How Hormones and Cellular Signals Influence Skin Pigmentation

Skin pigmentation is controlled by a complex interaction between genetics, melanocytes, hormones, local signalling molecules and environmental exposure. At the centre of this process is melanin—the pigment that contributes to the colour of the skin, hair and eyes and helps absorb some ultraviolet radiation.

Hormones can influence pigmentation, but they are only one part of the process. Pregnancy, certain medicines and endocrine conditions may be associated with changes in skin colour, while ultraviolet exposure can stimulate local signalling between skin cells.

Laboratory researchers also study synthetic compounds that interact with melanocortin receptors. Products described commercially as mt2 peptide have become valuable tools for scientists studying these mechanisms, offering insights into how our bodies control pigmentation at the molecular level.

They should not be confused with licensed dermatological treatments or naturally occurring hormones.

Skin pigmentation results from communication between melanocytes, keratinocytes, hormones, genes and environmental signals.

Quick Answer

Hormones influence skin pigmentation by affecting melanocytes—the cells responsible for producing melanin. Alpha-melanocyte-stimulating hormone can activate the MC1R receptor, increasing signals involved in melanin production.

Pregnancy-related hormonal changes, elevated ACTH in Addison’s disease, inflammation and ultraviolet exposure can also affect pigmentation. However, new, unexplained or changing pigmentation should be professionally assessed because appearance alone cannot identify the underlying cause.

Key Takeaways

• Melanocytes produce melanin inside structures called melanosomes.

• Eumelanin and pheomelanin contribute differently to skin and hair colour.

• MC1R is the melanocortin receptor most directly associated with pigmentation.

• α-MSH can be produced locally within the skin.

• Pregnancy and hormonal medicines may contribute to melasma in susceptible people.

• Increased ACTH can contribute to hyperpigmentation in Addison’s disease.

• Ultraviolet exposure is a major environmental stimulus for melanin production.

• Melanotan II is a synthetic research compound, not an authorised tanning treatment.

• Pigmentation changes cannot always be explained by hormones.

• A new or changing mole requires appropriate medical assessment.

Table of Contents

1. How Melanin Is Produced

2. How Hormones Affect Skin Pigmentation

3. The MC1R Signalling Pathway

4. UV Exposure and Local Skin Signalling

5. Research Compounds and Melanotan II

6. Pigmentation Conditions and Clinical Relevance

7. When to Seek Medical Assessment

8. How A to Zen Therapies Can Help

9. Frequently Asked Questions

How Melanin Is Produced

Melanin is produced by specialised cells called melanocytes, which are primarily located in the basal layer of the epidermis. Melanocytes manufacture pigment inside organelles called melanosomes and transfer these melanosomes to neighbouring keratinocytes.

This distribution helps create visible pigmentation and provides some protection against ultraviolet-induced cellular damage.

Melanin production begins with the amino acid tyrosine. An enzyme called tyrosinase helps initiate the chemical reactions that eventually produce pigment.

Human skin contains two principal forms of melanin:

• Eumelanin: Usually brown or black and generally more effective at absorbing ultraviolet radiation.

• Pheomelanin: Usually yellow or reddish and more prominent in people with red hair and some fair-skin phenotypes.

Individual pigmentation does not simply depend on the number of melanocytes. Differences in melanocyte activity and in the production, size, distribution and persistence of melanosomes are also important.

How Hormones Affect Skin Pigmentation

Hormonal effects on pigmentation vary according to the hormone, receptor, body area, genetics and environmental exposure.

Alpha-melanocyte-stimulating hormone

Alpha-melanocyte-stimulating hormone, usually abbreviated to α-MSH, is derived from a larger precursor molecule called proopiomelanocortin.

Although melanocortin hormones are associated with the pituitary system, α-MSH and related signalling molecules can also be produced locally by cells within the skin. These include keratinocytes and melanocytes.

When α-MSH binds to MC1R on a melanocyte, it activates intracellular signalling associated with increased production of eumelanin.

ACTH and Addison’s disease

Adrenocorticotropic hormone, or ACTH, is another proopiomelanocortin-derived hormone. It

can interact with melanocortin receptors because it shares part of its molecular sequence with α-MSH.

In primary adrenal insufficiency, also known as Addison’s disease, ACTH levels can become elevated as the body attempts to stimulate underactive adrenal glands. This can contribute to darker pigmentation, sometimes affecting skin creases, scars, lips or gums.

The NHS overview of Addison’s disease lists areas of skin becoming darker than the surrounding skin among its possible symptoms. Hyperpigmentation accompanied by severe fatigue, weight loss, dizziness, nausea or salt cravings requires medical assessment.

Pregnancy and melasma

Melasma causes symmetrical brown or grey-brown patches, most commonly on the face. Pregnancy, hormonal contraception, genetic susceptibility and sunlight can all contribute.

Estrogen and progesterone are thought to play a role, but melasma should not be described as the result of one hormone being “too high.” Its biology involves hormonal sensitivity, ultraviolet exposure, melanocyte activity and genetic factors.

