The life of the little worm called Caenorhabditis elegans consists mainly of foraging, feeding and laying eggs. So when any of these behaviors are disrupted, there’s cause for concern. In a new study, Salk Institute scientists have found that the «feel-good» brain chemical dopamine regulates anxiety behavior in worms in the presence of biting predators.
The findings, published in electronic on July 11, 2023, elucidates how this dopamine-regulated brain pathway may be involved in anxiety and may provide insights into the human condition, such as Post-traumatic stress disorder (PTSD).
Professor Sreekanth Chalasani, lead author of the new work, said: «The worms are an excellent model for studying anxiety because the cause of their anxiety is often known, like predation.» . «So we can use worms to better understand how the underlying neural pathways involved in anxiety and stress responses may be conserved across species.»
In this study, the researchers observed what happens when a predatory worm (Priest of Peace) biting into the worm, discouraging the worm from eating the food source. In response, the worms move away from the food source and predators can eat more. In addition, worms also lay eggs away from old food sources and the risk of being eaten.
The researchers found that the worms would stay away even after the predators had left – showing that the worms are learn that it would be safer to stay away. Furthermore, the behavior of laying eggs away from predators is regulated by dopamine. But when the researchers blocked dopamine transmission in the worms, they didn’t often avoid predators to lay their eggs.
«To understand how the brain works, it’s important to study it in its natural context,» said first author Amy Pribadi, a former PhD student in Chalasani’s lab. . «To do that, we can take a simple worm with an easy-to-build natural environment, and then look at how the worm’s brain molecules and networks regulate behavior in that environment. that ‘natural’ field.»
In addition, the researchers explored how the presence of smaller food patches away from the main food source affects interactions between worms and predators. While predators are busy monopolizing the main food source, the presence of alternative (albeit smaller) food sources elsewhere makes the worms more likely to avoid predators. than.
«Worms make decisions based on the same environmental changes as animals and more complex humans,» said Michael Rieger, co-first author, a postdoctoral researcher in Chalasani’s lab. . «Difficulty adapting to change – especially due to threat or stress – is common in humans, especially those with neurological disorders. Our study of the organism This simplicity reveals new avenues for exploring the neuroscience of decision-making, which we hope can generalize all the way to the human food chain.»
In the future, the team will look at the role of another brain chemical called serotonin in this avoidant behavior, as serotonin is known to regulate other dopamine-dependent behaviors, such as seeking get food. They also hope their study serves as a springboard for future investigation into the effects of other brain signaling pathways on eating, reproduction, and other behaviors.
“By looking at worms, you capture a lot of complex biology in an animal that has evolved over billions of years,” says Chalasani. «Any insight – even in worms – into the mechanisms of predator-prey behavior enriches our understanding of the many other phenomena that exhibit a pull-pull relationship. science, like the co-evolution of animals and their environment or the delicate balance of chemical conversation between cells.»
Other authors include Kaila Rosales and Kirthi C. Reddy of Salk.
The work was supported by a National Science Foundation Graduate Research Fellowship, Innovation Grants from the Kavli Brain and Mind Institute, and the National Institutes of Health (R01 MH113905).
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