Links for Keyword: Hormones & Behavior

Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.


Links 41 - 60 of 324

By Susan Milius OTTAWA — Some of the animal kingdom’s showiest extremes, from deer antlers to the outsized horn of the male rhinoceros beetle, may be natural insulin meters. As an animal grows, the nubbins of tissue that will form its big weapons or displays may be more sensitive to insulin than other developing body parts, Douglas Emlen of the University Montana said July 10 at the Evolution Ottawa scientific congress. The proposal “potentially narrows the range of explanations for the evolution of ornaments and weapons,” said Bob Montgomerie of Queen’s University in Kingston, Ontario, who studies courtship-related features in birds. Insulin orchestrates growth in tune with how much food a young animal gets, Emlen explained. A well-fed youngster flush with insulin will grow the most spectacular horns or other paraphernalia, while underfed rivals remain stunted. If the growing antlers or other extreme structures are supersensitive to insulin, they will supersize out of proportion to less sensitive tissue. That’s the case for the horns of the rhinoceros beetle, Trypoxylus dichotomus. Males of the species grow horns about two-thirds as long as the rest of their bodies. They use these fearsome weapons to knock rivals away from sap-oozing wounds on trees where females go to feed. The horns are eight times more responsive to insulin or insulin-like growth factors than some other body parts, Emlen said. That sensitivity fits with reports from other researchers that insulin or related signals affect development of antlers in red deer and the outsized male claws in a type of shrimp and one kind of crab. For those animals though, researchers haven’t yet explored how the weaponry tissues’ sensitivity compares with that of other body parts. © Society for Science & the Public 2000 - 2012

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 17037 - Posted: 07.14.2012

Shannon Pettypiece Testosterone replacement has long been prescribed for men who suffer from abnormally low levels of the male sex hormone, but overuse can lead to infertility and can even speed the growth of prostate cancer. That hasn't stopped Michael Murray, a healthy 43-year-old home stager who works in New York and Chicago, from getting frequent testosterone injections to raise his energy level and give his bodybuilding regime a boost. "Am I making a deal with the devil? A little bit, but I have to think about my quality of life," Murray explains. "It is like I'm in my 20s again." In what may become one of the most sought-after lifestyle drugs since the introduction of Pfizer's Viagra 14 years ago, new testosterone drugs from Eli Lilly, Abbott Laboratories, and other drugmakers are hot. Prescriptions for testosterone replacement therapies have more than doubled since 2006 to 5.6 million last year, according to data compiled by Bloomberg. Sales are expected to triple to $5 billion by 2017, forecasts Global Industry Analysts. As many as 13.8 million men older than 45 in the United States have low levels of testosterone, according to a 2006 study in the International Journal of Clinical Practice. The male sex hormone begins to decline after age 30, and tends to drop about 1 percent each year. Lower-than-normal levels can lead to a loss of libido, a decrease in bone and muscle mass, and depression. © 2012 Hearst Communications Inc.

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 16789 - Posted: 05.14.2012

by Daniel Strain Sharks may be known as terrors of the sea, but in some cases they're more like night lights. That's because many deep-sea sharks, like the smalleye pygmy shark (Squaliolus aliae), can make their own light, glowing from tail to snout as a possible means of camouflage. Now, a new study shows how this predator, the world's smallest shark, powers its luminescence. Smalleye pygmy sharks aren't just petite—they grow no more than 22 centimeters long—they're also hard to find, says study co-author Julien Claes, a shark biologist at the Catholic University of Louvain in Belgium. These fish swim hundreds of meters below the water's surface in the Indian and western Pacific oceans. When scientists do manage to pull one of these animals up, they sometimes catch an odd sight: a blue glow coming mostly from the shark's belly. Claes co-authored a paper in 2009 that showed that a second group of luminescent sharks, called lantern sharks (Etmopterus spinax), trigger their own glow using two hormones common in many animals: melatonin and prolactin. But it wasn't clear if smalleye pygmy sharks and their close relatives relied on the same molecules. So Claes and his colleagues launched a second survey, collecting 27 pygmy sharks off the coast of Taiwan. To determine what controlled their unearthly glow, the researchers took patches of the fish's skin and soaked them in various chemicals known to cue luminescence in other species. They then recorded the resulting glow—often so faint that it was tricky to see at a distance even in a dark room—using a light detector. And sure enough, when Claes tried melatonin, which in people helps to control cycles of sleep and waking, voila! There was light. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 10: Biological Rhythms and Sleep
Link ID: 16716 - Posted: 04.26.2012

