Further studies on the effects of centrophenoxine on lipofuscin pigment in neuroblastoma cells in culture: an electron microscopic study

Reversal of an aluminium induced alteration in redox status in different regions of rat brain by administration of centrophenoxine

Aluminium is one of the most studied neurotoxin, and its effects on nervous system are both structural and functional, involving various regions of brain. Aluminium toxicity is known to have multiple mechanisms of action in the central nervous system. Affinity of aluminium for thiol substrates is considered a possible molecular mechanism involved in aluminium neurotoxicity. The reduced glutathione (GSH) is especially important for cellular defence against aluminium toxicity. This study pertains to the modulatory action of centrophenoxine on GSH status in aluminium exposed different brain regions of the female rats. Aluminium was administered orally at a dose of 40 mg/Kg x b x wt x /day for a period of eight weeks whereas, centrophenoxine was administered intraperitoneally at a dose of 100 mg/Kg x b x wt x /day for a period of six weeks. The study was carried out in different regions of brain namely cerebrum, cerebellum, medulla oblongata and hypothalamus. Animals exposed to aluminum, registered a significant decrease in the levels of reduced glutathione, and oxidized glutathione as well as in the activity of glutathione reductase in all the different regions studied when compared to normal control animals. Post-treatment with centrophenoxine, showed a significant improvement in the thiol levels in different regions. Centrophenoxine when administered alone also had a profound effect on the levels of reduced glutathione as well as on the activity of glutathione reductase. From the present results, it can be stated that centrophenoxine administration, as a thiol-antioxidant, arrests the aluminium induced cellular damage by improving the thiol status in brain regions.

Formation of lipofuscin-like autofluorescent materials in NG108-15 cells: involvement of lysosomal protein degradation

We found that neuroblastoma x glioma hybrid NG108-15 cells accumulated lipofuscin-like autofluorescent materials during neuronal differentiation in culture in a medium containing 1% fetal calf serum, 1 mM dibutyryl cyclic AMP and 1 mM theophylline. The emission maximum of the lipofuscin-like autofluorescent materials was between 500 and 550 nm. Granules positive to acid phosphatase and periodic-acid Schiff were increased, as were the autofluorescent granules in NG108-15 cells. Thiolprotease inhibitors, N-(L-3-trans-carboxyoxirane-2-carbonyl)-L-leucine-4-aminobutyla mide (E-64) and acetyl-Leu-Leu-Arg (leupeptin), markedly accelerated the accumulation of the lipofuscin-like autofluorescent materials in NG108-15 cells. On the other hand, activities of lysosomal thiolproteases, cathepsin B, C and L, were increased during neuronal differentiation. Protein content in the cells was gradually increased with the neuronal differentiation, and the rise was significantly accelerated when proteolysis was inhibited by E-64. These results suggest that the lipofuscin-like autofluorescent materials contain peptidic substances as a component, and indicate that the increase in hydrolytic activities of thiolproteases during neuronal differentiation is not enough for the hydrolysis of peptidic substrates, resulting in the accumulation of autofluorescent materials in NG108-15 cells.

Effect of vitamin E on the accumulation of fluorescent material in cultured cerebral cortical cells of mice

The effect of vitamin E on the accumulation of lipofuscin-containing fluorescent material in the mouse cerebral cortical cells in primary culture was studied. Fluorescent material was extracted in ethanol:diethylether (3:1) and autofluorescence intensity of the extracts was measured by a spectrofluorophotometer. Although vitamin E at the concentration of 0.005 IU/ml was not effective, 0.01 IU/ml vitamin E inhibited the accumulation of fluorescent material. Fluorescent material accumulation was reduced to 76.3-86.4% of the control level in 6-, 12-, or 18-day treatment of 0.01 IU/ml vitamin E. High doses of vitamin E (0.05 or 0.1 IU/ml) were toxic for cultured cells. Ethanol, the vehicle of vitamin E, at the final concentration of 0.005% was also effective on the reduction of fluorescent material accumulation (81.0% of the control level at 18 days). The inhibitory effects of vitamin E as well as ethanol on the accumulation of fluorescent material in cultured cells are explained by their nature as free radical scavengers.

Age pigments in different populations of peripheral neurons in vivo and in vitro

The distribution and ultrastructure of lipopigments in the rat sympathetic, vagus and spinal ganglion neurons were studied in vivo and in vitro using fluorescence and electron microscopy. Newborn, 3-6 mo and 24-30 mo-old male Wistar rats were used. In vivo, the age pigments in the sympathetic neurons showed a tendency to form unipolar or bipolar caps, whereas in the vagus and spinal ganglion neurons pigment granules were packed in the peripheral area of the perikarya during aging. Ultrastructurally, lipid-like vacuoles and a rather homogeneous matrix were the components shared by pigment bodies of all types of peripheral neurons. However, pigment granules in sympathetic neurons frequently had a third, osmiophilic component, which likely represents neuromelanin. In vitro, the cytoplasmic area occupied by autofluorescent pigments was increased in most of the neurons. Some neurons, however, showed the same amount of lipopigments as in vivo. In electron microscopy, age pigment granules typical of each type of neuron were found, and their number and intracellular distribution seemed to be comparable with those in vivo. In most of the neurons cultured from all ages and of all types of ganglion, there appeared to be accumulations of another, very homogeneous and large type of pigment body. In some cases, they were structurally connected with classical pigment bodies or they had a finger print-like substructure. Large homogeneous pigment bodies were also seen in surrounding satellite cells. All these changes were most frequently seen in cultures of spinal ganglia from old animals. It is concluded that although classical age pigments maintain their characteristics in cultured peripheral neurons, there is, in addition, a rapid accumulation of ceroid-like pigments, which may be caused by the inability of the cultured neurons to cope with increased peroxidative damage.

Effects of centrophenoxine on lipofuscin in the retinal pigment epithelium of old mice

The effects of centrophenoxine on the retinal pigment epithelium (RPE) of 17 month old female mice have been studied. Animals were injected subcutaneously for 3 months (60 injections) with the drug (0.1 mg/g of body wt) daily in 0.1 M phosphate buffered saline at pH 7.0. The morphological changes in the pigment layers of the retina of both eyes were studied by light and electron microscopy and the lipofuscin pigment was demonstrated by its autofluorescence and ultrastructural characteristics. There was a significant reduction of the lipofuscin pigment in the treated animals, but the melanin pigment remained unchanged. The lipofuscin granules also appeared less osmiophilic and showed a greater preponderance of membranes and vacuoles. Although the precise mechanism of action of the drug is not clear, an increased protective function of the pigment epithelium by the drug has been suggested.