猫尿液气味持续暴露对褐家鼠FOS表达的影响

在室内条件下以室内繁殖褐家鼠（Rattus norregicus）和Wistar大鼠为研究对象,采用免疫组织化学技术研究其分别暴露于猫尿液气味0d、1d、3d、6d、9d、18d后的FOS蛋白表达量的变化,探讨生活环境对褐家鼠反捕食对策的影响。研究结果表明,猫尿液气味暴露后室内繁殖褐家鼠下丘脑前区后部（AHP）、下丘脑腹内侧中央部分（VMHC）、杏仁核内侧核蚁背区（MeAD）、基底外侧杏仁核前部（BLA）区域内的FOS阳性细胞平均光密度与对照相比均显著增加,而在性别间无明显的差异。Wistar大鼠在猫尿液气味暴露1d、3d、6d、9d后,其下丘脑（AHP、VMHC）和杏仁核（BLA）中FOS阳性细胞的平均光密度显著高于对照组,而暴露18d后的FOS阳性细胞的平均光密度又恢复到对照水平;Wistar大鼠在AHP和MeAD区域中FOS阳性细胞的平均光密度有显著差异,而在VMHC和BLA区域中FOS阳性细胞的平均光密度无性别间差异。持续暴露猫尿液气味后两种类型褐家鼠在AHP、VMHC、MeAD、BLA区域中FOS阳性细胞的平均光密度的相对变化率也存在显著差异。以上结果表明生活环境的变化能够影响褐家鼠对捕食者气味的反应对策。     

The distribution of dopamine D1 and D2 receptors in the brain of rodents and carnivores]

Studies have been made on the density of receptors and dissociation constants for dopamine D1- and D2-receptors in the striatum, n. accumbens with the olfactory tubercles and in the frontal cortex of Wistar rats, Norway rats and silver foxes. D1 binding was found to be significantly higher than D2 one in all the analysed brain structures of the animals studied, especially in the striatum. Although the analysis of D1- and D2-receptor binding kinetics revealed differences in Wistar and Norway rats, more significant differences were found between rats and silver foxes.     

Prophylactic neuroprotection by blueberry-enriched diet in a rat model of light-induced retinopathy

The role of anthocyanins is controversial in vision health. This study investigates the impact of a blueberry-enriched diet as neuroprotectant in a rat model of light-induced retinopathy. Thirty-eight albino Wistar rats and 25 pigmented Brown–Norway rats were fed by gavage with long (7 weeks) and short (2 weeks) intervention with fortified blueberry juice (1 ml; 2.8 mg cyanidin 3-glucoside equivalents) or with a placebo solution (7 weeks) that contained the abundant nonanthocyanin blueberry phenolic, namely, chlorogenic acid, before being submitted to 2 hours of intense light regimen (1.8×10⁴ lux). Retinal health was measured by fitting electroretinogram responses with the Naka–Rushton equation. The light-induced retinal damage was severe in the placebo groups, with the maximum amplitude of the electroretinogram being significantly reduced in both Wistar and Brown–Norway rats. The maximum amplitude of the electroretinogram was significantly protected from the light insult in the Wistar rats supplemented with blueberry juice for 7 or 2 weeks, and there was no significant difference between these two groups. The same dietary intervention in the Brown–Norway groups failed to protect the retina. Histological examination of retinal section confirmed the electroretinography results, showing protection of the outer nuclear layer of the retina in the Wistar rats fed with blueberries, while all placebo-fed rats and blueberry-fed Brown–Norway rats showed evidence of retinal damage concentrated in the superior hemiretina. The neuroprotective potential of anthocyanins in this particular model is discussed in terms of interaction with rhodopsin/phototransduction and in terms of antioxidative capacity.     

