It was in AAAS Fellow Carol Elias’s hometown of Piracicaba, Brazil, a place that gets its name from a meandering river, where Elias's dreams of practicing biomedical sciences transformed and her journey in reproductive health began.
"I loved the biology classes, I liked to learn about the human body and how things work," she says, recalling her high school days in Brazil. "I thought was going to be a doctor until I realized I was not good with treating diseases, so I decided to do biological sciences and biomedical research."
Elias would go-ahead to pursue her undergraduate studies at the University of Campinas, eventually moving to the University of Sao Paulo for her Ph.D. in Neurosciences and Behavior.
In 1994, two years before Elias came to the United States for her postdoctoral training, scientists had made a momentous discovery that would shape the contours of her field for years to come. "I started working in neurosciences because it was the area that I liked the most," she says. "I had the opportunity to do my postdoctoral training in neuroendocrinology in a wonderful laboratory at Harvard Medical School at the time (the hormone) leptin was discovered."
"It was a very interesting time to be there because the fields of neuroendocrinology and metabolism were full of excitement due to the discovery of leptin," Elias says. "When I moved back to Brazil, I started my own research program in the University of São Paulo focused on reproduction and development, and on defining the brain areas that integrate signals from nutritional states (e.g., leptin) and the reproductive system."
Leptin is secreted by fat cells, and it instructs the brain on how to regulate food intake and energy expenditure. By studying mice, Elias identified how changes in this biological process could be linked to human reproductive health conditions like early puberty in obese girls and decreased fertility in obese adults.
After working at the University of Sao Paulo for about 10 years, Elias returned to the United States on a one-year sabbatical at the Center for Hypothalamic Research. She was then invited to join the faculty at UTSW and eventually moved to the University of Michigan. She is currently serving as a Professor in the Department of Molecular and Integrative Physiology and the Department of Obstetrics and Gynecology, and as co-director of the Reproductive Sciences Program.
Elias recently published a comprehensive database describing the changes in the expression of genes in the brain during pubertal development in mouse models, 'Hypothalamic and Cell-Specific Transcriptomes Unravel a Dynamic Neuropil Remodeling in Leptin-Induced and Typical Pubertal Transition in Female Mice, iScience'
In the database, Elias reveals how epidemiological and genome-wide association studies from other laboratories work in humans showed a high correlation between childhood obesity and advance in puberty. She further notes that “advance in puberty is not only a harmful psychosocial issue. It is also associated with a series of morbidities including breast cancer, cardiovascular diseases, type 2 diabetes, and obesity."
According to Elias, it is still unclear if these effects are due to over secretion of leptin due to an increase in fat mass. The pros and cons of this argument are discussed at length in a review from Elias and her colleague, Jennifer W. Hill (from University of Toledo, OH) — 'Neuroanatomical Framework of the Metabolic Control of Reproduction’, published in Physiological Reviews.
In the review, Elias writes that "the genetically modified female mice that overexpress leptin are skinny and show advance in puberty indicating an important role of leptin.” These mice, however, also showed early reproductive aging suggesting that hyperleptinemia may induce reproductive failure in adult life. Whether hyperleptinemia explains the decreased fertility in obese adults is also the focus of our studies, she explains.
Elias is quick to point out other factors besides obesity as possible reasons for the early onset of puberty in girls. For example, she says BPA (from plastic) or toxicants in the environment.
"Some of these toxic agents can mimic the effects of estrogen and this can have a contribution to early puberty and related morbidities,” Elias says. And, access to nutritional food and genetic factors are also responsible for putting women of different socioeconomic classes and demographics at risk. For example, while rates of obesity are rising across all ethnicities and most socioeconomic groups, underprivileged, Black women and Latinas are more affected than others, according to Elias.
Elias’ decades of research in women’s reproductive health have also led to recognition amongst her peers in the scientific community. A few months ago, after about 10 years as a member of AAAS, Elias was elected as an AAAS Fellow.
“It is a huge honor to be part of such a select group of scientists,” she says. “It is still too early to have a complete figure, but I am sure it will open many doors for my career and our studies.”