By Janelle Weaver A micrograph view of crystallized oxytocin. Image: Alfred Pasieka/Photo Researchers, Inc. When we meet new people, we assess their character by watching their gestures and facial expressions. Now a study in the Proceedings of the National Academy of Sciences USA suggests that those nonverbal cues are communicating the presence of a specific form of a gene that makes us more or less responsive to others’ needs. The gene determines which type of receptor a person has for the hormone oxytocin. Oxytocin has been implicated in a variety of positive traits, such as trust, empathy and generosity. The hormone is detected by our body’s cells via their oxytocin receptors. In a past study, psychologist Sarina Rodrigues Saturn of Oregon State University and her collaborators found that people who have a certain variation of the receptor gene are more empathetic than those with the alternative form of the gene. In the new study, Saturn and her team showed volunteers 20-second silent video clips of individuals who were listening to their romantic partner recount an upsetting experience. The study participants watched for nonverbal behaviors, such as head nods and smiles, and rated every individual on a number of character traits. Those with the form of the oxytocin receptor gene associated with empathy were judged by the volunteers as being more trustworthy, compassionate and kind than those with the alternative form of the gene. “These slight genetic variations do have a big impact on not only how you feel internally but also how people perceive you,” Saturn says, adding that impressions based on nonverbal cues can help individuals quickly choose compatible friends or romantic partners. © 2012 Scientific American,

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 16704 - Posted: 04.25.2012

By Katherine Harmon Years of surgeries and medications were unable to stop Sultan Kosen’s runaway growth. In 2010 at age 27 and a height of 2.46 meters (eight feet, one inch), he became the world’s tallest living man, according to Guinness World Records. But he wasn’t done growing. Kosen had been diagnosed with a growth disorder at age 10 after doctors in his native Turkey found a tumor on his pituitary gland. The tumor triggered the gland to release too much growth hormone. As a result, he has suffered from both gigantism, a condition in which too much growth hormone is secreted during childhood, and acromegaly, a condition caused by too much growth hormone in adulthood. The tumor was technically benign, but it was lodged near the bottom of his brain, making it difficult to operate on. Thus ensconced, the tumor—along with Kosen’s whole body—continued to grow to dangerous proportions. sultan kosen uva surgery So in May 2010, doctors at the University of Virginia Medical Center put Kosen on new medication to limit growth hormone production. Perhaps more importantly, they were also able to perform gamma-knife radiosurgery on his hard-to-reach tumor. Guided by MRI, the doctors used this super-precise technique, which harnesses high-power gamma rays, to disable the tumor without having to do more dangerous invasive surgery. © 2012 Scientific American

Related chapters from BP7e: Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 16529 - Posted: 03.17.2012

By Marla Cone and Environmental Health News That is a main finding of a report, three years in the making, published Wednesday by a team of 12 scientists who study hormone-altering chemicals. Dozens of substances that can mimic or block estrogen, testosterone and other hormones are found in the environment, the food supply and consumer products, including plastics, pesticides and cosmetics. One of the biggest, longest-lasting controversies about these chemicals is whether the tiny doses that most people are exposed to are harmful. In the new report, researchers led by Tufts University's Laura Vandenberg concluded after examining hundreds of studies that health effects "are remarkably common" when people or animals are exposed to low doses of endocrine-disrupting compounds. As examples, they provide evidence for several controversial chemicals, including bisphenol A, found in polycarbonate plastic, canned foods and paper receipts, and the pesticide atrazine, used in large volumes mainly on corn. The scientists concluded that scientific evidence "clearly indicates that low doses cannot be ignored." They cited evidence of a wide range of health effects in people – from fetuses to aging adults – including links to infertility, cardiovascular disease, obesity, cancer and other disorders. "Whether low doses of endocrine-disrupting compounds influence human disorders is no longer conjecture, as epidemiological studies show that environmental exposures are associated with human diseases and disabilities," they wrote. © 2012 Scientific American

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 8: Hormones and Sex
Link ID: 16524 - Posted: 03.17.2012

