EFFECTS OF CULTURED ADRENAL CHROMAFFIN CELL IMPLANTS ON HINDLIMB REFLEXES OF THE 6-OHDA LESIONED RAT

The effects of implantation of cultured adrenal medullary cells on the recovery of neurotransmitter specific reflex activity were studied in the rat spinal cord using electrophysiological testing methods. Cell suspensions of cultured neonatal adrenal medullary chromaffin (AM) cel ls (which produce catecholamines), or Schwann (Sc) cells (controls) we re implanted into the lumbar region of the spinal cord 2 weeks after c atecholamine (CA) denervation by intracisternal injection of 6-hydroxy dopamine (6-OHDA). All cells were taken from 7 day neonates and cultur ed for 10 days ire the presence of nerve growth factor (NGF). Three mo nths after implantation, the extent of implant-associated recovery of reflex activity was determined by measuring electromyogram (EMG) activ ity and force associated with the long latency component of the hindli mb withdrawal reflex (which is CA modulated). After the electrophysiol ogical testing, rats were anesthetized, and the spinal cords were rapi dly removed and frozen. Spinal cords were sectioned longitudinally, an d implanted cells were visualized using glyoxylic acid techniques. Lab elled sections were examined to determine cell survival. Results indic ate that 1) chromaffin cells survive for 3 months in the segments of t he cord into which they have been implanted and 2) rats implanted with AM cells have significantly more forceful withdrawal reflexes than th ose that received Sc cells or received no implant after lesioning.