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1.
Sucrose aversions were induced by lithium chloride toxicosis in 9-week-old male and female mice of the C57BL/6J and DBA/2J strains. Under conditions of ad-lib access to fluids which required a long interval between the sucrose and toxicosis, the conditioned aversions were relatively weak when compared with the sucrose consumption of saline-injected controls. The aversions extinguished rapidly within all groups. Contrary to earlier reports in rats, no sexual dimorphism in extinction rate was observed in this paradigm. When a fluid-deprivation schedule was implemented in the conditioning procedure to shorten the interval between taste experience and toxicosis, strong aversions were noted; yet relatively fast extinction under ad-lib conditions occurred in all groups except male DBA/2J mice. No sexual dimorphism was observed in mice of the C57BL/6J genotype, even when two pairings between sucrose and toxicosis were administered.  相似文献   

2.
Burrows dug by house mice in laboratory burrow boxes were examined in two inbred strains (C57BL/6J and BALB/cJ) across five age groups and compared with burrows of wild trapped mice. Burrows of feral domestic mice were examined in an outdoor enclosure as well as in the laboratory. Results demonstrated that burrows differ between strains; highly active C57 mice tended to burrow more than did Balbs at all age ranges. Moreover, burrows became more complex with age in both strains. Differences among domestic, feral, and wild mice were minimal. Results are discussed in terms of possible genetic differences in activity and as evidence against the notions of degeneracy accompanying domestication.  相似文献   

3.
Twenty-four female mice from two inbred strains, BALB and C57BL, were tested for emotional behavior. Half of the animals had successfully raised their first litter to weaning, while the other half had eaten their first litter. Cannibalistic females of both strains were found to be more prone to auditory stress than controls. However, the relationship between emotional defecation and cannibalism was found to interact with strain, suggesting an optimum level of arousal.  相似文献   

4.
Noise was evaluated as an aversive stimulus in the C57BL/6J mouse, using a simple escape/avoidance procedure in which mice could terminate noise by entering and remaining in a designatedsafe area (corner or side) of a square apparatus. Exposed to pulsed noise of 87.5–90 dB, mice spent 45%–50% of total corner time in the safe corner or approximately 80% of total time in the safe side. Acquisition was significantly faster with moderate intensities of pulsed noise (87.5–90 dB) than it was with high-intensity pulsed noise (100 dB). In comparisons of continuous as opposed to pulsed noise, acquisition was significantly faster with continuous (87.5-dB) noise than it was with pulsed noise, and continuous noise was shown in a choice procedure to be more aversive. Continuous noise caused significant, though not severe, suppression of activity, but pulsed noise caused virtually none. Thus, pulsed noise is a mildly aversive stimuhis for C57BL/6J mice and may have promise for the study of stress-induced behaviors in freely moving animals, but continuous noise is clearly more effective for rapid short-term conditioning.  相似文献   

5.
It is widely accepted that body weight and adipose mass are tightly regulated by homeostatic mechanisms, in which leptin plays a critical role through hypothalamic pathways, and obesity is a result of homeostatic disorder. However, in C57BL/6J mice, we found that Rcan2 increases food intake and plays an important role in the development of age- and diet-induced obesity through a leptin-independent mechanism. RCAN2 was initially identified as a thyroid hormone (T3)-responsive gene in human fibroblasts. Expression of RCAN2 is regulated by T3 through the PI3K-Akt/PKB-mTOR-Rps6kb1 signaling pathway. Intriguingly, both Rcan2?/? and Rps6kb1?/? mutations were reported to result in lean phenotypes in mice. In this study we compared the effects of these two mutations on growth and body weight in C57BL/6J mice. We observed reduced body weight and lower fat mass in both Rcan2?/? and Rps6kb1?/? mice compared to the wild-type mice, and we reported other differences unique to either the Rcan2?/? or Rps6kb1?/? mice. Firstly, loss of Rcan2 does not directly alter body length; however, Rcan2?/? mice exhibit reduced food intake. In contrast, Rps6kb1?/? mice exhibit abnormal embryonic development, which leads to smaller body size and reduced food intake in adulthood. Secondly, when fed a normal chow diet, Rcan2?/? mice weigh significantly more than Rps6kb1?/? mice, but both Rcan2?/? and Rps6kb1?/? mice develop similar amounts of epididymal fat. On a high-fat diet, Rcan2?/? mice gain body weight and fat mass at slower rates than Rps6kb1?/? mice. Finally, using the double-knockout mice (Rcan2?/?Rps6kb1?/?), we demonstrate that concurrent loss of Rcan2 and Rps6kb1 has an additive effect on body weight reduction in C57BL/6J mice. Our data suggest that Rcan2 and Rps6kb1 mutations both affect growth and body weight of mice, though likely through different mechanisms.  相似文献   

