Posts tagged hormones
Articles and news from the latest research reports.
Double-barreled attack on obesity in no way a no-brainer
In the constant cross talk between our brain and our gut, two gut hormones are already known to tell the brain when we have had enough to eat. New research suggests that boosting levels of these hormones simultaneously may be an effective new weapon in the fight against obesity.
Dr Shu Lin, Dr Yan-Chuan Shi and Professor Herbert Herzog, from Sydney’s Garvan Institute of Medical Research, have shown that when mice are injected with PYY3-36 and PP, they eat less, gain less fat, and tend not to develop insulin-resistance, a precursor to diabetes. At the same time, the researchers have shown that the hormones stimulate different nerve pathways, ultimately, however, affecting complementary brain regions. Their findings are now published online in the journal Obesity.
While the double-barreled approach may seem like a no-brainer, the strongly enhanced effect seen was by no means inevitable. In the complex world of neuroscience, two plus two does not always make four.
Drug companies are in the process of conducting pre-clinical trials to examine the separate effects of boosting the hormones PYY3-36 and PP. Until now, there is no research to indicate the detailed molecular interactions that might occur when they are boosted in tandem.
When used together, the hormones independently, yet with combined force, reduce the amount of neuropeptide Y (NPY) produced by the brain, a powerful neurotransmitter that affects a variety of things including appetite, mood, heart rate, temperature and energy levels.
Each hormone also communicates with a different part of the arcuate nucleus in the hypothalamus, a region of the brain where signals can cross the normally impermeable blood / brain barrier. The stimulated regions then produce other neuronal signals deep within the hypothalamus, bringing about a powerful combined effect.
“There are many factors that influence appetite control – and we now realise that there won’t be a single molecular target, or a single drug, that will be effective,” said Dr Yan-Chuan Shi.
“It will be important for drug companies to try different combinations of targets, to see which combinations are most potent, and at the same time have no side effects, or at least minimal side effects.”
“At the moment, the only effective tool against obesity is surgery. Drug companies have so far failed to produce an effective drug without unacceptable side effects, such as mood disorders, nausea or cardiovascular problems.”
(Source: garvan.org.au)
Hormone levels may provide key to understanding psychological disorders in women
Women at a particular stage in their monthly menstrual cycle may be more vulnerable to some of the psychological side-effects associated with stressful experiences, according to a study from UCL.
The results suggest a monthly window of opportunity that could potentially be targeted in efforts to prevent common mental health problems developing in women. The research is the first to show a potential link between psychological vulnerability and the timing of a biological cycle, in this case ovulation.
A common symptom of mood and anxiety problems is the tendency to experience repetitive and unwanted thoughts. These ‘intrusive thoughts’ often occur in the days and weeks after a stressful experience.
In this study, the researchers examined whether the effects of a stressful event are linked to different stages of the menstrual cycle. The participants were 41 women aged between 18 and 35 who had regular menstrual cycles and were not using the pill as a form of contraception. Each woman watched a 14-minute stressful film containing death or injury and provided a saliva sample so that hormone levels could be assessed. They were then asked to record instances of unwanted thoughts about the video over the following days.
“We found that women in the ‘early luteal’ phase, which falls roughly 16 to 20 days after the start of their period, had more than three times as many intrusive thoughts as those who watched the video in other phases of their menstrual cycle,” explains author Dr Sunjeev Kamboj, Lecturer in UCL’s Department of Clinical, Educational and Health Psychology.
“This indicates that there is actually a fairly narrow window within the menstrual cycle when women may be particularly vulnerable to experiencing distressing symptoms after a stressful event.”
The findings could have important implications for mental health problems and their treatment in women who have suffered trauma.
“Asking women who have experienced a traumatic event about the time since their last period might help identify those at greatest risk of developing recurring symptoms similar to those seen in psychological disorders such as depression and post-traumatic stress disorder (PTSD),” said Dr Kamboj.
“This work might have identified a useful line of enquiry for doctors, helping them to identify potentially vulnerable women who could be offered preventative therapies,” continued Dr Kamboj.
“However, this is only a first step. Although we found large effects in healthy women after they experienced a relatively mild stressful event, we now need to see if the same pattern is found in women who have experienced a real traumatic event. We also need further research to investigate how using the contraceptive pill affects this whole process.”
(Source: ucl.ac.uk)
Hormone Combination Effective and Safe for Treating Obesity in Mice
Scientists at Indiana University and international collaborators have found a way to link two hormones into a single molecule, producing a more effective therapy with fewer side effects for potential use as treatment for obesity and related medical conditions.
The studies were carried out in the laboratories of Richard DiMarchi, the Standiford H. Cox Distinguished Professor of Chemistry and the Linda & Jack Gill Chair in Biomolecular Sciences in the IU Bloomington College of Arts and Sciences, and of Matthias Tschöp, professor of medicine and director of the Institute of Diabetes and Obesity, Helmholtz Center Munich, Germany. Results were published online this week by the journal Nature Medicine.
