Nerve growth factor (NGF) is suggested to be neuroprotective after nerve injury; however, retinal ganglion cells (RGC) degenerate following optic-nerve crush (ONC), even in the presence of increased levels of endogenous NGF. To further investigate this apparently paradoxical condition, a time-course study was performed to evaluate the effects of unilateral ONC on NGF expression and signaling in the adult retina. Visually evoked potential and immunofluorescence staining were used to assess axonal damage and RGC loss. The levels of NGF, proNGF, p75^NTR, TrkA and GFAP and the activation of several intracellular pathways were analyzed at 1, 3, 7 and 14 days after crush (dac) by ELISA/Western Blot and PathScan intracellular signaling array. The progressive RGC loss and nerve impairment featured an early and sustained activation of apoptotic pathways; and GFAP and p75^NTR enhancement. In contrast, ONC-induced reduction of TrkA, and increased proNGF were observed only at 7 and 14 dac. We propose that proNGF and p75^NTR contribute to exacerbate retinal degeneration by further stimulating apoptosis during the second week after injury, and thus hamper the neuroprotective effect of the endogenous NGF. These findings might aid in identifying effective treatment windows for NGF-based strategies to counteract retinal and/or optic-nerve degeneration.

Amyotrophic lateral sclerosis (ALS) stands as the leading neurodegenerative disorder affecting the motor system. One of the hallmarks of ALS, especially its bulbar form, is dysarthria, which significantly impairs the quality of life of ALS patients. This review provides a comprehensive overview of the current knowledge on the clinical manifestations, diagnostic differentiation, underlying mechanisms, diagnostic tools, and therapeutic strategies for the treatment of dysarthria in ALS. We update on the most promising digital speech biomarkers of ALS that are critical for early and differential diagnosis. Advances in artificial intelligence and digital speech processing have transformed the analysis of speech patterns, and offer the opportunity to start therapy early to improve vocal function, as speech rate appears to decline significantly before the diagnosis of ALS is confirmed. In addition, we discuss the impact of interventions that can improve vocal function and quality of life for patients, such as compensatory speech techniques, surgical options, improving lung function and respiratory muscle strength, and percutaneous dilated tracheostomy, possibly with adjunctive therapies to treat respiratory insufficiency, and finally assistive devices for alternative communication.