We could not survive without hormones. They are among the most common and vital chemical messengers in the body. From head to toe, each moment of life, they signal cells to perform tasks that range from the ordinary to the extraordinary. Among their many roles, hormones help regulate body temperature, blood pressure, and blood sugar levels. In childhood, they help us “grow up.” In the teen years, they are the driving force behind puberty.
What Is A Hormone?
Hormones are powerful chemicals that help keep our bodies working normally. The term hormone is derived from the Greek word, hormo, which means to set in motion. And that’s precisely what hormones do in the body. They stimulate, regulate, and control the function of various tissues and organs. Made by specialized groups of cells within structures called glands, hormones are involved in almost every biological process including sexual reproduction, growth, metabolism, and immune function. These glands, including the pituitary, thyroid, adrenals, ovaries, and testes, release various hormones into the body as needed.
Levels of some hormones like parathyroid hormone, which helps regulate calcium levels in the blood and bone, actually increase as a normal part of aging and may be involved in bone loss leading to osteoporosis. But the levels of a number of other hormones, such as testosterone in men and estrogen in women, tend to decrease over time. In other cases, the body may fail to make enough of a hormone due to diseases and disorders that can develop at any age. When this occurs, hormone supplements—pills, shots, topical (rub-on) gels, and medicated skin patches—may be prescribed.
How Hormones Work
Most hormones exist in very low concentrations in the bloodstream. Each hormone molecule travels through the blood until it reaches a cell with a receptor that it matches. Then, the hormone molecule latches onto the receptor and sends a signal into the cell. These signals may instruct the cell to multiply, to make proteins or enzymes, or to perform other vital tasks. Some hormones can even stimulate a cell to release other hormones. However, no single hormone affects all cells in the same way. One hormone, for example, may stimulate a cell to perform one task, while the same hormone can have an entirely different influence over another cell. The response of some cells to hormonal stimulation also may change throughout life.
DHEA
Dehydroepiandrosterone or DHEA is made from cholesterol by the adrenal glands, which sit on top of each kidney. Production of this substance peaks in the mid-20s, and gradually declines with age in most people. What this drop means or how it affects the aging process, if at all, is unclear. In fact, scientists are somewhat mystified by DHEA and have not fully sorted out what it does in the body. However, researchers do know that the body converts DHEA into two hormones that are known to affect us in many ways: estrogen and testosterone.
Human Growth Hormone
Human growth hormone (hGH) is made by the pituitary gland, a pea-sized structure located at the base of the brain. It is important for normal development and maintenance of tissues and organs and is especially important for normal growth in children.
Studies have shown that injections of supplemental hGH are helpful to certain people. Sometimes children are unusually short because their bodies do not make enough GH. When they receive injections of this hormone, their growth improves. Young adults who have no pituitary gland (because of surgery for a pituitary tumor, for example) cannot make the hormone and they become obese. When they are given hGH, they lose weight.
Like some other hormones, blood levels of hGH often decrease as people age.Although there is no conclusive evidence that hGH can prevent aging, some people spend a great deal of money on supplements. These supplements are claimed by some to increase muscle, decrease fat, and to boost an individual’s stamina and sense of well being. Shots—the only proven way of getting the body to make use of supplemental hGH—can cost more than $15,000 a year. They are available only by prescription and should be given by a doctor. Some dietary supplements, known as human growth hormone releasers, are marketed as a low-cost alternative to hGH shots. But claims that these over-the-counter products retard the aging process need to be examined. While some studies have shown that supplemental hGH does increase muscle mass, it seems to have less impact on muscle strength or function in older adults.
Testosterone
Ask an average man about testosterone, and he might tell you that this hormone helps transform a boy into a man. Or, he might tell that you that it has something to do with sex drive. Or, if he has read news stories in recent years, he might mention male menopause, a condition thought to be caused by diminishing testosterone levels in aging men.
Testosterone is indeed a vital sex hormone that plays an important role in puberty. In men, testosterone not only regulates sex drive (libido), it also helps regulate bone mass, fat distribution, muscle mass and strength, and the production of red blood cells and sperm.But contrary to what some people believe, testosterone isn’t exclusively a male hormone.
Women produce small amounts of it in their bodies as well. In men, testosterone is produced in the testes, the reproductive glands that also produce sperm. The amount of testosterone produced in the testes is regulated by the hypothalamus and the pituitary gland.
As men age, their testes often produce somewhat less testosterone than they did during adolescence and early adulthood, when productionof this hormone peaks. In fact, many of the changes that take place in older men often are incorrectly blamed on decreasing testosterone levels. Some men who have erectile difficulty (impotence), for instance, may be tempted to blame this problem on lowered testosterone. However, in many cases, erectile difficulties are due to circulatory problems, not low testosterone. Still, some men may be helped by testosterone supplementation. For these few men who have extreme deficiencies, testosterone therapy in the form of patches, injections, or topical gels may offer substantial benefit.
Testosterone products may help a man with exceptionally low testosterone levels maintain strong muscles and bones, and increase sex drive. However, what effects testosterone replacement may have in healthy older men without these extreme deficiencies requires more research.The NIA is investigating the role of testosterone therapy in delaying or preventing frailty. Results from preliminary studies involving small groups of men have been inconclusive, and it remains unclear to what degree supplementation of this hormone can sharpen memory or help men maintain stout muscles, sturdy bones, and robust sexual activity.
Many other questions remain about the use of this hormone in late life. It is unclear, for example, whether men who are at the lower end of the normal range of testosterone production would benefit from supplementation.Some investigators are also concerned about the long-term harmful effects that supplemental testosterone might have on the aging body. While some epidemiologic studies suggest that higher levels of testosterone are not associated with the higher incidence of prostate cancer, it is not yet known if testosterone therapy increases the risk of such cancer, the second leading cause of cancer death among men.
The bottom line: Although some older men who have tried testosterone therapy report feeling more energetic or younger, testosterone supplementation remains a scientifically unproven method for preventing or relieving any physical and psychological changes that men with normal testosterone levels may experience as they get older. The NIA is expanding its research to gather more evidence on the risks and benefits of testosterone supplementation in aging men with low testosterone levels.
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Article adapted by MD Only Sports Weblog from original press release.
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Source: National Institute on Aging
MD Sports Weblog 