Chapter 5. Hormones and the Brain
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By Bethany Brookshire WASHINGTON — Estrogen can protect the brain from harmful inflammation following traumatic injury, a new study in zebra finches suggests. Boosting levels of the sex hormone in the brain might help prevent the cell loss that occurs following damage from injuries such as stroke. Estrogen levels quadrupled around the damaged area in both male and female zebra finches after researchers gave them experimental brain injuries, Colin Saldanha and colleagues at American University in Washington, D.C., reported November 17 at the annual meeting of the Society for Neuroscience. When the scientists prevented finch brains from making estrogen, inflammatory proteins at damaged sites increased. The helpful estrogen didn’t come from gonads. It’s made within the brain by support cells called astrocytes close to the injury. Injury inflames the brain. Initially, this inflammation recruits helpful cells to the damaged area and aids in recovery. But the long-term presence of inflammatory proteins can cause harm, killing off brain cells and reducing functions such as movement and memory. The researchers hope that by understanding how estrogen reduces inflammatory proteins, therapies might boost this natural estrogen production to keep harmful inflammation at bay. © Society for Science & the Public 2000 - 2014.
By Melissa Hogenboom Science reporter, BBC News A small group of neurons that respond to the hormone oxytocin are key to controlling sexual behaviour in mice, a team has discovered. The researchers switched off these cells which meant they were no longer receptive to oxytocin. This "love hormone" is already known to be important for many intimate social situations. Without it, female mice were no more attracted to a mate than to a block of Lego, the team report in journal Cell. These neurons are situated in the prefrontal cortex, an area of the brain important for personality, learning and social behaviour. Both when the hormone was withheld and when the cells were silenced, the females lost interest in mating during oestrous, which is when female mice are sexually active. At other times in their cycle they responded to the males with normal social behaviour. The results were "pretty fascinating because it was a small population of cells that had such a specific effect", said co-author of the work Nathaniel Heintz of the Rockefeller University in New York. "This internal hormone gets regulated in many different contexts; in this particular context, it works through the prefrontal cortex to help modulate social and sexual behaviour in female mice. "It doesn't mean it's uniquely responsible because the hormone acts in several important places in the brain but it does show that this particular cell type is required for this aspect of female social behaviour," Dr Heintz told BBC News. To silence the neurons, the team used toxins that block the ability of the cells to transmit signals to other neurons - technology that has recently revolutionised the ability to study small populations of neurons. BBC © 2014
BY Bethany Brookshire We all need sleep, but attaining it can be delicate. Insomniacs can’t fall or stay asleep. Travelers suffer from jetlag. Anxiety keeps people up at night. Or maybe it’s just that jackhammer running across the street keeping your eyes open. Some people turn to earplugs, dark curtains or alcohol to soothe them to sleep. But others go to the supplement aisle and pick up melatonin. The hormone melatonin is secreted from our brains at night and helps regulate sleep. But this chemical is not restricted to humans, or even to mammals. The roots of melatonin’s role in our nightly slumbers go back much further in evolutionary history. A new paper focuses in on the role of melatonin in tiny marine creatures called zooplankton. It turns out that these animals use melatonin just as much as we do, suggesting that the origins of sleeplike behavior may lie under the sea. “For every system and feature that makes a human or other animal today, you can ask the question: Where did it start? How did it begin? What was its first role and function, and how did it become more complex?” says study coauthor Detlev Arendt, a zoologist at the University of Heidelberg in Germany. Arendt’s laboratory has been studying the answers to these questions in the marine ragworm Platynereis dumerilii. This unassuming, centipede-like, ocean-dwelling worm produces larvae that float through the open water as zooplankton. These small larvae propel themselves up and down in the water column with movements of their cilia, slender, hair-like appendages that protrude out from the organisms. © Society for Science & the Public 2000 - 2014.
