The sedative effects of climazolam and climazolam with fentanyl-fluanisone in rats (Rattus norvegicus)

A trial of the sedative effects of a novel benzodiazepine, climazolam, and of a mixture of climazolam and fentanyl-fluanisone was undertaken in male and female Sprague Dawley and Lewis strain rats (Rattus norvegicus) of different ages. At the recommended intravenous therapeutic dosage of 0.25 mg/kg, climazolam sedated the rats but failed to inhibit the righting reflex or responses to painful stimuli. Even at 25 times the recommended dosage, there was no anaesthetic effect. Predictable and satisfactory surgical anaesthesia was not obtained with the mixture of climazolam and fentanyl-fluanisone administered intraperitoneally. In contrast with diazepam and midazolam, climazolam failed to potentiate the sedative analgesic properties of fentanyl-fluanisone: indeed many animals retained their tail and pedal pinch reflexes. The results also revealed significant differences in effect related to strain and age but not to sex.     

Hemoglobin polymorphism in inbred strains of rats (Rattus norvegicus)

Hemoglobin phenotypes A and B were determined by polyacrylamide gel electrophoresis of erythrocyte lysates from 29 inbred strains of rats. Fourteen strains have phenotype A and fifteen have phenotype B, which are characterized by five and six hemoglobin bands, respectively. Breeding studies showed that the phenotypes are codominant and that they segregate in a simple Mendelian fashion in the (A×B) F₁×A backcross. Sex and hemoglobin phenotype assort independently, and the hemoglobin phenotype is not linked to the major histocompatibility complex (RT1) and to two erythrocyte alloantigenic systems (RT2 and RT3).This work was supported by National Institutes of Health Grant CA 18659.     

Polymorphisms detected in actin-related sequences of rats (Rattus norvegicus)

Southern blot hybridization of EcoRI digests of DNAs from 13 rat strains using human cardiac actin gene as a probe revealed polymorphisms in actin-related sequences of rats. EcoRI fragments of 11 kb, 7 kb, 6 kb, 5 kb, 4.5 kb and 4 kb detected in several strains were absent in the remaining strains. The presence of these fragments was suggested to be due to presence of extra sequences homologous to the actin genes, such as processed pseudogenes, in the particular strains. The 13 strains were assigned to each of 7 specific patterns of the polymorphic EcoRI fragments. It was concluded that the polymorphisms of actin-related sequences should be useful for genetic monitoring of laboratory rats.     

The influence of females upon aggression in domesticated male rats (Rattus norvegicus)

The aggression of adult male Long-Evans rats (Rattus norvegicus), toward males of the same strain, was tested before and after a 1-week period of cohabitation with a pair of intact females, ovariectomized females, or intact males, comparable to the females in size. Only cohabitation with intact females increased the aggression of resident males against unfamiliary male intruders. Female enhancement of aggression does not appear to be caused by sexual frustration of males, or a function of dominance-subordinance relations, per se. Increased aggression may be mediated by elevated testosterone production associated with mating.     

Etiological structure of icterohemorrhagic leptospirosis in gray rats (Rattus norvegicus)

In 93 Leptospira strains isolated from Norwegian rats serovar determination was made. As a result, leptospires circulating among Norwegian rats were found to belong mainly to serovar copenhageni, group Icterohaemorrhagiae, while leptospires of serovar icterohaemorrhagiae, even if occurring, were found only in the animals inhabiting pigsties. Leptospirosis epizooty among rats, caused by L. icterohaemorrhagiae, took its course independently of leptospirosis epizooty among mice, caused by L. hebdomadis, and simultaneously with it.     

The effects of reward quality on risk-sensitivity in Rattus norvegicus

Risk-sensitive foraging theory (RSFT) was developed to explain a choice between a variable (risk-prone) or constant (risk-averse) option. In the RSFT literature, qualitative shifts in risk-sensitivity have been explained by fluctuations in daily caloric energy budget (DEB). The DEB rule describes foragers’ choices as being based on fitness and rate of gain. If the DEB rule is correct, rewards that differ in caloric returns should cause differences in foragers’ sensitivity to risk. However, few studies have explored the influence of reward quality on risk-sensitivity in mammals. The present study was designed to examine the effects of reward quality on risk-sensitivity when reward magnitude, delay to reward, body mass, and response effort were controlled. Results from the current study demonstrated that subjects rewarded with a high calorie reward (i.e., sugar) made significantly fewer choices for a variable option than subjects rewarded with a lower calorie reward (i.e., grain). These results are consistent with the predictions of the DEB rule, and add to the RSFT literature where reward quality was manipulated by describing difference in risk-sensitivity in mammals. Suggestions for future research include an examination of risk-sensitivity where flavor and caloric return are manipulated.     

Comparative studies on mitochondrial respiration in four strains of rats (Rattus norvegicus)

Mitochondrial respiration and ATP synthesis were examined in young rats of the Sprague-Dawley, Wistar, BHE and Zucker strains. Both lean and obese Zucker rats were studied. Pyruvate-supported state 3 respiration was highest in mitochondria from Sprague-Dawley rats and least in mitochondria from obese Zucker rats. Succinate-supported state 3 respiration was highest in the Wistar group and least in the Sprague-Dawley rats. There appeared to be no relationship between oxygen consumption and the genetic tendency for hepatic hyperlipogenesis. ATP synthesis was greatest in the obese Zucker rats and least in the Sprague-Dawley rats. Differences in liver weights and mitochondrial yields may explain, in part, these observed strain differences in mitochondrial activity.     