By Scicurious Hi. In a few minutes I’d like you to stand up and give a short public speech to a judgmental group of people. The speech will be about the current national and international effects of Marbury v Madison, with particular focus on violations of interstate commerce. You have 15 minutes to prepare and the speech will have to be 15 minutes long. I hope you’ve done your research. Nervous yet? If you are, you’re not alone. Fear of public speaking (glossophobia, or just stage fright) is one of the most common fears in the Western world. But it’s ok. We’re going to have you sit with your loved one, who will be able to give you encouragement as you prepare. Do you feel a little bit better? I bet you do. But do you really, actually feel better? Does your body react to stress differently when you’ve got a loved one with you to help you out? It turns out that it might. At least, if you’ve got a specific kind of oxytocin receptor gene. Oxytocin gets a lot of press. And well it should. Recent findings on oxytocin have shown effects on trust, on generosity, on behaviors in austistic children even. Not to mention all the effects that oxytocin has on parental bonding and on your sex life. While many of these studies have looked at levels of circulating oxytocin, or the effects of giving oxytocin (usually as a nasal spray) on behavior, people have recently started to look at the other side of oxytocin: the oxytocin receptor. © 2011 Scientific American,

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 16167 - Posted: 12.20.2011

By Tim Wall A review of 142 studies on the effects of the herbicide atrazine had bad news for testes. "Essentially, atrazine chemically castrates animals. When you look at a male exposed to atrazine, the testes are missing sperm," Tyrone Hayes of the University of California, Berkeley told Discovery News. The effects of atrazine on male development are consistent across all examined animals, found a study published by a team of 22 researchers from more than 60 nations in the Journal of Steroid Biochemistry and Molecular Biology. Mammals, reptiles, and fish were all affected, but amphibians caught the worst of it. In a study by Hayes, male African clawed frogs turned into females after exposure to atrazine, which kills weeds around the world in everything from corn fields to orchards. "And this is not at extremely high concentrations" said co-author of the review Val Beasley of the University of Illinois in a press release. "These are at concentrations that are found in the environment." Humans aren't spared the effects of atrazine, the world's second most common herbicide after glyphosate, Hayes said. Hayes pointed to studies correlating atrazine exposure to low sperm quality, birth defects, miscarriage, and breast cancer © 2011 Discovery Communications, LLC.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 16108 - Posted: 12.03.2011

By HARRIET BROWN In patients with depression, anxiety and other psychiatric problems, doctors often find abnormal blood levels of thyroid hormone. Treating the problem, they have found, can lead to improvements in mood, memory and cognition. Now researchers are exploring a somewhat controversial link between minor, or subclinical, thyroid problems and some patients’ psychiatric difficulties. After reviewing the literature on subclinical hypothyroidism and mood, Dr. Russell Joffe, a psychiatrist at the North Shore-Long Island Jewish Health System, and colleagues recently concluded that treating the condition, which affects about 2 percent of Americans, could alleviate some patients’ psychiatric symptoms and might even prevent future cognitive decline. Patients with psychiatric symptoms, Dr. Joffe said, “tell us that given thyroid hormones, they get better.” The thyroid, a bow-tie-shaped gland that wraps around the trachea, produces two hormones: thyroxine, or T4, and triiodothyronine, known as T3. These hormones play a role in a surprising range of physical processes, from regulation of body temperature and heartbeat to cognitive functioning. Any number of things can cause the thyroid to malfunction, including exposure to radiation, too much or too little iodine in the diet, medications like lithium, and autoimmune disease. And the incidence of thyroid disease rises with age. Too much thyroid hormone (hyperthyroidism) speeds the metabolism, causing symptoms like sweating, palpitations, weight loss and anxiety. Too little (hypothyroidism) can cause physical fatigue, weight gain and sluggishness, as well as depression, inability to concentrate and memory problems. © 2011 The New York Times Company

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 12: Psychopathology: Biological Basis of Behavioral Disorders
Link ID: 16068 - Posted: 11.22.2011

by Catherine de Lange How kind you are could be affected by a change in a single gene. What's more, others can tell if you have the gene even if you don't speak a single word. There are several variations of the gene that codes for the receptor for the hormone oxytocin. Aleksandr Kogan at the University of Toronto, Canada, and colleagues wanted to check whether these variations influence behaviour, since high levels of oxytocin are believed to make people more sociable. Kogan's team asked 116 volunteers to watch 23 silent videos that were 20 seconds long. Each showed a person's response to their partner telling them a story of personal suffering. The volunteers were asked to rate how kind and trustworthy the person in the video appeared to be. People with the so-called GG version of the oxytocin receptor gene were judged to be kinder than those with GA or AA versions. The difference? Those with GG variations used significantly more non-verbal empathetic gestures in their storytelling such as smiling and nodding. Kogan expects that this is what influenced the observers' judgements. Further research will be needed to identify the effect of the different genetic variations on oxytocin levels. Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.111265810 © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 16039 - Posted: 11.15.2011

