Prolactin Peptide

Written by Ben Bunting: BA, PGCert. (Sport & Exercise Nutrition) // British Army Physical Training Instructor // S&C Coach.


The prolactin peptide is a hormone that is produced by the prolactin-releasing hormone gene (PRLH).

It stimulates the release of prolactin and regulates the expression of prolactin in the body. It binds to a receptor called the prolactin peptide receptor.

Prolactin Peptide Role

The prolactin peptide has a role in the development of mammary glands and the promotion of milk synthesis in mammals.

It is expressed in the hypothalamus and the pituitary gland. The neuropeptide is also found in the hypothalamus.

The peptide is also present in teleosts. Its amino acid sequence is similar to that of human growth hormone.

It stimulates the breast epithelium to produce milk and also supports maternal behavior.

In addition to its role in lactation, prolactin may play other physiological roles in the body, including the inhibition of the stress response and regulating hypothalamic hormones.

However, it is not fully understood how prolactin functions when it is not secreted by the pituitary gland.

Prolactin is a 23-kDa polypeptide that circulates in the blood. Several prolactin cleavage products exist in the blood, some of which may have functions unrelated to lactation.

For example, prolactin cleavage products may be involved in certain conditions such as peripartum cardiomyopathy and preeclampsia.

There are also a number of macroprolactins, which are formed by covalently bonding prolactin monomers. They have a prolonged half-life and can be diagnostically difficult.

Endogenous prolactin production correlates with breast cancer cell apoptosis. It is also involved in regulating angiogenesis.

Although the exact mechanism is not known, many studies have found an association between high serum levels of prolactin and breast cancer risk factors.

For instance, high serum levels of the hormone were associated with higher breast cancer risk in postmenopausal women.

Prolactin releasing peptides are peptide hormones that activate the secretion of prolactin.

The PRL receptor is located in the anterior pituitary lobe. This peptide stimulates the release of prolactin by binding to the receptor.

Prolactin is produced in breast cancer cells and in normal breast tissue. The presence of prolactin receptor mRNA in breast cancer cells has also been observed.

Moreover, it has been reported that prolactin inhibits breast cancer cell growth and survival. These findings support the theory that the hormone acts in a paracrine/autocrine way inside the mammary gland.

Prolactin is regulated primarily by the hypothalamus.

In addition to its effect on lactotrophs, prolactin has many other functions including the immune system and osmoregulation.

Its receptors are linked to protein kinases. Peptides that stimulate prolactin secretion have been found to have multiple functions.

During the reproductive cycle, oestrogen, an essential hormone in the female reproductive cycle, increases prolactin secretion in the blood.

Higher levels of circulating prolactin are required for lactation to occur. Other hormones, such as oxytocin and anti-diuretic hormone, are also involved in the release of prolactin.

Is Prolactin a Peptide Or Protein?

Prolactin is a 199-amino acid polypeptide that circulates in the blood. It contains several cleavage products and is implicated in peripartum cardiomyopathy and preeclampsia.

It also exists at lower concentrations as macroprolactins, which are polypeptides formed by covalent bonding of prolactin monomers.

These compounds have a long half-life and can complicate diagnostics.

The production of prolactin is controlled by the prolactin-releasing peptide, which is located in the brain.

It is thought to play a role in the regulation of cell growth and stress. It is thought to regulate hormone production in the blood by stimulating lactotrophs cells. However, prolactin is not secreted by every cell in the body.

Although prolactin is a multifunctional hormone, conventional view suggests its major target organ is the mammary gland.

However, the truth is that this is not the case as prolactin is synthesized in many other tissues. A study conducted by Hinuma et al. identified a potent prolactin-releasing hormone that can regulate breast development.

Prolactin is a single-chain protein that has two tryptophans and six cysteines. A genetic analysis of its sequence determined its closest evolutionary relatives, fin whale prolactin and porcine prolactin.

In equine prolactin, 17 of the 199 amino acids have undergone changes. Its putative precursor protein, on the other hand, has undergone changes in four amino acids. 

What Triggers Prolactin Release?

Prolactin is a hormone that helps the body produce milk. It is produced by the pituitary gland. High levels of prolactin are considered unhealthy, and are especially harmful for pregnant women and nursing mothers.

They can cause milky discharge from the nipples, irregular menstrual cycles, and vaginal dryness. It can also be a sign of a tumor on the pituitary gland, or a condition known as prolactinoma.

Prolactin secretion is triggered by a number of factors, but suckling is the most prominent physiological stimulus.

Other stimuli that increase prolactin secretion include stress and exercise. However, there is no clear link between prolactin secretion and a specific phase of sleep.

High prolactin levels cause the mammary glands to enlarge during pregnancy. They also increase milk production.

But, high levels of progesterone act on the breasts and stop milk ejection until the hormone levels drop after childbirth.

Progesterone is also responsible for newborn babies secreting milky substances from their nipples, known as witch's milk. Fortunately, this milky substance usually stops soon after the baby's birth.