Study on the optimum number of trials and intensity of unconditioned stimulants and strain difference in the two-way shuttle-box avoidance test using rats

In order to determine the optimun conditions suitable for a number of trials and the intensity of unconditioned stimulant (US) in the two-way shuttle-box avoidance test in Sprague-Dawley strain rats, which are used most frequently in reproduction studies, conditioned avoidance response was observed under various conditions for 30 and 60 trials and the low and high US levels. Investigation was also conducted in Wistar rats under a high US level with 30 and 60 trials. Latency time of the escape response in Sprague-Dawley rats was shortened with increasing trials. Body weight gains of both strains of rats in the high US level with the 60-trial group decreased during the observation period. These findings suggest that the high US level with the 60-trial group is not suitable for the two-way shuttle-box avoidance test. The rate and latency time of the avoidance response were lower in Wistar rats than in Sprague-Dawley rats, although those of the escape response were higher. Significant changes in the following were observed, mainly from first to third sessions: the avoidance rate of all groups in strains of rats, escape rate of 60-trial group in Sprague-Dawley rats, avoidance and escape latency time of the 60-trial groups in both strains of rats and escape latency time of the 30-trial group in Sprague-Dawley strain rats.     

Orchiectomized Fischer 344 male rat models body composition in hypogonadal state

The hypogonadal state in men is accompanied by substantial decreases in muscle and bone mass and by an increase in adiposity. Most of the strains of orchiectomized (ORX) rat that have been used to model this state display substantial losses in bone, but only subtle changes in adiposity and muscle mass. In order to identify a rat model displaying a robust catabolic response to ORX, we studied three strains: Fischer 344 (F344), Brown Norway and Wistar. ORX caused a significant and sustained decrease in weight gained by F344, but only a trend toward reduced weight gain in Brown Norway rats and a modest reduction weight gain in Wistar rats that was significant only after 56days. ORX suppressed food intake in F344 rats, and to a lesser degree in Brown Norway and Wistar rats. ORX reduced muscle mass significantly in F344 rats, but not in Brown Norway or Wistar rats. ORX increased adiposity moderately in F344 rats and substantially in Wistar rats. ORX caused a marked reduction in prostate mass and increase in bone resorption in all three strains. Thus, F344 was the only strain in which ORX produced substantial decreases in food intake, body weight and muscle mass with increased adiposity and increased bone resorption. We conclude that the F344 rat displays a broad range of catabolic effects following ORX and is the best rat model for studying the androgenic pathway and strategies for reversing catabolic changes induced by hypogonadism.     

Habitat use by three rat species (

The relative abundance of ship rats (Rattus rattus), Norway rats (R. norvegicus), and Pacific rats (R. exulans), was measured in four vegetation types on Stewart Island/Rakiura, over six consecutive seasons. Ship rats were found in all four vegetation types and dominated in podocarp-broadleaf forest and riparian shrubland. Norway rats were most common in subalpine shrubland and Pacific rats dominated in manuka (Leptospermum scoparium) shrubland. Analysis of micro-habitat affinities for the three species showed that ship rats were habitat generalists. Norway rats were associated with plants of damp sites. Pacific rats showed a significant positive relationship with increasing amounts of the ground cover wire rush, (Empodisma minus). Reasons for the observed habitat use on Stewart Island could include physiological adaptation to cold and wet conditions in Norway rats; the avoidance of predation or inter-specific competition by Pacific rats; and possibly preference for more structurally complex vegetation types by ship rats.     

Spontaneous and conditioned behavior of Wistar and Long Evans rats

Spontaneous behavior (locomotion, feeding, drinking, and exploration in a two box apparatus) as well as conditioned behavior (passive and active avoidance responding, and freezing in the light-dark box apparatus) were studied in naive male Wistar and Long Evans rats. Concerning spontaneous behavior, Long Evans rats were more active during both light and dark periods, and showed better exploratory performance than Wistar rats. Concerning conditioned behavior, Long Evans rats acquired and retained better active and passive avoidance responses, and exhibited longer initial freezing than Wistar rats in the range of 0.6-1.4 mA footshocks. The results better define the important behavioral differences existing between the two strains, Long Evans rats showing consistently a higher level of alertness and a better conditioned performance.     

Resistance to myocardial ischemia in five rat strains: is there a genetic component of cardioprotection?