6.
We examined context-dependent and tone-cued fear conditioning during the activity and rest periods of C57BL/6J mice. Wheel-running activity was measured continuously as a marker of circadian phase. To control the effects of light on the response, the animals were kept in a skeleton photoperiod (two 15-min light pulses per day, indicating the beginning and the end of the day). Half the animals were trained and tested for context-dependent fear conditioning 2 h after the morning light pulse; the other half were trained and tested 2 h after the evening light pulse. Animals were tested every 24 h for 5 days to analyze the conditioned response and the rate of extinction. They were then trained for tonecued fear conditioning at the same time and tested for 5 consecutive days. A significant difference between the morning and the evening groups was observed in the conditioning level and extinction rate of context-dependent fear conditioning, but not in tone-cued fear conditioning. These results suggest a modulating effect of the biological clock on the context fear-conditioning pathway.  相似文献   

7.
We have investigated comprehensively the effects of thyroid function on gallstone formation in a mouse model. Gonadectomized gallstone-susceptible male C57BL/6 mice were randomly distributed into three groups each of which received an intervention to induce hyperthyroidism, hypothyroidism, or euthyroidism. After 5 weeks of feeding a lithogenic diet of 15% (w/w) butter fat, 1% (w/w) cholesterol, and 0.5% (w/w) cholic acid, mice were killed for further experiments. The incidence of cholesterol monohydrate crystal formation was 100% in mice with hyperthyroidism, 83% in hypothyroidism, and 33% in euthyroidism, the differences being statistically significant. Among the hepatic lithogenic genes, Trβ was found to be up-regulated and Rxr down-regulated in the mice with hypothyroidism. In contrast, Lxrα, Rxr, and Cyp7α1 were up-regulated and Fxr down-regulated in the mice with hyperthyroidism. In conclusion, thyroid dysfunction, either hyperthyroidism or hypothyroidism, promotes the formation of cholesterol gallstones in C57BL/6 mice. Gene expression differences suggest that thyroid hormone disturbance leads to gallstone formation in different ways. Hyperthyroidism induces cholesterol gallstone formation by regulating expression of the hepatic nuclear receptor genes such as Lxrα and Rxr, which are significant in cholesterol metabolism pathways. However, hypothyroidism induces cholesterol gallstone formation by promoting cholesterol biosynthesis.  相似文献   

8.
Squirrel monkeys were given either forward pairings of a bite-tube CS and shock US or backward pairings of these stimuli. Backward pairings produced stronger control of biting by the bite tube alone than did forward pairings. In a second experiment, subjects received backward pairings of US and CS with either a fixed ITI or a random ITI. Conditioned biting was obtained only when trials were presented with a fixed ITI. The magnitude of unconditioned biting was also significantly greater with the fixed ITI. It was argued that these results demonstrate that conditioning in this situation depends upon the degree to which biting predicts a relatively long shock-free period. When trials occur randomly in time, biting predicts no definite shock-free period; hence, it is not learned.  相似文献   

