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J M Long

Publications and source records attributed to J M Long.

100 records · Page 6Linked to original sources
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Chronic treatment of aged mice with L-deprenyl produces marked striatal MAO-B inhibition but no beneficial effects on survival, motor performance, or nigral lipofuscin accumulation.

Male C57BL/6J mice were provided I-deprenyl (at 0, 0.5 mg/kg or 1.0 mg/kg per day) in their drinking water beginning at 18 months of age. A battery of motor tests, including open-field, tightrope, rotorod, inclined screen, runwheel, and rotodrum tests, was administered before treatment and then 6 months later at 24 months of age. A subsample of mice was retested again at 27 months of age. An untreated group of 9-month-old mice served as young controls. Deprenyl treatment reduced striatal MAO-B activity by up to 60% after 6 months on treatment but had no significant effects on striatal catecholamine levels. No significant effects of deprenyl treatment were observed on body weight, fluid intake, or survival of the mice. Chronic deprenyl treatment also did not affect motor performance in any test, except rotodrum performance at 27 months of age, which was significantly better in the 1.0 mg/kg group treated group compared to controls. No age or deprenyl effects were observed with respect to cell counts in the substantia nigra. However, nigral cells containing lipofuscin increased with age, but this neurohistochemical parameter was also unaffected by deprenyl treatment.

Aging↗
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Stereological analysis of astrocyte and microglia in aging mouse hippocampus.

Recent evidence suggests neuroglia-mediated inflammatory mechanisms may stimulate neurodegenerative processes in mammalian brain during aging. To test the hypothesis that the number of microglia and astrocytes increase in the hippocampus during normal aging, unbiased stereological techniques were used to estimate total cell number in hippocampal subregions (CA1, dentate gyrus and hilus) of male C57BL/6J mice of different ages: 4-5 months, 13-14 months and 27-28 months. Immunocytochemical visualization for microglia and astrocytes were via Mac-1 and GFAP antibody, respectively. Estimates of total microglia and astrocyte number were assessed using the optical fractionator. No statistically significant age differences were found in the numbers of microglia or astrocytes in the hippocampal regions sampled. These findings suggest that age-related increases in the total numbers of hippocampal microglia and astrocytes is not causal for observed age-related increases in cytokine response.

Aging↗
PubMedDate not supplied

Hippocampal neuron and synaptophysin-positive bouton number in aging C57BL/6 mice.

A loss of hippocampal neurons and synapses had been considered a hallmark of normal aging and, furthermore, to be a substrate of age-related learning and memory deficits. Recent stereological studies in humans have shown that only a relatively minor neuron loss occurs with aging and that this loss is restricted to specific brain regions, including hippocampal subregions. Here, we investigate these age-related changes in C57BL/6J mice, one of the most commonly used laboratory mouse strains. Twenty-five mice (groups at 2, 14, and 28-31 months of age) were assessed for Morris water-maze performance, and modern stereological techniques were used to estimate total neuron and synaptophysin-positive bouton number in hippocampal subregions at the light microscopic level. Results revealed that performance in the water maze was largely maintained with aging. No age-related decline was observed in number of dentate gyrus granule cells or CA1 pyramidal cells. In addition, no age-related change in number of synaptophysin-positive boutons was observed in the molecular layer of the dentate gyrus or CA1 region of hippocampus. We observed a significant correlation between dentate gyrus synaptophysin-positive bouton number and water-maze performance. These results demonstrate that C57BL/6J mice do not exhibit major age-related deficits in spatial learning or hippocampal structure, providing a baseline for further study of mouse brain aging.

Aging↗
PubMedDate not supplied

Age-related psychomotor and spatial learning deficits in 129/SvJ mice.

The 129 mouse strain has been widely used to construct mutations that model behavioral aging in humans. The current study found significant age-related declines in both psychomotor and swim maze performance of 5-, 17-, and 27-month-old 129/SvJ mice. However, the age differences in swim maze acquisition were inconsistent with poor performance in the probe trial which assesses spatial memory. This inconsistency may result from the high degree of genetic polymorphisms and age-related visual pathology which afflicts this mouse strain. Therefore, we concluded that 129/SvJ mice present a problematic model of mammalian cognitive aging and involve a risk for behavioral contamination in studies involving mutant mice derived from this strain.

Aging↗
PubMedDate not supplied

Prefrontal cortex and working memory for spatial response, spatial location, and visual object information in the rat.

In the first experiment, rats were trained on a working memory task for a spatial response (right-left turn) information using a delayed matching-to-sample procedure. Following lesions of the medial prefrontal cortex (MPF), which includes anterior cingulate and medial precentral cortex, there was a profound working memory deficit even at the shortest delay. In the second experiment, rats were trained on a working memory task for spatial location information using a delayed matching-to-sample procedure. Following lesions of the MPF, there was only a mild working memory deficit, whereas following dorsal hippocampal lesions there was a profound working memory deficit even at the shortest delay. In the third experiment, rats were trained on a working memory task for visual object information using a delayed nonmatching-to-sample procedure. Following lesions of the MPF, there were no working memory deficits, whereas following lesions of the prelimbic and infralimbic cortex there was a profound working memory deficit even at the shortest delay. The results suggest that different neural subregions of the prefrontal cortex mediate working memory for specific attribute information.

Animals↗
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Bioelectrical impedance as a discriminator of pressure ulcer risk.

In an effort to identify objective measures of tissue structure and function associated with pressure ulcer risk, bioelectrical impedance analysis (BIA) was measured in three progressively larger zones over the trochanter and coccyx in patients assessed at high risk for pressure ulcers (HR group) and age-matched normal controls (CONT group). Local BIA measures were significantly lower in the HR group for each individual site and zone (p < .01). Full-thickness tissue biopsies obtained from each measurement zone did not differ between groups. However, additional nutritional and metabolic parameters were significantly different (p < or = .05). These results suggest that local BIA may be useful in assessing pressure ulcer risk.

Aged↗