Vitamin E deficiency alters the in vivo Rb+ discrimination of rat brain cortical cells

The in vivo Rb+ uptake and release of rat brain cortical cells of 11-months-old rats fed with a vitamin E deficient diet was investigated. The animals were treated with a daily dose of 30 mg RbCl/100 g body weight for 14 days. After discontinuation of the RbCl treatment the animals were killed at intervals of 2, 4, 9 and 15 days, respectively. The intracellular Rb+ and K+ contents were analyzed by energy dispersive X-ray microanalysis, whereas concentrations of these two ions were determined by atomic absorbtion spectrophotometry in the serum and cerebrospinal fluid. Vitamin E deficient rats accumulate more Rb+ than age-matched normally fed animals at any time taken into account. Rb+-discrimination ratios calculated on the basis of Rb+ and K+ contents of both, cortical cell cytoplasm and cerebrospinal fluid, are higher in vitamin E deficient rats than in the controls (+20%), which supports the view that the enhanced membrane lipid peroxidation induced by vitamin E deficiency impairs the passive membrane permeability for Rb+ (and K+).

Quantitative investigation of the morphological plasticity of synaptic junctions in rat dentate gyrus during aging

The morphological plasticity of synaptic junctions was investigated by means of quantitative stereology in the dentate gyrus supragranular layer of young (3 months), adult (12 months) and old (30 months) female Fisher 344 rats. The numerical (Nv) and surface (Sv) density and the average surface area (S) of EPTA-stained synaptic junctions were calculated on 100 EM pictures per age group. We found that Nv significantly increased between the young and adult group and decreased in old animals when compared both to 3 and 12 months of age. Sv was unchanged in young and adult rats, whereas it underwent a significant reduction in the old group. The percentage distribution of S showed that at 3 months of age the majority of the synaptic population had an average size ranging between 0.12 and 0.20 micron 2, whereas during adulthood and aging there was a shift towards smaller and larger synaptic contacts, respectively. Taking into account Nv, Sv and S all together per age group, the present findings demonstrate that the morphological aspect of synaptic plasticity is markedly influenced by time and that during aging it undergoes a serious impairment. The possible involvement in memory and learning processes of these synaptic age-related morphological adaptations and the fact that the investigated junctions are supposed to be cholinergic is discussed.

Chronic dietary choline modulates synaptic plasticity in the cerebellar glomeruli of aging mice

A morphometric investigation was carried out on ethanolic phosphotungstic acid (E-PTA) stained synaptic junctions in the cerebellar glomeruli of adult, old, old choline-deficient and old choline-supplemented mice. Numerical (Nv) and surface (Sv) density as well as average length (L) of the synapses were calculated on 100 pictures per group. A significant reduction of Nv and Sv, as well as an increase of L was found during aging. Choline deficient animals did not show any change as compared to old animals of the same age. In choline supplemented mice Nv and Sv were significantly increased and L significantly decreased, respectively, as compared to old control littermates. No difference was found between adult and choline supplemented mice. In the cerebellar glomeruli only a small fraction of fibers are cholinergic, therefore the present findings support the idea that dietary choline can influence systems other than cholinergic. The possible role of choline supplementation in the modulation of synaptic plasticity via the synthesis and/or turnover of neuronal membrane choline phospholipids, is discussed.

Amiloride inhibits the PHA-evoked mouse splenic lymphocyte proliferation

The present study was aimed to ascertain whether Na+ influx can be involved in regulation of blastogenesis and proliferation of PHA stimulated mouse splenic lymphocytes. The cells were cultivated in the presence of different concentrations of amiloride, an inhibitor of passive Na+ influx, and cellular activation was monitored by 3H-thymidine incorporation and blast index determination. The drug was not toxic and inhibited cell growth in concentrations ranging from 1 X 10(-3) to 1 X 10(-5) mmol/ml. The results are in agreement with the hypothesis that Na influx is necessary for PHA evoked mouse splenic lymphocyte activation.

Amiloride, a diuretic with in vitro antimicrobial activity

The effect of amiloride, an inhibitor of passive sodium influx in animal cells, was investigated on the in vitro bacterial growth. Amiloride blocked the growth of different bacterial strains at concentrations ranging from 25 to 1,300 micrograms/ml. While generally the block was bacteriostatic and bacteria, on amiloride removal, recovered their ability to growth, the drug showed a killing activity on hemolytic streptococci. Gram-positive bacteria revealed a greater susceptibility to amiloride than gram-negative ones. Although an hitherto unknown effect of amiloride cannot be excluded, from the known mechanism of action of amiloride on animal cells it might be suggested that sodium permeability plays a critical role on bacterial multiplication.