Prolactin secretion is regulated by the hypothalamic neuronal circuit. The hypothalamic peptide VIP, or pituitary adenylyl cyclase activating polypeptide, stimulates pituitary prolactin release in male rats and non-suckled lactating female rats.

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Do Men Have Prolactin?

Prolactin is a hormone produced by the pituitary gland, located in the brain. It has many uses, including stimulating breast development and milk production in women.

Men do not have this hormone in large amounts, but high levels can lead to a number of problems. It can cause erectile dysfunction, low sex drive, and insomnia. It is also a potential cause of depression.

Additionally, some people's levels of prolactin may be affected by high levels of stress or strenuous exercise.

Prolactin is thought to be involved in hundreds of physiological processes. Studies have shown that prolactin is important for the post-ejaculatory refractory period in males.

This period occurs after the male ejaculates, but before he recovers sexually. Treatments that interfere with prolactin release can be effective in shortening this period.

A high level of prolactin can be a sign of a medical condition. Certain medicines, such as birth control pills and high blood pressure medicines, may increase prolactin.

Blood tests to determine prolactin levels are inexpensive and safe. Prolactin levels can vary significantly among patients, so it's important to consult a physician to ensure the best course of treatment.

What does Prolactin do in Men?

Prolactin is a hormone that is found in both men and women. It regulates milk production in women and is also involved in metabolism and the immune system.

Low prolactin levels can cause a variety of symptoms in both sexes. However, the role of prolactin in men is less well-understood.

Prolactin may have a neuroprotective effect on the central nervous system and promote neurogenesis. It may also have anti-stress and anxiolytic effects.

However, these benefits are only observed when prolactin levels are within physiological limits. Prolactin may also prepare men for parenting and increase their desire to comfort children.

In one study, researchers found that elevated levels of prolactin were associated with an increased risk of cardiovascular disease (CVD).

However, this association was not significant for the other outcome measures. Among the asymptomatic study participants, elevated prolactin levels were associated with a greater risk of stroke and coronary artery disease.

Prolactin levels can range from slightly elevated to over 1,000 times the normal range.

The level of prolactin in a blood sample can be a sign of an enlarged pituitary gland, but there is no certainty that the level is a symptom of cancer.

The pituitary gland is a small bean-shaped gland that affects almost every part of the body.

It produces hormones that control many functions, including sex. An excess of prolactin, or prolactinoids, in the pituitary gland, can lead to a condition called prolactinoma.

This tumor reduces hormone levels in the testicles and ovaries. It may lead to symptoms in men and women, including headaches and fatigue. This condition is usually treatable with medications and surgery. 

How Does Prolactin Affect Testosterone?

Testosterone is a male hormone that regulates the production of prolactin. Several studies have indicated that testosterone and prolactin interact to influence male reproductive physiology.

In fact, systemic levels of prolactin have a deterministic effect on spermogenesis. However, the exact mechanisms by which prolactin and testosterone interact are unclear.

Prolactin is a hormone produced by the pituitary gland. This gland is located in the middle of the head, just below the brain.

It contains cells called lactotrophs that produce prolactin. In women, prolactin stimulates lactation. Some women experience increased prolactin levels due to benign pituitary tumors called prolactinomas.

These tumors can affect the ovaries and testicles.

There is also some evidence that prolactin may inhibit testosterone. Testosterone nadir and the bioactive LH surge between nine and eleven hours suggest that testosterone suppression suppresses the release of prolactin.

However, this does not mean that prolactin is the cause of the suppression of testosterone. Rather, it may be a consequence of the hormone's proliferative effect on pituitary GH3 cells.

Prolactin secretion is regulated by many different factors. Prolactin can inhibit the release of testosterone by upregulating the LH receptors in Leydig cells.

However, no clear evidence supports this conclusion. Prolactin and testosterone are thought to be closely connected but it is still unclear how this hormone affects male fertility.

High blood prolactin levels can cause symptoms of hypopituitarism in women. It can also interfere with the production of estrogen.

In addition, high levels of prolactin can inhibit the production of testosterone in men, leading to erectile dysfunction and a decrease in interest in sex.

Interestingly, high levels of prolactin may be a sign of secondary hypogonadism. Normal levels of prolactin will not indicate a structural abnormality in the pituitary, but high levels of prolactin indicate a problem with the pituitary.

For this reason, a doctor may want to measure prolactin levels as part of their initial evaluation of a patient suffering from erectile dysfunction.

There are a variety of theories about how prolactin affects testosterone. One theory is that excessive prolactin suppresses testosterone secretion by the pituitary. This in turn lowers testosterone levels.

As a result, men suffering from low testosterone may suffer from reduced interest in sex, impotence, and infertility. Men suffering from prolactinomas may also suffer from inappropriate lactation.

Treatment for prolactinomas usually involves a combination of drugs that can suppress prolactin. These drugs are highly effective and can reduce the size of prolactinomas.

