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Elevated testosterone kills nerve cells
September 27, 2006New Haven, Conn.-A Yale School of Medicine study shows for the first time that a high level of testosterone, such as that caused by the use of steroids to increase muscle mass or for replacement therapy, can lead to a catastrophic loss of brain cells.
Taking large doses of androgens, or steroids, is known to cause hyperexcitability, a highly aggressive nature, and suicidal tendencies. These behavioral changes could be evidence of alterations in neuronal function caused by the steroids, said the senior author, Barbara Ehrlich, professor of pharmacology and physiology.
"Next time a muscle-bound guy in a sports car cuts you off on the highway, don't get mad, just take a deep breath and realize that it might not be his fault," said Ehrlich.
Testosterone is the main male hormone and it plays fundamental roles in development, differentiation, and cellular growth. In neurons, testosterone acts as a neurosteroid and can induce changes at the cellular level, which in turn lead to changes in behavior, mood and memory. Both neuroprotective and neurodegenerative effects of androgens have been reported.
The researchers showed that high levels of testosterone triggered programmed cell death in nerve cells in culture. Cell death, or apoptosis, is critical in many life processes, including development and disease. It is characterized by membrane instability, activation of caspases, which are the executioner proteins in apoptosis, change in membrane potential, and DNA fragmentation.
"In the present study we have demonstrated for the first time that the treatment of neuroblastoma cells with elevated concentrations of testosterone for relatively short periods, six to 12 hours, induces a decrease in cell viability by activation of a cell death program," Ehrlich said. "Low concentrations of testosterone had no effects on cell viability, whereas at high concentrations the cell viability decreased with incremental increases in hormone concentration."
The testosterone-induced apoptosis described in this study occurs through overactivation of intracellular Ca2+ signaling pathways. Overstimulation of the apoptotic program in neurons has been associated with several neurological illnesses, such as Alzheimer disease and Huntington disease.
Yale University
Testosterone is the main male hormone and it plays fundamental roles in development, differentiation, and cellular growth. In neurons, testosterone acts as a neurosteroid and can induce changes at the cellular level, which in turn lead to changes in behavior, mood and memory. Both neuroprotective and neurodegenerative effects of androgens have been reported.
The researchers showed that high levels of testosterone triggered programmed cell death in nerve cells in culture. Cell death, or apoptosis, is critical in many life processes, including development and disease. It is characterized by membrane instability, activation of caspases, which are the executioner proteins in apoptosis, change in membrane potential, and DNA fragmentation.
"In the present study we have demonstrated for the first time that the treatment of neuroblastoma cells with elevated concentrations of testosterone for relatively short periods, six to 12 hours, induces a decrease in cell viability by activation of a cell death program," Ehrlich said. "Low concentrations of testosterone had no effects on cell viability, whereas at high concentrations the cell viability decreased with incremental increases in hormone concentration."
The testosterone-induced apoptosis described in this study occurs through overactivation of intracellular Ca2+ signaling pathways. Overstimulation of the apoptotic program in neurons has been associated with several neurological illnesses, such as Alzheimer disease and Huntington disease.
Yale University
Testosterone Current Events and Testosterone News RSSHeart and bone damage from low vitamin D tied to declines in sex hormones
Researchers at Johns Hopkins are reporting what is believed to be the first conclusive evidence in men that the long-term ill effects of vitamin D deficiency are amplified by lower levels of the key sex hormone estrogen, but not testosterone.
Pilot study relates phthalate exposure to less-masculine play by boys
A study of 145 preschool children reports, for the first time, that when the concentrations of two common phthalates in mothers' prenatal urine are elevated their sons are less likely to play with male-typical toys and games, such as trucks and play fighting.
Hormone that affects finger length key to social behavior
The hormones, called androgens, are important in the development of masculine characteristics such as aggression and strength.
Postmenopausal women with higher testosterone levels
Postmenopausal women who have higher testosterone levels may be at greater risk of heart disease, insulin resistance and the metabolic syndrome compared to women with lower testosterone levels.
Fetal study highlights impact of stress on male fertility
Exposure to a combination of excess stress hormones and chemicals while in the womb could affect a man's fertility in later life, a study suggests.
Studies examine how living conditions impact reproductive health
When costs outweigh benefits, successful pregnancies are less likely to occur. Life is all about tradeoffs and recently published research by Virginia J. Vitzthum, a senior scientist at Indiana University's Kinsey Institute for Research in Sex, Gender, and Reproduction, and professor in the IU College of Arts and Sciences' Department of Anthropology, has shown that during periods of intense labor and low food intake, rates of early pregnancy loss can more than double.
BUSM researchers propose a relationship between androgen deficiency and cardiovascular disease
Researchers from Boston University School of Medicine (BUSM) in collaboration with researchers from Lahey Clinic Northshore, Peabody, Mass., believe that androgen deficiency might be the underlying cause for a variety of common clinical conditions, including diabetes, erectile dysfunction, metabolic syndrome and cardiovascular disease (CVD).
Prostate cancer patients on hormone therapy at increased risk for various heart diseases
New research has found that hormone therapy used to treat men with advanced prostate cancer is associated with an increased chance of developing various heart problems. Some choices of therapy appear, however, to be less risky than others.
Obesity increases risk of prostate cancer recurrence for both blacks and whites
A new look at a large database of prostate cancer patients shows that obesity plays no favorites when it comes to increasing the risk of recurrence after surgery: Being way overweight is equally bad for blacks and whites, say researchers at Duke University Medical Center.
Life and death in the living brain
Like clockwork, brain regions in many songbird species expand and shrink seasonally in response to hormones. Now, for the first time, University of Washington neurobiologists have interrupted this natural "annual remodeling" of the brain and have shown that there is a direct link between the death of old neurons and their replacement by newly born ones in a living vertebrate.
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