Escape conditioning in wild and domestic Norway rats.

Tested 16 female wild (lab-reared) and 16 female domestic Norway rats for acquisition of a conditioned escape response. To escape from an aversive stimulus (air blasts) Ss were required to open 1 of 8 doors (simulated burrow entrances) on the presence of a visual cue. Stocks did not differ in the rate of conditioning. Wild Ss exhibited significantly shorter latencies for ambulation and escape than domestic Ss. Removal and reinstatement of the visual cue following acquisition confirmed that the Ss used the cue for orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of environmental enrichment on the open-field behavior of wild and domestic Norway rats.

Early postweaning experience in an enriched environment had a greater influence on the open-field behavior and body weight of 32 wild Norway rats than of their 32 counterparts. Genetic changes accompanying the domestication process may have reduced the relative impact of postweaning experience on the development of the domestic S's response to changes in its environment. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of the post-weaning environment on the climbing behaviour of wild and domestic Norway rats

The climbing behaviour of wild and domestic Norway rats (Rattus norvegicus) was compared after early rearing in three post-weaning environments offering different climbing experiences. Wild rats climbed in the test apparatus even when denied early climbing experience; male domestic rats did not. Early climbing experience increased the climbing scores of both stocks but influenced the climbing proficiency of wild rats only. Treatment differences in climbing behaviour may be related to specific motor experiences gained during development and the effect of early experience on the response to a novel environment (test apparatus). Stock differences in climbing behaviour may reflect a general reduction in motor activity among domestic rats and their reduced sensitivity to stimulus change or novelty.     

Olfactory recognition of conspecifics by domestic Norway rats

In order to learn more about their ability to recognize one another via olfaction, domestic male rats were given a series of preference tests in which pairs of odors from male conspecifics were presented. Both immature and mature males prefer (p less than .05) the odor from immature strangers over that from immature cage mates but are indifferent to the ordors from mature strangers versus cage mates. Both immature and mature males prefer (p less than .05) the odor from mature novel cage mates over that from mature cage mates to which they are temporarily habituated but are indifferent to the odors from immature novel versus familial cage mates. Mature males prefer (p less than .08) the odor from a cage mate over the subject's own odor, and they prefer (p less than .01) their own odor over no odor. Under certain conditions, male rats can discriminate between the odors from (a) strangers versus cage mates, (b) two cage mates, and (c) their own body versus a cage mate.     

The hooded allele and selection of wild Norway rats Rattus norvegicus for behavior

Selection of wild gray rats for domestication (tame behavior) resulted in a sharp increase in the frequency of heterozygotes at the h allele of hooded, the main locus of rat depigmentation. The observed effect of the selection on the manifestation of the h allele is compared with similar effects giving rise to piebaldness in other animals subjected to experimental domestication. The results are discussed in terms of genetic specificity of piebaldness and of the selection vector.     

Ontogeny of defensive reactions in Norway rats.

In 3 experiments, 219 Sprague-Dawley albino rats of several ages were presented with stimuli (a caged domestic cat, a footshock, and a suddenly moving object) known to be aversive to adults and disruptive of behavior in mature animals. 20-day-old Ss were relatively unaffected by these events, while Ss aged 30 days and older tended to reduce their locomotion and freeze upon the presentation of these cues. Data are consistent with R. C. Bolles's (1970, 1971) hypothesis that shock-elicited responses are innate defensive reactions. It is suggested that the inefficient passive avoidance learning in juvenile rats may result from their deficit in shock-induced freezing. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A natural food aversion in Norway rats.

During a single 1-hr feeding test, adult male Norway rats were offered intact carcasses of adult male rodents, sacrificed by CO? asphyxiation. In Exp I, 79 Ss fed more readily on conspecifics dead 24–220 hrs than on conspecifics dead 10 min or 6 hrs. In Exp II, 22 Ss fed readily on roof rats (Rattus rattus) whether they had been dead 10 min or 24 hrs. In Exp III, 15 Ss rendered anosmic by zinc sulfate treatment fed more readily on conspecifics dead for 10 min than did 17 controls. In Exp IV, 34 Ss consumed more flesh from house mice coated with roof rat urine than from mice coated with Norway rat urine. It is concluded that Norway rats exhibit a natural aversion to feed on the intact carcasses of freshly sacrificed adult conspecifics in the sense that they are more likely to feed on other species of rodent. The aversion diminishes with the dissipation of the chemoreceptive cue(s) identifying the carcass as a conspecific. (64 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Antibodies to orthopoxvirus in domestic cats in Norway

Hemangiomata is the more frequent pediatric tumor, absent at birth and usually growing, sometimes very quickly, during the first week of life. It potentially represents a serious problem because of his unforeseeable evolution during the time: is it more useful to use a corticosteroid therapy or to wait for the involution of the tumor? Here we have the results of the treatment on 51 babies who presented with hemangiomas of various sites: 52.6% of the lesions were on the face and head, 13.4% on chest wall, 10% on upper limbs, 4% on abdominal wall, 10% on pelvis region and 10% multiple. Therapy was compression in 10% of patients, corticosteroid injection in 66%, oral administered corticosteroid in 12%, surgery post corticosteroid therapy in 11.5%, others in 2.5%. Best results were obtained on the lesion of the head and face (good in 96%), worst in those of the abdomen (any modification in 100%).     

