How Stress Hormones and Oxidative Damage Stall Hair Growth Through Substance P

What the researchers found

Chronic psychological stress in mice delayed hair growth by prolonging the telogen (resting) phase and postponing the next growth phases. Stress increased oxidative damage markers (lipid peroxidation) while reducing protective antioxidant enzymes (SOD and GSH-Px) in skin tissue. It also elevated autophagy markers LC3-II and Beclin-1 in the skin. Blocking the substance P receptor with RP67580 restored antioxidant enzyme activity, reduced oxidative damage, lowered autophagy markers, and normalized the hair cycle. The antioxidant Tempol produced similar protective effects. This is the first evidence linking substance P, oxidative stress, and autophagy together in stress-induced hair growth disruption.

Why it matters

Stress-related hair loss is extremely common, but the biological mechanisms have been poorly understood. This study identifies a clear pathway: psychological stress triggers substance P release and oxidative stress, which activate autophagy in skin cells, disrupting the hair cycle. This opens up two potential treatment targets — blocking substance P receptors or reducing oxidative stress — that could lead to new approaches for stress-related hair loss.

How the study worked

Male C57BL mice were subjected to 18 days of chronic restraint stress (a standard psychological stress model). Some groups received either Tempol (a free radical scavenger/antioxidant) or RP67580 (a substance P NK1 receptor antagonist). Researchers then measured hair growth cycle stages, oxidative stress markers (lipid peroxidation, SOD, GSH-Px), and autophagy proteins (LC3-II, Beclin-1) using ELISA and Western blot analysis.

Who was studied

Male C57BL mice subjected to chronic restraint stress for 18 days

What this study cannot tell us

This was an animal study in mice, so the results may not directly translate to human stress-related hair loss. The restraint stress model is an approximation of psychological stress. The specific molecular cascade connecting substance P, oxidative stress, and autophagy was not fully mapped. Sample size was not reported in the abstract.

How to read the evidence

This is a preclinical study in mice using a controlled stress model. It provides strong mechanistic evidence but has not been tested in humans.

When this study was published

Published in 2015. The substance P and hair loss connection has continued to be explored, and this study remains cited as foundational evidence for the autophagy link.

The bigger picture

Millions of people experience hair thinning or loss during stressful periods, but treatments have been limited because the biology wasn't well understood. This study identifies a specific molecular chain of events — from substance P release to oxidative stress to autophagy — that explains how stress disrupts hair follicles. NK1 receptor antagonists (substance P blockers) already exist as approved drugs for other conditions, making this a plausible therapeutic target.

Questions still open

• Would NK1 receptor antagonists like aprepitant (already approved for nausea) prevent stress-related hair loss in humans?
• Does this substance P-autophagy mechanism also play a role in alopecia areata, an autoimmune form of hair loss?
• Is the autophagy in hair follicles protective or destructive — could modulating it in either direction affect outcomes?

Common questions

Read the original research

Oxidative stress and substance P mediate psychological stress-induced autophagy and delay of hair growth in mice.

Archives of dermatological research, 307(2), 171-81

Citation

Wang, Lei; Guo, Ling-Ling; Wang, Lin-Hui; Zhang, Guo-Xing; Shang, Jing; Murao, Koji; Chen, Deng-Feng; Fan, Xiang-Hua; Fu, Wen-Qing. (2015). Oxidative stress and substance P mediate psychological stress-induced autophagy and delay of hair growth in mice.. Archives of dermatological research, 307(2), 171-81. https://doi.org/10.1007/s00403-014-1521-3