Previously, researchers knew that insulin plays an important role in the regeneration and growth of certain types of neurons that transmit environmental sensory information to our brain, such as vision. . However, they know relatively little about insulin’s role in the sense of smell. Now, researchers at the Monell Chemical Senses Center have shown that insulin plays an important role in the maturation of immature olfactory sensory neurons (OSNs) after injury. The team published their findings on eNeuro earlier this month.

Lead author Akihito Kuboki, MD, a postdoctoral fellow in the laboratory of Johannes Reisert, PhD, said: “Our studies show that nasal insulin delivery can be developed as a therapy for trauma caused by many problems.”

Insulin is already known to be part of optic nerve cell repair, and Kuboki suspects that the hormone may also play some role in the maturation of olfactory sensory neurons. OSNs) after injury. He also noted that there are many insulin receptors in the olfactory region of the brain. Taking these factors into account, Kuboki concluded that insulin may also be involved in the sense of smell.

“Although scientists don’t fully understand how it works, we do know that insulin plays an important role in preventing cell death,” says Kuboki. If insulin levels drop, diabetics are very susceptible to cell death, which can cause loss of smell.” He is focusing on this direction of research to clarify why people with diabetes often do not perceive odors or lose their sense of smell.

The team induced type 1 diabetes in mice to reduce the level of insulin circulating to olfactory sensory neurons (OSNs). Reduced insulin interferes with the regeneration of olfactory sensory neurons (OSNs), leading to an impaired sense of smell. They analyzed how the structure of olfactory tissue in the nasal cavity and smell was impaired by comparing the number of mature olfactory sensory neurons (OSNs) and the activity levels of the fibers. their axis to the sense of smell. The team also recorded odorant-induced responses to olfactory sensory neurons (OSNs) in the nasal cavity. A behavioral experiment using scent to determine olfactory function by having rats find cookies through their ability to smell.

In addition, the team damaged olfactory sensory neurons (OSNs), which have a unique regenerative capacity in mammals. This approach allowed the researchers to find out whether they need insulin to regenerate, which they believe is true. Furthermore, they found that these olfactory sensory neurons (OSNs) were highly susceptible to insulin deficiency-induced cell death 8 to 13 days after injury. This time period indicates that during the critical period, new olfactory sensory neurons (OSNs) are generated that are dependent on insulin. They also found that insulin must be given to regenerate olfactory sensory neurons (OSNs) at a critical time in neuronal development in order for the mice’s sense of smell to be restored. .

Equally important, the team found that insulin promotes the regeneration of recovering olfactory sensory neurons (OSNs) in both type 1 diabetes and non-diabetic mice. Disconnect the road. “Even in non-diabetic mice, we found that insulin can promote the regeneration of olfactory sensory neurons (OSNs),” says Kuboki. found this could be a treatment for olfactory dysfunction in non-diabetic patients. Specifically, the team examined only the regeneration of olfactory sensory neurons (OSNs) after injury in mice with type 1 diabetes and did not test the effect in type 2 diabetes. , but there will be plans in the future.

“Our studies show that insulin plays an important role when olfactory sensory neurons (OSNs) need to regenerate after severe injury that causes cell death in many of these cells,” said Kuboki. “From here, we hope that insulin aerosol can be applied to treat loss of smell for a variety of reasons, including head trauma and viral infections.”

Information sources:

Materials provided by Monell Chemical Senses Center. Note: Content may have been modified in presentation and length.

References:

1. Insulin-dependent maturation of newly generated olfactory sensory neurons after injury

Akihito Kuboki, Shu Kikuta, Nobuyoshi Otori, Hiromi Kojima, Ichiro Matsumoto, Johannes Reisert, Tatsuya Yamasoba. enero, 2021; ENEURO.0168-21.2021

DOI: https://www.eneuro.org/content/8/3/ENEURO.0168-21.2021

The article is translated and edited by ykhoa. org – please do not reup without permission!

Source: ScienceDaily

Link: https://www.sciencedaily.com/releases/2021/05/210517194653.htm

Author: Roxie Duong