There is a need to develop new and more consistent animal models of cardioprotection. Traditionally, outbred dogs, rabbits, and rats have been studied. We determined resistance to ischemia in isolated hearts from inbred strains of rats. Hearts from inbred rats: SS/Mcw (Dahl S, Dahl salt-sensitive), DA/Hsd (Dark Agouti), LEW/Hsd (Lewis), and BN/SsN/Mcw (Brown Norway); and from an outbred rat: Hsd:WIST (Wistar) were subjected to 27 min of global, no-flow ischemia, followed by 3 h of reperfusion. Infarct size in the Brown Norway rat was 2.5 times less than that observed in the Dahl S rat, with the Dark Agouti, Lewis, and Wistar rats intermediate in response. Hearts from Brown Norway rats were also most resistant to ischemia in terms of postischemic enzyme leakage and contractile and vascular function compared with other strains. The average polymorphism rate between strains revealed that such strains were genetically diverse. This study demonstrates strain differences in resistance to myocardial ischemia, suggesting these rats could be used to study a genetic and/or environmental basis for these differences and to provide new animal models for the physiological study of cardioprotection.     

Intra uterine survival and growth of Wistar and Wistar x Brown Norway rat embryos

Embryos of the Wistar strain and its F(1) cross (Wistar females mated with Brown Norway males) of rats were transferred nonsurgically to 48 Wistar, 17 F(1) cross and 20 Wistar-Imamichi recipients. The two types of embryos were transferred together to each recipient to compare the viability of the embryos. Pregnancy rate was 78.8% (67 85 ). The survival rate of fetuses to term was 11.5% (20 174 ) and 25.1% (42 168 ) for the Wistar and F(1) embryos, respectively. Placental weight differed significantly (P<0.05) between embryo types and among recipient types while fetus weight differed (P<0.01) only among recipient types, with a significant interaction between recipient and embryo types (P<0.01). It was concluded that the F(1) embryos (Wistar x Brown Norway) were twice as viable as Wistar embryos under the conditions provided.     

Effects of copper metabolism on neurological functions in Wistar and Wilson's disease model rats

Behavioral functions of Wistar and Long-Evans Cinnamon (LEC) rats, Wilson's disease animal model, were compared by measuring the open-field, acoustic startle reflex and prepulse inhibition (PPI), and shuttle-box avoidance learning tests with or without oral supplementation with copper or D-penicillamine, copper chelator. All of the LEC rats, irrespective of the treatment, exhibited higher locomotor activity, a decreased habituation to startle response or a lower PPI, compared with Wistar rats. The copper content of all brain regions examined, except for the medulla oblongata of LEC rats, was significantly lower than those in Wistar rats. Besides, in the region of the striatum and the nucleus accumbens of the LEC rats, lower content of norepinephrine, and higher content of dopamine and serotonin were observed compared with Wistar rats. Although copper supplementation did not affect the brain copper content, it reduced the PPI in both Wistar and LEC rats. In contrast, D-penicillamine supplementation decreased both the brain copper content and locomotor activity, and enhanced the startle amplitude only in Wistar rats. These findings suggest that an imbalance in copper homeostasis affects monoamine metabolism and behavioral functions.     

Stock differences in the susceptibility of rats to learned helplessness training

Learned helplessness (LH) consists of shock escape deficits evidenced by animals previously exposed to inescapable shock. This phenomenon has shown promise as a behavioral screen for new antidepressant drugs. Unfortunately, some stocks of rats evidence low susceptibility to LH training. Accordingly, male rats from 8 different stocks were tested for susceptibility to LH training. The outbred stocks consisted of Harlan SD, Sasco Holtzman, and Charles River Holtzman. The inbred stocks (i.e. strains) tested were Lewis, Wistar Kyoto, Brown Norway, Fischer F-344, and Buffalo. The Lewis, Brown Norway, Fischer and Sasco Holtzman rats were found to be virtually non-susceptible to LH training. Harlan SD and Buffalo rats evidenced intermediate susceptibilities of 28% and 33%, respectively. Kyoto and Charles River Holtzman rats were the most susceptible at 53% and 55%, respectively. No stock differences between control animals were observed. These results indicate that wide differences in susceptibility to LH training exist in rats from different stocks or suppliers and researchers should be careful to choose subjects from a susceptible stock. Charles River Holtzman and Wistar Kyoto rats appear to be very susceptible to LH training.     

