Intranasal BDNF administration promotes visual function recovery in adult amblyopic rats

Amblyopia is the most common cause of visual impairment in one eye, with a prevalence of 1–5% in the world population. While amblyopia can be efficiently treated in children, it becomes irreversible in adults, due to the decline in neural plasticity past the end of the visual cortex critical period. Accordingly, no pharmacological approaches are available to rescue visual functions in adult amblyopic subjects. We report that non-invasive intranasal infusion of BDNF increased levels of this neurotrophic factor in V1 and induced a recovery of visual acuity, ocular dominance and visual depth perception in adult amblyopic rats, both in reverse-occluded animals and in those with unrestricted binocular sight. Visual recovery was long-lasting, and was prevented by pharmacological blockade of TrkB signaling in the visual cortex. These results underscore the possibility to replace invasive BDNF central administration with a safe procedure of potential interest in a number of currently still cureless central nervous system pathologies.