Eye-brain communication and NGF eye drops

NGF applied on ocular surface in form of eye drops (eNGF) has showed to reach the retina and optic nerve, and stimulate retinal cell and nerve recovery after injury. Neurotransmission in primary brain visual areas is also restored by eNGF treatment following optic nerve crush further demonstrating the NGF role in the maintenance of central visual pathways and functions. The optic nerve represents the anatomical link between the eyes and the brain, and its structural and functional integrity guarantees the transfer of both image and non-image forming visual information to the subcortical and cortical brain areas. The central processing and integration of visual information is today recognised as essential to balance body functions, and to regulate different aspects of cognition, including alertness, attention, and memory. Beside the thalamocortical area, eNGF also activates neurons in different limbic regions, including the hippocampus, the cortex and the hypothalamus, and modulates the expression levels of other neurotrophic factors, as for example BDNF and NPY. Further, similar to the intracerebral infusion, eNGF is able to exert a survival effect on mature and precursor brain cells, and stimulates differentiation and neurogenesis. Neuroprotective/reparative and anti-inflammatory actions, and reduced manifestation of disease symptoms, including the loss of body weight and behavioural impairment are also reported in animal models, suggesting the eNGF as a useful experimental paradigm to investigate the neurotrophin role in brain, and to explore new potential NGF-based therapeutic strategies for neurodegenerative diseases.