The reactivity of the hypophyseal-adrenal system in rats with different forms of adaptive behavioral pathology]

The dexamethasone suppression test (DST) was applied to male Wistar rats with different models of depression: group with the learned helplessness, group with informational neurosis provided by time-deficit conditioned avoidance training, as well as groups of rats of two strains selected for low (KLA)--and high (KHA) avoidance learning. The pre-dexamethasone basal and stress-induced corticosterone levels were similar in intact rats and those exposed to inescapable shock. The dexamethasone administration (5 mkg/kg) failed to decrease the serum corticosterone level in rats with learned helplessness. The informational neurosis increased significantly the basal corticosterone level and decreased the stress response. Serum corticosterone levels were similar in KLA and KHA rats. These results give evidence that two stress-induced rat models of depression with similar behavioural disturbances (reduction of escape/avoidance reactions) exhibit marked differences in the activity of hypothalamo-pituitary-adrenal (HPA) axis.     

Three variations of hairlessness associated with albinism in the laboratory rat

The relationship of three variants of hairlessness, or hypotrichosis, in laboratory rats were examined morphologically, genetically and histologically. The results indicated that the recessive gene causing the fuzzy characteristic in Wistar Furth rats and genes responsible for two other hypotrichotic coat variants in albino rats were the same gene or closely linked genes. The genes were in Linkage Group I of the Norway rat and were closely associated with the albino gene (c), with a recombination percentage of approximately 18%. The hypotrichotic animals had fewer and smaller hair follicles, smaller hair shafts, and a reduction of medullated hair shafts.     

The participation of platelets in anaphylactic shock in the rat

In the IgE-sensitized Brown Norway rats, the intravenous antigen challenge resulted in systemic anaphylactic shock without thrombocytopenia. In the IgG-sensitized Wistar rats, thrombocytopenia occurred during the anaphylactic shock. It is linked with circulating immun-complexes. Treatment of IgG-sensitized Wistar rats by antiplatelet serum, by promethazine (anti-H1), cyproheptadine (anti-5-HT1) or phenidone, a cyclo-oxygenase and lipoxygenase inhibitor, did not protect against the anaphylactic shock. In the rat, platelets did not play a significant r?le in the pathogenesis of the various forms of the anaphylactic shock.     

Synthesis of thiostatins (major acute-phase alpha 1 proteins) in different strains of Rattus norvegicus

1. Two different thiostatin proteins were detected by crossed immunoelectrophoresis in plasma of the following inbred strains of Rattus norvegicus; Wistar, Sprague Dawley, Hooded Wistar, Lewis, Porton-Albino, ACI, Long Evans, and Katholiek, a mutant strain of the Brown Norway. 2. Only one thiostatin protein was detected using crossed immunoelectrophoresis in plasma from the Buffalo rat. 3. Comparison of partially purified thiostatins from Buffalo, Wistar, and Sprague Dawley rats in polyacrylamide gels showed that the thiostatin protein in Buffalo rat plasma corresponded to thiostatin 1 of the two thiostatins of the Wistar and Sprague Dawley rats. 4. Thiostatin 1 mRNA and thiostatin 2 mRNA, of approximately 1.7 kilobases, were both demonstrated in RNA from Buffalo rat liver.     

Aggression and learning in a strain of rats predisposed to catalepsy

Noradrenaline content is lower in the diencephalon of rats with genetic predisposition to catalepsy as compared to control Wistar population. Besides, there is a statistically non significant tendency to a lower noradrenaline level in the striatum and hippocampus. Pain stimulus induces in cataleptic rats a smaller decrease in noradrenaline than in Wistar. The shock-induced aggression is higher in cataleptic rats than in Wistar. All these data point to a lower noradrenergic activity in rats with genetic predisposition to catalepsy. In cataleptic rats, both the development and extinction of the conditioned avoidance reaction is slower than in Wistar. The changes of noradrenergic activity and learning are similar to those described in chronic amphetamine intoxication. It is supposed that these changes in learning are caused by increased serotonergic (found earlier) and decreased noradrenergic activity.     