By Tina Hesman Saey Researchers have grown a mouse pituitary gland for the first time from embryonic stem cells. Or rather, the pituitary gland grew itself, after Japanese researchers coaxed embryonic stem cells to form the type of tissues that normally surround the gland. The accomplishment, reported online November 9 in Nature, could be the first step toward replacement pituitary glands for people. Self-made glands growing in lab dishes may also help researchers learn how the organs develop inside the body. “There’s a lot in it to be excited about, whether you’re a developmental biologist or interested in clinical applications,” says Sally Camper, a developmental geneticist at the University of Michigan in Ann Arbor. Camper has tried, and failed, to coax embryonic stem cells to form pituitary glands. “It’s a gorgeous piece of work, and it’s just really, really exciting,” she says. Scientists have persuaded stem cells to form particular types of tissues before, but growing a whole organ in a lab dish has been an elusive goal, says pediatric endocrinologist Mehul Dattani of the University College London Institute of Child Health and Great Ormond Street Hospital for Children in London. What allowed Yoshiki Sasai of the RIKEN Center for Developmental Biology in Kobe, Japan, and colleagues to succeed where others have failed is that the group recreated conditions that exist in the part of the brain where the pituitary normally grows. © Society for Science & the Public 2000 - 2011

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 16014 - Posted: 11.11.2011

by Marianne English Though research has shown that women are more likely than men to remember the emotional details of an event, there may be another dividing factor when it comes to memory: birth control. Scientists know people's hormones shape how their memories form. For instance, our fight-or-flight hormones influence how the brain encodes a specific memory, with traumatic events making more of an impact than everyday activities. A portion of the brain called the amygdala works on the receiving end of these hormones and is thought to play a central role in making and storing new memories. Birth control works by reducing the amount of estrogen and progesterone in a woman's body to limit ovulation, but it's unclear whether these hormones affect how a person recalls an event. In one study, researchers looked at whether women taking oral contraceptives remembered events from an experiment differently than women with normal menstrual cycles not on birth control. Seventy-two female subjects were recruited for the study, half on the pill and half not. Each group watched variations of a slide show story that involved a young boy being hit by a car. Before and throughout the slide show, researchers collected saliva samples to measure alpha-amylase -- a chemical that signifies a drop or rise in the fight-or-flight hormone norepinephrine, which increases a person's heart rate during emergencies or stressful situations. © 2011 Discovery Communications, LLC.

Related chapters from BP7e: Chapter 17: Learning and Memory; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 8: Hormones and Sex
Link ID: 15819 - Posted: 09.20.2011

by Elizabeth Norton Humans are probably the only species on Earth who nurture their young for 20 years or more. For men in particular, the intensive demands of parenting can come as such a shock that a built-in biological mechanism has evolved to help cope with the change. A new study shows that becoming a father leads to a sharp decline in testosterone, suggesting that although high levels of the hormone may help men win a mate, testosterone-fueled traits such as aggression and competition are less useful when it comes to raising children. Previous research had shown that among new fathers, testosterone levels were lower than in men of the same age who didn't have children. But no study addressed whether parenthood itself was responsible, or whether men who became committed partners and fathers started out with lower levels of the hormone than did their single, footloose friends. To sort out cause and effect, anthropologists Lee Gettler, Christopher Kuzawa, and colleagues at Northwestern University in Evanston, Illinois, and the University of San Carlos in Cebu City, Philippines, checked testosterone levels in a group of men participating in the ongoing Cebu Longitudinal Health and Nutrition Survey. The survey began with a group of some 3000 women who were pregnant in 1983 and followed the general health, nutrition, medical care, and survival of their children; it has since expanded into an intergenerational study of health, education, and sexual behavior as those children grew up and are now having children of their own. © 2010 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 15795 - Posted: 09.13.2011

