Can l tyrosine cause prolactin levels to increase?

Should not: If it has any effect at all, tyrosine should decrease prolactin. It is the immediate precursor for dopamine, which is released from the hypothalamus onto the pituitary and, among other things, affects prolacting release; however, the effect of increased Dopamine would be to decrease prolactin. Drugs that block Dopamine receptors (antipsychotics) can cause marked increases in prolactin levels.