Melanocyte Stimulating Hormone MSH in Human Physiology

Melanocyte-stimulating hormone refers to a group of peptide hormones released by the pituitary gland and hypothalamus. Its development by the skin and pituitary is increased in response to ultraviolet (UV) radiation, and it plays a key role in the production of coloured pigmentation in the skin, hair, and eyes. It accomplishes this by causing melanocytes, which are specialised skin cells, to produce melanin, a pigment that protects cells from DNA damage, which can lead to skin cancer (melanoma).

As we already discussed, MSH full form now will study MSH, MSH hormone, and melanocyte stimulating hormone function.

Melanocyte-Stimulating Hormones Synthesis

Melanocyte-stimulating hormones are made from the same pro-opiomelanocortin precursor molecule as adrenocorticotropic hormone (POMC).

By acting on receptors in the hypothalamus, melanocyte-stimulating hormone, which is formed in the hypothalamus, may also suppress appetite. Leptin, a hormone produced by fat cells, enhances this effect.

MSH Hormones Structure 

-MSH, -MSH, and -MSH is the MSH peptide. They differ from one another in terms of their preferential binding to different melanocortin receptors (MCRs), by which they exert their effects, and their structure, with each arising from a different region of POMC. For example, the -MSH peptide is derived from the middle region of POMC, while -MSH is derived from the C-terminus (the carboxyl group-containing end) and -MSH is derived from the N-terminus (the end containing an amine group). The peptide adrenocorticotropic hormone (ACTH) is another result of POMC cleavage, and it can be further cleaved to form alpha-MSH.

The -MSH peptide is made up of 13 amino acids that appear in the same order in all of the organisms studied. The duration and sequence of -MSH and -MSH is different. The ability of the MSH peptides to activate various MCRs is thought to be due to their different amino-acid sequences.

Melanocyte Stimulating Hormone Function

1. MSH induces the synthesis and release of melanin hormone  (a mechanism known as melanogenesis) by melanocytes in the skin and hair by acting on the melanocortin 1 receptor.

2. MSH suppresses appetite by acting on the hypothalamus. -MSH, which is generated in the hypothalamus, is also involved in sexual arousal.

3. Melanocyte-stimulating hormone has anti-inflammatory properties, can influence the release of the hormone aldosterone, which regulates salt and water balance in the body, and has an impact on sexual behaviour, among other things.

4. When certain animals are in a dark environment, their MSH output increases. This allows the pigment to diffuse in pigment cells in the toad's skin, making it darker and more difficult to detect for predators. Since melanophores are pigment cells, the hormone is also referred to as melanophore-stimulating hormone in amphibians.

5. In humans, an improvement in MSH results in darker skin. During pregnancy, MSH levels rise in humans. Increased pigmentation in pregnant women is caused by this, as well as increased estrogens. Excess adrenocorticotropic hormone (ACTH) in Cushing's disease may trigger hyperpigmentation, such as acanthosis nigricans in the axilla. Skin darkening (hyperpigmentation) is common in people with primary Addison's disease, even in places that aren't exposed to the sun; common locations include skin creases (e.g., on the hands), the breast, and the inside of the cheek (buccal mucosa); new scars become hyperpigmented, but older scars don't.

6. Different levels of MSH aren't the main cause of skin colour variation. However, there are differences in hormone receptors in certain redheads and other people who don't tan well, causing them to not respond to MSH in the blood.

Over Production of Melanocyte

• Increased melanin development is a direct result of elevated levels of the melanocyte-stimulating hormone. This can happen as a result of excessive sun exposure or tanning. People with elevated blood levels of melanocyte-stimulating hormone, on the other hand, do not always tan well or have even skin pigmentation. Due to differences in their melanocyte-stimulating hormone receptors, very fair-skinned people produce less melanin and do not respond to melanocyte-stimulating hormone levels in the blood.

• Patients with primary adrenal insufficiency (Addison's disease) have hyperpigmentation or abnormal darkening of the skin. The adrenal glands do not contain enough hormones in Addison's disease (including cortisol). In order to induce the adrenal glands to generate more cortisol, the hypothalamus stimulates the pituitary gland to release more adrenocorticotropic hormone. Melanocyte-stimulating hormone is generated when the adrenocorticotropic hormone is broken down, resulting in skin hyperpigmentation.

• Melanocyte-stimulating hormone levels rise during pregnancy and in women who take birth control pills, which can lead to skin hyperpigmentation. Hyperpigmentation may also be a symptom of Cushing's syndrome, which is caused by an excess of adrenocorticotropic hormone.

Low Secretion of Melanocyte

A lack of melanocyte-stimulating hormone causes a lack of skin pigmentation and, as a result, a loss of natural protection from the sun's UV rays. Damage to the pituitary gland prevents the release of adrenocorticotropic hormone and melanocyte-stimulating hormone in secondary adrenal insufficiency, resulting in decreased skin pigmentation. Increased inflammation, discomfort, and sleeping problems may result from a lack of the melanocyte-stimulating hormone, as well as a drop in antidiuretic hormone levels, which causes thirst and frequent urination. Increased food consumption and obesity can also be caused by a lack of melanocyte-stimulating hormone.

Did You Know?

• The anterior pituitary is in charge of producing and secreting many important hormones in the body. The following hormones are among them:

• HGH (Human Growth Hormone) is a hormone that regulates the growth and repair of all cells in the body.

• Thyroid Stimulating Hormone (TSH) stimulates the thyroid gland to produce its own hormone, thyroxine. Thyrotropin is another name for TSH.

• Adrenocorticotropic Hormone (ACTH): Induces the release of Cortisol, also known as the "stress hormone," through the adrenal gland. Corticotropin is another name for ACTH.

• Luteinising Hormone (LH) and Follicle-Stimulating Hormone (FSH): Gonadotropins are hormones that regulate male and female sexual and reproductive characteristics.

• Prolactin (PRL) is a hormone that causes the breasts to produce milk. Despite the fact that it is present at all times, the secretion is increased during and immediately after pregnancy.