Posts tagged menstrual cycle

A UW-Madison research team reports today that the brain can produce and release estrogen — a discovery that may lead to a better understanding of hormonal changes observed from before birth throughout the entire aging process.

The new research shows that the hypothalamus can directly control reproductive function in rhesus monkeys and very likely performs the same action in women.

Scientists have known for about 80 years that the hypothalamus, a region in the brain, is involved in regulating the menstrual cycle and reproduction. Within the past 40 years, they predicted the presence of neural estrogens, but they did not know whether the brain could actually make and release estrogen.

Most estrogens, such as estradiol, a primary hormone that controls the menstrual cycle, are produced in the ovaries. Estradiol circulates throughout the body, including the brain and pituitary gland, and influences reproduction, body weight, and learning and memory. As a result, many normal functions are compromised when the ovaries are removed or lose their function after menopause.

"Discovering that the hypothalamus can rapidly produce large amounts of estradiol and participate in control of gonadotropin-releasing hormone neurons surprised us," says Ei Terasawa, professor of pediatrics at the UW School of Medicine and Public Health and senior scientist at the Wisconsin National Primate Research Center. "These findings not only shift the concept of how reproductive function and behavior is regulated but have real implications for understanding and treating a number of diseases and disorders."

For diseases that may be linked to estrogen imbalances, such as Alzheimer’s disease, stroke, depression, experimental autoimmune encephalomyelitis and other autoimmune disorders, the hypothalamus may become a novel area for drug targeting, Terasawa says. “Results such as these can point us in new research directions and find new diagnostic tools and treatments for neuroendocrine diseases.”

The study, published today in the Journal of Neuroscience, “opens up entirely new avenues of research into human reproduction and development, as well as the role of estrogen action as our bodies age,” reports the first author of the paper, Brian Kenealy, who earned his Ph.D. this summer in the Endocrinology and Reproductive Physiology Program at UW-Madison. Kenealy performed three studies. In the first experiment, a brief infusion of estradiol benzoate administered into the hypothalamus of rhesus monkeys that had surgery to remove their ovaries rapidly stimulated GnRH release. The brain took over and began rapidly releasing this estrogen in large pulsing surges.

In the second experiment, mild electrical stimulation of the hypothalamus caused the release of both estrogen and GnRH (thus mimicking how estrogen could induce a neurotransmitter-like action). Third, the research team infused letrazole, an aromatase inhibitor that blocks the synthesis of estrogen, resulting in a lack of estrogen as well as GnRH release from the brain. Together, these methods demonstrated how local synthesis of estrogen in the brain is important in regulating reproductive function.

The reproductive, neurological and immune systems of rhesus macaques have proven to be excellent biomedical models for humans over several decades, says Terasawa, who focuses on the neural and endocrine mechanisms that control the initiation of puberty. “This work is further proof that these animals can teach us about so many basic functions we don’t fully understand in humans.”

Leading up to this discovery, Terasawa said, recent evidence had shown that estrogen acting as a neurotransmitter in the brain rapidly induced sexual behavior in quails and rats. Kenealy’s work is the first evidence of this local hypothalamic action in primates, and in those that don’t even have ovaries.

"The discovery that the primate brain can make estrogen is key to a better understanding of hormonal changes observed during every phase of development, from prenatal to puberty, and throughout adulthood, including aging," Kenealy says.

(Source: news.wisc.edu)

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)