Training pathologists in mouse pathology.

Expertise in the pathology of mice has expanded from traditional regulatory and drug safety screening (toxicologic pathology) primarily performed by veterinary pathologists to the highly specialized area of mouse research pathobiology performed by veterinary and medical pathologists encompassing phenotyping of mutant mice and analysis of research experiments exploiting inbred mouse strains and genetically engineered lines. With increasing use of genetically modified mice in research, mouse pathobiology and, by extension, expert mouse research-oriented pathologists have become integral to the success of basic and translational biomedical research. Training for today's research-oriented mouse pathologist must go beyond knowledge of anatomic features of mice and strain-specific background diseases to the specialized genetic nomenclature, husbandry, and genetics, including the methodology of genetic engineering and complex trait analysis. While training can be accomplished through apprenticeships in formal programs, these are often heavily service related and do not provide the necessary comprehensive training. Specialty courses and short-term mentoring with expert specialists are opportunities that, when combined with active practice and publication, will lead to acquisition of the skills required for cutting-edge mouse-based experimental science.

Influence of dietary fat, vitamin E, ethoxyquin and indomethacin on the synthesis of prostaglandin E2 in brain regions of mice.

The regional brain synthesis of prostaglandin E2 (PGE2) of rats varies with age and dietary vitamin E. We investigated ex-vivo synthesis of PGE2 in brain regions of 24-mo-old male C57BL/6Nia mice. Mice were fed semipurified diets containing 1) 5% by weight of vitamin E-stripped corn oil, nonhydrogenated coconut oil or fish oil, or 2) 3.8% lard + 1.2% stripped corn oil (control), each supplemented with 30 or 500 mg of vitamin E per kg for 6 wk. In addition, two groups of mice were fed control diets containing 2500 mg of ethoxyquin/kg or 1 mg of indomethacin/(kg.day). Mice fed fish oil had lower (P less than 0.01) plasma alpha-tocopherol than those fed coconut oil. Vitamin E supplementation had no effect on the concentration of alpha-tocopherol in most brain regions. The rank order of PGE2 synthesis among all groups was cerebrum = cerebellum greater than midbrain greater than brainstem. Vitamin E supplementation tended to reduce brain PGE2 synthesis. Fat with 30 mg/kg of vitamin E in their diet. In the brainstem, fish oil significantly reduced PGE2 relative to mice fed corn oil. Ethoxyquin lowered plasma alpha-tocopherol by 42% and reduced the PGE2 synthesis in brain regions, and indomethacin reduced it by 50%. Thus, ethoxyquin and indomethacin significantly reduced the brain's regional capacity for PGE2 synthesis, whereas vitamin E was not effective for the period tested. The reduction of PGE2 synthesis in the brain with fish oil feeding in this study was not as notable as reported for other tissues unless combined with high-dose vitamin E supplementation.

Postprandial changes in the plasma concentration of alpha- and gamma-tocopherol in human subjects fed a fat-rich meal supplemented with fat-soluble vitamins.

The plasma concentrations of alpha (alpha)- and gamma (gamma)-tocopherol in 10 male and 15 female subjects (n = 14) received 1 g fat/kg body wt as soybean oil, and the meal was supplemented with 100% of the RDA for fat-soluble vitamins. In expt. 2, the subjects (n = 11) received 1 g fat/kg body wt as 50% soybean oil + 50% cream, and the meal was supplemented with 200% of the RDA for fat-soluble vitamins. The ratio of gamma- :alpha-tocopherol given in the test meal of expt. 1 was 2.8:1 and in expt. 2 was 0.9:1. Blood samples were obtained 0, 3, 6, 9 and 12 h after the meal. Tocopherol concentration was measured in plasma and lipoprotein fractions. In both studies, plasma triglyceride concentration increased significantly after the meal (P less than 0.001). Mean plasma cholesterol and alpha-tocopherol concentrations were unchanged, but plasma gamma-tocopherol concentration was significantly increased at 6, 9 and 12 h after the meal (P less than 0.05). The increase in plasma gamma-tocopherol was due to increases within the triglyceride-rich lipoprotein (TRL) fraction (d less than 1.006 g/ml) at earlier timepoints, followed by a sustained increase within low density lipoprotein (LDL) and high density lipoprotein (HDL) fractions at later timepoints. In contrast, alpha-tocopherol in LDL and HDL decreased postprandially, concomitant with a rise in TRL alpha-tocopherol. Our results are consistent with the concept that there are differences in the distribution of alpha- and gamma-tocopherol in postprandial lipoproteins.

Effect of dietary vitamin E and selenium on susceptibility of brain regions to lipid peroxidation.