Effects of Litoralon (gamma-L-glutamyl-taurine) and its analogues on fear-motivated behaviour of rats

The effects of a single post-trial intraperitoneal administration of the dipeptide Litoralon (gamma-L-glutamyl-taurine) and some of its analogues were tested on the passive avoidance latency of male and female Wistar rats. The avoidance latency was significantly decreased by Litoralon and gamma-aminobutyryl-ethanolamine phosphate but lengthened by DL-beta-aminoisobutyryl-ethanolamine phosphate. No differences were observed between the responses of immature male and female rats following Litoralon treatment. The observed inter-group differences in passive avoidance behaviour following dipeptide administration were also demonstrable in tests of the open-field activity of the animals examined immediately after the 24-hour retention test. The results are discussed on the basis of a central Litoralon effect on emotional arousal and the anti-conflict potencies of the dipeptide.     

Effect of sildenafil (Viagra) on memory retention of a passive avoidance response in rats

The effects of an intraperitoneal (i.p.) injection of different doses of sildenafil, a cyclic guanosin monophosphate (cGMP) specific phosphodiesterase type 5 (PDE 5) inhibitor, on memory retention of young (2-month-old) and middle aged (12-month-old) male Wistar rats were investigated. Passive avoidance behaviour was studied in a one trial learning, step--through type, passive avoidance task utilizing the natural preference of rats for a dark environment. In each category (young or middle-aged) different groups of rats received vehicle or sildenafil (1, 3, 10, 20 mg*kg(-1), i.p.) immediately after training and one group remained uninjected serwing as control. Retention latencies were measured 48 h later. To asses a possible non-specific proactive effect of sildenafil, the response latencies in a group of rats not receiving foot shock were also tested. The results showed that the post-training i.p. administration of sildenafil did not facilitate retention performance of a passive avoidance response in both young and middle aged rats compared to control or vehicle groups. Also, sildenafil did not affect response latencies in rats not having received the footshock on the training trial, indicating that sildenafil does not show a non-specific proactive affect on retention performance. The comparison of retention time between young and middle aged rats showed that the memory of the latter had been significantly reduced. In conclusion, this study suggests that sildenafil has no effects on memory retention in Wistar rats.     

Influence of acoustic signal with ultrasonic components on the development of defensive conditioned reflex in Wistar rats

Short-term (90 s) effects of the complex acoustic signal (CAS) with ultrasonic components on the development of defensive conditioned reflex of two-way active avoidance in a shuttle-box were studied in female Wistar rats. The learning ability of rats was measured on a scale designed in our laboratory. It was shown that CAS stimulation triggered an audiogenic seizure of different strength in 59% of animals. The CAS was extremely stressful for Wistar rats: it prevented the active avoidance learning in early terms after its application (the first training session in 4 or 6 days). This effect did not depend on the presence or intensity of audiogenic seizures during CAS. In the second training session in 9 days (the first session was in 4 days), learning was impaired as compared to control without CAS. However, during repeated training procedure 1.5 months after the CAS (the first session in 6 days), rats rapidly reached the criterion of learning (10 consecutive avoidance reactions). On the other hand, if the CAS was presented with different time lags (immediately, in 3 or in 45 days) after the first training session, the ability of animals to learn during the second session was not impaired both in early and late terms after exposure to the stressor. The results suggest that exposure to CAS prevents development of short-term memory but does not affect consolidation process and long-term memory.     

Brain aromatase in control versus castrated Norway Brown, Sprague-Dawley and Wistar adult rats.

Brain aromatase cytochrome P450 converts androgens to estrogens that play a critical role in the development of sexually dimorphic neural structures, the modulation of neuroendocrine function(s), and the regulation of sexual behavior. We characterized the influence of surgical castration on brain aromatase in Norway Brown and Wistar adult rats and compared their responses to Sprague-Dawley rats that were surgically or biochemically castrated (with flutamide, a known androgen receptor blocker). Aromata enzyme activity was measured by the tritiated water release assay in the medial basal hypothalmus/preoptic area (MBH/POA) and amygdala brain regions. The present results demonstrate that independent of the rat strain examined, MBH/POA aromatase is regulated by androgens (in Sprague-Dawley, Norway Brown and Wistar males). However, intact Wistar animals displayed significantly higher MBH/POA aromatase levels compared to Sprague-Dawley control values. Conversely, in the amygdala region, there was an apparent lack of androgen hormone action upon aromatase enzyme activity in some of the rat strains tested. The importance of brain aromatase regulating estrogen biosynthesis and influencing brain development and function is covered.