INTRO.Rapamycin mice, which begins to consume rapamycin
INTRO.Rapamycin is discovered as antifungal metabolite and anti-proliferative properties given out by Streptomyces hygroscopicus. Shortly afterward, it was found to contain immunosuppressive and anti-proliferative effects in mammalian cells. It is a genetical inhibitor of mTOR (mechanism target of rapamycin) which regulates homeostasis, metabolism, cell growth and proliferation in organism. Hence, deregulating the mTOR pathway can affect organism’s health status and also has been implicated in several aging diseases.RESEARCHIn the past, studies have been conducted and proven that inhibition of TOR signalling pathway can regulate the lifespan in C.elegants(worm) and Drosophila(flies).
(Vellai et al., 2003; Kapahi et al., 2004) However, these organisms are not genetically closely related to human as their internal structures are totally different compare to human.
Hence, rapamycin may cause unknown side effect when introduced into human body.Several researches implicate rapamycin can enhance longevity in mice. . As demonstrated in John.E et al study by using mice, rapamycin slows down age-dependent changes in heart, liver, adrenal glands, endometrium, and tendon as well as spontaneous activity. The study also implicates a negative effect in mice, which begins to consume rapamycin at 9 months old, has a higher chance in developing testicular degeneration and cataracts. For this reason, further studies must be conducted on the timing, dosage and specificity of tissue actions of rapamycin in order to improve clinically useful in inhibition of TOR action. Furthermore, the study has no clear evidence to distinguish whether it beneficially inhibits the deadly neoplastic diseases, or declines the multiple features of agingMoreover, cancer is an age-dependent disease and hence slowing aging process retards cancer-related diseases (Yancik R.
, 2005). As mentioned, rapamycin is an inhibition of mTOR and thus it delays cancer by supressing cell proliferation of cancerous cells. However, one research shows that only the cancer prone p53+/- mice that treated before the initiation of cancer can prevent cancer (Komarova EA., et al).
This shows that rapamycin has limited effect on aging, no doubt it can increase murine lifespan.In the 4 years study of Blagosklonny MV on rapamycin and quasi-programmed aging, he concluded that the inhibition of TOR delays aging process with five main evidences as follow:1. Rapamycin suppresses geroconversion: conversion from cellular quiescence to senescence.
Geroconversion is cellular basis of organismal aging.2. Genetic manipulations that deregulate the TOR pathway extend life-span in diverse species from yeast to mammals.3. Rapamycin extends lifespan in all species tested.4. Calorie restriction, which inhibits mTOR, extends lifespan.
5. MTOR is involved in diseases of aging and rapamycin prevents these diseases in animal models.The latest research related to rapamycin is the dog aging process at the university of Washington. About 70% of dogs that took the highest dose of drug were also noticeable more active. They also mentioned some side effects of the drug on human when treated with high dose during kidney transplant and cancer. Although there is a risk of using rapamycin, should scientist encourage life-threatening disorder patient to take the medicinal rapamycin treatment? Can the human lifestyle, such as smoking, affect the effectiveness of the drug?
