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Tag: "testosterone" at biology news

ASU research shows connection between testosterone, dietary antioxidants and bird coloration

...They appear to fight off the negative impacts that testosterone can have on an animal’s health. The researcher...th price to the animal.” “This study shows that testosterone may not be as costly as previously thought, so long as animals can nutritionally offset the immune d...

Sleep quantity affects morning testosterone levels in older men

The testosterone levels of healthy men decline as they get older. ...p a healthy older man gets can affect his level of testosterone in the morning, according to a study published in the April 1st issue of the journal SLEEP. The stu...

The price of vanity: Mating with showy males may reduce offspring's ability to fight off pathogens

...tes with showy traits, many of which are linked to testosterone levels. However, a new study suggests that, in fis...t colors or long tails and fins ?results in higher testosterone levels in males over many generations. Because male and female testosterone levels are correlated, ...

Phthalates now linked to fat, related health risks

...halates and other common chemicals may be reducing testosterone levels or function in men, and thereby contributin...l Health Perspectives. "Substantial declines in testosterone levels and sperm quality have been observed in the United States and other countries over the last s...

Growth hormone is not the anti-aging bullet for healthy adults

...enhancers. GH, often in conjunction with vitamins, testosterone and other hormones, is said to increase muscle strength and mass, decrease body fat, improve mood and motivation, increase exercise capacity, increase bone density and (wink, wink) make wives and girlfriends happy. Despite these enticing claims, c...

Cancer researchers add spice to research against rare neuromuscular disease

...ptor, the protein that is central to the action of testosterone and other male hormones. Chang's laboratory, in co...gen receptor, they have taken away substances like testosterone that bind to and activate the receptor," said Chang. "But this can cause many unwanted, systemic sid...

Hair-growth drug artificially lowers PSA levels in prostate cancer screening, study finds

..." Researchers have known for years that the same testosterone metabolism responsible for prostate growth also ca...5-alpha reductase and preventing the conversion of testosterone to DHT. The data in The Lancet study were collected by Dr. Roehrborn from 1998 to 2000 ...

Exposure to dioxins influences male reproductive system, study of Vietnam veterans concludes

...ting the growth of the prostate gland and lowering testosterone levels, researchers at UT Southwestern Medical Cen...igher dioxin exposure is associated with decreased testosterone levels, Dr. Gupta said. "It is known that lower testosterone levels are associated with decreased...

Changing length of days reverses how estrogen affects aggressiveness in mice

... of the few that has shown how hormones other than testosterone can affect aggression in mammals. "This goes against the common belief that testosterone is the hormone that regulates aggression," said Randy Nelson, co-author and professor of psychology ...

Jefferson scientists find aging gene also protects against prostate cancer development

...e androgen receptor by giving agents that shut off testosterone production. In one experiment, the scientists took a series of mutations in androgen receptors from prostate cancer patients who are resistant to hormonal therapy and showed that SIRT1 blocks receptor activity, halting cancer growth. “We systematic...

Orange, grapefruit juice for breakfast builds bones in rats

...cessary, the researchers said, because the hormone testosterone is known to reduce antioxidants. "This is a problem with aging men, because, the level of testosterone decreases as men age," said Deyhim, adding a similar study on female rats has begun. Deyhim said fr...

Gene discovery opens door to tackling disease

... to shut down oestrogen in breast cancer cells and testosterone in prostate cancer cells. "Most of those cancers depend on the hormones to stay alive, so if we can use SLIRP to block the hormones we may be able to help stop those diseases in their tracks." Professor Leedman said the discovery could open the doo...

Mechanism for neurodenegerative diseases linked to transport proteins

...ding SBMA, in which a mutation in the receptor for testosterone leads to the loss of motor neurons. In the new study, Brady and his co-workers were able to show that polyQ-AR, the mutated protein in SBMA, caused inhibition of fast axon transport by activating an enzyme called JNK that can inhibit these transport ...

High estrogen levels associated with dementia in older men

...increased risk of dementia. By contrast, levels of testosterone were not associated with cognitive decline. The st...irment and dementia. However, the evidence for how testosterone levels affect men is contradictory. To better understand the role of sex hormones in dementia, re...

Sex chromosome genes influence aggression andmaternal behavior, say UVa researchers

...each other, especially in males, because they have testosterone and the Y chromosome. "It is our hope that these data could lead to the discovery of new genetic bases for aggression and parental behavior in other animals, including humans." ...

Males with elevated levels of testosterone lead shorter lives but have more success siring offspring

Comparative studies have studied testosterone levels and related them to mating systems and aggr...ion, but very few studies have attempted to relate testosterone to fitness, that is, the combination of lifetime reproductive success and survival, in the wild or e...

New brain hormone puts brakes on reproduction

...onads, where in males they stimulate production of testosterone and the maturation of sperm. In females, the hormones stimulate production of estradiol, a sex steroid hormone and the body's main form of estrogen, and regulate ovulation, the production of fertile eggs. Estradiol and testosterone, in turn, feed ba...

'Executive' monkeys influenced by other executives, not subordinates

... influence ranking. For example, we can manipulate testosterone levels, or give anxiety-reducing drugs, to determi...One theory, for example, holds that high levels of testosterone in utero cause "hypermasculinization" of the brain, which suppresses the reflexive ability to orient...

Male rivalry increases when females at most fertile, say researchers

...-looking man, as their features are linked to high testosterone levels, demonstrating good genetic qualities that ...hase, she tends to prefer faces that indicate high testosterone levels, which indicate good genes; masculine faces reflect these qualities." ...

The brain is broadly wired for reproduction

... ovulation, and the menstrual cycle in females and testosterone production in males -- by regulating the release of hormones from the pituitary gland. Interestingly, GnRH neurons also appear to be involved in the control of sexual behaviors. "Consistent with the idea that GnRH neurons might have additional func...

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