9.
Objective: To investigate the enhancive effect ofN, N'-dinitrosopiperazine (DNP) on induced carcinogenesis in nasal and/or nasopharyngeal epithelia among TgN(p53mt-LMP1)/HT transgenic mice to examine the underlying mechanism for the development of nasopharyngeal carcinoma (NPC). Methods: TgN(p53mt-LMPI)/HT transgenic mice and the same strain of C57BL/6J wild-type mice both at the age of 5 months were randomly divided into 2 groups in parallel, respectively, I.e., TgN(p53mt-LMPI)/I-IT cancerous lesion-inducing group (TI), TgN(p53mt-LMP1)/HT control group (TC), C57BL/6J cancerous lesion-inducing group (CI), and C57BL/6J control group (CC). TI and CI mice were treated only with DNP for 16 weeks, twice each week, while TC and CC mice were given the same volume of saline as controls.At the end of treatment, animals were sacrificed to collect epithelial tissue samples from nasal cavity and nasopharynx for pathohistological evaluation by haematoxylin and eosin (HE) staining and for determination on the expression ofTRAF2, c-Jun, and pl 6 by immunohistochemistry. Results: Atypical hyperplasia was more significant in the samples of TI than in those of TC, CI, and CC, with the rates of lesions being 90%, 10%, 0, and 0 (P<0.01) respectively, though DNP was used alone in a much shortened inducing period at less dosage and without the use of carcinogenic promoter 12-O-tetradecanoylphorbol-13-acetate as usual. The expressions of tumor necrosis factor (TNF) recep-tor-associated factor 2 (TRAF2) and c-Jun in these samples were significantly up-regulated in TI (P<0.01), while the expression of p16 was significantly lower in TI than in the other groups (P<0.01). Conclusion: TgN(p53mt-LMP1)/HT mice hold inherited con-stitutional defect in immune surveillance function, which can be aggravated by environmental carcinogens, such as DNP used even though in a much less strength. The enhanced carcinogenesis-inducing effect of DNP on TgN(p53mt-LMP1)/HT mice should be closely associated with abnormal signaling of activator protein-1 (AP-1) pathway, especially up-regulated expressions of TRAF2 and c-Jun, and down-regulated expression of p 16.  相似文献   

10.
Rabbits (Oryctolagus cuniculus) were given either a 100% or a 50% reinforcement schedule in classical conditioning. Two groups received an aversive US (shock) and two groups received an appetitive US (water to the oral cavity). With parameter estimates for the two-phase model serving as the dependent variables, it was possible to define more precisely the effect of US omission with the intermittent reinforcement schedule. For the aversive preparation, the major effect of intermittent reinforcement was to increase the duration of Phase 1, a phase during which response likelihood remains constant at its initial value. Only a small proportion of subjects reflected the effect of US omission during Phase 2, the “learning” phase, this being a low operator limit following trials on which neither the CR nor the US occurred. The major effect of US omission for the appetitive preparation was in Phase 2, primarily a result of a minority of subjects having a low operator limit following trials on which neither the CR nor the US occurred. Many subjects required separate operators for trials on which the CR did or did not occur. The results were interpreted to pose difficulties for strength theories of conditioning, and the limitation implied for successful application of the Rescorla-Wagner theory are discussed. The implications of the data for response-contingent interpretations and for individual differences are also discussed.  相似文献   

11.
目的：探讨PPARoL在器官移植中的作用。方法：C57BL／6J级口给予非诺贝特或者Wyl4643,连续7d,取脾脏,同时取BALB／c小鼠的脾脏,分离脾细胞进行混合淋巴细胞反应。结果：经过非诺叹特或者Wyl4643处理的小鼠,其脾细胞在混合淋巴细胞反应中表现为无应答。结论：非诺贝特或者Wyl4643激活的PPARα具有抑制混合淋巴细胞反应的作用。  相似文献   

12.
The dense granule protein 4 (GRA4) is a granular protein from Toxoplasma gondii, and is a candidate for vaccination against this parasite. In this study, the plasmid pcDNA3. 1-GRA4 (pGRA4), encoding for the GRA4 antigen, was incorporated by the dehydration-rehydration method into liposomes composed of 16 mmol/L egg phosphatidylcholine (PC), 8 mmol/L dioleoyl phosphatidylethanolamine (DOPE), and 4 mmol/L 1,2-diodeoyl-3-(trimethylammonium) propane (DOTAP). C57BL/6 mice and BALB/c mice were immunized intramuscularly three times with liposome-encapsulated pGRA4 to determine whether DNA immunization could elicit a protective immune response to T. gondii. Enzyme-linked immunosorbent assay (ELISA) of sera from immunized mice showed that liposome-encapsulated pGRA4 generated high levels of IgG antibodies to GRA4. Production of primary interferon (IFN)-γ and interleukin (IL)-2 in GRA4-stimulated splenocytes from vaccinated mice suggested a modulated Th1-type response. 72.7% of C57BL/6 mice immunized with liposome-encapsulated pGRA4 survived the challenge with 80 tissue cysts of ME49 strain, whereas C57BL/6 mice immunized with pGRA4 had only a survival rate of 54.5%. When immunized BALB/c mice were intraperitoneally challenged with 103 tachyzoites of the highly virulent RH strain, the survival time of mice immunized with liposome-encapsulated pGRA4 was markedly longer than that of other groups. Our observations show that liposome-encapsulated pGRA4 enhanced the protective effect against infection of T. gondii.  相似文献   