By Jennifer Balmer Each summer, leatherback sea turtles (Dermochelys coriacea) migrate thousands of kilometers from their tropical breeding grounds to feed in cooler waters. Yet how the animals know when to begin their long journey back south at the end of the season has mostly remained a mystery. New findings, to be published in an upcoming issue of the Journal of Experimental Marine Biology and Ecology, suggest that leatherback sea turtles may be able to sense seasonal changes in sunlight by means of an unpigmented spot on the crown of their head—known as the pink spot (pictured). Researchers conducted an examination of the anatomical structures beneath the pink spot and found that the layers of bone and cartilage were remarkably thinner than in other areas of the skull. This thin region of the skull allows the passage of light through to an area of the brain, called the pineal gland, that acts as biological clock, regulating night-day cycles and seasonal patterns of behavior. The authors suggest that the lack of pigment in the crowning pink spot and thin skull region underlying it act as a “skylight,” allowing the turtles to sense the subtle changes in sunlight that accompany changing seasons, signaling them to return south when autumn approaches. © 2014 American Association for the Advancement of Science
|By Gary Stix A biochemical produced in the brain called oxytocin has entered popular culture in recent years as the “love,” “cuddle” or “bonding” hormone. That’s a lot to choose from. Oxytocin plays a role in producing contractions at childbirth and in helping in lactation, but we’ve known that for more than a century. Experiments in the 1990s showed that it was instrumental in leading prairie voles, known for their monogamous behavior, to pick a lifelong mate. Later studies then demonstrated that the chemical contributes to trust and social interactions in various animals, including humans. After the vole study, interest in the nine–amino acid peptide started to rise. In a TED talk economist Paul Zak called it “the moral molecule” because of its link to trust, empathy and prosperity. The Internet DIY brain-makeover market then took up the meme. Vero Labs of Daytona Beach, Fla., sells “Connekt” oxytocin spray for $79 that purports to “strengthen workplace bonds” and “increase positive self-awareness.” The company has also come out with a his-and-her“Attrakt” spray that mixes oxytocin with pheromones—chemical sex attractants that help mice get it on, but whose role in triggering mating behavior in humans is hotly disputed. (Researchers who study oxytocin warn prospective buyers away from these purchases, saying that long-term use in humans has not been studied.) © 2014 Scientific American
By LISA SANDERS, M.D. On Thursday, we challenged Well readers to take on the case of a 19-year-old man who suddenly collapsed at work after months of weakness and fatigue dotted with episodes of nausea and vomiting. More than 500 of you wrote in with suggested diagnoses. And more than 60 of you nailed it. The cause of this man’s collapse, weakness, nausea and vomiting was… Addisonian crisis because of Addison’s disease Addison’s disease, named after Dr. Thomas Addison, the 19th-century physician who first described the disorder, occurs when the adrenal glands stop producing the fight-or-flight hormones, particularly cortisol and adrenaline and a less well known but equally important hormone called aldosterone that helps the body manage salt. In Addison’s, the immune system mistakenly attacks the adrenal glands as if they were foreign invaders. Why this happens is not well understood, but without these glands and the essential hormones they make, the body cannot respond to biological stress. The symptoms of Addison’s are vague. That’s one reason it’s so hard to diagnosis. Patients complain of weakness and fatigue. They often crave salt. And when confronted with any stress — an infection or an injury — patients with Addison’s may go into adrenal crisis, characterized by nausea and vomiting, low blood pressure and, sometimes, physical collapse. Their blood pressure may drop so low that oxygen-carrying blood cannot reach the extremities, causing skin to turn blue; if blood fails to reach even more essential organs, it can lead to death. © 2014 The New York Times Company
Keyword: Hormones & Behavior
Link ID: 20037 - Posted: 09.06.2014
By MATTHEW PERRONE AP Health Writer WASHINGTON (AP) — The Food and Drug Administration says there is little evidence that testosterone-boosting drugs taken by millions of American men are beneficial, though the agency is also unconvinced by studies suggesting the hormone carries serious risks. The agency posted its review online Wednesday ahead of a public meeting to discuss the benefits and risks of treatments that raise levels of the male hormone. Regulators agreed to convene the September 17 meeting after two federally funded studies found links between testosterone therapy and heart problems in men. The scrutiny comes amid an industry marketing blitz for new pills, patches and formulations that has transformed testosterone a multibillion-dollar market. Advertisements for prescription gels like Fortesta and Androgel promise aging men relief from ‘‘Low-T,’’ a condition they link to low libido, fatigue and weight gain. But FDA reviewers state that ‘‘the need to replace testosterone in these older men remains debatable.’’ While testosterone levels naturally decline after age 40, it’s unclear whether those lower levels actually lead to the signs commonly associated with aging, including decreased energy and loss of muscle. The FDA first approved testosterone injections in the 1950s for men who had been diagnosed with hypogonadism, a form of abnormally low testosterone caused by injury or medical illness. But the recent advertising push is focused on otherwise healthy men who simply have lower-than-normal levels of testosterone.
