Impact of moderate physical exercise--in comparison with dietary restrictions--on age-associated decline in cell-mediated immunity of Sprague-Dawley rats

Investigations into cytotoxic effects of the herbal preparation Abnormal Savda Munziq

OBJECTIVE

To evaluate the effects of Abnormal Savda Munziq (ASMq), a traditional herbal medicine, for the prevention and treatment of human diseases, e.g. bowel cancer.

METHODS

The parameters total polyphenol content, cell proliferation and DNA-damage as well as RNA and protein-oxidation were analysed in vitro. Besides, the expressions of miRNA and tumor suppressor genes as well as cellular senescence were evaluated.

RESULTS

ASMq had a high polyphenol content and induced damage to proteins, RNA as well as to DNA, which is correlated with its cytotoxicity. Furthermore ASMq up-regulated the tumor suppressor genes p21, p53 and p16 and down-regulated the micro-RNAs hsa-mir-17 and hsa-mir-106b. In addition cellular growth arrest and SA-β-gal-staining were induced.

CONCLUSION

ASMq has the ability to induce DNA damage and cellular senescence, which are double-edged mechanisms in fighting cancer, as they might also have harmful side effects.

Effects of dietary restriction or swimming on lymphocytes and macrophages functionality from old rats

Although aging compromises the functionality of macrophages (MΦ) and lymphocytes (LY), and dietary restriction (DR) and exercise partially counterbalance immunosenescence, it is unknown what effects of both strategies have on the functionality of these immune cells. Rats were randomly distributed into adult control (AD), older group (OLD), older submitted to 50% of DR (DR) and older submitted to swimming (EX) (n = 10 in each group). The function of immune cells (proliferative index, phagocytic capacity and H₂O₂ production), the weight and protein content of lymphoid organs (thymus and spleen), plasma glutamine concentration, interleukins (IL-1, IL-2, IL-6) and, immunoglobulins (IgA and IgG) were analysed. There was an increase of 74% in body weight in aged animals as compared with the AD group, while body weight reduced 19% in the DR as compared with the OLD group. Swimming training stimulated MΦ phagocytosis, while the EX group presented a decrease of the proliferative capacity of LY from the mesenteric lymph nodes (44% and 62%, respectively), when stimulated with ConA and LPS as compared with the old rats. These data demonstrated that DR and exercise affects differentially MΦ and LY function.

Exercise Training and Immunosenescence

During the aging process, a decrease in the ability of the immune system to control infection, known as immunosenescence, takes place. Paradoxically, aging also results in chronic low-level inflammation and exaggerated inflammatory responses. A number of studies have investigated the effects of a variety of exercise training interventions on the immune system both in humans and using animal models of aging. Cross-sectional studies that compared masters athletes to untrained, age-matched controls found that the athletes had significantly better immune function, but these studies suffered because of the difficulty in generalizing results from highly trained athletes to a general population of physically active older adults. Prospective studies in humans have attempted to address this, but these studies have resulted in sometimes equivocal findings, possibly as a result of the differences in exercise training programs used. Finally, animal studies, both observational and mechanistic, have almost universally supported the exercise effect on enhancing immune status in the aged. More research is needed to determine the mechanism by which exercise influences immunity in the aged and to identify exercise training programs for use in this population. It is clear, however, that exercise is likely to be effective at boosting immunity in the older people when undertaken regularly.

Splanchnic sequestration of amino acids in aged rats: in vivo and ex vivo experiments using a model of isolated perfused liver

Splanchnic sequestration of amino acids (SSAA) is a process observed during aging that leads to decreased peripheral amino acid (AA) availability. The mechanisms underlying SSAA remain unknown. The aim of the present study was to determine whether a high-protein diet could increase nitrogen retention in aged rats by saturating SSAA and whether SSAA could be explained by dysregulation of hepatic nitrogen metabolism. Adult and aged male Sprague-Dawley rats were housed in individual metabolic cages and fed a normal-protein (17% protein) or high-protein diet (27%) for 2 wk. Nitrogen balance (NB) was calculated daily. On day 14, livers were isolated and perfused for 90 min to study AA and urea fluxes. NB was lower in aged rats fed a normal-protein diet than in adults, but a high-protein diet restored NB to adult levels. Isolated perfused livers from aged rats showed decreased urea production and arginine uptake, together with a release of alanine (vs. uptake in adult rats) and a hepatic accumulation of alanine. The in vivo data suggest that SSAA is a saturable process that responds to an increase in dietary protein content. The hepatic metabolism of AA in aged rats is greatly modified, and urea production decreases. This result refutes the hypothesis that SSAA is associated with an increase in AA disposal via urea production.