Is the adrenal tissue actually producing dopamine, or some other substance that stimulates the brain's own dopamine system?

Scientists believe that once in the brain, certain fetal or adrenal tissues produce dopamine.

Buoyed by early, successful animal experiments, a team of researchers in Sweden implanted adrenal tissue into four patients in 1982 and 1984 with disappointing results.

Many scientists believe transplants of human fetal brain cells, rather than adrenal tissue, will ultimately prove more effective in treatment of Parkinson's disease.

The advantage is that fetal tissue is a better match for the missing brain cells than adrenal tissue.

Frank Williams, national director of the American Parkinson Association, says his group has received thousands of requests for the treatment using adrenal tissue.

The treatment, involving implants of adrenal tissue into patients' brains, seemed highly promising last year after Mexican surgeons reported dramatic successes.

The hypothesis was that adrenal tissue could cause production in the brain of dopamine, a nervous system hormone that Parkinson patients lack.

He implanted the adrenal tissue and then invited observers to examine his handiwork.

The medication is used in the controlled destruction of adrenal tissue, leading to a decrease in cortisol production.