Morphometry of age pigment (lipofuscin) and of ceroid pigment deposits associated with vitamin E deficiency

High-Carbohydrate Diets Affect Accumulation of Lipofuscin-Like Pigment in the Kidneys of Mice and Rats: Autofluorescence Confocal Microscopy Analysis

The accumulation of lipofuscin-like granules in liver, kidneys, and spleen cells in mice and rats of different lines receiving 30% sugar solutions (fructose, glucose, their mixture, and sucrose) in addition to balanced semisynthetic diet for 62 or 122 days was studied by the method of laser scanning confocal microscopy. The granules were detected by their autofluorescence at maximum λ_ex =570-600 nm and λ_ex=488 nm. In the kidneys of rats receiving glucose and, especially, the mixture of glucose and fructose, significant accumulation of lipofuscin-like granules was found that was absent in the control group animals receiving water. Intensive accumulation of the granules was observed in the kidneys of all groups of mice receiving sugars (except for glucose). Lipofuscin-like granules were located in the cytoplasm of epithelial cells of the distal and proximal convoluted tubules. In the liver of rats and mice, the signs of accumulation of lipofuscin-like granules were absent or minimal. In rat spleen, lipofuscinlike granules were found in the red pulp in all groups, but their accumulation significantly increased in animals receiving the diet enriched with glucose and sucrose.

Protective effects of a catechin-rich extract on the hippocampal formation and spatial memory in aging rats

Green tea (GT) displays strong anti-oxidant and anti-inflammatory properties mostly attributed to (-)-epigallocatechin-3-gallate (EGCG), while experiments focusing on other catechins are scarce. With the present work we intended to analyze the neuroprotective effects of prolonged consumption of a GT extract (GTE) rich in catechins but poor in EGCG and other GT bioactive components that could also afford benefit. The endpoints evaluated were aging-induced biochemical and morphological changes in the rat hippocampal formation (HF) and behavioral alterations. Male Wistar rats aged 12 months were treated with GTE until 19 months of age. This group of animals was compared with control groups aged 19 (C-19M) or 12 months (C-12M). We found that aging increased oxidative markers but GTE consumption protected proteins and lipids against oxidation. The age-associated increase in lipofuscin content and lysosomal volume was also prevented by treatment with GTE. The dendritic arborizations of dentate granule cells of GTE-treated animals presented plastic changes accompanied by an improved spatial learning evaluated with the Morris water maze. Altogether our results demonstrate that the consumption of an extract rich in catechins other than EGCG protected the HF from aging-related declines contributing to improve the redox status and preventing the structural damage observed in old animals, with repercussions on behavioral performance.

Modulation of age-related changes in oxidative stress markers and energy status in the rat heart and hippocampus: a significant role for ozone therapy

Oxidative stress emerges as a key player in the ageing process. Controlled ozone administration is known to promote an oxidative preconditioning or adaptation to oxidative stress. The present study investigated whether prophylactic ozone administration could interfere with the age-related changes in the heart and the hippocampus of rats. Four groups of rats, aged about 3 months old, were used. Group 1 (Prophylactic ozone group) received ozone/oxygen mixture by rectal insufflations (0.6 mg/kg) twice/week for the first 3 months, then once/week till the age of 15 months. Group 2 (Oxygen group) received oxygen as vehicle for ozone in a manner similar to group 1. Group 3 (Aged control group) was kept without any treatment until the age of 15 months. A fourth group of rats (Adult control group) was evaluated at 3 months of age to provide baseline data. Ozone alleviated age-associated redox state imbalance as evidenced by reduction of lipid and protein oxidation markers, lessening of lipofuscin deposition, restoration of glutathione levels in both tissues and normalization of glutathione peroxidase activity in the heart tissue. Ozone also mitigated age-associated energy failure in the heart and the hippocampus, improved cardiac cytosolic Ca(2+) homeostasis and restored the attenuated Na(+) , K(+) -ATPase activity in the hippocampus of aged rats. These data provide new evidence concerning the anti-ageing potential of prophylactic ozone administration.

