Figure 1. A simplified model of the levels of hormones and lifespans between sexes. Males have a shorter lifespan than females. The significant difference between the males and females is that the level of testosterone level in males is much higher than in females and the estrogen level in females is much higher than that in males.
Figure 2. Hypothetic effects of estrogen in different life stages on females: (A) the life stages and normal lifespan in females; (B) the extension of the growth and reproductive life stages by lowering or slowing down the increase in estrogen before puberty; (C) the shortening of the reproductive life stage and lifespan using oophorectomy after puberty and before menopause; (D) the elimination of the production of estrogen and shortening of the lifespan using oophorectomy performed after menopause.
Figure 3. Life stages and strategies to extend the female lifespan. The upper section shows the phenotypic changes at different life stages. The middle section shows the physiological and biological alterations inside the body during the transition of different life stages. The bottom section shows the proposed life-stage-specific strategies to extend the lifespan of males.
Figure 4. Current status of the studies of estrogen levels with oophorectomy in animal and human populations. Oophorectomy performed during reproductive and aging stages causes complications and leads to a shorter lifespan in mouse, rat, and human populations. Oophorectomy in grasshoppers extends the lifespan. In dogs, the lifespan is also extended or is not shortened when the oophorectomy is performed most likely before puberty. There are conflict reports on the impact on the lifespan when the oophorectomy is performed before puberty. More studies should be done with animals, in particular with monkeys.
Figure 4. Current status of the studies of estrogen levels with oophorectomy in animal and human populations. Oophorectomy performed during reproductive and aging stages causes complications and leads to a shorter lifespan in mouse, rat, and human populations. Oophorectomy in grasshoppers extends the lifespan. In dogs, the lifespan is also extended or is not shortened when the oophorectomy is performed most likely before puberty. There are conflict reports on the impact on the lifespan when the oophorectomy is performed before puberty. More studies should be done with animals, in particular with monkeys.
Table 1. Examples of the effects of ovariectomy at different stages and effects in mouse and rat models.
Table 1. Examples of the effects of ovariectomy at different stages and effects in mouse and rat models.
SpeciesTime of ConductApproximate Human Age Equivalents * [17,18]Effect on LifespanReference # and NoteMiceOne month, after the first estrous cycle; 5 months of age14 years of age and 30 years of ageShortens the life span[19]Thirteen months of age60 years of ageImmunosenescence and oxi-inflamm-ageing[20]At postnatal day 5018 years of ageCorrelation of the estrogen levels and the disease progression including lifespan[21]Two weeks prior to behavioral testing (at ages of 5,17, and 22 months), mice were ovariectomized30, 65, and 68 years of agesShortened lifespan in comparison with intact animals.[22]At 4 weeks, bilaterally
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