Researchers combined a peptide hormone from the digestive system, GLP-1, with the hormone estrogen and administered it to obese laboratory mice. While both GLP-1 and estrogen have demonstrated efficacy as therapy for obesity and adult-onset diabetes, the combination was more effective in producing weight loss and other beneficial results than using either compound on its own. And it produced fewer adverse effects, such as excessive tissue growth linked to tumor formation.
"We find that combining the hormones as a single molecule dramatically enhanced their efficacy and their safety," DiMarchi said. "The combination improves the ability to lower body weight and the ability to manage glucose, and it does so without showing the hallmark toxicities associated with estrogen."
Hormone affects distance men keep from unknown women they find attractive
Men in committed relationships choose to keep a greater distance between themselves and an unknown woman they find attractive when given the hormone oxytocin, according to new research in the November 14 issue of The Journal of Neuroscience. The findings suggest oxytocin may help promote fidelity within monogamous relationships.
Oxytocin plays a vital role in triggering childbirth and facilitating nursing. The hormone, which is produced in a region of the brain called the hypothalamus, is also involved in the formation of social bonds. In humans and other animals, this brain chemical is known to promote bonds between parents and children, and between couples. Additionally, previous studies have shown oxytocin increases trust among people. However, scientists had yet to determine what, if any, role oxytocin played in maintaining monogamous human relationships.
In the current study, led by René Hurlemann, MD, PhD, of the University of Bonn, researchers found that men in committed relationships who were given oxytocin kept a greater distance when approaching or being approached by an unknown woman they found attractive compared with those given a placebo. In contrast, oxytocin had no effect on single men.
“Previous animal research in prairie voles identified oxytocin as major key for monogamous fidelity in animals,” Hurlemann said. “Here, we provide the first evidence that oxytocin may have a similar role for humans.”
New University of Otago research into two sex hormones released by the testes of male fetuses and boys may help solve the enduring mystery of why autism is much more common in boys than girls.
The researchers studied blood samples from 82 boys with ASD and 16 control boys, all aged between 4.4 to 8.9 years. Measuring the levels of the two hormones, the researchers found that these were highly variable from boy to boy, but no different on average between the two groups of boys.
Professor McLennan says the findings indicate that male hormones are important for autism, but not because autistic boys have abnormal levels.
While it has been previously suggested that exposure in the womb to excessive levels of testosterone might be creating an ‘extreme male brain’, this does not explain why some females have autism, or why males with autism do not exhibit an extreme male physical form.
"Our data suggest that the still-elusive primary initiating cause of ASD is common to both males and females, with the condition being more frequent in males because normal levels of male hormones exacerbates the pathology,” he says.
The researchers say that their hypothesis now needs further testing through longitudinal studies of at-risk male babies to determine whether their levels of AMH and InhB early in development can predict the breadth of autistic traits later in life.
(Image credit: ©iStockphoto.com/ktaylorg)
Study examines effects of growth hormone-releasing hormone on cognitive function
6-Aug-2012
Treatment with growth hormone-releasing hormone appears to be associated with favorable cognitive effects among both adults with mild cognitive impairment and healthy older adults, according to a randomized clinical trial published Online First by Archives of Neurology, a JAMA Network publication.
"Growth hormone-releasing hormone (GHRH), growth hormone and insulinlike growth factor 1 have potent effects on brain function, their levels decrease with advancing age, and they likely play a role in the pathogenesis of Alzheimer disease," the authors write as background information in the study.
To examine the effects of GHRH on cognitive function in healthy older adults and in adults with mild cognitive impairment (MCI), Laura D. Baker, Ph.D., of the University of Washington School of Medicine and Veterans Affairs Puget Sound Health Care System, Seattle, and colleagues, conducted a randomized, double-blind, placebo-controlled trial in which participants self-administered daily injections of a form of human GHRH (tesamorelin), or placebo.
The authors enrolled 152 adults ranging in age from 55 to 87 years (average age, 68 years) and 137 participants (76 healthy patients and 61 patients with MCI) successfully completed the study. At baseline, at 10 and 20 weeks of treatment, and after a 10-week washout (30 weeks total), the authors collected blood samples and administered parallel versions of cognitive tests.
Among the original 152 patients enrolled in the study, analysis indicated a favorable effect of GHRH on cognition, which was comparable in adults with MCI and healthy older adults. Analysis among the 137 patients who successfully completed the trial also showed that treatment with GHRH had a favorable effect on cognition among both groups of patients. Although the healthy adults outperformed those with MCI overall, the cognitive benefits relative to placebo was comparable among both groups.
Treatment with GHRH also increased insulin like growth factor 1 levels by 117 percent, which remained within the physiological range, and increased fasting insulin levels within the normal range by 35 percent in adults with MCI but not in healthy adults.
"Our results replicate and expand our earlier positive findings, demonstrating that GHRH administration has favorable effects on cognitive function not only in healthy older adults but also in adults at increased risk of cognitive decline and dementia," the authors conclude. "Larger and longer-duration treatment trials are needed to firmly establish the therapeutic potential of GHRH administration to promote brain health in normal aging and ‘pathological aging.’"
Source: EurekAlert!