by Bethany Brookshire Premenstrual syndrome, or PMS, can be a miserable experience. Women report over 200 symptoms in the days before menstruation occurs. The complaints run the gamut from irritable mood to bloating. PMS can be so slight you don’t even notice, or it can be so severe it has its own category — premenstrual dysphoric disorder. But to some, PMS is just a punchline, a joke featured in pop culture from Buffy the Vampire Slayer to Saturday Night Live. Michael Gillings, who studies molecular evolution at Macquarie University in Sydney, thinks that PMS could have a purpose. In a perspective piece published August 11 in Evolutionary Adaptations, Gillings proposes that PMS confers an evolutionary advantage, increasing the likelihood that a woman will leave an infertile mate. He hopes that his idea could lead to more research and less stigma about the condition. But while his hypothesis certainly sparked a lot of discussion, whether it is likely, or even necessary, is in doubt. Gillings first began to think about PMS when he found out that premenstrual dysphoric disorder was being added to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders. “I started to think that we have a normal distribution of PMS responses, where some people don’t get any symptoms, the majority gets mild symptoms, and some get severe symptoms,” he explains. Including PMDD in DSM-5 made a statement, he says, that “we were going to take one end of this normal curve, the extreme far right end, and we were going to draw a line and say, those people there have a disease we’re going to label in our book. But if 80 percent of women get some kind of premenstrual symptoms, then it’s normal. And I wondered, if it’s so normal, what could be the reason for it?” © Society for Science & the Public 2000 - 2014.
By NICHOLAS BAKALAR Childhood treatment with human growth hormone is strongly associated with an increased risk for stroke in early adulthood, a new study has found. The study adds evidence to previous reports suggesting an increased cardiac and cerebrovascular risk in children treated with growth hormone. Researchers studied 6,874 children, average age 11, who were small for their age but otherwise generally healthy and were treated with growth hormone from 1985 to 1996. They followed them to an average age of 28. There were 11 strokes in the group, four of them fatal. The analysis found that this was more than twice as many strokes as would be expected in a population this size, a statistically significant difference. The results, published online in the journal Neurology, were particularly striking for hemorrhagic stroke, the type caused by a ruptured blood vessel — there were more than seven times as many as would be expected. The authors acknowledged that they were unable to take into account some risk factors for stroke, such as family history and smoking. “Subjects on growth hormones should not panic on reading these results,” said the senior author, Dr. Joël Coste, a professor of biostatistics and epidemiology at the Hôtel Dieu hospital in Paris. “The doctor prescribing the hormone or the family doctor should be consulted and will be able to inform and advise patients.” © 2014 The New York Times Company
Older people who have a severe vitamin D deficiency have an increased risk of developing dementia, a study has suggested. UK researchers, writing in Neurology, looked at about 1,650 people aged over 65. This is not the first study to suggest a link - but its authors say it is the largest and most robust. However, experts say it is still too early to say elderly people should take vitamin D as a preventative treatment. There are 800,000 people with dementia in the UK with numbers set to rise to more than one million by 2021. Vitamin D comes from foods - such as oily fish, supplements and exposing skin to sunlight. However older people's skin can be less efficient at converting sunlight into Vitamin D, making them more likely to be deficient and reliant on other sources. The international team of researchers, led by Dr David Llewellyn at the University of Exeter Medical School, followed people for six years. All were free from dementia, cardiovascular disease and stroke at the start of the study. At the end of the study they found the 1,169 with good levels of vitamin D had a one in 10 chance of developing dementia. Seventy were severely deficient - and they had around a one in five risk of dementia. 'Delay or even prevent' Dr Llewellyn said: "We expected to find an association between low vitamin D levels and the risk of dementia and Alzheimer's disease, but the results were surprising - we actually found that the association was twice as strong as we anticipated." He said further research was needed to establish if eating vitamin D rich foods such as oily fish - or taking vitamin D supplements - could "delay or even prevent" the onset of Alzheimer's disease and dementia. But Dr Llewellyn added: "We need to be cautious at this early stage and our latest results do not demonstrate that low vitamin D levels cause dementia. BBC © 2014
By Darryl Fears At first she was surprised. Then she was disturbed. Now she’s a little alarmed. Each time a different batch of male fish with eggs in their testes shows up in the Chesapeake Bay watershed, Vicki Blazer’s eyebrows arch a bit higher. In the latest study, smallmouth bass and white sucker fish captured at 16 sites in the Delaware, Ohio and Susquehanna rivers in Pennsylvania had crossed over into a category called intersex, an organism with two genders. “I did not expect to find it quite as widespread,” said Blazer, a U.S. Geological Survey biologist who studies fish. Since 2003, USGS scientists have discovered male smallmouth and largemouth bass with immature eggs in several areas of the Potomac River, including near the Blue Plains Advanced Wastewater Treatment Plant in the District. The previous studies detected abnormal levels of compounds from chemicals such as herbicides and veterinary pharmaceuticals from farms, and from sewage system overflows near smallmouth-bass nesting areas in the Potomac. Those endocrine-disrupting chemicals throw off functions that regulate hormones and the reproductive system. In the newest findings, at one polluted site in the Susquehanna near Hershey, Pa., 100 percent of male smallmouth bass that were sampled had eggs, Blazer said. With the mutant bass, she said, “we keep seeing . . . a correlation with the percent of agriculture in the watershed where we conduct a study.”