THERE was at least one downside to Farinelli's castration. The operation may have preserved the 18th-century singer's treble voice into adulthood, making him a musical legend, but it also condemned him to a skull deformity that may have affected his mind. Farinelli was exhumed in 2006 so that his skeleton could be studied. Lead investigator Maria Giovanna Belcastro of the Alma Mater Studiorum University of Bologna, Italy, was able to identify two unusual features. Like those of other castrati, Farinelli's limb bones were unusually long. And the front of his skull had grown inwards in a lumpy mass, in places twice as thick as unaffected bone (Journal of Anatomy, DOI: 10.1111/j.1469-7580.2011.01413.x). This is called hyperostosis frontalis interna (HFI). It is thought to be caused by hormonal disorders, particularly too much oestrogen, which explains why it is normally found in post-menopausal women and is rare in men. HFI was thought to be harmless, says Israel Hershkovitz of Tel Aviv University in Israel, but is now linked to behavioural disorders, headaches and neurological diseases like Alzheimer's. Though any such symptoms probably would not have affected Farinelli until late in life, Hershkovitz says. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 15607 - Posted: 07.26.2011

by Elizabeth Norton Life for those with a genetic disease called Prader-Willi syndrome, which affects an estimated one out of 15,000 people, can be challenging both for the patient and his or her family. Sufferers have an insatiable hunger that can lead to life-threatening obesity if access to food is not restricted. And worse, they have behavioral problems akin to autism. Tantrums and tears are common because these patients have difficulty understanding the motives of others and controlling their own emotions. But treatment with the brain hormone oxytocin may help bring both emotions and eating into balance, according to a new study. Several clues pointed to the potential of oxytocin, often thought of as the "trust hormone." Research conducted on the brain tissue donated after death from Prader-Willi patients showed that the hypothalamus (the body's thermostat) has abnormalities in the nerve cells that produce this hormone. Moreover, the hypothalamus releases oxytocin in response to touching, social interactions, relaxation, and trust—all the things people with Prader-Willi syndrome have trouble with. And oxytocin treatments have improved the social skills of autistic patients. Finally, the hormone is thought to contribute to feelings of fullness after eating, "satiety" in scientific parlance. To see whether oxytocin could benefit individuals with Prader-Willi syndrome, endocrinologist Maïthé Tauber of the Children's Hospital in Toulouse, France, and colleagues injected oxytocin or a placebo into the noses of 24 adult patients. The researchers monitored the patients' behavior; they also used cartoon stories to test patients' grasp of social interactions and pictures of faces to see how well they could recognize emotions. © 2010 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 15485 - Posted: 06.25.2011

By KATHRYN HARRISON Readers who can’t identify Jean-Martin Charcot as the name of the French neurologist whose 19th-century experiments with hypnosis influenced Sigmund Freud’s theory of neurosis may yet recognize the work he conducted at the Saltpêtrière Hospital in Paris. Photographs and illustrations of Charcot’s patients, all women suffering hysteria, remain in currency today, 140 years after they were made, if more as curiosities than as clinically valuable documents. Once seen, these images — of, for example, a woman wearing little more than a tangle of bed sheets, her eyes rolled up into her head in either “ecstasy” or “delirium,” or fixed on the invisible object of her “amorous supplication” — are not easily forgotten, let alone dismissed. Poses classified as “passionate attitudes,” they have the disquieting aspect of pornography masquerading as intellectual inquiry. Charcot, as portrayed in Asti Hust­vedt’s consistently enthralling “Medical Muses,” focused intently — myopically, one could argue — on using hypnosis to induce hysteria and make “his hysterics, with their bizarre fits and spasms, into ideal medical specimens.” But the provocative behavior of those “specimens” transformed Saltpêtrière into something closer to a carnival than a teaching hospital. As much showman as physician, Charcot gave weekly two-hour lectures to a packed amphitheater, including demonstrations designed to captivate an audience accustomed to staged séances and exhibitions of mesmerism or telepathy. One of Charcot’s students described the dramatic potential of exhibiting hypnotized women: “We can cut them, prick them and burn them, and they feel nothing.” © 2011 The New York Times Company

Related chapters from BP7e: Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 15460 - Posted: 06.20.2011

FOR people worried about the feminising effect of oestrogen-like chemicals in the water there is now a modern-day equivalent of the canary in the coal mine: a genetically modified fish in a bowl. Male fish exposed to oestrogen have delayed sperm development and grow smaller testes. Some industrial chemicals, such as bisphenol A, mimic oestrogen, but little is known about how the effects of different oestrogen-like chemicals add up in water. To find out, Xueping Chen and colleagues at Vitargent, a biotechnology company in Hong Kong, have created a genetically engineered fish that glows green when it is exposed to oestrogen-like chemicals. Chen's team took the green fluorescent protein gene from jellyfish and spliced it into the genome of the medaka fish, Oryzias melastigma, next to a gene that detects oestrogen. Chemicals that have oestrogen-like activity cause the fish to express the modified gene, making them glow. When the team tested the fish at eight sites around Hong Kong, they found that some chemicals that showed weak or no oestrogenic activity, including UV filters used in sunscreen, had combined in water to amplify or create an oestrogenic effect. The work is as yet unpublished. William Price of the University of Wollongong in New South Wales, Australia, warns the approach does not detect a biological response. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 8: Hormones and Sex
Link ID: 15415 - Posted: 06.11.2011