Effect of chronic vitamin E deficiency on the synapses of cerebellar glomeruli in young rats

A morphometric investigation has been carried out on the synaptic junctions in the cerebellar glomeruli of young-adult rats chronically deprived of vitamin E for 10 months and control animals of the same age. The following parameters were evaluated: the average length of the synapses (L), the numerical (NV) as well as the surface (SV) density of the synaptic contact zones. The results from these experimental groups were compared with data from young, adult and old rats. The results obtained show a significant decrease of the surface density of the synaptic contact zones in old and alpha-tocopherol deprived young-adult (11-month-old) rats as compared to younger and normally fed animals. This reduction of the synaptic contact area seems to be due to the marked decline in the number of synapses found in both cases. The average size (L) of the synaptic junctions, on the other hand, was increased in alpha-tocopherol deficient rats as compared to normally fed littermates. The significant reduction of the synaptic contact area in old and vitamin E deprived young rats supports the hypothesis that a common denominator may be responsible to explain this alteration. Because of the recognized protective role of alpha-tocopherol against free radical attacks on plasma membranes, the present findings support an involvement of membrane structural alterations in aging as well as in vitamin E deficiency.

X-ray microanalysis of monovalent electrolyte contents of quiescent, proliferating as well as tumor rat hepatocytes

Energy-dispersive X-ray microanalysis was carried out on normal and regenerating liver as well as on 3924 A hepatoma cells. Specimens were quickly removed from the sacrificed animals, frozen in liquid isopentane, fractured still in the frozen state and freeze-dried under vacuum. The dried samples were examined in secondary electron image mode, and the X-ray spectra were recorded by means of an EDAX 707A system. Sodium and chlorine contents were higher both in nuclei and cytoplasms of regenerating and tumor hepatocytes than in normal liver. Moreover, hepatoma cells showed higher sodium and chlorine contents than did normal proliferating hepatocytes. Potassium contents did not show any differences among the experimental models. The increased sodium content and the resulting increased Na:K ratios of proliferating normal and tumor cells were not due to a generalized increase of these parameters in all the cells, but to the presence of new cell populations with high Na content and high Na:K ratios. Findings of present work are consistent with the hypothesis that high sodium content is associated with mitogenesis. Moreover, the much higher concentration of sodium in tumor cells as compared with normal proliferating hepatocytes supports the hypothesis that the concentration of this ion is related to oncogenesis of hepatocytes.

In vitro block of murine L 1210 leukemia cell growth by amiloride, an inhibitor of passive Na+ influx

The present study was aimed to decide whether Na+ influx can be involved in regulation of murine L 1210 leukemia cell growth. Cells were cultivated in the presence of different concentrations of amiloride and cellular growth was monitored by 3H-thymidine incorporation/10(5) cells. This drug inhibited cell growth in concentrations ranging from 1 X 10(-5) to 1 X 10(-3) mmol/ml. Even short time treatments with amiloride caused irreversible alterations: the cells, although survived, lost their ability to divide. The results support the hypothesis that Na+ influx is necessary for the duplication of tumor cells.

The effect of acute and chronic centrophenoxine treatment on the synaptic plasticity of old rats

The cerebellar glomerulus was studied by electron microscopic morphometry in female Wistar rats. Age-dependent alterations have been revealed from 3 to 28 mth of age, and the effect of centrophenoxine (CPH) was analyzed in two different patterns of administration. First, 27-mth-old rats were treated daily for 6 wk (acute treatment), and second, 18-mth-old rats were treated 3 times per week for 5 months (chronic treatment). The dose was 100 mg CPH/kg body weight, injected intraperitoneally. The surface density (SV), the numerical density (NV) and the average length (L) of the synaptic junctions were calculated from data obtained on ethanol-phosphotungstic acid stained ultrathin sections. An age-dependent reduction of SV and NV of the synaptic contact zones was found, and the L increased in the oldest animals. CPH-treatment resulted in a marked increase of SV in both types of application, whereas the other two parameters behaved differently in the two groups. The chronic treatment resulted in a significant slowing down of the decrease of NV, whereas L remained invariate. On the contrary, the acute treatment increased L but did not alter significantly NV. The results and the differences between the treatment types are discussed in terms of synaptic plasticity and are interpreted as different manifestations of the same reactive synaptogenetic process.