13.
The dense granule protein 4 (GRA4) is a granular protein from Toxoplasma gondii, and is a candidate for vaccination against this parasite. In this study, the plasmid pcDNA3.1-GRA4 (pGRA4), encoding for the GRA4 antigen, was incorporated by the dehydration-rehydration method into liposomes composed of 16 mmol/L egg phosphatidylcholine (PC), 8 mmol/L dioleoyl phosphatidylethanolamine (DOPE), and 4 mmol/L 1,2-diodeoyl-3-(trimethylammonium) propane (DOTAP). C57BL/6 mice and BALB/c mice were immunized intramuscularly three times with liposome-encapsulated pGRA4 to determine whether DNA immunization could elicit a protective immune response to T. gondii. Enzyme-linked immunosorbent assay (ELISA) of sera from immunized mice showed that liposome-encapsulated pGRA4 generated high levels of IgG antibodies to GRA4. Production of primary interferon (IFN)-γ and interleukin (IL)-2 in GRA4-stimulated splenocytes from vaccinated mice suggested a modulated Th1-type response. 72.7% of C57BL/6 mice immunized with liposome-encapsulated pGRA4 survived the challenge with 80 tissue cysts of ME49 strain, whereas C57BL/6 mice immunized with pGRA4 had only a survival rate of 54.5%. When immunized BALB/c mice were intraperitoneally challenged with 103 tachyzoites of the highly virulent RH strain, the survival time of mice immunized with liposome-encapsulated pGRA4 was markedly longer than that of other groups. Our observations show that liposome-encapsulated pGRA4 enhanced the protective effect against infection of T. gondii. Project supported by the Science Foundation of the Health Bureau of Zhejiang Province, China (Nos. 2003QN003 and 2005A001) and the Science Foundation of the Science and Technology Department of Zhejiang Province, China (No. 2006C13022)  相似文献   

14.
The effects of compounding two conditioned stimuli (CSs), each of which had been extinguished to varying degrees in different groups of rats given identical acquisition training, was examined within the conditioned emotional response paradigm. Greater suppression to the compound than to the individual CSs was observed following 6, 12, 48, 72, and 96 stimulus extinction trials, although after only 12 extinction trials suppression to the individual stimuli was no longer observed. The amount of compound suppression decreased progressively as the number of extinction trials increased until, after 120 extinction trials on each stimulus, the compound no longer elicited observable suppression. Control group data indicated that the observed summation effect could not be attributed to disinhibition. The possible role of the summation of undetected excitation in studies examining configurai conditioning, avoidance conditioning and reinstatement is discussed briefly.  相似文献   

15.
It has been proposed that playing chess enables children to improve their ability in mathematics. These claims have been recently evaluated in a meta-analysis (Sala & Gobet, 2016, Educational Research Review, 18, 46–57), which indicated a significant effect in favor of the groups playing chess. However, the meta-analysis also showed that most of the reviewed studies used a poor experimental design (in particular, they lacked an active control group). We ran two experiments that used a three-group design including both an active and a passive control group, with a focus on mathematical ability. In the first experiment (N = 233), a group of third and fourth graders was taught chess for 25 hours and tested on mathematical problem-solving tasks. Participants also filled in a questionnaire assessing their meta-cognitive ability for mathematics problems. The group playing chess was compared to an active control group (playing checkers) and a passive control group. The three groups showed no statistically significant difference in mathematical problem-solving or metacognitive abilities in the posttest. The second experiment (N = 52) broadly used the same design, but the Oriental game of Go replaced checkers in the active control group. While the chess-treated group and the passive control group slightly outperformed the active control group with mathematical problem solving, the differences were not statistically significant. No differences were found with respect to metacognitive ability. These results suggest that the effects (if any) of chess instruction, when rigorously tested, are modest and that such interventions should not replace the traditional curriculum in mathematics.  相似文献   

16.

Objectives

The aim of the study is to evaluate the cognitive-enhancing effects of hydrolysate of polygalasaponin (HPS) on senescence accelerate mouse P8 (SAMP8) mice, an effective Alzheimer’s disease (AD) model, and to research the relevant mechanisms.

Methods

The cognitive-enhancing effects of HPS on SAMP8 mice were assessed using Morris water maze (MWM) and step-through passive avoidance tests. Then N-methyl-d-aspartate (NMDA) receptor subunit expression for both the cortex and hippocampus of mice was observed using Western blotting.

