Randrup and Munkvad (96)... created schiz behaviour in rats by giving them amphetamines (increase dopa) then took schiz behaviour away by giving them neuroleptics (decrease dopa)
Iversen (79)... post mortems on people who'd had schiz found excess dopa in limbic system.
Javitt et al (00)... found that glycine (glutamate receptor agonist), reverses phencyclindine hydrochloride-induced psychosis (similar to schiz) in rats and improved people with schiz. Glutamate theory support.
Healy (00)... pharmaceutical companies keen to see dopa theory promoted as they would make profit from manufacturing anit-psychotics that inhibited dopa.
Lloyd et al (84)... even if dopa is a cause it may be indirect. Because abnormal family circumstances may lead to high levels of dopa that then trigger symptoms.
Differences in biochemistry of schiz could be an effect rather than a cause.