Domestication, sophistication, and avoidance in Norway rats.

Administered successive 1-way and 2-way avoidance tasks which included treatments of postweaning handling to docility, prior learning sophistication, and differential shock intensity. In this 2-stage paradigm, with 32 wild and 32 hooded Long-Evans rats, escape and avoidance behaviors of wild and laboratory Ss were indistinguishable. Sophistication in laboratory-learning experience and high shock contributed significantly to the performance of both wild and domestic Ss in 1-way, but not 2-way, avoidance. In contrast, effects of handling were apparently negligible. Findings do not support the notion of degeneracy of learning ability in the domesticated rat. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Free-operant avoidance behavior in rats with lateral septal lesions: Effect of shock intensity

The purpose of experiment 1 was to examine the relationship between shock intensity and normal rats' free-operant (Sidman) avoidance performance on a 3-component, multiple schedule. The results showed an inverted U-shaped relation between response rate and shock intensity, but no consistent relation between shock rate and shock intensity was found. Experiment 2 showed that lateral sptal lesions produced a bidirectional change in reactivity to electric shock. An increased reactivity was observed in the initial sessions starting on the 11th day after the surgery, while a reduced reactivity was observed in the final sessions when stable performance had been reacquired. These changes were not a function of the waning of general hyperreactivity with post-operative recovery: the septal lesions in this study did not produce any "sham rage". From 40 to 80% of the variance in response rates was accounted for by this bidirectional change in the reactivity to shock.     

Olfactory cues and movement: Stimuli mediating intraspecific aggression in the wild Norway rat.

Established male sibling pairs of laboratory-bred wild rats (R. norvegicus) in enclosures and in 4 experiments observed their aggressive, amicable, and sexual behavior following the introduction of conspecifics. Intact male Ss behaved amicably toward familiar male conspecifics, both aggressively and sexually towards unfamiliar anestrous and estrous female conspecifics, and aggressively toward unfamiliar male conspecifics. Anosmic males exhibited amicable and sexual behavior toward unfamiliar males, but did not initiate aggression toward them. The storing of a member of a resident pair in a cage with or without wood shavings, urine, and feces from a foreign colony did not affect behavior toward him by his cage mate. The storing of a foreign male in the wood shavings, urine, and feces of a colony did not affect behavior of that colony toward him. Cessation of movement on the part of an intruder of either sex inhibited attack, while immobile anesthetized male intruders elicited aggression. When presented simultaneously with moving and anesthetized intruders, resident Ss attacked only the former. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cross-reactivity of workshop antibodies with cells from domestic and wild ruminants

Reactivities of the monoclonal antibodies (mAbs) from the workshop panel with cells from cattle, sheep, goats, Cape buffalo (Syncerus caffer) and waterbuck (Kobus defassa) were tested. One hundred and sixty-nine mAbs reacted with bovine cells and 111 with sheep cells; 86 were shown to react with goat cells, 71 with buffalo cells and 70 with waterbuck cells. Some mAbs cross-reacted with all five ruminants tested, and are likely to react with epitopes that are conserved in other ruminant species. Such mAbs will obviate the need to produce mAbs panels to leukocyte antigens of other ruminants.     

Some determinants of a natural food aversion in Norway rats.

Adult male Long-Evans rats were permitted to feed on the carcasses of adult male rodents, freshly sacrificed by CO? asphyxiation. In a 2-choice preference test (Exp I), hungry Ss were offered 1 conspecific and 1 house mouse, the pair of carcasses being either intact or skinned. 18 Ss offered intact carcasses fed on the mouse or on neither carcass, but 18 Ss offered skinned carcasses fed indiscriminately, usually on both carcasses. In Exp II, 10 hungry Ss that earlier had observed a cagemate feeding on intact conspecific carcasses fed more readily on a similar carcass during a single-choice test than did 8 controls. In Exp II, 20 food-deprived Ss (96 hrs) fed more readily and consumed more tissue from an intact conspecific carcass than did 20 nondeprived Ss. It is concluded that the aversion to feeding on the intact carcass of a freshly sacrificed adult conspecific is deprivation dependent and is mediated by chemoreceptive stimuli from the skin and/or fur. The aversion is diminished by social facilitation. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Free-operant performance on variable interval schedules with a linear feedback loop: No evidence for molar sensitivities in rats.

