Bilateral recovery of striatal dopamine after unilateral adrenal grafting into the striatum of the 1‐methyl‐4‐(2′methylphenyl)‐1,2,3,6‐tetrahydropyridine (2′CH³‐MPTP)‐treated mouse

A rodent model of Parkinson's disease, the 1‐methyl‐4‐(2′methylphenyl)‐1,2,3,6‐tetrahydropyridine treated mouse, was used to determine whether striatal dopamine levels recover following grafting adrenal medulla into the striatum. Four types of grafts were performed: (1) adult mouse adrenal medulla, (2) adult adrenal medulla that had been freeze‐thawed to kill viable cells, (3) postnatal day 7 adrenal medulla, and (4) sham grafts lacking tissue. At 1 month after grafting, only postnatal day 7 grafts contained surviving cells. However, all three types of tissue grafts promoted a unilateral recovery of host dopaminergic fibers on the side of the graft. In striking contrast to the unilateral recovery of the dopaminergic fibers, striatal dopamine levels were increased bilaterally in all tissue grafted mice. These observations suggest that adrenal tissue grafted into the striatum, whether it remains viable or not, has more widespread biochemical effects on the host dopaminergic system than previously recognized. Moreover, these observations bear on mechanisms that may underlie the general recovery of motor disturbances reported in human Parkinson's disease patients who have received a striatal graft of adrenal tissue.