Effects of the type of dietary fat at two levels of vitamin E in Wistar male rats during development and aging. III. Biochemical and morphometric parameters of the liver

Ginger and alpha lipoic acid ameliorate age-related ultrastructural changes in rat liver

Because of the important role that oxidative stress is thought to play in the aging process, antioxidants could be candidates for preventing its related pathologies. We investigated the ameliorative effects of two antioxidant supplements, ginger and alpha lipoic acid (ALA), on hepatic ultrastructural alterations in old rats. Livers of young (4 months) and old (24 months) Wistar rats were studied using transmission electron microscopy. Livers of old rats showed sinusoidal collapse and congestion, endothelial thickening and defenestration, and inconsistent perisinusoidal extracellular matrix deposition. Aged hepatocytes were characterized by hypertrophy, cytoplasmic vacuolization and a significant increase in the volume densities of the nuclei, mitochondria and dense bodies. Lipofuscin accumulation and decreased microvilli in bile canaliculi and space of Disse also were observed. The adverse alterations were ameliorated significantly by both ginger and ALA supplementation; ALA was more effective than ginger. Ginger and ALA appear to be promising anti-aging agents based on their amelioration of ultrastructural alterations in livers of old rats.

Dietary factors in lipofuscinogenesis and ceroidogenesis

The presence of ceroid pigments in human and animal tissues is associated with numerous pathological conditions in which the main pathogenic factor is the primary or secondary deficiency of vitamin E or imbalances between anti- and pro-oxidants. That oxidative stress, particularly through its consequent lipid peroxidation, plays a capital role in the genesis of ceroid pigments, is supported by numerous in vitro and in vivo studies. Discussed in this presentation are two examples of oxidative stress on ceroidogenesis, namely the in vivo rat model of dietary hepatic necrosis, and the in vitro formation of ceroid pigments by the aerobic incubation of unsaturated fat and blood cells. Although it is widely believed that the progressive accumulation of lipofuscin is also a marker of oxidative stress, and that this pigment can be modulated by the dietary anti- and pro-oxidant factors, the evidence for these related notions is highly questionable. Some years ago, this controversial problem was reexplored in our laboratories by a series of studies in Wistar male rats, and the results indicated that neither the type of dietary fat, nor the pharmacological amounts of vitamin E significantly influenced the amounts of lipofuscin in cerebral neurons, cerebellar Purkinje cells, hepatocytes or cardiac myocytes. It was also found that the indices of lipid peroxidation determined in this study (production of malonaldehyde, and detection of conjugated dienes) did not correlate with the progressive accumulation of lipofuscin with age. All these results strongly suggest that the presence and cellular accumulation of lipofuscin can hardly be considered a marker of oxidative stress.

Pigments in aging: an overview

Although during the normal aging process there are numerous pigmentary changes, the best recognized are those of melanin and lipofuscin. Melanin may increase (e.g., age spots, senile lentigo, or melanosis coli) or decrease (e.g., graying of hair or ocular melanin) with age, while lipofuscin (also called age pigment) always increases with age. In fact, the time-dependent accumulation of lipofuscin in lysosomes of postmitotic cells and some stable cells is the most consistent and phylogenetically constant morphologic change of aging. This pigment displays a typical autofluorescence (Ex: approximately 440; Em: approximately 600 nm), sudanophilia, argyrophilia, PAS positiveness, and acid fastness. Advances on its biogenesis, composition, evolution, and lysosomal degradation have been hampered by the persistent confusion between lipofuscin and the large family of ceroid pigments found in a variety of pathological conditions, as evidenced by the frequent use of the hybrid term lipofuscin/ceroid by investigators mainly working with in vitro systems of disputable relevance to in vivo lipofuscinogenesis. While lipofuscin and ceroid pigments may share some of their physicochemical properties at one moment or another in their evolutions, these pigments have different tissue distribution, rates of accumulation, origin of their precursors, and lectin binding affinities. Although it is widely believed that lipofuscin is a marker of oxidative stress, and that it can be, therefore, modified by antioxidants and prooxidants, these assumptions are mainly based on in vitro experiments and are not generally supported by in vivo studies. Another common misconception is the belief that lipofuscin can be extracted from tissues by lipid solvents and measured spectrofluorometrically. These and other disturbing problems are reviewed and discussed in this presentation.

