Welcome to this week’s Research Roundup. These Friday posts aim to inform our readers about the many stories that relate to animal research each week. Do you have an animal research story we should include in next week’s Research Roundup? You can send it to us via our Facebook page or through the contact form on the website.
- Researchers at the University of Utah have developed a zebrafish model of opioid drug self-administration. Zebrafish were trained to swim over a yellow platform that would trigger food to be released into the tank. When the food was replaced by the opioid hydrocodone, the fish swam over the platform much more often. When the researchers reduced the dosage, the fish swam over the platform even more often to compensate. The zebrafish also continued to swim over the platform after it had been raised up – forcing the fish to fight their own dislike for shallower water. It is hoped this animal model could be used to try to develop new drugs that would block opioid-addiction or drug-seeking behavior. The research was published in Behavioral Brain Research.
- New study suggests a relationship between higher levels of lithium in drinking water and dementia. The amount of lithium found in water varies by location. This study compared the health records of around 800,000 Danish people, with around 74,000 people having dementia. Tap water of 151 cities were then also tested. “Moderate lithium levels (between 5.1 and 10 micrograms per litre) increased the risk of dementia by 22% compared with low levels (below five micrograms per litre).However, those drinking water with the highest lithium levels (above 15 micrograms per litre) had a 17% reduction in risk. Lithium is used in the treatment of bipolar disorder, although the levels found in water are much lower. Prof Simon Lovestone, from the department of psychiatry at the University of Oxford, states, “In neurons in a dish and in mouse and fruit-fly models of Alzheimer’s disease, lithium has been shown to be protective.” This study, published in the journal JAMA Psychiatry, although correlative is intriguing nonetheless, and may highlight a useful of avenue for subsequent research.
- Stem cell therapy proved effective in monkey model of Parkinson’s disease. Parkinson’s disease is caused by the loss of neurons that use the neurotransmitter dopamine, particularly in the basal ganglia of the brain. In order to reverse the symptoms of Parkinson’s these neurons not only have to be replaced, but also they have to survive for long periods of time, and form appropriate connections with other parts of the brain. This week, a team from Japan and Sweden showed that grafting dopamine-producing neurons derived from human induced pluripotent stem cells (iPSCs) into the brains of macaque monkeys not only achieves both of these aims, but also reverts some of the most marked symptoms of Parkinson’s, such as the tremors. The effect lasted for at least 2 years, and there was no rejection or formation of tumours- two of the main risks anticipated for such treatments. The team responsible for this research is now preparing for the next step- a human clinical trial. “We need to confirm efficacy and safety of the cells which will be used in the clinical trial. We are now doing these experiments using rats and mice”, said lead author Dr. Jun Takahashi. This study was published in the journal Nature.
- Cancer induced anorexia inspires new anti-obesity drug studied in rats, mice, and monkeys. Anorexia and weight loss are a large part of the wasting syndrome of late-stage cancer, which further contributes to the morbidity and mortality of the cancer. This week, researchers from three major pharmaceutical companies have independently published research describing one major and responsible protein for this cancer induced anorexia or wasting syndrome; called growth differentiation factor-15 (GDF15). Specifically, they identified that GDF15 bound to a single protein receptor, whose function was previously unknown — GFRAL. They determined that GFRAL can be found in areas of the brain that are linked to appetite regulation, and then compared mice that didn’t have GFRAL receptors (knockout mice) to those that did. Following systematic injections of GDF15 in both types of mice across several weeks they found that only mice with GFRAL receptors lost weight. Another study compared weight loss in rats given GDF15 and different levels of food restriction. They found that rats without GDF15 but with food restriction lost similar amounts of weight compared to rats given GDF15 and no food restriction — thus suggesting that GDF15 suppresses appetite. Additionally, other researchers created a long-lasting version of GDF15 which allowed cynomolgus monkeys to drop 4% in body weight across 4 weeks. An exciting part of this research is that similar results are being found across multiple species. The studies on mice, rats, and monkeys were published this week in Nature Medicine.
- New study in rats indicates walnuts may promote gut health and act as a prebiotic. Researchers at Louisiana State University studied two groups of lab rats, one that received a standard diet and one that received a diet enhanced with ground walnuts equivalent to about 2oz (1/2 cup) per day in humans. Importantly, the calorie and nutrient intake was similar between the two groups. Rats that consumed walnuts saw an increase in beneficial gut bacteria species including Lactobacillus, Roseburia, and Ruminococcaceae, as well as greater species diversity. “Walnuts are the only nut that contain a significant amount of alpha-linolenic acid, the plant-based omega-3 fatty acid (2.5 grams per one ounce) and also offer protein (4 grams per one ounce) and fiber (2 grams per one ounce),” the study authors said. These bioactive components may be a mechanism by which health benefits are conferred. The study was published in the Journal of Nutritional Biochemistry.
- This week, the FDA has given “green light” for ‘ecstasy’ to be tested as a therapy for post-traumatic stress disorder (PTSD). There are only two approved drugs for the treatment of PTSD, and both are considered ineffective for treatment of this disorder in war veterans. ‘Ecstasy’ has long been considered as a good candidate to treat psychological trauma due to its euphoria-inducing and fear-reducing effects. However, it was only after this psychedelic drug was deemed non-neurotoxic in rats and monkeys that FDA allowed for small-scale clinical trials. The results obtained in the last two decades indicate that ‘ecstasy’ doesn’t cause neurotoxicity in humans, in the dosages tested. This has led to FDA giving approval for large-scale phase 3 clinical trials, which will start next year, and will enroll 200-300 volunteers in 14 locations, to evaluate whether ‘ecstasy’ could be the next treatment for PTSD and, possibly, other psychiatric conditions.
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