49-67
Transgenic and Gene-Knockout Rodents as Research tools for Cardiovascular Disorders
by Kapil Kapoor& Madhu Dikshit

Cardiovascular disorders like hypertension, cerebral stroke, heart failure and thromboembolism account for a high degree of morbidity and mortality all over the World. As the regulation of the cardiovascular system is complex, the study of cardiovascular disorders has been limited to whole-organism models. The last decade has witnessed an upsurge in transgenic and gene knockout technologies, which have played a major role in the discovery of a particular gene, or its product, implicated in various cardiovascular disorders. Knockout and transgenic animals are likely to become important tools in drug development to determine the physiological sites of action for newly developed pharmacological agents. The present review will briefly discuss the methods and types of genetically engineered rodents (transgenic and gene knockout models) with alterations in second messenger systems involved in cardiovascular disorders.

73-80
A Comparison of Two Models of Experimental Periodontitis in Rats
by BH Bentzen, MCB Grauballe, MJ Björnsson, K Stoltze, E Hjørting-Hansen, P Holmstrup

Rats are being used in models of experimental periodontitis because the periodontal anatomy in the molar region bears much resemblance to that of man. Furthermore, rats are available with different genomes and microbial status. The main purpose of the study was to compare two different methods of inducing experimental periodontitis in rats, by ligature or LPS injection. Rats were bred and housed on wire-mesh floor with no bedding material and fed a special diet to avoid periodontal destruction caused by impaction of bedding and dietary fibers interdentally. Because no bedding was used it was suggested that in future studies PVC tubes (diameter: 7 cm, length: 12-15 cm) be placed in the cages to improve the environment for the rats. The possible effect of doing so was therefore also examined in this study. Periodontitis was established either with peridental silk ligatures for 1 or 4 weeks or with gingival injections of lipopolysaccharide (LPS) every other day for a 6-day-period to provoke inflammation. For each experimental group a corresponding control group was established. In all groups the number of rats was 14. In addition 10 rats receiving no treatment were placed in cages with PVC-tubes. Alveolar bone loss was measured by means of morphometrical and radiographical methodologies. A previously described method for breeding and housing periodontitis-free rats was reproduced. The access to PVC-tubes did not result in differences in alveolar bone destruction when compared to the 4-week control group and therefore, PVC-tubes may be used as an environmental improvement for the rats in future studies. Compared to the control groups significantly more alveolar bone loss was established in the ligated rats both after 1 and 4 weeks, with the 4-weeks-ligature group having significantly more alveolar bone destruction than the 1-week-ligature group. No effect of LPS injections could be demonstrated and therefore, the study did not confirm earlier findings of significant effect of LPS injection on alveolar bone destruction as compared to saline injection.

85-97
Influence of Dextran Sulphate, Fibrin, and Ubiquitin on the Development of Casein-Induced Experimental AA Amyloidosis in C57BL/6 mice
by L. Leonaviciene, D. Povilenaite, R. Bradunaite, D.Vaitkiene, A.Venalis

