Inhibition of Hair Growth by Subcutaneous Injection of a Sympathetic Neurotoxin, 6-Hydroxydopamine in Neonatal Mice

The study investigated the effects of the sympathetic neurotoxin 6-hydroxydopamine (6-OHDA) on hair growth in neonatal mice. Newborn mice were injected subcutaneously with 6-OHDA, resulting in distinct hairless areas by day 10, which diminished by day 15 and were covered with hair by day 20. Control mice injected with bovine serum albumin (BSA) showed no such effects. The 6-OHDA-treated mice exhibited thinner skin compared to controls, indicating a significant delay in hair growth. Immunohistochemical analysis revealed complete depletion of sympathetic fibers in treated areas, suggesting that sympathetic neurons play a role in skin thickness and hair growth in neonatal mice.