Quantification of ceroid and lipofuscin in skeletal muscle

Ceroid and lipofuscin are autofluorescent granules thought to be generated as a consequence of chronic oxidative stress. Because ceroid and lipofuscin are persistent in tissue, their measurement can provide a lifetime history of exposure to chronic oxidative stress. Although ceroid and lipofuscin can be measured by quantification of autofluorescent granules, current methods rely on subjective assessment. Furthermore, there has not been any evaluation of variables affecting quantitative measurements. The article describes a simple statistical approach that can be readily applied to quantitate ceroid and lipofuscin. Furthermore, it is shown that several factors, including magnification tissue thickness and tissue level, can affect precision and sensitivity. After optimizing for these factors, the authors show that ceroid and lipofuscin can be measured reproducibly in the skeletal muscle of dystrophic mice (ceroid) and aged mice (lipofuscin).

Mitochondrial turnover and aging of long-lived postmitotic cells: the mitochondrial-lysosomal axis theory of aging

It is now generally accepted that aging and eventual death of multicellular organisms is to a large extent related to macromolecular damage by mitochondrially produced reactive oxygen species, mostly affecting long-lived postmitotic cells, such as neurons and cardiac myocytes. These cells are rarely or not at all replaced during life and can be as old as the whole organism. The inherent inability of autophagy and other cellular-degradation mechanisms to remove damaged structures completely results in the progressive accumulation of garbage, including cytosolic protein aggregates, defective mitochondria, and lipofuscin, an intralysosomal indigestible material. In this review, we stress the importance of crosstalk between mitochondria and lysosomes in aging. The slow accumulation of lipofuscin within lysosomes seems to depress autophagy, resulting in reduced turnover of effective mitochondria. The latter not only are functionally deficient but also produce increased amounts of reactive oxygen species, prompting lipofuscinogenesis. Moreover, defective and enlarged mitochondria are poorly autophagocytosed and constitute a growing population of badly functioning organelles that do not fuse and exchange their contents with normal mitochondria. The progress of these changes seems to result in enhanced oxidative stress, decreased ATP production, and collapse of the cellular catabolic machinery, which eventually is incompatible with survival.

Lipofuscin: detection and quantification by microscopic techniques

Since lipofuscin, the so-called "aging pigment", turned out to play a fundamental role in the aging process, particularly in the postmitotic senescence of muscle or neuronal cells, it became a focus of aging and stress research. During normal aging, lipofuscin accumulates in a nearly linear way, whereas its rate of formation can increase in the final stages of senescence or in the progress of several pathologic processes. Thus, both in senescence and pathologic processes, lipofuscin can be used as a detectable "marker" to estimate the remaining lifetime of single cells, the amount of long-term oxidative stress cells were subjected to or to quantify and qualify a pathologic progress in vivo or in vitro. To enable this, a quick and easy applicable method of detection and quantification of lipofuscin has to be used, as is provided by fluorescence microscopy determining the autofluorescence via of the "aging pigment". In this review, we take a look at different methods of detection and quantification of lipofuscin in single cells by using its physical or chemical features.

Lysosomes in iron metabolism, ageing and apoptosis

The lysosomal compartment is essential for a variety of cellular functions, including the normal turnover of most long-lived proteins and all organelles. The compartment consists of numerous acidic vesicles (pH approximately 4 to 5) that constantly fuse and divide. It receives a large number of hydrolases ( approximately 50) from the trans-Golgi network, and substrates from both the cells' outside (heterophagy) and inside (autophagy). Many macromolecules contain iron that gives rise to an iron-rich environment in lysosomes that recently have degraded such macromolecules. Iron-rich lysosomes are sensitive to oxidative stress, while 'resting' lysosomes, which have not recently participated in autophagic events, are not. The magnitude of oxidative stress determines the degree of lysosomal destabilization and, consequently, whether arrested growth, reparative autophagy, apoptosis, or necrosis will follow. Heterophagy is the first step in the process by which immunocompetent cells modify antigens and produce antibodies, while exocytosis of lysosomal enzymes may promote tumor invasion, angiogenesis, and metastasis. Apart from being an essential turnover process, autophagy is also a mechanism by which cells will be able to sustain temporary starvation and rid themselves of intracellular organisms that have invaded, although some pathogens have evolved mechanisms to prevent their destruction. Mutated lysosomal enzymes are the underlying cause of a number of lysosomal storage diseases involving the accumulation of materials that would be the substrate for the corresponding hydrolases, were they not defective. The normal, low-level diffusion of hydrogen peroxide into iron-rich lysosomes causes the slow formation of lipofuscin in long-lived postmitotic cells, where it occupies a substantial part of the lysosomal compartment at the end of the life span. This seems to result in the diversion of newly produced lysosomal enzymes away from autophagosomes, leading to the accumulation of malfunctioning mitochondria and proteins with consequent cellular dysfunction. If autophagy were a perfect turnover process, postmitotic ageing and several age-related neurodegenerative diseases would, perhaps, not take place.

