Bilateral effects of unilateral intrastriatal GDNF on locomotor-excited and nonlocomotor-related striatal neurons in aged F344 rats

In order to determine its effects on locomotor-related striatal electrophysiology in aged rats, glial cell line-derived neurotrophic factor (GDNF) was infused (vehicle or 30 μg) into the right striatum of 24–25-month-old Fischer 344 (F344) rats. Multi-wire electrode arrays were then chronically implanted in striatum bilaterally. Thirty days later, striatal electrophysiological activity was recorded during freely moving conditions. Individual neurons were classified as locomotor-excited if they exhibited significant increases in firing rates during locomotor bouts versus periods of nonmovement. GDNF produced a significant increase in overall firing rates in locomotor-excited striatal neurons. This effect was observed in both the infused and the contralateral striatum. GDNF also attenuated the bursting activity of nonlocomotor-related striatal neurons, an effect that was also present bilaterally. These results suggest that GDNF's antiparkinsonism effects are associated with increased excitability of motor-related striatal neurons and diminished activity of neurons that do not exhibit explicit motor-related changes in activity. Such studies may aid in understanding the mechanism of potential therapies for movement disorders seen in aging and Parkinson's disease.