The American Academy of Dermatology explains that melasma often begins during pregnancy and that increased hormone levels may act as triggers in susceptible people.

Readers interested in wider endocrine influences can also explore How to Treat Hormonal Imbalance, while remembering that pigmentation changes require their own appropriate assessment.

The MC1R Signalling Pathway

Five melanocortin receptors have been identified: MC1R, MC2R, MC3R, MC4R and MC5R.

They have different tissue distributions and functions.

MC1R is the receptor most directly associated with pigmentation in melanocytes.

When α-MSH activates MC1R:

1. The receptor activates a G protein.

2. Adenylyl cyclase activity increases.

3. Cellular cyclic AMP levels rise.

4. Protein kinase A becomes active.

5. Transcription factors including CREB influence gene expression.

6. MITF helps regulate melanogenic enzymes.

7. Melanin synthesis may increase.

MITF—microphthalmia-associated transcription factor—is important for melanocyte development, survival and function. It helps regulate genes involved in melanin synthesis, including tyrosinase and tyrosinase-related proteins.

Other pathways, including MAPK, PI3K/AKT, Wnt and endothelin signalling, can modify melanocyte behaviour. This cross-talk is one reason pigmentation cannot be explained through MC1R alone.

Genetic variation in MC1R

Variants in the MC1R gene can affect receptor activity and the balance between eumelanin and pheomelanin. Some variants are associated with red hair, fair skin, freckles and increased sensitivity to ultraviolet damage.

However, MC1R is not the only pigmentation gene. Human pigmentation is polygenic, meaning that many genes contribute to the final visible characteristics.

Hormonal and environmental signals activate receptors and cellular pathways that regulate melanin production and distribution within the skin.

📊 Evidence Snapshot

Melanocytes do not work in isolation. Keratinocytes, fibroblasts, immune cells and local signalling molecules all influence their behaviour. Following ultraviolet exposure, keratinocytes can increase signalling that encourages melanocytes to produce and distribute more melanin. Research summarised by the NCBI Bookshelf describes the role of keratinocyte signalling, p53 activity and α-MSH in the tanning response.

This does not mean that a tan prevents ultraviolet damage. Tanning is evidence that the skin has responded to radiation, and it should not replace sunscreen, protective clothing and shade.

Ultraviolet Exposure and Local Skin Signalling

Ultraviolet radiation is one of the most important external influences on pigmentation. It can cause DNA damage in skin cells and activate signalling between keratinocytes and melanocytes.

This response can increase melanin production, resulting in tanning or the darkening of existing areas of hyperpigmentation.

UV exposure may also worsen:

• Melasma

• Freckles

• Post-inflammatory hyperpigmentation

• Solar lentigines or age spots

• Uneven pigmentation following some skin procedures

Sun protection is therefore central to managing many hyperpigmentation conditions.

Depending on skin type and medical advice, this may include:

• Broad-spectrum sunscreen

• Protective clothing

• A wide-brimmed hat

• Seeking shade

• Avoiding deliberate tanning

• Reapplying sunscreen as directed

The American Academy of Dermatology’s melasma guidance explains that sun protection can help prevent melasma from becoming darker or returning after treatment.

Research Compounds and Melanotan II

Melanotan II is a synthetic analogue designed to interact with melanocortin receptors. It has been investigated in laboratory and experimental contexts, but it is not the same as naturally occurring α-MSH.

The abbreviation “MT2” can also refer to unrelated substances in other areas of research. Scientific content should therefore use the full compound name where possible.

Specialist research suppliers such as NextGen Peptides may make synthetic peptides available for laboratory investigation. Supplier information is commercial material and should be considered separately from peer-reviewed research, regulatory authorisation and clinical guidance.

Commercial availability does not establish that a compound is safe or appropriate for human use.

The US Food and Drug Administration identifies potential safety concerns associated with Melanotan II, including impurities, immune reactions and serious adverse-event reports. The FDA’s information on bulk substances that may present safety risks specifically includes Melanotan II.

UK regulatory information also states that Melanotan II products are unauthorised medicines. The MHRA advises people who have used Melanotan II injections or nasal sprays to stop and seek medical advice if adverse effects occur.

This distinction allows the research anchors to remain without implying that A to Zen Therapies recommends personal use.

💡 Expert Tip

Do not assume that a pigmentation change is cosmetic simply because it is painless.

Record when the change appeared, whether it is spreading and whether it followed pregnancy, a medicine, sun exposure, inflammation or a skin injury. Photographing the area in consistent lighting may help a clinician assess change over time.

Avoid attempting to lighten, darken or remove an unexplained lesion before it has been properly identified.

Pigmentation Conditions and Clinical Relevance

Pigmentation changes can arise from very different biological mechanisms. Similar-looking patches do not necessarily have the same cause.

Melasma

Melasma involves increased pigmentation, frequently on the face. Sunlight, pregnancy, hormonal medicines and genetic susceptibility may contribute.

Treatment usually combines rigorous sun protection with dermatologist-directed topical treatments or procedures.