Lysosomes and oxidative stress in aging and apoptosis

The lysosomal compartment consists of numerous acidic vesicles (pH approximately 4-5) that constantly fuse and divide. It receives a large number of hydrolases from the trans-Golgi network, while their substrates arrive from both the cell's outside (heterophagy) and inside (autophagy). Many macromolecules under degradation inside lysosomes contain iron that, when released in labile form, makes lysosomes sensitive to oxidative stress. The magnitude of generated lysosomal destabilization determines if reparative autophagy, apoptosis, or necrosis will follow. Apart from being an essential turnover process, autophagy is also a mechanism for cells to repair inflicted damage, and to survive temporary starvation. The inevitable diffusion of hydrogen peroxide into iron-rich lysosomes causes the slow oxidative formation of lipofuscin in long-lived postmitotic cells, where it finally occupies a substantial part of the volume of the lysosomal compartment. This seems to result in a misdirection of lysosomal enzymes away from autophagosomes, resulting in depressed autophagy and the accumulation of malfunctioning mitochondria and proteins with consequent cellular dysfunction. This scenario might put aging into the category of autophagy disorders.

Autophagy, organelles and ageing

As a result of insufficient digestion of oxidatively damaged macromolecules and organelles by autophagy and other degradative systems, long-lived postmitotic cells, such as cardiac myocytes, neurons and retinal pigment epithelial cells, progressively accumulate biological 'garbage' ('waste' materials). The latter include lipofuscin (a non-degradable intralysosomal polymeric substance), defective mitochondria and other organelles, and aberrant proteins, often forming aggregates (aggresomes). An interaction between senescent lipofuscin-loaded lysosomes and mitochondria seems to play a pivotal role in the progress of cellular ageing. Lipofuscin deposition hampers autophagic mitochondrial turnover, promoting the accumulation of senescent mitochondria, which are deficient in ATP production but produce increased amounts of reactive oxygen species. Increased oxidative stress, in turn, further enhances damage to both mitochondria and lysosomes, thus diminishing adaptability, triggering mitochondrial and lysosomal pro-apoptotic pathways, and culminating in cell death.

Regional responses in antioxidant system to exercise training and dietary Vitamin E in aging rat brain

We have evaluated the effect of exercise, Vitamin E and a combination of both on the antioxidant enzymes (AOEs)-superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) along with the products of lipid peroxidation (LP)-malondialdehyde (MDA) and lipofuscin-like auto fluorescent substances (LF-like AFS) in discrete brain regions of rats of 4 (young adults), 8 (old adults), 12 (middle-age) and 22 months (mos) old of age. Hippocampus (HC) showed greater increase in GSH-Px activity than cerebral cortex (CC) to exercise and Vitamin E and was irrespective of the age. A combination of both was effective in the CC of all age groups but not in the supplemented sedentary of 12- and 22-mo-olds. CAT activity increased significantly in the HC of supplemented and trained rats but not in the combination group of any age. SOD increased in both the regions of supplemented trainees. However, old were more benefited in terms of maximal elevation in the HC. Vitamin E reduced MDA content in both regions of adult. LF-like AFS decreased significantly in supplemented sedentary and trainees of all ages. Our results demonstrate that an age-related deficit in AOEs in the CC and HC can be overcome through Vitamin E plus exercise, and further suggests the rationale for looking at these markers of oxidative stress in several age-related neuronal diseases.