Acute intranasal treatment with nerve growth factor limits the onset of traumatic brain injury in young rats

Background and purpose: Traumatic brain injury (TBI) comprises a primary injury directly induced by impact, which progresses into a secondary injury leading to neuroinflammation, reactive astrogliosis, and cognitive and motor damage. To date, treatment of TBI consists solely of palliative therapies that do not prevent and/or limit the outcomes of secondary damage and only stabilize the deficits. The neurotrophin, nerve growth factor (NGF), delivered to the brain parenchyma following intranasal application, could be a useful means of limiting or improving the outcomes of the secondary injury, as suggested by pre-clinical and clinical data.

Experimental approach: We evaluated the effect of acute intranasal treatment of young (20-postnatal day) rats, with NGF in a TBI model (weight drop/close head), aggravated by hypoxic complications. Immediately after the trauma, rats were intranasally treated with human recombinant NGF (50 μg·kg^-1 ), and motor behavioural test, morphometric and biochemical assays were carried out 24 h later.

Key results: Acute intranasal NGF prevented the onset of TBI-induced motor disabilities, and decreased reactive astrogliosis, microglial activation and IL-1β content, which after TBI develops to the same extent in the impact zone and the hypothalamus.

Conclusion and implications: Intranasal application of NGF was effective in decreasing the motor dysfunction and neuroinflammation in the brain of young rats in our model of TBI. This work forms an initial pre-clinical evaluation of the potential of early intranasal NGF treatment in preventing and limiting the disabling outcomes of TBI, a clinical condition that remains one of the unsolved problems of paediatric neurology.