Molecules move not only from the brain to the endocrine system but also from the endocrine system, indeed, from all parts of the body to the brain. - Richard Bergland

Already in animals, some gland-like cells have been transplanted from the adrenal gland into the brain, where they not only survive but continue their secretions.

Scientists have mastered the techniques of hormone analysis, measurement and manufacture. What is lacking is the correlation between a specific brain disease and a specific brain hormone. …these correlations can only come from a medical team of co-operating physicians.

Genetic engineers are powerless in all of this without some cooperative effort from people working in allied fields.