by Researchers from Osaka University have conducted a study published in Molecular Psychiatry, where they used a mouse model of depression to explore the impact of low doses of ketamine, a common anesthetic, in improving social impairments by restoring functioning in the anterior insular cortex, a specific brain region.
Ketamine, often used in low doses to treat depression, is a mixture of two forms: (S)-ketamine and (R)-ketamine. These mirror isomers have the same molecular formula but differ in their three-dimensional forms. Both forms are beneficial for treating depression, albeit with varying effects.
The study involved testing the effects of (S)-ketamine and (R)-ketamine on depression-like symptoms in mice using a chronic social isolation model, induced by isolating mice for at least six weeks. The researchers directly compared neuronal activation in mice treated with (S)-ketamine, (R)-ketamine, or saline post-behavioral tests to evaluate their impact on the entire brain.
Lead author Rei Yokoyama states that the study observed differences in neuronal activation between (S)-ketamine and (R)-ketamine across the entire brain without a predefined hypothesis. The findings revealed that chronic social isolation reduced neuronal activation in the anterior insular cortex, a crucial region for emotional regulation, during social contact, and (R)-ketamine reversed this effect, unlike (S)-ketamine.
The study also demonstrated that mice treated with (R)-ketamine showed improved social cognition in recognizing unfamiliar versus familiar mice in a social memory test. Notably, when neuronal activity was inhibited in the anterior insular cortex, the positive effects of (R)-ketamine disappeared.
According to senior author Hitoshi Hashimoto, the results underscore the significance of the anterior insular cortex in the beneficial effects of (R)-ketamine on social impairments in mice. The study suggests that (R)-ketamine may be more effective than (S)-ketamine in enhancing social cognition by reinstating neuronal activation in the anterior insular cortex.
The findings are crucial as global rates of social isolation and depression are surging. (R)-ketamine shows promise as a treatment for isolation-induced social impairments, offering a potential improvement in the quality of life for individuals with associated disorders.
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1. Source: Coherent Market Insights, Public sources, Desk research
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