Dopamine is a novel, direct inducer of catagen in human scalp hair folliclesin vitro

The study from 2012 investigated the effects of dopamine on human scalp hair follicles in vitro, specifically looking at hair growth, pigmentation, and dopamine receptor expression. Treating microdissected human scalp hair follicles from women with dopamine led to a significant induction of catagen phase (hair follicle regression), a decrease in keratinocyte proliferation (P < 0.01), and reduced melanin production within the follicles. Dopamine receptor transcripts were found in both hair follicles and skin. The study, which included groups of 9-39 hair follicles from women aged 47-68, concluded that dopamine acts as an inhibitor of hair growth and could potentially be used to treat unwanted hair growth, while suggesting that dopamine receptor antagonists might promote hair growth. Further research is needed to confirm these findings in a larger sample size and in vivo.