Favourable effect of K, Mg aspartate on serum proteins in aging rats

The serum concentration of individual proteins in aging rats was studied. We have made an attempt to slow down the changes in concentration occurring in rats from 5 up to 17 months of age by application of aspartate given in drinking water containing 500 mg% of monopotassium DL asparagicum and 500 mg% of monomagnesium D,L asparagicum. The solution was administered continuously for 14 days a month for 1 year. In a part of animals, the aging process was accelerated by ionizing radiation with a single dose of 4.0 Gy. We found out that administration of aspartate caused slowing of changes in concentration of all proteins observed (prealbumin, albumin, A1-globulin, haptoglobin and hemopexin) in non-irradiated and prealbumin, albumin, A1-globulin in irradiated rats in comparison with the values of proteins in rats drinking water only. The preparation did not influence more significantly the changes in the serum concentration of haptoglobin and hemopexin in rats whose aging was accelerated by radiation. A favourable effect of the preparation used manifested also in the values of survival, because the animals protected with K, Mg aspartate survived by 25-30% longer.

Prooxidant and antioxidant hepatic factors in rats chronically fed an ethanol regimen and treated with an acute dose of lindane

While acute lindane treatment and chronic ethanol feeding to rats have been associated with hepatic oxidative stress, the possible roles of these stresses in the pathogenesis of hepatic lesions reported in acute lindane intoxication and in those observed in some models of chronic alcoholism have not been established. Our previous studies in rats chronically fed ethanol regimens and then treated with a single intraperitoneal (i.p.) dose of lindane (20 mg/kg) showed that while lindane per se was invariably associated with hepatic oxidative stress, chronic ethanol feeding only produced this stress when the dietary level of vitamin E was relatively low. Chronic ethanol pretreatment did not significantly affect the lindane-associated oxidative stress, and neither chronic ethanol feeding nor acute lindane, single or in combination, produced any histologic and biochemical evidence of liver damage. In the present experiment, the acute dose of lindane was increased to 40 mg/kg, and we have studied a larger number of prooxidant and antioxidant hepatic factors. Male Wistar rats (115.5 +/- 5.4 g) were fed ad lib for 11 weeks a calorically well-balanced and nutritionally adequate basal diet, or the same basal diet plus a 32% ethanol/25% sucrose solution, also ad lib, and were then injected i.p. with a single dose of lindane or with equivalent amounts of corn oil. The results indicated that acute lindane treatment to naive rats increased practically all the prooxidant hepatic factors examined (cytochromes P450 and b5, NADPH cytochrome c reductase, NADPH oxidase), as well as the generation of microsomal superoxide radical and thiobarbituric acid reactive substances of liver homogenates, but did not modify any of the antioxidant hepatic factors studied. Conversely, the chronic administration of ethanol alone did not significantly affect the prooxidant hepatic factors but reduced some of the antioxidants (i.e., the activities of GSH-Px and the contents of alpha-tocopherol and ubiquinols 9 and 10). Although chronic ethanol pretreatment further increased the superoxide generation induced by lindane per se, it did not increase but generally reduced the effects of lindane per se on the other prooxidant factors studied. Furthermore, although acute lindane administration to ethanol-pretreated rats was associated with decreases in GSH and catalase (not affected by ethanol or lindane treatment alone), it did not substantially modify the reducing effects of ethanol feeding per se on GSH-Px, alpha-tocopherol, and ubiquinols. Once again, neither chronic ethanol feeding nor lindane treatment, single or in combination, was associated with any evidence of liver damage.