By Helen Briggs Health editor, BBC News website The timing of when a girl reaches puberty is controlled by hundreds of genes, say scientists. And age at first period may vary in daughters from the same family because of genetic factors, research shows. The findings, published in Nature, could give clues to why early puberty may be linked to an increased risk of health conditions. Scientists at 166 institutions analysed the DNA of more than 180,000 women in one of the largest studies of its kind. They found that hundreds of genes were involved in the timing of puberty. Unusually, a girl's first period was also influenced by imprinted genes - a rare event where genes from either the mother of father are silenced. "Our findings imply that in a family, one parent may more profoundly affect puberty timing in their daughters than the other parent," said lead researcher Dr John Perry of the University of Cambridge. He said the biological complexity revealed in the study was "amazing". "We identified more than 100 regions of the genome associated with puberty timing, but our analysis suggests there are likely to be thousands," he told BBC News. Lifestyle BBC © 2014
|By William Skaggs Jet lag is a pain. Besides the inconvenience and frustration of traveling more than a few time zones, jet lag likely causes billions of dollars in economic losses. The most effective treatment, according to much research, is structured exposure to light, although the drug melatonin may also sometimes be helpful at bedtime. Both approaches have been used for more than 20 years, and during that time no viable new interventions have appeared. Recently, however, research into the molecular biology of circadian rhythms has raised the prospect of developing new drugs that might produce better results. Jet lag occurs when the “biological clock” in the brain becomes misaligned with the local rhythm of daily activity. The ultimate goal of circadian medicine is a treatment that instantly resets the brain's clock. Failing that, it would be helpful to have treatments that speed the rate of adjustment. Four recent discoveries suggest new possibilities. The first involves vasopressin, which is the main chemical signal used to synchronize cellular rhythms of activity in the brain area that is responsible for our biological clock. Blocking vasopressin makes it much easier to reset this clock. Potentially, a drug that interferes with vasopressin could work as a fast-acting treatment for jet lag. The second and third possibilities involve a pair of brain chemicals called salt-inducible kinase 1 (SIK1) and casein kinase 1ε (CK1ε), both of which limit the ability of light to reset the brain's clock. Drugs already exist that interfere with their action and greatly increase the effectiveness of light exposure. The existing drugs are not viable jet-lag treatments, because they are hard to administer and have unpleasant side effects, but researchers hope better drugs can be developed that work in a similar way. © 2014 Scientific American,
By LISA SANDERS, M.D. On Wednesday, we challenged Well readers to solve the case of a middle-aged woman who suddenly began to have episodes of confusion caused by low blood sugars. Her endocrinologist thought she might have an insulinoma, an insulin-producing tumor of the pancreas, but the testing he did seemed to rule out that diagnosis. Nearly 200 of you took on the challenge of trying to figure out what was causing her life-threatening drops in blood sugar level. The correct diagnosis is… Insulinoma The first respondent to make the diagnosis was Karen Unkel of Kinder, La. She is not a doctor but has a longstanding interest in hypoglycemia that allowed her to recognize the disease even in the face of an apparently negative work-up. Well done, Ms. Unkel. An insulinoma is a rare tumor of pancreatic tissue that makes and secretes insulin