The influence of subcutaneous injections of dextran sulphate (DS) and fibrin (F), as well as of an intraperitoneal injection of ubiquitin (Ub), was investigated on 48 male C57BL/6 mice subjected to conventional casein (C) induced amyloidosis. Histopathological examination of spleen and kidney tissue 3 and 5 weeks after termination of the amyloidogenic stimulus showed that the amount of amyloid deposited (rated trace, minimal, moderate or heavy) increased progressively with the duration of the amyloidogenic stimulus. After 3 weeks of stimulation, 16.7% of mice injected with C had some perifollicular amyloid deposits in the spleen while all had traces of amyloid in the kidney. Some amyloid was detected in the spleen of 33.3% of the mice treated with C+DS and C+Ub and 83.3% treated with C+F. Half the latter group also showed traces and half minimal amyloid deposits in their kidneys. In the other test groups, the incidence of kidney amyloidosis was less. The most extensive tissue deposits were seen at 5 weeks postinjection (p.i.) with most in the C+F-treated animals, all showing significantly more than the control C-treated group. Thus half the C+F-treated animals had moderate and half heavy deposits throughout their spleens. Glomerulonephritis, kidney tubular edema and some amyloid deposits were present in all of the animals. C+Ub resulted in a similar incidence of amyloid accumulation in the spleen but in the kidneys 66.7% of animals had only traces of amyloid and 33.3%, minimal amyloid deposits. Amyloid was deposited in the mouse kidneys predominantly in the arterial walls but also occurred in the basement membrane and interstitial tissues. A post-mortem examination of the internal organs revealed splenomegaly in all the test groups and increased liver weight in the C-, C+F-, and C+Ub-treated groups. The leukocyte count and ESR (erythrocyte sedimentation rate) were also higher in all the experimental groups. Thus, the results indicated that F and Ub play a role in the amyloid deposition process in the experimentally induced disorder in C57BL/6 mice and could enhance this pathological process.

103-112
Open Field Behaviour and Reaction to Novelty in Göttingen Minipigs: Effects of Amphetamine and Haloperidol
by Nanna Marie Lind, Sidse Marie Arnfred, Ralf Peter Hemmingsen, Axel Kornerup Hansen and Karin Hjelholt Jensen

The purpose of the study was to quantify behavioural changes of healthy Göttingen minipigs in response to experimentally altered dopamine neurotransmission. Since dopamine function is important in the pathogenesis of several human neuropsychiatric diseases, it is important for future evaluation of minipig models of diseases involving dopamine that the changes in behaviour in response to changed neurotransmitter function can be quantified. We recorded the behaviour of eight Göttingen minipigs in a ten-minute open field and a five-minute novelty test, and investigated the effects of d-amphetamine (0.7 mg/kg) and haloperidol (0.2 mg/kg) in this setting. D-amphetamine as well as haloperidol produced appreciable changes in motor behaviour and decreased explorative behaviour in line with the elsewhere reported effect of these drugs. It was possible to make a clear distinction between the behavioural profiles of these compounds. In conclusion, we have demonstrated the usefulness of a ten-minute open field and a five-minute novelty test for quantifying behavioural changes of Göttingen minipigs in response to experimentally altered dopamine neurotransmission. This provides the basis for using these behavioural tests in future evaluations of minipig models of diseases characterised by dopaminergic disturbances.

117-123
Fluctuating Asymmetry in Relation to Stress and Social Status in Inbred Male Lewis Rats
by D.B. Sørensen, C. Stub, I.M. Jegstrup, M. Ritskes-Hoitinga and A.K. Hansen

Environmental or intrinsic stressors acting on growing animals and humans may be expressed as small, random deviations from symmetry in otherwise bilaterally symmetrical characters – a phenomenon known as fluctuating asymmetry (FA), the mechanism behind which is not yet clear. In this study, we investigated the effects of two known stressors (grid floor and single housing) on the development of FA in young male Lewis rats compared to housing under normal conditions (bedding) or an enriched environment. It was found that such environmental factors have an impact on FA in rats. Initially, FA was found to be high in all rats. In bedding and in enrichment groups, FA decreased throughout the study (P<0.05 in bedding group and P<0.001 in enrichment group from five to eleven weeks of age). FA in singly housed rats and in rats on a grid floor did not change significantly throughout the study. FA in these rats was considerably higher than in rats housed on bedding with or without environmental enrichment (P<0.001). Moreover, the influence of social status on FA was evaluated. Dominant rats housed in the enriched environment were found to have a higher FA of combined traits than subordinate rats at eight weeks of age (P<0.01), but except for this result, no relationship between FA and dominance was found. Singly housed rats showed significantly higher FA than dominant as well as subordinate rats (P<0.001). In conclusion, FA of selected traits may hold a potential for measuring stress influences in laboratory animals, which can be of some importance in welfare research.