Gordon M. Harrington

Strain differences in open-field behavior of the rat

Parameters of open-field behavior measures are reported for 12 inbred strains of laboratory rats: ACI, A990, A35322, F344, INR, IR, MNR, MNR-a, MR, TS1, TS3, and WAG. Strain differences were highly significant. Genetic drift in defecation is attributed to selection pressures. An analysis of covariance was used to obtain genetic and environmental correlations. The results suggested that any genetic factors underlying the relationship between defecation and ambulation in the open field involve physiological mechanisms that are different from those mediating environmental effects.

The har strains of rats: Origins and characteristics

Origins of the principal lines ofRattus norvegicus used in behavior genetic research are identified. Broad descriptions are provided for 15 of the Har strains and substrains of well-established inbred lines and behaviorally selected stocks. Marker genes are identified for coat and major histocompatibility complex (MHC) loci. Detailed characteristics are summarized for 12 of these lines using a comprehensive behavioral test battery composed of a variety of measures of expressive behavior, learning, and physiological characteristics.

Benzodiazepine anti-conflict effects in maudsley reactive (MR/Har) and non-reactive (MNRA/Har) rats

The Maudsley Reactive (MR/Har) and Non-Reactive (MNRA/Har) rat strains, bred originally by Broadhurst for differences in Open Field Defecation, also differ in their control (i.e., non-drug) behavior in the Conditioned Suppression of Drinking (CSD) conflict procedure, a second “model” behavior for the study of anxiety and/or emotionality in rats. The present studies compared the effects of diazepam and alprazolam on CSD behavior in these two strains of rats. In daily 10-min sessions, water-deprived rats were trained to drink from a tube that was occasionally electrified (0.2–0.5 mA), electrification being signaled by a tone. Both diazepam and alprazolam increased punished responding in a dose-related manner. The per cent increase in punished responding (for diazepam only) was comparable in the two strains; however, both statistical and empirical approaches indicated that the magnitude of the anti-conflict effect of benzodiazepines in MNRA/Har versus MR/Har rats was not related to differences in baseline (i.e., non-drug) punished responding. Based on the absolute change in shocks received, rats of the MNRA/Har strain exhibited a significantly greater anti-conflict effect following diazepam or alprazolam treatment than did rats of the MR/Har strain. These findings further the hypothesis that the behavioral differences exhibited by Maudsley MR/Har and MNRA/Har rat strains may constitute a genetically-based “animal model” for the study of emotionality and/or anxiety.

Strain differences among rats initiating exploration of differing environments

Latencies for emerging from the home cage were obtained in familiar and in strange surroundings for 557 rats from 12 inbred strains: ACI, A990 A35322, F344, INR, IR, MNR, MNR-a, MR, TS1, TS3, WAG. Significant strain effects, condition effects, and genetic-enviromental interaction were found.

Strain differences in rotating wheel activity of the rat

Parametric comparisons of activity in a wheel were made for 694 rats from 12 inbred strains: ACI, A990, A35322, F344, INR, IR, MNR, MNR-a, MR, TS1, WAG. Where comparable, the data were consistent with the data of previous studies, though pointing toward different interpretations.

Two forms of minority-group test bias as psychometric artifacts with an animal model (Rattus norvegicus).

Controversy abounds over attributing group differences on tests to nature, nurture, or test bias. Limitations of correlational sampling from natural populations necessitate experimental methods to resolve underlying issues. In classical psychometrics test items are selected from a larger item pool through analysis of item responses in a sample of subjects. Rats of six inbred strains (n = 366) were tested in multiple mazes to provide a large item pool. Six populations were created, each with differing proportions of each strain. Items selected through independent item analyses within each population yielded six tests. An independent cross-validation sample (n = 146) provided scores on all six tests. This sample was also tested in another set of maze problems defined as the criterion to be predicted. Strain means and intrastrain predictive validities for the six tests varied with strain representation in the population used for item selection (p less than .001). Conventional item-selection procedures clearly produced two forms of minority test bias.

Strain differences in open-field behavior of the rat. II

Strain differences in parameters of open-field behavior measures were replicated after a 7-year interval for the Har sublines of 12 inbred strains of rats: ACI, A990, A35322, F344, INR, IR, MNR, MNRA, MR, TS1, TS3, and WAG, and were extended to an additional strain: B. Breeding stocks had been subjected to major environmental stress in the intervening years. No significant changes were found. The B strain was found to be distinctiive in showing both high ambulation and high defecation.

Strain differences in shuttle avoidance conditioning in the rat

Conditioned Responses in A Shuttle Avoidance Apparatus Were Measured For 480 Rats From 12 inbred Strains: Aci, A990, A35322, F344, inr, Ir, Mnr/Har, Mnra, Mr/Har, Ts1, Ts3, Wag. The Results Provide Parametric Data For Methodological Use And Add To The Standardization Of These Strains As Behaviorally Defined Lines. Differences From Previously Reported Data Are Discussed.

Quantitative Coronary Arteriography and Its Assessment of Atherosclerosis: Part I. Examining the Independent Variables

Background. Previous work has demonstrated that quantitative coronary arteriography (QCA) can accurately measure phantom images to within ±0.1 mm and has been accepted as a reliable and reproducible method of measuring human coronary artery disease (CAD). Assessment of CAD by QCA involves the measurement of numerous variables, which are currently required to calculate stenosis flow reserve (SFR). Methods and Results. In this study 1040 stenotic lesions were analyzed by two well- accepted methods with demonstrated accuracy and reproducibility. These methods measure percent diameter stenosis (%DS), absolute diameter, percent area stenosis, length, as well as entry and exit angles to and from a stenotic coronary artery lesion respectively Based upon these results, the mean ± standard deviations and range seen in CAD were determined for each of these independent variables. This study demonstrated that atherosclerotic coronary artery lesions do not appear to exceed an entry angle of -39°, an exit angle of +35°, or an absolute length of 4.84 cm when accurately measured by QCA. It was also noted that, once percent diameter stenosis exceeded 89% (regardless (continued on next page) of the visual estimate) or percent area stenosis exceeds 99%, coronary arteries become completely occluded as measured by QCA. Conclusions. While previously suspected that once certain critical limits are exceeded in the deposit of cholesterol and calcium within the coronary artery, the artery will close, this study demonstrated by QCA what the limitations in human coronary arteries appear to be. These limits may be in part due to turbulent factors resulting in platelet activation or local mediators from endothelium of the coronary artery. ABSTRACT Contemporary quantitative coronary arteriography (QCA) was used to measure the different variables present in atherosclerotic coronary arteries. While the interaction of each of the independent variables undoubtedly plays a role in the determination of coronary artery blood flow and closure, the limitations of each of these variables have not yet been defined in humans. This study, based on the results of human coronary arteri ograms as analyzed by QCA, demonstrates the limitations of each of these variables, after which coronary arteries close and blood flow equals zero.

Strain differences in free operant leverpress levels in the rat

Unconditioned leverpress operant levels were obtained in a standard apparatus for 485 rats from 12 inbred strains: ACI, A990, A35322, F344, INR, IR, MNR/Har, MNRA, MR/Har, TS1, TS3, WAG. The results provide parametric data for methodological use and add to the standardization of these strains as behaviorally defined lines. Free operant rate did not appear to be genetically related to other common measures of spontaneous activity.