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Archive - Jul 21, 2019

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Scientists ID Cellular Connetion Between Diabetes and Blood Vessel Narrowing; Further Study Could Confirm Molecular Target for Possible Reduction of Blood Vessel Complications of Diabetes

A team of University of Calfornia (UC)-Davis Health scientists and physicians has identified a cellular connection between diabetes and one of its major complications -- blood vessel narrowing that increases risks of several serious health conditions, including heart disease and stroke. The authors hope their work leads to diabetes treatments -- beyond blood sugar monitoring and insulin therapy -- that target the molecular source of the disease’s damaging effects on the vascular system. The same team previously found that high blood glucose, the hallmark symptom of diabetes, activates an enzyme known as protein kinase A (PKA), which increases calcium channel activity and constricts blood vessels. "This was a surprise, because PKA is typically associated with blood vessel widening and wasn't really on our radar," said senior author Manuel Navedo, PhD, Professor of Pharmacology at UC Davis Health. "We wanted to understand the molecular processes that created this opposite reaction." For the new study, published online on June 4, 2019, in The Journal of Clinical Investigation, the Navedo lab team conducted a series of experiments on the effects of high glucose on cerebral blood vessels and arterial cells that control blood flow. The tests were conducted on a unique genetically modified mouse and two mouse models of diabetes that were developed at UC Davis for studies of cardiovascular health. The open-access article is titled “Adenylyl Cyclase 5-Generated cAMP Controls Cerebral Vascular ReactivityDuring Diabetic Hyperglycemia.”

Pioneering Study Shows Decrease in One Type of Dopapime Receptor in Wild Songbirds Under Captivity Stress

Dopamine is a chemical in the brain that is important for learning and memory. Louisiana State University (LSU) Department of Biological Sciences Assistant Professor Christine Lattin, PhD, and colleagues conducted this study of wild songbirds showing that dopamine is important in responding to chronic stressors, which can help wildlife conservation efforts in response to environmental stressors such as habitat destruction, natural disasters, extreme weather events and increases in predation. Dr. Lattin, who is the lead author on the study published online on July 18, 2019 in Nature Scientific Reports, applied a biomedical imaging technology called Positron Emission Tomography (PET) scans, that are used commonly on humans but rarely on wild animals, to quantify dopamine receptors in house sparrows. The open-access article is titled “In Vivo Imaging of D2 Receptors and Corticosteroids Predict Behavioural Responses to Captivity Stress in a Wild Bird.”"This Study Is Exciting Because It Is The first time PET scans have been used in wildlife to quantify dopamine receptors in the brain. Developing this technique has opened the door to being able to scan animals and release them back into the wild," she said. "We need to know how these wild birds are coping with stressors and responding to changes to the environment so we can understand how to best protect them." In addition to the biomedical imaging, Dr. Lattin and colleagues tracked changes in the birds' body mass and hormone levels, and observed their behavior using a remotely operated video camera to study wild house sparrows' response to captivity over four weeks. The birds were scanned after being brought in to the lab and then again four weeks later. By using PET scans, the scientists were able to study how the stress of captivity affected the birds over time.