ISSN:0304-324X    

DOI:10.1159/000212922

出版商:S. Karger AG    

年代:1988

数据来源: Karger

ISSN:0304-324X    

DOI:10.1159/000212923

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

The article presents questions for discussion and proposes trends for further studies of neurohumoral mechanisms of aging at all stages of the vital activities of the organism.

ISSN:0304-324X    

DOI:10.1159/000212924

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

In experiments on 2-, 10- and 22-month-old rats it was found that the Bmax values of dopamine (DA2), serotonin (5-HT1) and enkephalin (Enk) receptors as well as th( 5-HT level in the three brain regions (cortex, striatum and hypothalamus) decreased with age; the DA level in the brain cortex and striatum and the noradrenaline (NA) content in the brain cortex decreased, while the NA level in the striatum and the 5-hydroxyindolacetic acic (5-HIAA) level in the brain cortex and the striatum as well as the MAO-T and MAO-A activities in the three brain structures increased. It is suggested that these and other change: observed in brain neurotransmission are an important element in the neurochemical bases oï the age-related changes in behavior

ISSN:0304-324X    

DOI:10.1159/000212925

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

Loss of motor control is an important functional manifestation of aging. This dysfunction appears to be at least partially due to loss of striatal dopamine receptors. We have examined the possible mechanisms by which such a deterioration occurs as well as possible manipulations to delay and/or reverse these impairments.

ISSN:0304-324X    

DOI:10.1159/000212926

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

The synaptic deficit of brain dopaminergic activity involves a complex pattern of changes both at presynaptic and at postsynaptic level. The aged dopaminergic nuclei present a reduced number of dopamine terminals, a decreased ability to synthesize and reuptake dopamine and defective recognition sites both in terms of absolute number of D2 receptors and of transducing mechanisms linked to D1 receptors. These changes suggest that the dopaminergic system may be particularly sensitive during aging to environmental, iatrogenic and toxic factors, which may easily make the elderly develop symptoms of central dopamine deficiency.

ISSN:0304-324X    

DOI:10.1159/000212927

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

The release of neurotransmitter amino acids 14C-Asp, 14C-Glu and 14C-GABA from rat brain synaptosomes in aging is studied. It is established that K+-induced Ca2+-dependent and Ca2+-independent release of these amino acids decreases significantly in the old animals. K+ (40 mM) stimulates strongly their release for both ages, but the effect of K+ ions in old animals is less marked. Removal of Ca2+ has a greatly inhibitory effect on synaptosomal release in young as well as in old rats. The degree of inhibition does not depend on age, though it takes place at a lower level in old rats.

ISSN:0304-324X    

DOI:10.1159/000212928

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

Experiments on adult (6–8 months) and old (24–28 months) male rats under chronic emotional-pain stress showed that in aging the reliability of the control system of corticosterone secretion remains unchanged while that of aldosterone secretion decrea

ISSN:0304-324X    

DOI:10.1159/000212929

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

The maximal glucocorticoid responsiveness and the adaptation degree are reduced in old rat liver as demonstrated by cortisol stimulation of RNA polymerases. Nevertheless the concentration of unoccupied 3H-dexamethasone binding sites in molybdate-stabilized cytosol of adrenalectomized old animals is significantly increased in comparison with young adult rats. The KD constants showed an increasing tendency, but not a significant one. In the molybdate-free cytosol the results are similar. First studies of the binding kinetics in the molybdate-free system showed a sigmoidal saturation curve in the cytosol of young adult rats, but usual hyperbolic saturation kinetics in the cytosol of old animals. The Hill coefficient was 1.0 ± 0.1 for old and 1.9 ± 0.3 for young animals. The binding of activated 3H-dexamethasone receptor complexes to liver nuclei showed no significant age-dependent differences in binding kinetics, acceptor site concentration or affinity. Attention must be paid to altered glucocorticoid receptor binding in the cytosol and in nuclei as a potential cause of changes in hormone-induced gene expression at the pretranscriptional leve

ISSN:0304-324X    

DOI:10.1159/000212930

出版商:S. Karger AG    

年代:1988

数据来源: Karger

摘要:

A profound influence of steroidal (and possibly growth) hormone change during aging on the P-450 functions has been found in male rats. Direct and rapid autonomic nervous controls on glycogen metabolism in the liver is also greatly affected by aging. However, neither the responses of isolated rat hepatocyte preparations to adrenergic agonists nor the bindings of hepatocyte surface membrane preparations to adrenergic ligands was found to change with age, suggesting that the age effect on autonomic nervous control may be of central (presumably hypothalamic) origin. The present methodology of evaluating the receptor functions using Scatchard plot analysis does not seem sufficient to explore the functional alterations of receptor systems during aging and a need for new approaches that can determine certain physicochemical alterations of receptor, namely the measurement of the lateral mobility of membrane proteins during aging, is proposed.

ISSN:0304-324X    

DOI:10.1159/000212931

出版商:S. Karger AG    

年代:1988

数据来源: Karger