Effects of repeated early life anesthesia exposure on visual system development in mice.

Background: General anesthesia is administered to millions of children annually, yet its long-term effects on neurodevelopment remain a concern. We previously reported that even a single early exposure to general anesthesia for minor surgery impairs visual attention in children. This study investigates the effects of early repeated general anesthesia exposure on visual system maturation in mice and explores the role of tissue-type plasminogen activator in mediating these effects during development. Methods: Male SWISS and C57BL/6J mice (wild-type or deficient for tissue-type plasminogen activator), were exposed to general anesthesia with 1.3% isoflurane in 50% oxygen for 90 minutes per day from postnatal day 4 to 10. Control animals received 50% oxygen alone. Visual system integrity and inflammation were assessed at postnatal day 15 and at 6 weeks using behavioral tests, high-resolution imaging, and immunohistochemistry. In SWISS mice, circulating tissue-type plasminogen activator levels were measured using a biochemical approach, and neurovascular coupling was evaluated by functional ultrasound imaging. Results: Early repeated general anesthesia exposure delayed eyelid opening (median P13 [95 %CI 0.52-1.45] vs P15 [95% CI 0.62-1.92]; p< 0.0001), caused lasting visual function deficits (depth perception and oculomotor reflex), and reduced retinal (0.2627 ±0.04 mm vs 0.1667 ±0.03 mm; p< 0.0001) and primary visual cortex thickness (0.8000 ±0.08 mm vs 0.7282 ±0.05 mm; p= 0.0235). Notably, lower circulating tissue-type plasminogen activator levels were observed in general anesthesia-exposed SWISS mice (11.580 ±2.19 ng/mL vs 7.654 ±1.31 ng/mL; p= 0.0082). Tissue-type plasminogen activator-deficient mice exhibited attenuated or absent general anesthesia-induced visual alterations. Conclusions: These findings indicate that early repeated exposure to general anesthesia disrupts visual system maturation in mice and suggest that altered tissue-type plasminogen activator pathways may contribute to these effects, identifying tPA as a potential marker of anesthesia-related neurodevelopmental vulnerability. Additional experimental work will be required to further support this association and clarify its underlying mechanisms.