Sex-dependent differences in the effects of aging on antioxidant defense mechanisms of rat liver

Information about age-related factors that influence sensitivity to hepatotoxic injury is important to geriatric medicine and environmental health. The purpose of the present study was to determine whether age-associated changes occur in hepatic antioxidant defense mechanisms of male and female Fischer 344 rats. Liver homogenates and post-mitochondrial supernatant fractions from rats aged 4, 14, 24 and 29 months were analyzed for antioxidant enzyme activities and for vitamin E and malondialdehyde content. Age-associated changes in catalase and glutathione reductase activities were observed that could be described as sex-determined differences that disappeared in old age. Cytosolic superoxide dismutase and glutathione peroxidase activities displayed sex-dependent variations in activity but were unaffected by aging. Hepatic vitamin E concentrations were lower in male rats than in female malondialdehyde concentrations also were lower in males than in females; malondialdehyde content increased in old males and decreased in old females. The results indicate that age-associated changes in enzymatic and nonenzymatic antioxidant defense mechanisms of rat liver are sex-dependent. In addition, comparison with findings from other studies in rats suggests that the effects of aging may also depend on the strain of rat.

Effect of an antioxidant compound (2-mercaptoethanol) on the nerve terminals of the aging small intestine

The effect of 2-mercaptoethanol (2-ME) treatment on the nerve elements of the small intestine has been investigated in old mice. In control animals only a few synapses and a very small number of vesicles were found in the nerve terminals. Some of the nerve fibers were observed to be degenerating. After drinking 2-ME daily for 17 months, both the number of synapses and vesicles within the nerve terminals increased. No degenerated fibers were observed. It is assumed that 2-ME has a beneficial influence on the peripheral intestinal nervous system increasing the number of synapses and the vesicle population in the nerve terminals.

Functional units in rainbow trout (Salmo gairdneri, Richardson) liver: III. Morphometric analysis of parenchyma, stroma, and component cell types

Hepatic stroma and parenchyma with its component cell types were quantitatively described in adult male and female actively-spawning 5-year-old rainbow trout (Salmo gairdneri, Richardson). Point-count morphometry of glycol methacrylate sections estimated volume compartments for stroma and parenchyma. Veins composed 85% of the stroma while arteries and bile ducts occupied approximately 6-7% each. Parenchyma accounted for 95% of hepatic volume. Point-count morphometry of transmission electron micrographs estimated volume compartments as well as numerical and surface density measurements for parenchymal components. Within the hepatic parenchymal compartment, hepatocytes occupied 85% and showed significant sex differences. Female hepatocytes were significantly more numerous but were smaller, only 60% of the volume of male hepatocytes. Since hepatocyte nuclear volume was equal in both sexes, differences were due to reduced cytoplasmic volume in females. Perisinusoidal macrophages of females occupied larger volumes of their respective parenchymal compartments, and their larger mean cytoplasmic volumes suggested activation. Biliary epithelial cells of preductules and ductules were numerous. Ratios of numerical density of hepatocytes to biliary epithelial cells were consistent with a tubular arrangement of hepatocytes. Factors possibly mediating the sexual dimorphism are discussed.

Effect of 2-mercaptoethanol on some metabolic indices of ageing of CBA/Ca inbred mice

It has been shown in several studies that 2-mercaptoethanol (2-ME) improves the life span and aspects of life performance of laboratory animals. To obtain further details on the beneficial effects of 2-ME, a long-term study has been performed on male CBA/Ca inbred mice treated with this antioxidant. Four month-old mice were each given 4 micrograms of 2-ME in physiological saline via intraperitoneal (i.p.) injection 3 x per week. Measurements were made of the following: cold tolerance (heat performance), apparent total body protein turnover (T1/2), changes in the major lipid and fatty acid compositions of the liver, superoxide dismutase activity and formation of malondialdehyde and observations on a range of pathological changes. It was found that the basal rectal temperatures of the treated mice were higher and in the oldest group, heat performance capacity was better than those of the controls. After about 1 year of age the apparent biological half-life time of total body protein (T1/2) was observed to be shorter in the treated mice. Significant increases were observed to occur in the proportions of the polyunsaturated fatty acids in the lipids of the liver in the mice injected with 2-ME. Although no differences were observed in the superoxide dismutase activities, malondialdehyde concentrations in the livers of the experimental mice were significantly increased. Autopsy data showed that Dunn-sarcomas associated with amyloidoses occurred more frequently in the untreated mice.