In addition, they may improve general pituitary function. Some women may also benefit from hormone supplements. In such cases, a doctor may prescribe thyroid hormone tablets, steroid tablets, or testosterone supplements.

The prolactin-blocking medication is taken on a regular basis. The dosage is generally between 0.2 mg and 0.5 mg once a week.

In some cases, it is necessary to use an escalating dosage for best results. If the levels remain elevated, there are other causes for the symptoms, such as impotence.

Does Prolactin Cause Erectile Dysfunction?

Prolactin is normally found in levels of less than 20 nanograms per milliliter in males. But if it is higher than 20 nanograms per milliliter, this can lead to sexual dysfunction.

High prolactin levels are associated with low testosterone levels. In fact, studies have found that elevated prolactin levels contribute to male infertility. It may also affect sperm motility and quality.

In addition to the effects of prolactin on erectile function, lifestyle factors can contribute to its development. For instance, smoking and alcohol consumption can increase the risk of developing erectile dysfunction.

Physical activity is another way to reduce the risk. It can also improve physical health and reduce stress and anxiety.

Elevated levels of prolactin inhibit the production of luteinizing hormone. In men with hypogonadism, elevated prolactin is known to inhibit the secretion of LH and decreases testosterone.

Prolactin and Muscle Loss

Prolactin is a hormone that affects a variety of metabolic processes. It has many functions in the body, including lactation and gonadal function.

Several studies have linked high levels of prolactin to increased weight, although the mechanism of this effect is not known.

There have been some reports that show that the hormone can alter insulin sensitivity and glucose homeostasis. In addition, men with high prolactin levels may experience hyperglycemia.

While low levels of prolactin are generally not a concern, high levels of prolactin are a serious problem. High levels of prolactin are a sign of a health condition known as hyperprolactinemia.

High levels of prolactin can cause a range of symptoms, including headaches, muscle loss, and erectile dysfunction (impotence).

Although prolactin is normally found in small quantities in the body, it can also be caused by other conditions. For example, men with hypothyroidism can have high levels of prolactin.

Hypothyroidism can cause the pituitary gland to enlarge, and it can be treated through thyroid hormone replacement therapy.

Another cause of high levels of prolactin is a pituitary tumor. This condition may require surgery or medical treatment

Patients with prolactinomas are usually treated with medications that act like dopamine in the brain to reduce the prolactin level.

This treatment will help restore fertility and eliminate symptoms. The dosage of the medication depends on the size of the prolactinoma.

Patients with prolactinomas should use contraception if they are trying to conceive, and should stop taking the dopamine agonist tablets if they decide to conceive.

However, some patients may need to continue dopamine agonist therapy during pregnancy.

How to Measure Prolactin Levels

Knowing how to measure prolactin levels is important for determining whether a condition is causing elevated levels.

Some conditions can affect how much prolactin is produced by the body, and higher levels may indicate a serious underlying health problem.

If your prolactin levels are elevated, your doctor will need to run additional tests to determine what may be causing them.

Additional testing may include a physical exam, medical history review, or magnetic resonance imaging (MRI) scan.

Women and men usually have small levels of prolactin in their blood, and levels rise and fall throughout the day.

Prolactin is highest in the morning, so taking a blood sample after waking up and resting quietly for about 30 minutes is the best time to get the best results.

People with low levels of prolactin may be suffering from hypopituitarism, a condition where the glands don't produce enough prolactin to control the body's hormone levels. Some medications may also cause low prolactin levels.

People with high levels of prolactin can experience irregular menstrual periods or lower libido. It can even lead to bone fragility, a risk factor for fractures.

However, higher levels of prolactin are normal for pregnant women and breastfeeding women. However, it is important to know that high levels can indicate an underlying health issue, such as a tumor or a pituitary gland disease.

Prolactin Peptide Conclusion

Prolactin releasing peptide (PRP) is a hormone expressed in the pituitary gland that regulates the secretion of prolactin.

This hormone is involved in many aspects of animal life, including energy metabolism, reproduction, and stress response. It also has neuroprotective properties.

While the peptide is expressed throughout the body, its main function is in the brain. A variety of stimuli can trigger its release.

Prolactin-releasing peptide affects gastric motor function in rats and modulates synaptic transmission in the dorsal vagal complex.

This hormone is also involved in body weight regulation. Its interaction with the hormone leptin influences body weight in humans.

In mice, a deficiency in this hormone affects body weight homeostasis. It also causes altered energy expenditure. Several studies have investigated the role of this hormone in regulating appetite.

Some of these studies are summarized below. The study in the journal Prog. Neurobiol describes several experiments examining how a GPR10 deficiency affects the onset of hunger and appetite.

PrRP was named after its ability to release prolactin in a rat pituitary adenoma cell line. Its activity was confirmed in female and male rats in the proestrous and estrous stages.

Male rats required higher doses of the compound to increase prolactin levels. However, the peptide did not have typical features of a hypophysiotropic hormone.

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