Study Links Shank3 Gene Mutation to Social Behavior Changes in Mice

A recent study sheds light on how a mutation in the Shank3 gene, which is linked to autism, impacts social behavior by affecting vasopressin release in the brain. In mouse models, this mutation led to decreased sociability and reduced defensive aggression, primarily because less vasopressin reached an area known as the lateral septum.

The researchers discovered that vasopressin operates through two distinct receptors: AVPR1a, which influences sociability, and AVPR1b, which governs aggression. By focusing on AVPR1a, they managed to enhance social interactions in the mice without amplifying aggressive tendencies, which opens up possibilities for tailored autism treatments.

Key Insights

• Mechanism Discovered: The mutation in Shank3 results in fewer vasopressin releases in the lateral septum, affecting sociability and aggression.
• Receptor Functions: The AVPR1a receptor is linked to sociability, and the AVPR1b receptor is tied to aggression.
• Potential for Therapy: Activating AVPR1a improved social behavior without heightening aggression in mice.

Led by Félix Leroy at the Institute for Neurosciences, a collaboration between the Spanish National Research Council and Miguel Hernández University, this research marks the first comprehensive investigation into how a mutation in the Shank3 gene correlates with social behavior issues.

Using a mouse model with the autism-related mutation, the study found that vasopressin—a crucial hormone for social interaction—was not effectively released in the lateral septum. Published in Nature Communications, the findings highlight how vasopressin release in this brain region is essential for regulating social behaviors through two unique receptor pathways.

Interestingly, in the mutant mice, some of the vasopressin-releasing neurons in a specific area known as the bed nucleus of the stria terminalis (BNST) were missing. This loss meant that much less vasopressin got sent to the lateral septum, explaining why these mice showed less sociability and a notable drop in defensive aggression, which is typically a crucial behavior for males to protect their territories.

The team demonstrated that vasopressin functions in the lateral septum through two different receptors, each linked to distinct behaviors: AVPR1a influences sociability, while AVPR1b is responsible for aggression. By manipulating these two receptors separately, they succeeded in restoring these behaviors independently.

“We were able to enhance sociability without increasing aggression, which is vital for considering future treatments,” Leroy pointed out.

To achieve these results, researchers utilized a new vasopressin biosensor developed in partnership with Yulong Li’s lab at Peking University. This innovative tool allowed for real-time visualization of vasopressin release in the brain.

“Thanks to this technology, we discovered that the issues were localized in a specific circuit rather than the entire nervous system,” noted María Helena Bortolozzo-Gleich, the study’s lead author.

Validation through collaboration with the University of Zurich ensured the reliability of their data analysis.

The research findings are backed by a patent aimed at developing medications that selectively activate the AVPR1a receptor, which plays a role in sociability. There’s a clear goal here: design treatments that enhance social interactions in individuals with autism while avoiding side effects linked to aggression.

The study focused solely on male mice because the vasopressin pathway is more pronounced in males, who also exhibit the territorial aggression under examination. This could suggest why autism appears more often in males; however, it may also hint that the disorder presents differently or is underreported in females.

“Our results imply that future treatments might be tailored, considering these differences,” Leroy added.

Funding and Development

This research received financial backing from various organizations, including the European Research Council and the National Institutes of Health. It also forms part of a broader project investigating motivated behaviors associated with the lateral septum.

Leroy’s extensive expertise in this realm was further recognized after a 2023 publication in Cell focused on signaling pathways affecting interactions among familiar individuals. His significant contributions were acknowledged with a recent award from the European Brain and Behaviour Society.