Salicylate intoxication, which causes tinnitus and anxiety in humans, induces anxiety-like behavior and a specific brain oscillation called type 2 theta (theta2) in the hippocampus of young mice with normal hearing, but not in older mice. A single dose of the hallucinogenic compound 5-MeO-DMT prevents both the anxiety-like behavior and the increase in theta2 and slow gamma oscillations in the ventral hippocampus and medial prefrontal cortex after salicylate injection. These findings suggest that the anxiety triggered by salicylate depends on normal hearing and that hallucinogenic compounds may be effective for treating tinnitus-related anxiety.
A single dose of the short-acting psychedelic 5-MeO-DMT alters expression of genes related to plasticity and neuronal activity in specific brain regions of mice, including the anterior cingulate cortex, basolateral amygdala, and ventral hippocampus. Immediate early genes Arc and Zif268 changed within hours, while TRIP8b, a modulator of neuronal activity, increased in the ventral hippocampus after five days. Behaviorally, 5-MeO-DMT produced mixed anxiety-reducing and anxiety-increasing effects in standard tests, but mice pre-treated with the compound and then exposed to acute stress showed lower corticosterone levels and strong anxiety-reducing effects. The findings suggest molecular pathways through which 5-MeO-DMT may produce anxiolytic effects.
The psychedelic 5-MeO-DMT alters brain activity in rats by increasing delta waves and decreasing theta waves in the hippocampus, changes that are not explained by movement. It also reduces slow and mid gamma power and disrupts theta phase modulation. The overall brain state resembles patterns seen during slow-wave sleep and REM sleep, suggesting that the drug's effects involve mixing waking behavior with sleep-like neural oscillations.