Genetic differences in milk proteins among laboratory rats (Rattus norvegicus)

Genetic differences in the electrophoretic pattern of milk proteins were observed among different inbred rat strains. The results of segregation analysis made on a limited number of females is consistent with the hypothesis of two codominant autosomal alleles system.     

Genetic control of two esterases of rat plasma (Rattus norvegicus)

Three electrophoretic variants of plasma esterase in the albumin zone, presumably carboxylesterase, have been demonstrated in 250 rats representing a laboratory population of Wistar rats. Electrophoretic variants of the enzyme are believed to be controlled by two codominant alleles at the autosomal locus referred to as Es-2. The variant of carboxylesterase represented by a fast-migrating single band on starch gel electrophoresis is determined by the gene named Es-2 ^a, whereas the slow-migrating variant, represented by two bands, is under control of the allelic gene Es-2 ^b. Animals with Es-2 ^a/Es-2 ^b genotype have three bands of carboxylesterase in the albumin zone. Genetically determined polymorphism of plasma esterase, presumably carboxylesterase, in the prealbumin zone was shown in both laboratory and wild populations of rats. Breeding tests suggest that the gene referred to as Es-1 ^a, responsible for the presence of carboxylesterase in the prealbumin zone, is inherited dominantly, whereas animals homozygous for the allele Es-1 ^b locked this esterase fraction.     

The pleiotropic effect of selection for behavior on coat color in grey rats (Rattus norvegicus)

The effects of selection for a type of behavior relative to humans (tame and aggressive) on the intensity of coat color in agouti rats with the AAHH genotype were studied. Animals that were not under selection for behavior (wild animals) were used as the control. Morphometric analysis of the hair parameters that influence the intensity of coat color demonstrated that, on the one hand, polymorphism in the main coat color exists in the population of wild agouti rats, that is, both light and dark agouti animals exist. On the other hand, it was demonstrated that selection for a type of behavior in rats is accompanied by selection of animals that differ in the intensity of the main genetically identical coat color. Dark-colored animals are more prevelent among the aggressive animals, while light-colored animals prevail among tame animals. The association of the effects of selection for behavior with the modification of coat color is probably caused by the presence of common neurohormonal mechanisms for the regulation of these processes.     

Effect of dietary protein on zinc phosphide toxicity in albino rats (Rattus norvegicus)

Adult male and female albino rats (R. norvegicus) were administered rodenticide, zinc phosphide ranging from 4, 2, 1, 0.5, 0.25 and 0.125% in the diet containing 10(A), 17(B) and 24%(C) protein. Zinc phosphide induced 100% mortality at 4, 2, 1, 0.5% in diet A; 4 and 2% in diet B; and 4% in diet C. The results reveal influence of dietary protein in modulating the toxicity of zinc phosphide, suggesting that greater caution should be exercised while formulating its baits for effectiveness. The results also suggest that baits having 10% protein are more suitable to carry the rodenticide from view point of acceptability and efficacy towards the target species.     

The Effects of Environmental Control on Cognition in Rats (Rattus norvegicus)

The aim of this study was to allow nonhuman animals to control their environment using operant conditioning procedures and to assess the effect of control on cognitive tasks. The study tested 4 predictions: (a) rats (Rattus norvegicus) will control a light stimulus; (b) animals will exhibit preferences for particular stimulus strengths; (c) animals who exert control over environmental stimuli will show improved performance on cognitive tasks compared with animals who lack control; and (d) at the end of the operant phase, experimental subjects will have lower corticosterone levels than animals who lack control. Experimental subjects did show control over a light stimulus and performed significantly better over time in a discrimination task compared with subjects who could not control their environment. There was no difference in corticosterone levels between control and experimental subjects. The results will both contribute to our understanding of how control of environmental stimuli affects the welfare of animals in captive environments and aid in designing experimental conditions that will increase validity and reliability in research.     

Effects of welding fumes on haematological parameters of male albino rats (Rattus norvegicus)

Welders or metal workers not being an exception are exposed to metals ions or oxides (fumes) at trace concentrations either through direct contact supplementation at occupational sites or indirectly through uptake from contaminated food, water or contaminated soil, dust, or air. The study aims to determine the effects of welding fumes exposure on haematological parameters in blood of experimental animals. The fumes were collected from welding sites during the activity by a skilled welder. 130 male experimental animals were utilized and made into 13 groups. 12 groups were given dosages calculated to correspond to real life workers exposure regimes and 1 group served as control. The dosages were administered intratracheally after been anaesthetized weekly for 12 weeks. The animals were sacrificed and whole blood samples were taken which was then subjected to haematological analysis. The parameters have revealed changes in values whereby RBC, WBC, % lymphocytes, HGB, HCT, MCV, MCH, PLT, PCT and P-LCC have exceeds the control groups values. There was an increase across the treatment groups. However, lymphocytes, MID, granulocytes, % granulocytes, MCHC and MPV have values which were less than the control and no different from one another statistically. This indicates that exposure to welding fumes could cause alterations to most RBC, WBC and PLT indices majorly by effecting an increase. Further studies should be carried out on the response of other markers of toxicity so as to have a broad perception of the effects.     

Idiopathic megaesophagus in a rat (Rattus norvegicus)

Necropsy and histopathologic examination of a rat (Rattus norvegicus) revealed megaesophagus and gangrenous bronchopneumonia. The esophageal dilitation, mural atrophy with persistence of neural structures, regurgitation and bronchopneumonia seen in this case were similar to findings in other animals with megaesophagus.