bio aging final exam inTERcellular processes.txt

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bio aging final exam inTERcellular processes.txt
2012-12-12 14:58:04
inTERcellular processes

Bio Aging final inTERcellular processes
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  1. Intercellular systemic or stochastic
    Most are SYSTEMIC
  2. HomeoSTATIC mechanisms
    • systemic mech that attempts to retain physiological parameter at constant level throughout life
    • ie: body temperature or blood glucose
  3. HomeoDYNAMIC mechanism
    • systemic mech that attempts to retain normal circadian rhythm of physiological systems
    • ie: reproductive cycle
  4. Nathan Shock
    thought of Intercellular systemic theories as INTEGRATIVE theories
  5. Caleb Finch
    Proponent of Neuroendocrine theory of aging
  6. Roy Walford and Richard Miller
    Proponents of Immunological Theories of aging
  7. Types of Neuroendocrine Theories
    • 1. Reproductive Senescence
    • 2. Gene expression and neuroendocrine control
    • 3. Stress responses
  8. Reproductive Senescence (neuroendocrine theory of aging)
    • female reprod. senescence most studied in mammals:
    • young ovaries into old mice: showed reproductive cycling at impaired level (intercellular mech involved), vs.
    • old ovaries into young mice: showed reduced reproductive cycling also (inTRAcellular mech invovled).
    • However if old mice had no ovaries early in life then transplant of young ones later they showed improvement in reprod. cycling.
    • ESTROGEN caused DECLINE in hypothalamic control of cycling
    • Testosterone supplementation no significant increase in reproductive capability, although castration studies show life expectancy can be INCREASED
  9. Gene expression and neuroendocrine control (neuroendocrine theory of aging)
    • Growth hormone injections: improved muscle mass and bone strength in elderly, BUT mice showed decrease in lifespans
    • Vasopressin: INCREASED with AGE in rat
  10. Stress responses (neuroendocrine theory of aging)
    • Epi and nor-epi: these hormones (including cortisol) cause INCREASED SENESCENCE in mice and salmon
    • High exposure to Glucocorticoids: DEATH results in # of hippocampal neurons of mice (not seen in other rodents or humans)
    • Transplantation studies: showed systemic changes had greater effect on declining responsiveness
  11. Glucocorticoid level effects
    • Lifetime glucocort. levels reduced by: calorie restriction (reduces corticosterone, from Masaro), grooming of rats by mothers
    • Impaired learning and memory: associated with HIGHER than normal Glucocort. levels
  12. DHEA
    • Steroid hormone: precursor to androgens and estrogens, DECLINES after puberty in humans
    • DHEA supplementation: INCREASES lifespan in some rodents, not others
  13. Immunological Theories of aging
    • 1. Age-related increase in bacterial and viral infections: impaired immune fxn related to senescence. Thymus replaced with fatty adipose tissue with age
    • 2. Thymus function correlated with immune fxn: some mice with increased thymus show increased lifespan. Nude mice never grows thymus, and dies at young age b/c impaired T-cell function
  14. 3 methods of improving immune function that have been tested
    • 1. Zinc supplementation: increases thymuline (thymic hormone), and SLOWS thymic involution
    • 2. Calorie restriction: results in smalller thymus, but amount of ACTIVE thymocytes are INCREASED
    • 3. Thymic peptide supplementation: stimulate INCREASED thymic activity in old mice
  15. Integrative effects of Neuroendocrine-Immune System
    • 1. women have HIGHER immune response vs. men: higher estrogen, INHIBITION of progesterone and testosterone
    • 2. circadian variation of immunoglobulins: such as IgM, which are high at night
    • 3. MHC genes connected to lifespan and reproduction in mice