Increased levels of nerve growth factor in the urinary bladder and hypertrophy of dorsal root ganglion neurons in the diabetic rat.

The level of nerve growth factor (NGF) in the streptozotocin (STZ)-diabetic rat was measured at approximately weekly intervals after STZ induction, using an ELISA assay technique. In addition, the area profiles of L6-S1, and L1-L2 dorsal root ganglion neurons (DRG), labelled by fast blue dye injected into the bladder, were measured at the same weekly intervals. Compared to control animals, the levels of NGF rose rapidly to a maximum at one week and then slowly declined over the next three weeks. The areas of the DRGs increased to a peak after which they also started to decline. The peak increase in DRG area profiles was delayed relative to the peak level of bladder NGF. The data suggest that bladder NGF is transported retrogradely to the DRG neurons where it transforms the cell economy to cause an increase in size.