The effect of dietary vitamin E and/or selenium (Se) supplementation (200 IU and/or 0.2 ppm, respectively) or deficiency for two months on lipid peroxidation in cerebrum, cerebellum, mid-brain, and brain stem of one-month-old male F344 rats was investigated. Dietary treatment had a minimal effect on weight gain of rats for the period tested. Plasma alpha-tocopherol (alpha-T) concentration and glutathione peroxidase (GSH-Px) activity were reflective of dietary treatments. Supplementation of diets with vitamin E and/or Se increased plasma alpha-T and/or GSH-Px activity, while diets devoid of these nutrients reduced them significantly. Increased GSH-Px activity in Se-supplemented rats was further enhanced by vitamin E supplementation. Differential concentrations of alpha-T among brain regions were affected by dietary vitamin E but not by Se. In vitro lipid peroxidation of brain homogenates was inhibited by dietary vitamin E supplementation and increased by deficiency. Addition of 0.25 mM ascorbic acid or 0.1 mM of Fe2+ to brain homogenates markedly increased in vitro lipid peroxidation. Ascorbic acid-induced lipid peroxidation was inversely correlated with dietary vitamin E and Se in cerebrum. In vitro Fe2+-addition induced the greatest stimulation of lipid peroxidation, with cerebellum and brain stem of vitamin E-deficient rats showing the highest response to Fe2+ challenge. These findings indicate that concentrations of alpha-T among the brain regions are different and can be altered by dietary vitamin E treatments, cerebellum and brain stem are more susceptible to in vitro challenge by peroxidative agents than other regions, and the degree of lipid peroxidation of brain regions is partially affected by dietary vitamin E but not by Se in the levels tested.

Effect of age and dietary fat (fish, corn and coconut oils) on tocopherol status of C57BL/6Nia mice.

The effect of age and dietary fat type on tocopherol status was investigated using young and old C57BL/6Nia mice fed semipurified diets containing 5% (by weight) fish, corn or coconut oils and supplemented with 30, 100 or 500 ppm dl-alpha-tocopheryl acetate for 6 wk. Tocopherol levels in the diets, plasma, liver, kidney and lung were measured by high performance liquid chromatography following appropriate extractions. The results indicate that mice fed fish oil maintain lower plasma and tissue tocopherol concentrations than those fed corn and coconut oils (fish less than corn oil less than coconut oil). The difference was not due to a loss of tocopherol prior to consumption, but rather appeared to occur during the absorption process. Old mice had lower plasma and liver tocopherol concentrations than young mice. Old mice fed fish oil, however, maintained plasma tocopherol levels better than young mice fed fish oil, presumably due to their larger tocopherol pool. No age effect was detected on kidney and lung tocopherol levels. It is concluded that tocopherol status is affected by age and dietary fat type, especially fish oil.

Influence of dietary vitamin E, selenium and age on regional distribution of alpha-tocopherol in the rat brain.

Concentrations of alpha-tocopherol (alpha-T) in plasma, cerebrum, cerebellum, midbrain and brain stem and activity of selenium (Se)-dependent glutathione peroxidase (GSH-Px) in plasma were measured in 1- and 15-month-old male F344 rats fed diets containing vitamin E (E, IU/kg) and Se (ppm) in the following combinations: 30 E, 0.1 Se (control diet, minimum requirements); 200 E, 0.2 Se; 0.0 E, 0.2 Se; 200 E, 0.0 Se; 0.0 E, 0.0 Se for 8 or 20 weeks. alpha-T and GSH-Px levels in plasma were reflective of dietary treatment in young rats in which an interaction of the two nutrients was noted. A longer period of dietary vitamin E deficiency was necessary to deplete plasma alpha-T and depress GSH-Px activity significantly in the old rats. Among the brain regions of all ages, cerebrum and midbrain had the highest concentrations of alpha-T while cerebellum showed the lowest. However, cerebellum of young rats and cerebellum and brain stem of old rats had a greater alpha-T accumulation with doubly supplemented diets, whereas only cerebellum of young and old rats showed a marked increase of alpha-T with vitamin E supplementation. In old rats, vitamin E deficiency resulted in greater depletion of alpha-T in cerebellum and brain stem than cerebrum and midbrain regions. Se deficiency in brain stem of young and old rats significantly decreased alpha-T accumulation by vitamin E supplementation. Se supplementation marginally alleviates vitamin E depletion in brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of dietary vitamin E and selenium on the ex-vivo synthesis of prostaglandin E2 in brain regions of young and old rats.

The potential for synthesis of prostaglandin E2 (PGE2) in cerebrum (CC), cerebellum (CM), mid-brain (MB) and brain stem (BS) was measured in 1 and 15 month old male F344 rats fed diets containing 0, 30, or 200 IU vitamin E (-E, E, +E, respectively) and 0.0, 0.1, or 0.2 ppm selenium (-Se, Se, +Se, respectively) for 8 or 20 weeks. Regardless of dietary treatments, the rank order of PGE2 synthesis was CC greater than CM greater than BS = MB in the young rats; CC greater than MB greater than BS = CM in the old rats; and CC greater than MB greater than BS greater than CM in the aged rats. PGE2 synthesis in all brain regions were significantly influenced by dietary treatments except CC. -E diets increased and +E diets decreased PGE2 production. Young rats were most susceptible to PGE2 alteration by vitamin E deficiency while old rats responded most markedly to supplementation. All brain regions showed decreases in their capacity to synthesize PGE2 with age, except MB where the opposite effect was seen. Dietary Se treatment had a minimal role in PGE2 synthesis in gross anatomical regions of brain. The degree to which PGE2 synthesis is affected is more dependent on dietary vitamin E level and tissue alpha-tocopherol content than on Se. CM and BS of aged rats appear to require more alpha-tocopherol to maintain steady state levels than other areas, thus the synthesis of PGE2 in these regions could be highly susceptible to alterations in dietary vitamin E.