Mean food intake decreased by only 2% and mean T3 blood concentration was lowered to 85,6% of the concentration observed under thermoneutral conditions. These results lead to the conclusion that the Frisian animals had more difficulty in tolerating high temperatures, the Limousine and Alentejana ones had an intermediate difficulty, and the Mertolenga animals were by far the most heat tolerant.