D-serine, a co-agonist at NMDA receptors, produces antidepressant-like effects in rodents. A single acute dose of D-serine reduced immobility in the forced swim test without affecting motor function, reversed sexual reward-seeking deficits caused by serotonin depletion, and reversed learned helplessness behavior. Mice lacking NMDA receptor NR1 subunits in forebrain excitatory neurons showed a depression-like phenotype and did not respond to D-serine. These findings suggest D-serine has antidepressant-like effects and support the idea of complex glutamatergic dysfunction in depression, though it remains unclear whether D-serine shares a convergent mechanism with NMDA antagonists like ketamine.
Intensive meditation during a one-month residential Insight retreat was associated with an apparent increase in telomere length compared to a control group of experienced meditators not on retreat. Personality traits moderated this effect: retreat participants highest in neuroticism and lowest in agreeableness showed the greatest telomere length increases. Changes in telomere-related gene expression suggested improved telomere maintenance, including increases in Gar1 and HnRNPA1. No group-level changes in telomerase activity were observed, but retreat participants' telomerase activity at post-assessment was inversely related to retreat engagement and prior meditation experience. Neuroticism also predicted variation in telomerase activity across the retreat.