independently of blood glucose levels. This results in episodes of hypoglycemia that can be quite severe, even life-threatening. The diagnosis is suspected when a patient fulfills what is known as Whipple’s triad: 1) symptoms of hypoglycemia 2) associated with low measured blood sugar and 3) which improve when blood sugar is raised to the normal range. The diagnosis is made when doctors show that the patient is making too much insulin given his or her blood sugar level. Measuring insulin levels is not always accurate because insulin is processed rapidly in the body and because it is difficult to distinguish between insulin made naturally in the pancreas and any insulin that the patient might be injecting. What is measured instead is something known as C-peptide. Insulin is first made as a larger molecule known as proinsulin. When blood sugar rises, an extra bit is shaved off the molecule; that extra bit is C-peptide, and both the resulting insulin and C-peptide are released into the bloodstream. © 2014 The New York Times Company
by Laura Sanders Some brain cells need a jolt of stress to snap to attention. Cells called astroglia help regulate blood flow, provide energy to nearby cells and even influence messages’ movement between nerve cells. Now, scientists report June 18 in Neuron that astroglia can be roused by the stress molecule norepinephrine, an awakening that may help the entire brain jump into action. As mice were forced to walk on a treadmill, an activity that makes them alert, astroglia in several parts of their brains underwent changes in calcium levels, a sign of activity, neuroscientist Dwight Bergles of Johns Hopkins University School of Medicine and colleagues found. Norepinephrine, which acts as a fight-or-flight hormone in the body and a neural messenger in the brain, seemed to cause the cell activity boost. When researchers depleted norepinephrine, treadmill walking no longer activated astroglia. It’s not clear whether astroglia in all parts of the brain heed this wake-up call, nor is it clear whether this activation influences behavior. Norepinephrine might help shift brain cells, both neurons and astroglia, into a state of heightened vigilance, the authors write. © Society for Science & the Public 2000 - 2013.
Virginia Morell If we humans inhale oxytocin, the so-called “love hormone,” we become more trusting, cooperative, and generous. Scientists have shown that it’s the key chemical in the formation of bonds between many mammalian species and their offspring. But does oxytocin play the same role in social relationships that aren’t about reproduction? To find out, scientists in Japan sprayed either oxytocin or a saline spray into the nostrils of 16 pet dogs, all more than 1 year old. The canines then joined their owners, who were seated in another room and didn’t know which treatment their pooch had received. The owners were instructed to ignore any social response from their dogs. But those Fidos that inhaled the oxytocin made it tough for their masters not to break the rule. A statistical analysis showed the canines were more likely to sniff, lick, and paw at their people than were those given the saline solution. The amount of time that the oxytocin-enhanced dogs spent close to their owners, staring at their eyes, was also markedly higher, the scientists report online today in the Proceedings of the National Academy of Sciences. Getting a whiff of oxytocin also made the dogs friendlier toward their dog pals as determined by the amount of time they spent in close proximity to their buddies. The study supports the idea, the scientists say, that oxytocin isn’t just produced in mammals during reproductive events. It’s also key to forming and maintaining close social relationships—even when those are with unrelated individuals or different species. © 2014 American Association for the Advancement of Science.
