Sea Animals Can Help People with Diabetes

13:00, December 24, 2018

Experiments with a small aquarium fish allow the researchers to trace the link between diabetes and brain dysfunction

A small (up to 4 centimeters in length) river fish zebrafish (Danio rerio), living in streams and rivers of Southeast Asia, proved to be an excellent model organism for studying the effects of diabetes on the functions of the central nervous system. This conclusion was made by an international team of scientists from Russia, China, USA and China. An article about this was published in the prestigious international journal “Progress in Neuropsychopharmacology & Biological Psychiatry”.

‘Fish belong to the group of vertebrates and have a complex nervous system, while invertebrates are not complex enough for proper research,’ Alan Kaluev, co-author of the article and leading researcher at the Ural Federal University’ Petrochemical Laboratory, explains. ‘The older the species, the closer it is to the base of the evolutionary pyramid, the more it can tell us about the relicts which had been evolving millions of years ago, and the causes of the diseases that are inherent in humans as well. If different species, beginning with the most ancient and including humans, have the same mechanism of contraction and course of the disease, then this is precisely the basis of the pathology laid down by nature and must be dealt with by therapeutic means.’

The scientists have identified the link between diabetes, brain inflammation and the development of stress, depression, anxiety, neurodegenerative diseases such as Alzheimer's. The next step could be to use the resulting model to solve such an important practical problem as screening (testing and selecting) new drugs, both neuroactive and antidiabetic.

‘Another great news is that experiments with zebrafish helped establish that seafood rich in polyunsaturated fatty acids, which are good for the brain, is an efficient means of treating diabetes,’ Kaluev says.

Scientists note that zebrafish reproduce quickly and productively: in a couple of weeks, two fish can produce 700-800 offsprings. In addition, the fish are distinguished by high endurance and survival, and they develop rapidly: a full-fledged specimen is formed in just 90 days. The small size of the zebrafish allows to place up to a thousand fish in special aquatic installations the size of a bookcase, which helps save space in the laboratories. Aquarium fish are also "economical" in terms of maintenance and nutrition, which is not true for rodents, let alone for primates. They are also convenient in that it is easy to evoke diabetes in this species. It is enough to place the zebrafish in a sugar solution for two weeks.

Along with the nematode worm, fruit fly, mouse and human, the zebrafish is included in the “elite club” of completely genetically identified species and is very convenient for genetic manipulations and the creation of mutant specimens. Since the egg, larva, and the adult fish are transparent, this allows the researchers to visually observe the effects of various solutions and not test them at the level of the individual cells and tissues, but the whole organism.

‘So, we observe the formation of foci of neuronal inflammation, plaques, record the death of neurons, cognitive deterioration in fish living in a sugar solution,’ Kaluev adds. ‘Thus, experiments on zebrafish are much simpler, faster and more economical than experimentsin rodents, for example. Apart from that, the information obtained is richer and more varied. Thanks to this, many more pharmaceuticals can be tested on zebrafish, meaning and scientists are more likely to find the one that will slow down the disorders in the fish’s brain and its nervous system. Besides, since we know that the genes in fish and humans are similar by about 70%, then, with a 70 percent probability, we can expect similar reactions in humans. As a comparison, humans and mice are 80% identical, and a person’s genetic similarity with some primate species is 99%.’

The researcher adds that choosing fish as an experimental material was one of his best research solutions. Note that zebrafish is used for scientific purposes not only on Earth. These fish have also been to space.