Age-dependence of the stimulatory effect of triiodothyronine on the DNA synthesis of rat hepatocytes

The effect of a single subcutaneous injection of triiodothyronine (T3) on DNA synthesis rate and liver growth was studied in young and old female Wistar rats. The hormonal treatment was effective in stimulating DNA synthesis, resulting in an increase of the specific liver volume as well as volume and numerical density of nuclei/100 g body wt. in young animals. In the old animals T3 injection induced a reduced and delayed synthesis of DNA, which did not affect the morphometric parameters of liver/100 g body wt.

Morphometric studies on synapses of the cerebellar glomerulus: the effect of centrophenoxine treatment in old rats

Young, adult and old female Wistar rats (3, 18 and 28 months of age, respectively), were studied using electron-microscopic stereology. Synaptic parameters of the cerebellar glomerulus were calculated and compared with similar data obtained from old Wistar rats of the same breed treated with centrophenoxine (CPH; HelferginR, Promonta, Hamburg) in the form of intraperitoneal injections (100 mg/kg body weight) for 40 days. This treatment resulted in a sort of "rejuvenation" of synaptic structures. Namely, the surface density and the total length of synaptic contact zones were markedly reduced in the untreated old group, but in the treated animals these parameters returned to the values found in the young and adult animals. At the same time the numerical density of synapses remained unaltered in the treated group, while the average synaptic length displayed some further increase. The results are interpreted in terms of the age-dependent decrease in reactive synaptogenesis, suggesting that CPH stimulates the metabolism of the nervous elements persisting in old brain. The possible mechanism of CPH effect is also discussed.

Electron-microscopic morphometric analysis of mouse liver. I. Experimental studies on the morphogenetic significance of the thymus in nude and normal mice

Haired, nude, thymus-grafted nude and haired thymectomized Balb/c-nu mice 2 months of age were studied by electron-microscopic stereology. Each group consisted of 5 animals and a complete morphometric analysis was carried out on their livers. In the absence of the thymus there is a slowing down of the development of the whole organism. Among the liver parameters especially the nuclear ones displayed alterations. Namely, the volume of hepatocyte nuclei increased above the normal level and this phenomenon was reversed by thymus graft into the nude mice. The hepatocyte volume also increased significantly in the surgically thymectomized group, influencing all the morphometric parameters regarding mitochondria and endoplasmic reticulum, when measured per hepatocyte. On the basis of the results obtained, one can conclude that the thymus has a regulatory role in the development of hepatocyte morphology. The findings agree with the biochemical observations demonstrating non-immunological effects of the thymus on cellular development.

Electron-microscopic morphometric analysis of mouse liver. II. Effect of ageing and thymus transplantation in old animals

The influence of age and thymus on liver cells has been investigated by performing a complete morphometric analysis. The age-dependence was tested in three groups of mice aged 2, 12, and 24 months, while the action of the thymus was studied on 24-month-old mice grafted with neonatal thymus 30 days before the analysis was performed. Among the investigated parameters, the most considerable changes were found in the mean nuclear volume, which displayed a significant increase during ageing. The thymus was capable of reversing such an age-dependent increase when grafted into old animals. The volume of single hepatocytes also displayed an age-dependent increase which was not corrected by thymus grafting. The data presented suggest that the thymus influences the mitotic activity of the hepatocytes and further support the hypothesis that the thymus also plays an important role in non-immunological processes of ageing.

Effects of centrophenoxine on the monovalent electrolyte contents of the large brain cortical cells of old rats

The effect of centrophenixine has been studied on the monovalent electrolyte contents of the brain cortical cells of old female Wistar rats by means of energy dispersive x-ray microanalysis. The drug was administered in form of an intraperitoneal injection of 100 mg/kg body weight for 20 days. The treatment decreased the potassium content in both the nucleus and cytoplasm in terms of dry mass fraction, whereas the sodium concentration remained unchanged. The Na+/K+ ration increased significantly in both cell compartments. The chloride content of the nuclei decreased slightly. If one supposes just 1--2% rehydration of the old cytoplasm, the decrease of the total ionic strength may be of considerable extent, it may even reach the values obtained in young adult animals. The results are interpreted in terms of a recently developed 'membrane hypothesis' of aging.