Results

HPS (25 and 50 mg/kg) improved the escape rate and decreased the escape latency and time spent in the target quadrant for the SAMP8 mice in the MWM after oral administration of HPS for 10 d. Moreover, it decreased error times in the passive avoidance tests. Western blotting showed that HPS was able to reverse the levels of NMDAR1 and NMDAR2B expression in the cortex or hippocampus of model mice.

Conclusions

The present study suggested that HPS can improve cognitive deficits in SAMP8 mice, and this mechanism might be associated with NMDA receptor (NMDAR)-related pathways.
  相似文献   

17.
Four experiments with rats tested their ability to anticipate serial patterns made from elements of reward magnitudes (14, 7, 3, 1, or 0 food pellets). Anticipation was measured by the running time in a straight alley. Elements arranged in a monotonically descending pattern were more easily anticipated than were the same elements arranged in a nonmonotonic pattern. Better anticipation was also observed when training utilized four trials per day with short interrun intervals (10–15 sec), spent in the startbox of the runway, than when training utilized one trial per day with long interrun intervals (4–5 min), spent in the rat’s home cage. Anticipation of the monotonie sequence was also superior when training consisted of one trial per day with a short interrun interval relative to that observed with four trials per day and a long interrun interval. Following acquisition of anticipation of the monotonie sequence with a short interrun interval, transfer to the same sequence with a long interrun interval resulted in disruption of anticipation. Finally, anticipation of a well-learned monotonie sequence was not disrupted by replacement of individual rewarded elements in the sequence with a 0-pellet element. These experiments indicate that the duration between runs of a trial, but not that between trials or the number of trials per day, is important in the formation of serial expectancies. They also suggest that the rats come to represent the sequence as items in serial position.  相似文献   

18.
Three emotionally divergent strains of mice (SWR/J, A/HeJ, and SJL/J) were mated to produce three populations: a pure strain population (N = 90), an F1 population (N = 120), and an F2 population (N = 96). All Ss were tested on a battery of measures of emotionality. Each population was factored separately by principal components factoring with varimax and promax rotations. Factorial invariance was assessed quantitatively by congruence coefficients. Eight of the resultant factors were found to be replicable across populations. These were autonomic balance, motor discharge, territorial marking, acrophobia, tunneling-1, tunneling-2, underwater swimming, and audiogenic reactivity. Of the eight factors, motor discharge was most distinct in each population and tunneling-1 was least distinct.  相似文献   

19.
Rats were trained on a series of reversals of a successive discrimination in which the percentage of S+ trials ending in food was varied. Changes in the discrimination index occurred more slowly with 50% reinforcement than with 100% reinforcement when the number of training trials was equated across conditions, but were approximately invariant when the conditions were equated with respect to the number of obtained reinforcements. Presentation of free reinforcement during the intertrial intervals reduced the overall rate of discrimination acquisition, but left this invariance unaffected. Invariance in reinforcements necessary to attain acquisition also occurred when different discriminations correlated with different percentages of reinforcement were intermixed within experimental sessions. The failure of the invariance effect to be disrupted by either manipulation suggests that previous accounts of the invariance effect in terms of “comparator” models of conditioning (e.g., Gibbon & Balsam, 1981) are inadequate.  相似文献   

20.
The serial presentation of two different CSs, with each stimulus having an 8-sec duration (S18/S28), consistently has resulted in most of the shuttlebox avoidance responses being recorded to the S2 component. Experiment 1 attempted to attenuate this serial CS, delayed-response effect by conditioning the separate components of a serial CS prior to ordering them sequentially. Ten component-training trials were administered, with subjects receiving CS-US pairing to S1 only, S2 only, or to both S1 and S2 presented on separate trials. Two CS durations (8 or 16 sec) during this phase also were compared. Subjects were then given 100 avoidance test trials using the standard serial procedure. The 10 best avoidance responders in each group were selected for analysis. Shorter avoidance latencies were obtained only for subjects receiving component conditioning to S1. CS duration was not a factor in establishing the shorter latencies. Component conditioning to S2 resulted in increasing the total avoidances. Experiment 2 increased the number of component-training trials and the generality of the findings by using a different strain of rats and by extending the testing phase of the study so that all subjects could be included in the analysis. Comparable results were obtained. The theoretical implications of these data were discussed.  相似文献   

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