Effect of aging on aqueous-phase antioxidants in tissues of male Fischer rats

The purpose of this study was to determine the influence of aging on concentrations of the important aqueous-phase antioxidants in rat tissues. Ascorbic acid, glutathione and uric acid were measured in tissues and organs of male Fischer 344 rats at 6, 15 and 26 months of age. Blood, liver, lungs, heart, kidneys, brain, testes and lenses were excised rapidly and were extracted with cold metaphosphoric acid. Aging diminished the concentration of ascorbic acid in liver, lung and lens; levels in 26-month-old rats were 40-60% of those in 6-month-old rats. Glutathione content was diminished only in lens, where it decreased almost 50% between 15 and 26 months. Some age-associated increases in antioxidant levels also were seen; testis ascorbic acid and kidney glutathione levels were elevated in the old compared with the younger rats. Uric acid concentrations were much lower than glutathione or ascorbic acid concentrations in every tissue except plasma. Old rats had lower levels of uric acid in liver but higher levels in heart, kidney and testis. These results demonstrate that aqueous-phase antioxidant levels are not uniformly diminished in tissues of old rats.

Quantification of age pigments (lipofuscin)

1. Three methods have hitherto been applied for age pigment quantification: (a) numerically from micrographs; (b) fluorimetrically from histological sections; (c) spectrofluorimetrically from dissolved age pigments. 2. The spectrofluorimetric method is at present the most commonly used technique for quantification of age pigments. 3. By comparing the related publications since introduction of the spectrofluorimetric method, it has become apparent that few authors specify fluorimetrically significant factors, such as temperature and pH which influence the sample fluorescence during measurement. 4. Recent developments in fluorimetrical age pigment quantification using chloroform/methanol as solvent have additionally revealed the necessity to measure and present the age pigments dissolved in both phases: the polar and non-polar solvents.

Lipofuscin and lipofuscin-like substances

Lipofuscin is defined as being a yellowish brown, lipid-rich, heterogeneous, cytoplasmic granular pigment emitting an intense yellow autofluorescence when excited with ultraviolet light, which accumulates in various tissues of animals during their aging. It is believed that the pigments are derived from the reaction of some of reactive secondary products including malonaldehyde, formed during membranous lipid peroxidation, with amino groups of phospholipids and proteins, etc., and that these formations are accompanied by alteration of the membrane structure and inactivation of the enzymes. The fluorescence measurement of the pigments is widely used as a parameter of lipid peroxidation in vivo as well as in vitro. However, their origin, chemical structure, biological significance or fate has not as yet been fully elucidated. This article introduces and discusses the recent studies on these problems.

Heart and liver lipid fatty acid and behavior changes in mice after a diet change

270-Day old, male Ham/ICR mice were subjected to a diet change from high protein and carbohydrate and low fat to a diet higher in fat and lower in carbohydrate and protein. Age matched mice were maintained on laboratory rodent chow as controls. The diet change was not defined so the observed differences could not necessarily be ascribed to altered protein, carbohydrate, or fat intake. Comparison of the controls with the experimental mice revealed the " junk food" mice differed in lipid fatty acid profiles of the heart and liver and in percentage of lipid palmitic and oleic acids in these organs and also in plasma. Appearance was altered in the experimental mice which had dull, greasy coats. In addition, the experimental animals were less active, slept singly, and were slower in negotiating a three-choice maze than their comparably housed counterparts, indicating altered activity/curiosity behavior.

Effect of high vitamin A or tocopherol intake on hepatic lipid metabolism and intestinal absorption and secretion of lipids and bile acids in the chick

The effect of high dietary vitamin A or tocopherol, or both, on lipid absorption and secretion in the gastrointestinal tract and on serum and hepatic lipids was determined in the chick. High dietary vitamin A increased secretion of cholesterol, bile acids, phospholipids and fatty acids to the duodenum, and tocopherol enhanced cholesterol and bile acid secretion to the duodenum. No differences in over-all absorption were observed. Serum cholesterol was depressed by vitamin A and hepatic lipids were enhanced, except phosphatidyl choline which was depressed. Tocopherol increased hepatic triglycerides and cholesterol. In vitro fatty acid synthesis from lactate by liver homogenates was enhanced by vitamin E and cholesterogenesis enhanced by both vitamin A and tocopherol. delta 9 Desaturation was also enhanced by vitamin E. It is concluded that both vitamin A and tocopherol affect the hepatic synthesis and catabolism of cholesterol and that vitamin E also influences fatty acid metabolism.