Keyword: Hormones & Behavior
Link ID: 19716 - Posted: 06.10.2014
By NICHOLAS BAKALAR The hormone estrogen is the recommended treatment for menopausal night sweats and hot flashes, but some women are unable or unwilling to use it. Now a clinical trial suggests that the antidepressant venlafaxine, often used as an alternative, is equally effective. In an eight-week placebo-controlled double-blind study, researchers randomly assigned 339 perimenopausal and postmenopausal women to one of three treatments: 0.5 milligrams a day of estrogen (in the form of estradiol), 75 milligrams a day of the antidepressant venlafaxine (a generic form of Effexor), or a placebo. Before the start of the study, all the women had had symptoms at least 14 times a week. Compared to the rate before the study — an average of 8.1 episodes a day — the frequency of hot flashes and night sweats declined by 52.9 percent in the estradiol group, 47.6 percent in the Effexor group, and 28.6 percent among those who took a placebo. Both Effexor and estradiol were effective treatments, but the study, published online in JAMA Internal Medicine, was not large enough to show that one was significantly better than the other. “Women have important choices of different medications to discuss with their doctors,” said the lead author, Dr. Hadine Joffe, an associate professor of psychiatry at Harvard. “They should know, as they think about these options, that both are effective.” © 2014 The New York Times Company
Keyword: Hormones & Behavior
Link ID: 19673 - Posted: 05.31.2014
Lida Katsimpardi Could the elixir of youth be as simple as a protein found in young blood? In recent years, researchers studying mice found that giving old animals blood from young ones can reverse some signs of aging, and last year one team identified a growth factor in the blood that they think is partly responsible for the anti-aging effect on a specific tissue--the heart. Now that group has shown this same factor can also rejuvenate muscle and the brain. "This is the first demonstration of a rejuvenation factor" that is naturally produced, declines with age, and reverses aging in multiple tissues, says Harvard stem cell researcher Amy Wagers, who led efforts to isolate and study the protein. Independently, another team has found that simply injecting plasma from young mice into old mice can boost learning. The results build on a wave of studies in the last decade in which investigators sewed together the skins of two mice, joining their circulation systems, and studied the effects on various tissues. “It’s still a bit creepy for many people. At meetings, people talk about vampires,” says Stanford University neuroscientist Tony Wyss-Coray, who led the study of learning. But he, Wagers, and others think unease will give way to excitement. The new work, he says, “opens the possibility that we can try to isolate additional factors” from blood, “and they have effects on the whole body.” Hope and hype are high in the anti-aging research arena, and other researchers caution that the work is preliminary. “These are exciting papers,” but “it’s a starting point,” says neuroscientist Sally Temple of the Neural Stem Cell Institute in Rensselaer, NY. Adds Matthew Kaeberlein, a biologist who studies aging at the University of Washington, Seattle, “The therapeutic implications are profound if this mechanism holds true in people.” But that “is the million dollar question here, and that may take some time to figure out.” © 2014 American Association for the Advancement of Science
by Andy Coghlan A pregnancy hormone could prove a simple way to treat multiple sclerosis, after showing promise in a trial of 158 women with MS. MS is a neurological condition that results from damage to the brain and nerves inflicted by the body's own immune system. It affects 2.3 million people worldwide. Symptoms include extreme tiredness, blurred vision, muscle weakness and problems with balance and movement. The symptoms of women with MS tend to ease when they are pregnant, but worsen again after giving birth. This could be because of a hormone called oestriol, which is only produced in significant amounts during pregnancy. The hormone is thought to help suppress the mother's immune system to prevent it attacking the fetus. Fewer relapses Rhonda Voskuhl of the University of California, Los Angeles, and her colleagues wondered whether giving oestriol to people with MS who aren't pregnant might also help with symptoms. They gave 8 milligrams of oestriol daily to 86 women with MS, along with their medication, Copaxone (glatiramer acetate). The women had the most common form of MS, called relapsing-remitting MS, which results in periodic flare-ups of symptoms followed by recovery. After one year, they had 47 per cent fewer relapses than a control group that took Copaxone and a placebo. After two years, the relapse rate was 32 per cent lower than the control group in the group given the hormone, suggesting the effects had plateaued. "We think the oestriol group had bottomed out, and there was nothing left to improve," Voskuhl said, as she presented the preliminary results at the annual meeting of the American Academy of Neurology in Philadelphia last week. © Copyright Reed Business Information Ltd.
A UBC neuroscientist says motherhood permanently alters the brain, exposing moms to different health risks than women without children. Liisa Galea, a professor in the university's psychology department, says some changes are temporary while others are permanent. The most obvious example is size. According to Galea, a mother's brain shrinks by up to eight per cent during pregnancy. While it bounces back about six months after birth, she notes the reaction could have repercussions. “Our research shows that, as a result of these transformations, mothers experience different cognitive abilities and health risks than women without children,” said Galea. And she warns that women who’ve borne children may even react to medication differently. “If mothers’ brains are different than other women’s brains, as our research finds, it means we must embrace greater personalization of medical care – not only for men versus women, but even among women with different life experiences,” she said. But that’s a challenge that may be insurmountable given that medical research studies at the animal model level have relied predominantly on the use of male rats. “Why would we assume that what works in a male rat automatically works in a female patient before testing it on a female rat?” questioned Galea. She claims one of the big failures of translational studies is that most fail to acknowledge how subjects’ gender, or other unique characteristics, like motherhood, plays a role. © CBC 2014