Biomedical subjects

W Raaijmakers

Publications and source records attributed to W Raaijmakers.

6 recordsLinked to original sources

PubMed1992

Reduced level of anxiety in adult Lewis rats after chronic ethanol consumption.

Many studies have shown that chronic ethanol consumption leads to a decline in learning and memory performance in rats and mice. However, other aspects of behavior have received less attention. Anxiety, for example, is known to be affected in alcoholics but has not been studied in animal models of ethanol consumption. In order to study the effects of chronic ethanol consumption on anxiety, twelve 3-month-old Lewis rats were given a 20% ethanol solution for 6 months as the only source of liquid, while a control group (n = 11) received tap water. Both groups were subjected to three different tests three weeks after cessation of treatment. Data analysis indicated that in all three tests the level of anxiety was reduced in the chronic ethanol-treated rats. Therefore, learning and memory measures, especially in aversively motivated tasks, may be confounded by differences in levels of anxiety between control and ethanol-treated rats.

Alcohol Drinking↗

PubMed1992

Chronic dietary choline enrichment affects DRL responding of old, but not of adult CPBB rats.

Using adult (11-month-old) and aged (22-month-old) inbred female CPBB rats, we tested the hypothesis that chronic dietary choline supplementation affects timing behavior. The rats had received choline chloride in their tap water for about 9 months before they acquired responding on a differential reinforcement of low-rate schedule with a critical delay of 8 s (DRL-8"). One retention session and two extinction sessions were given 4 weeks after the end of acquisition. The treatment had no effect on the timing behavior of the adult rats. Choline-treated old animals made more perservation errors, i.e., responses with interresponse times (IRTs) < 2 s, than the untreated old control rats. Even after correction for burst responses, the frequency of short IRTs was higher in the treated than in the control group, indicating that choline supplementation slightly impaired timing behavior. The mechanisms underlying the action of supplemented choline are still unknown.

Aging↗

PubMed1990

Genetic correlations in validating emotionality.

Sixty-six rats of seven inbred strains were observed in an open field (OF) and in a light-dark preference box (LDB). Each set of apparatus provides measures of locomotor activity and of the time spent in the "most protected" area (the corners in the OF, the dark compartment in the LDB). These measures are proposed to be indices of emotionality. In the present study, the reliability and validity of the OF and LDB measures were determined by genetic correlations. Genetic correlations (rGEN) within and between tests were used as they provide a more coherent picture of reliability and validity of the measures than product-moment correlations (rPM), since rGEN's are appropriate estimates of "true" individual scores. It appeared that the activity measure in the OF and the occupancies of the most protected parts of OF and LDB were valid indices of emotionality, while the activity measure in the LDB was not. We recommend that the occupancy measures in the OF and the LDB should be used in addition to the commonly used activity measure in the OF to assess emotionality. The results indicate that genetic correlations provide a useful tool to validate measures in animal research. The only experimental manipulation in this approach consists of using the variation between inbred strains.

Animals↗

PubMed1990

Differential effect of acetyl-l-carnitine on open field behavior in young and old rats.

Acetyl-l-carnitine (ALCAR) exerts antiaging effects with study we evaluated the effect of a chronic treatment with ALCAR (6 weeks, 50 mg/kg/day) on the open field behavior of 5-month-old and 26-month-old male Wistar rats. Old rats defecated more, made fewer crossings, and spent more time in the corner squares. However, it is difficult to interpret these findings in terms of an increase in emotional reactivity with age because locomotor performance generally has been found to be impaired in old rats. Consequently, treatment effects were analysed within age groups. ALCAR had no effect in young rats, but the old ALCAR-treated rats ambulated less and spent more time in the corner squares than the old control rats. We have interpreted this in terms of an enhanced emotional reactivity of old ALCAR-treated rats.

Acetylcarnitine↗

PubMed1990

The effects of aging in rats on working and reference memory performance in a spatial holeboard discrimination task.

The effects of aging on spatial memory performance of rats was studied in a holeboard task in which 4 of 16 holes were baited with food. Brown-Norway rats of five ages (4, 13, 19, 25, and 30 months) received a total of 80 acquisition trials. A clear age-related decline of spatial working and reference memory performance was found. The decline was most profound between 19 and 25 months of age. The speed of visiting holes and the development of a preferred pattern of hole-visits did not influence spatial discrimination performance. Correlational analysis supported the view that the working and reference memory measures represent distinct aspects of spatial memory.

Aging↗

PubMed1990

The cone field: a spatial discrimination task for the automatic and simultaneous assessment of working and reference memory in rats.

A cone field apparatus was developed in which spatial working memory (WM) and reference memory (RM) can be assessed automatically and simultaneously. The cone field is a large open field with 16 cones in it. A configuration of four cones was baited with a food pellet. In the holeboard, the predecessor of the cone field, no clear criteria exist to distinguish between accidental and directed orientations toward the target (hole). In the cone field the visit to the target (cone) is unambiguously defined. We found that senescent rats were impaired on both the WM and the RM. The development of a fixed pattern of visiting the baited cones was effectively prevented by starting the rats randomly from four different positions. When only one start position was used, rats developed a fixed pattern of visiting the baited cones. This pattern was more pronounced in the young than in the senescent animals. In the last experiment we explored whether the task might be suited for the assessment of WM and RM performance in longitudinal studies. Rats performed like naive animals on both memory components when re-acquisitions were separated by 4-month intervals without training.

Aging↗