Impairment of learning and memory and the accessory symptom in aged rat as senile dementia model (3): Oral administration of propentofylline produces recovery of reduced NGF content in the brain of aged rats.

The relationship between nerve growth factor (NGF) and senile dementia of the Alzheimer type is of interest. The administration of NGF in clinical trials has been expected; however, NGF cannot cross the blood brain barrier, since it is a polypeptide. We demonstrate here that oral administration of propentofylline, a stimulator of NGF synthesis in vitro, produced recovery of reduced NGF content. In aged rats (24-months-old), NGF content in the frontal cortex, parietal cortex, and hippocampus was lower than in young rats (8-weeks-old). Twenty-one-day successive administration of propentofylline (10 and 25 mg/kg, p.o.) produced recovery of reduced NGF content in the frontal cortex and parietal cortex of aged rats to a significant extent. There were no differences among aged, young, and propentofylline-treated groups in choline acetyltransferase activity in any brain regions. These results suggest that NGF content in the brain is reduced in aged rats and that oral administration of propentofylline leads to a recovery of this reduction.