Four experiments examined rats' sensitivity to molar and molecular factors on instrumental schedules of reinforcement. rats were exposed to a variable interval schedule with a positive feedback loop (VI+), such that faster responding led to a shorter interreinforcement interval. In Experiments 1 and 2, rats responded faster on a variable response (VR) schedule than on either a VI schedule matched for reinforcement rate or a VI + schedule matched for the feedback function. In Experiment 3, rats responded no differently on a VI schedule than they did on a VI+ schedule with equated rates of reinforcement. In Experiment 4, rats responded faster on a VI+ schedule with an interresponse time requirement yoked to that experienced on a VR schedule, than on a VI+ schedule with the same feedback function as the VR schedule. Taken together these results suggest that rats are more sensitive to the molecular than the molar properties of the schedules. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of the nonagouti pelage-color allele on the behavior of captive wild Norway rats (Rattus norvegicus).

The objective of the present study was to determine the extent to which the nonagouti pelage-color allele influences selected behaviors (including docility) of the wild Norway rat. Agouti and nonagouti (black) littermates were compared in tests for handling, open-field behavior, platform jumping, and response to a novel food item, all of which clearly differentiate wild and domestic rats. Nonagouti rats were significantly easier to approach, capture, and handle than their agouti sibs. However, differences between agouti and nonagouti rats for the other variables studied were not significant. Although the presence of the nonagouti allele cannot fully account for the behavioral differences between wild and domestic Norway rats, it may have facilitated the domestication of this species by improving ease of handling. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clozapine and PD149163 elevate prepulse inhibition in Brown Norway rats.

Unmedicated schizophrenia patients exhibit deficits in prepulse inhibition (PPI) of the acoustic startle response. Similar deficits can be induced in rodents via a variety of manipulations and these deficits can be reversed by antipsychotics. Brown Norway (BN) rats exhibit natural PPI deficits under certain parametric conditions. We treated BN rats with haloperidol or clozapine to determine if the BN rat is a useful animal model with predictive validity for the effects of antipsychotics. In addition, we also tested PD149163, a neurotensin-1 receptor agonist, which has been shown to exhibit antipsychotic-like effects in several other animal models. BN rats received subcutaneous injections of either saline or one of two doses of haloperidol (0.5 mg/kg, 1.0 mg/kg), clozapine (7.5 mg/kg, 10 mg/kg) or PD149163 (1.0 mg/kg, 2.0 mg/kg). PPI was measured in startle chambers 30 min after injection. Systemic clozapine and PD149163 but not haloperidol facilitated PPI in BN rats (p     

Crowding and isolation: Determinants of agonistic and food-seeking behavior in Norway rats.

Alternately isolated and crowded 2 groups of 12 male Long-Evans rats. Order of housing and familiarity of the Ss with the test apparatus were also varied systematically. Ss were deprived of food, trained to bar press, and allowed to compete in pairs for sugar water in a Skinner box. Isolated pairs produced more agonistic and contact behaviors and fewer bar presses than did crowded pairs. Weight was found to increase more rapidly during free feeding when animals were isolated. Familiarity of only 1 isolate with the testing environment led to the display of less aggression than was observed in other isolate conditions. (20 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Strain comparisons of DFP neurotoxicity in rats

The purpose of this study was to assess intraspecies differences in behavioral and autonomic function in three strains of rat following administration of diisopropyl fluorophosphate (DFP), an irreversible inhibitor of acetylcholinesterase activity. Male rats of the Long-Evans (LE), Fischer 344 (F344), and Sprague-Dawley (SD) strains wer administered DFP at doses of 0-1.5 mg/kg (sc). The animals were placed 60 min later into one of two motor activity chambers and tested for 30 min. Motor activity was measured using either a Doppler-based system or a commercial photocell device. Following measurement of motor activity in the Doppler system, body temperature (Tb) was measured and blood was then withdrawn by cardiac puncture and analyzed for serum cholinesterase activity (ChE). The remaining rats were retested 1 d after DFP administration in the photocell device. The results showed a significant influence of strain on the effects of DFP. Motor activity of LE rats was reduced by DFP at doses of 1.0 and 1.5 mg/kg, whereas the activity of F344 rats was reduced only at 1.5 mg/kg. The relative sensitivity of SD rats depended on the device used to measure motor activity. The SD rats resembled F344 rats in their response to DFP when motor activity was measured in the photocell device, and LE rats when motor activity was measured in the Doppler system. The Tb of F344 rats was unaffected by DFP, while the LE and SD rats became hypothermic at 1.5 mg/kg. The DFP-induced inhibition of serum ChE activity was significantly less in F344 rats. All three strains retested the day after DFP still showed significant decreases in motor activity. Overall, it appears that the F344 strain is relatively resistant to the behavioral and autonomic effects of DFP. This intraspecies variability should be considered in selecting appropriate experimental models for assessing the neurotoxicological hazards of cholinesterase-inhibiting pesticides.