Post-inflammatory hyperpigmentation

Inflammation or injury can leave darker areas after acne, eczema, burns, insect bites or cosmetic procedures. It is more noticeable and may persist longer in darker skin tones.

Treating the underlying inflammation and preventing additional UV exposure are important. Aggressive products can worsen irritation and pigmentation.

Vitiligo

Vitiligo causes areas of skin to lose pigment because functioning melanocytes are reduced or lost, often through an autoimmune process. It is not caused by low α-MSH or a simple nutritional deficiency.

The NHS guide to vitiligo explains that it often begins as a pale patch that gradually becomes white.

Albinism

Albinism refers to inherited conditions affecting melanin production. Different genetic variants can affect pigmentation of the skin, hair and eyes. It cannot be corrected by simply stimulating melanocortin receptors.

Addison’s disease

Hyperpigmentation can be part of primary adrenal insufficiency, particularly when accompanied by systemic symptoms. Treating the endocrine condition—not merely the visible pigmentation—is essential.

Melanoma and changing moles

Melanoma is a skin cancer arising from melanocytes. Although pigmentation genes such as MC1R can influence susceptibility, melanoma is not simply a disorder of excessive melanin production.

The National Cancer Institute recommends checking for the ABCDE features:

• A — Asymmetry

• B — Irregular border

• C — Uneven colour

• D — Changing or concerning diameter

• E — Evolution or change

Not every melanoma follows this pattern. A new, changing, bleeding, itching or unusual lesion should be professionally assessed.

Similar-looking pigmentation changes can have different causes, making professional diagnosis important before treatment begins.

When to Seek Medical Assessment

Consult a GP or dermatologist if pigmentation:

• Appears suddenly without a clear explanation

• Is rapidly spreading

• Develops alongside fatigue, dizziness or weight loss

• Follows a new medicine

• Occurs with inflammation, pain, bleeding or itching

• Affects the eyes or vision

• Causes significant emotional distress

• Does not improve with appropriate skin care

• Involves a new or changing mole

Pregnant people should seek advice before using prescription-strength lightening ingredients, retinoids, chemical peels or other active treatments.

How A to Zen Therapies Can Help

A to Zen Therapies does not diagnose pigmentation disorders or provide medical treatment for melasma, vitiligo, Addison’s disease or suspicious skin lesions. These concerns should be assessed by a GP, dermatologist or other appropriately qualified professional.

For clients who have already received suitable medical advice, cosmetic acupuncture or facial sculpting massage may support general facial relaxation and cosmetic wellbeing.

These treatments do not control melanocortin receptors, reduce melanin production or treat pigmentation disorders. Tell your practitioner about active skin conditions, recent procedures and prescribed treatments before booking.

Continue Exploring Skin and Hormone Health

Pigmentation is influenced by genetics, ultraviolet exposure, inflammation, hormones and underlying health conditions. Explore our Skin Health Hub, Hormone Health Hub and Women’s Health Hub for further evidence-informed articles.

Frequently Asked Questions

Which hormone is mainly associated with skin pigmentation?

Alpha-melanocyte-stimulating hormone is an important regulator because it can activate MC1R on melanocytes. Pigmentation is nevertheless influenced by multiple genes, hormones and local signals.

Can hormonal changes make the skin darker?

Yes. Pregnancy, hormonal medicines and certain endocrine conditions may contribute to hyperpigmentation. A change in skin colour does not reveal which hormone is involved, so unexplained changes require appropriate assessment.

Why does pregnancy sometimes cause melasma?

Pregnancy-related hormone changes may increase melanocyte sensitivity in susceptible individuals. Genetics and ultraviolet exposure also contribute.

Can diet increase melanin production?

Nutrients are required for normal skin function, but there is insufficient evidence that taking extra tyrosine, copper or antioxidant supplements safely or predictably darkens the skin. Excessive supplementation may be harmful.

Is Melanotan II the same as α-MSH?

No. Melanotan II is a synthetic melanocortin analogue. It is not identical to naturally occurring α-MSH and is not an authorised tanning medicine.

Does a tan protect the skin from UV damage?

A tan offers limited protection and is itself a response to ultraviolet exposure. It does not replace sunscreen, shade or protective clothing.

Can massage or acupuncture treat melasma?

No. Massage and acupuncture should not be presented as treatments for melasma or other pigmentation disorders. A dermatologist can recommend evidence-based options following diagnosis.

When should a changing mole be checked?

Arrange an assessment if a mole changes in size, shape, colour or sensation, or if it begins

bleeding, itching or appearing different from your other moles.

References

• NCBI Bookshelf — Melanocyte Stem Cells and Skin Pigmentation

• American Academy of Dermatology — Causes of Melasma

• American Academy of Dermatology — Melasma Treatment

• NHS — Addison’s Disease

• NHS — Vitiligo

• National Cancer Institute — Moles and Melanoma Risk

• FDA — Bulk Drug Substances That May Present Significant Safety Risks

• MHRA — Safety Information Concerning Melanotan II