In vivo stimulation of nerve cells by phytohemagglutinin. I. Alterations of some cytological aging parameters in rat brain cells

Phytohemagglutinin P (PHA-P) was administered in form of intralumbar injection to old (24-27 months) female Wistar rats. PHA-P has an inductive effect also on the nerve cells. The thermal denaturation characteristics of the DNA in situ as well as the numerical density of perichromatin granules being connected to the extranucleolar RNA synthesis returned practically to the young levels in the large brain cortical cells and in the cerebellar granular cells 20 h after the injection. The reversal of these aging phenomena was accompanied by a significant decrease of intranuclear and intracytoplasmic K+ content measured by X-ray microanalysis in the dry mass, whereas Na+ and Cl- remained unchanged. If PHA-P causes also some (1-2%) rehydration of the old neurons, the total ionic strength in the cell due to the monovalents may even reach the young level. The possible regulatory role of the ionic strength and the Na+/K+ ratio in the chromatin function is discussed on the basis of experimental data. It is the first time that the reversibility of some cytological aging parameters has been demonstrated in vivo.

Age-dependent changes of the protein synthetic machinery of liver cell cytoplasm as revealed by electron microscopic morphometry

Complete electron microscopic morphometric explorations of the liver were carry out in groups of 5 each young, adult and old female Wistar rats. In addition, livers were studied 1, 5, 10, 20 days after 2/3 hepatectomy in old rats. Characteristic age-dependent change: Decrease of the surface density of total endoplasmic reticulums between 1 and 12--27 months of age. After the partial hepatectomy the regenerated old liver "shows a certain" rejuvenation. The results suggest the validity of the theory of accumulation of somatic mutations during aging.

Age-dependent increase of intranuclear monovalent electrolytes as revealed by quantitative energy dispersive x-ray microanalysis

The concentration of univalent electrolytes in the cell nucleus and cytoplasm of the big neurons of the brain and in hepatocytes was established in young, mature and old rats by means of microanalysis with X-rays. It was demonstrated that the Na+ and Cl-- content increases with aging in both tissues, while K+ increases in the neurons but not in the nuclei of the hepatocytes, At the same time some ions in the cytoplasm increase, while others decrease or remain stable. If a possible loss of water during aging is taken into consideration the result is a considerable increase in ion concentration in the nucleus. This may be regarded as one of the principal reasons for the increased density which accompanies aging and possibly as one of the cause of the aging process.

Alterations in the numerical density of perichromatin granules in different tissues during ageing and cell differentiation

Perichromatin granules (PG) were counted on electron micrographs of different tissues taken from young and old female Wistar rats as well as in the basal and spinous layers of adult human epidermis. A significant age-dependent decrease was observed in the following cell types: large brain cortical cells, cerebellar granular cells, hepatocytes, parotid gland cells. No significant decrease was found in the heart muscle nuclei and in the erythroblasts of identical maturation level. The number of PG decreased during the erythroblast maturation almost to zero, and increased in the cells of spinous layer of human epidermis as compared to the basal cells. There is a very wide variation in the number of PG per nucleus between the different tissues. The correlation between the transcriptional activity, the protein synthesis, ageing and cell differentiation is discussed.

On the reversibility of some cytological ageing parameters of rat brain cells by phytohemagglutinin

It has been shown that the thermal stability of DNA in the brain cortical cells increases with the age. At the same time, the number of perichromatin granules being connected in some way to the messenger RNA synthesis and transport of the interphase nuclei, decreases in the same cells. In vivo treatment of the old animals by mitogens like phytohemagglutinin induced a reversal of both ageing phenomena: the thermal stability of DNA returned almost completely to that of the young animals, whereas the number of perichromatin granules rised again to the young level.

On the relationship between the perichromatin granules and cellular ageing as well as cell differentiation

Current hypotheses ascribe the role of pre-RNA storage or transport structures to the perichromatin granules. Their numerical density is directly related to the transcription activity of the nucleus. The perichromatin granules (P.K.) can be demonstrated in ultrathin sections with the stain used by Bernhard (1969) for ribonucleo-proteins. We have established the numerical density per unit of area in nuclear cross-sections of cells in young rats (1-2 months), old rats (26-29 months) and in relation to various cell function types. Cell aging causes a reduction in the numerical density of perichomatin granules in the big neurons of the cerebral cortex, the cerebellar granulocytes, the hepatocytes and the parotid cells. No age-related changes were found in the myocardial cells and erythroblasts of the same maturity. However, at the end of maturation, the number of perichromatin granules both in young and old erythroblasts was nil. (1) There is a quantitative reduction of perichromatin granules primarily in postmitotic and relatively postmitotic cells; (2) cell types showing no age-related reduction in perichromatin granules maintain high synthetic activity throughout their life; (3) the results confirm that relationships exist between numerical density of the perichromatin granules and cell activity; (4) the big fluctuations in the numbers of perichromatin granules in various cell types are probably connected with cell function.