A recent study by researchers at Brown and other institutions found that suppressing the protein opsin 3 in mice can reduce food consumption. Their work has sparked discussions about the possibility of using a similar mechanism to treat diseases such as diabetes and obesity in humans.
Opsin 3, or OPN3, is a protein within the opsin family, which primarily allows animals to detect light. But OPN3 is a non-visual opsin, meaning its function is not related to the processing of light in vision. According to lead author Hala Haddad PhD’23, OPN3 has been found in the hypothalamus — the area of the brain responsible for controlling processes like body temperature, hunger and sleep — while visual opsins are typically located inside the eye.
Haddad worked on the project alongside Professor of Medical Science Elena Oancea and other researchers from Oancea’s lab. The team collaborated with researchers at the Cincinnati Children’s Hospital Medical Center, Stanford University and the Instituto Multidisciplinario de Biología Celular in Argentina.
The researchers used an animal model to test their findings. When the team designed mice that were missing OPN3, “we could show that they had changed food consumption behavior” and ate less, said Richard Lang, the director of the Visual Systems Group at Cincinnati Children’s Hospital Medical Center and co-director of the Science of Light Center.
It also made neurons in the hypothalamus more excitable, “so they responded to signals from outside much faster,” Oancea said.
While the study focused specifically on the hypothalamus, Haddad said she is interested in exploring OPN3 function in other parts of the brain, including the cerebellum and hippocampus, which are primarily responsible for memory and spatial navigation.
Lang is also interested in whether OPN3 interacts with other non-visual opsins in the brain, including OPN5, which has been found to help regulate the body’s temperature cycle.
“What I’m most excited about next is to try and understand how OPN5 and OPN3 integrate their activity to regulate” energy stability, food consumption and body temperature, Lang said.
Lang said the results of the study may have implications for human diseases, including obesity and diabetes. But both Lang and Oancea noted that additional work must be done to determine whether these mechanisms occur in humans and the potential clinical implications of these findings.
Jonathan Kim is a senior staff writer covering Science and Research. He is a first-year student from Culver City, California planning to study Public Health or Health and Human Biology. In his free time, you can find him going for a run, working on the NYT crossword or following the Dodgers.