By LISA SANDERS, M.D. A fiercely independent and active 76-year-old woman spent the past decade caring for her aged mother, who died at 99. Weeks after her mother’s death, the woman collapsed at home. She was found to have bleeding from a collection of abnormal blood vessels (known as AVMs, or arteriovenous malformations) in her colon. In the months after, the patient’s red-blood-cell count returned to normal, but she never regained her old energy and strength. She told her daughters that she was weaker and more tired than she had ever been in her life. Dr. Susan Wiskowski, a family physician in Hartford, was the woman’s doctor. Until recently, the patient was in good health for her age, with only a few medical problems: high blood pressure, which was controlled with one medication; hypothyroidism, treated with Synthroid; and cataracts, which had been surgically repaired. Now, out of the blue, she was experiencing rapid weight gain, swelling and weakness in her legs, which made it hard to walk. A couple of weeks after the cardiac work-up, the patient’s behavior became erratic and strange. Despite her complaints of weakness, she veered between bursts of activity — endlessly cleaning her house, giving large dinner parties — and days of isolation and fatigue. She was sometimes elated, telling her four daughters that she’d found where heaven was located. She began to talk about giving away her possessions. One afternoon she seemed completely out of control. A neighbor called 911, and the patient was rushed by ambulance to St. Francis Hospital in Hartford. © 2011 The New York Times Company

Related chapters from BP7e: Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 8: Hormones and Sex
Link ID: 15297 - Posted: 05.07.2011

By Amina Zafar, CBC News The role estrogen plays in women's brains remains murky but researchers are beginning to clarify it. The first Women's Brain Health Academic Symposium in Toronto on Wednesday brought together experts from North America leading a discussion about trying to better understand the female brain. "Seventy per cent of Alzheimer's patients are women," said Lynn Posluns, founder and chair of the Women of Baycrest, which aims to raise $5 million for a research chair devoted to women's brain health. Researchers want to uncover exactly how estrogen affects different regions of the female brain.Researchers want to uncover exactly how estrogen affects different regions of the female brain. Brian Snyder/Reuters Yet most laboratory studies today are done on male rats because female rats are considered too complex, Posluns said. "I'm saying there's a real disconnect here. It is time for scientists to better understand the female brain." At the symposium, Gillian Einstein, a professor of psychology and public health at the University of Toronto, talked about her early findings exploring the role of estrogen on brain functions such as mood and memory. "I want women to be circumspect about the effect of their hormones on their mood and cognition," said Einstein. "It may or may not be PMS that makes you grumpy. It's possible that your husband really did do something crappy, and you have a reasonable response to it. [On the other hand] I also think it's important to think they may be having an effect." © CBC 2011

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 15191 - Posted: 04.07.2011

CONJURE up an image of a financial risk-taker, and you'll probably picture an aggressive Wall Street trader, testosterone surging as he closes the deal. But new research suggests that people with low levels of the male sex hormone are also likely to take financial risks. Previous studies have linked high levels of testosterone to certain risk-seeking behaviours. To investigate whether financial risk-taking follows a similar pattern, Scott Huettel at Duke University in Durham, North Carolina, measured the testosterone levels of 298 people, who then took part in trials in which they chose between a fixed known reward or a gamble between getting a payout - mostly larger than the fixed reward - or nothing. Overall, the volunteers generally preferred the known return than the gamble, even if they would have been better off, on average, by taking a chance. Surprisingly, the biggest risks were taken by people with very high or very low testosterone, compared with the average levels for their gender (Psychological Science, DOI: 10.1177/0956797611401752). Economists want to predict who is likely to be successful at playing financial markets, says Dario Mastripieri at the University of Chicago. "It's legitimate to ask if biology is going to have an effect." © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 5: Hormones and the Brain; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 11: Emotions, Aggression, and Stress
Link ID: 15118 - Posted: 03.21.2011