Hypothalamus Hormone Released
by Benjamin Bunting BA(Hons) PGCert
Written by Ben Bunting: BA, PGCert. (Sport & Exercise Nutrition) // British Army Physical Training Instructor // S&C Coach.
Welcome to the fascinating world of the hypothalamus hormones, the unsung heroes of our body's regulatory system.
Nestled deep within our brain, the hypothalamus acts as the conductor of our body's symphony, orchestrating various functions such as temperature regulation, hunger and thirst, sleep-wake cycles, and even emotions.
But it's the hormones secreted by the hypothalamus that truly steal the spotlight. These tiny chemical messengers play a vital role in maintaining homeostasis, ensuring that our body functions smoothly and efficiently.
From oxytocin, the "love hormone," that fosters social bonds and childbirth, to vasopressin, the "anti-diuretic hormone," that regulates our water balance, each hormone has its own unique role to play.
Functions of the Hypothalamus
The hypothalamus is a small but mighty region of the brain that is responsible for numerous essential functions.
It acts as the control center for the autonomic nervous system, which regulates involuntary bodily functions such as heart rate, blood pressure, and digestion.
Additionally, the hypothalamus plays a crucial role in maintaining body temperature, ensuring that we stay within a narrow range for optimal functioning.
It achieves this by detecting changes in temperature and triggering appropriate responses such as sweating or shivering.
Furthermore, the hypothalamus is involved in regulating our appetite and metabolism. It produces hormones such as neuropeptide Y and melanocortin, which play a role in hunger and satiety signals.
These hormones help us maintain a healthy body weight by influencing our eating behavior and energy expenditure. Dysfunction in this system can lead to conditions such as obesity or eating disorders.
Finally, the hypothalamus is involved in the sleep-wake cycle, also known as the circadian rhythm.
It produces hormones like melatonin, which help regulate our sleep patterns and ensure that we get the rest we need.
Disturbances in the hypothalamic control of the sleep-wake cycle can lead to sleep disorders such as insomnia or narcolepsy.
Overview of Hypothalamic Hormones
The hypothalamus secretes a variety of hormones that play a crucial role in maintaining homeostasis.
These hormones act as chemical messengers, traveling through the bloodstream and binding to specific receptors in target tissues to initiate a response. Let's take a closer look at some of these key hormones and their functions as outlined in this document.
1. Oxytocin: Known as the "love hormone," oxytocin is involved in social bonding, trust, and emotional attachment. It plays a crucial role in childbirth, facilitating uterine contractions and milk ejection during breastfeeding. Oxytocin is also involved in promoting feelings of love and connection between individuals.
2. Vasopressin: Also known as the "anti-diuretic hormone," vasopressin regulates water balance in the body. It acts on the kidneys to promote water reabsorption, reducing urine output and helping to maintain proper hydration. Vasopressin also plays a role in vasoconstriction, which helps regulate blood pressure.
3. Corticotropin-releasing hormone (CRH): CRH is involved in the stress response, triggering the release of other hormones such as adrenocorticotropic hormone (ACTH) and cortisol. These hormones help the body respond to stress by increasing energy production, suppressing the immune system, and enhancing memory formation.
4. Thyrotropin-Releasing Hormone Explained: TRH (pyroglutamyl-histidyl-prolineamide) is one of the simplest hypothalamic neurohormones and plays an integral role in stimulating production and secretion of thyroid stimulating hormone by the pituitary gland. An appropriate 30 minute TSH response to TRH suggests adequate suppression of the pituitary thyroid axis in patients with Graves' disease; any blunted response indicates inadequacies in this regard.
5. Gonadotropin-Releasing Hormone Explained: GnRH secretion regulates FSH and LH levels in the pituitary gland, thus affecting sexual steroids (testosterone) production as well as gametes production (sperm). Failing to produce GnRH results in Kallmann's syndrome with its characteristic eunuchoidal body shape and infertility. The kisspeptin-neurokinin-dynorphin neuronal network in the hypothalamus mediates both negative and positive feedback control of GnRH secretion.
6. Somatostatin Explained: Endogenous somatostatin inhibits the release of insulin, glucagon, and other hormones by the brain, including restricting gastrointestinal secretions and altering memory formation. Synthetic versions (lanreotide and octreotide) have also been developed as drugs to decrease symptoms associated with pancreatic somatostatin-secreting tumors while improving diabetes control by suppressing hyperglucagon production.
7. Dopamine Explained: Dopamine is a chemical messenger between brain cells. It plays an integral part in mood regulation, movement and the way we experience pleasure. Dopamine can also be produced using the amino acid tyrosine, found in protein-rich foods like cheese and nuts. Supplementation may help conditions associated with low dopamine production such as Parkinson's disease.
These are just a few examples of the hormones secreted by the hypothalamus. Each hormone has its own unique role and interacts with other hormones and systems in the body to maintain overall balance and health. Let's look at them deeper.
Over the past few years, scientists have discovered that the hormone oxytocin plays an essential role in many functions beyond childbirth and milk ejection.
Commonly referred to as the "love hormone" or the "cuddle chemical," oxytocin can produce various anti-stress-like effects like increased pain threshold and anxiolytic-like responses; stimulate various forms of positive social interaction and attachment behavior; support growth and healing, and may even have potential use against neuropsychiatric conditions like autism and postpartum depression.
Oxytocin acts both as a hormone and neurotransmitter. Hormones function within the endocrine system while neurotransmitters perform their duties within the nervous system (including brain). Many molecules can serve both functions, with some like oxytocin playing different roles within each system.
Mechanoreceptors located in the newborn's nipple and cervix become activated as it suckers, creating a positive feedback loop of mechanoreceptor activation and increased release of synthetic oxytocin that encourages further sucking.
Synthetic oxytocin can be used by physicians in obstetrics as an inducer or augmentor of labor, controlling postpartum bleeding after birth and stimulating milk let-down for breast-feeding purposes.
Oxytocin has long been linked with bonding and social interactions. But recent studies have also demonstrated its benefits beyond these interactions - increasing self-perception, trust and altruism among human subjects, as well as decreasing anxiety levels and improving moral judgement and decision making.
Oxytocin may even play a role in treating social phobia, autism and postpartum depression psychiatric conditions; furthermore it has even been proposed as treatment against chemo-radiotherapy-induced intestinal damage as it increases prostaglandin production among cells lining this organ lining the intestinal wall.
Also referred to as AVP or antidiuretic hormone (ADH), vasopressin (AVP) is a peptide hormone produced in magnocellular neurosecretory neurons in the supraoptic and paraventricular nuclei (PVN) by magnocellular neurosecretory neurons located within these nuclei and released via axons for release into the posterior pituitary gland.
AVP acts predominantly as a vasopressor while also exerting vasoconstrictive properties which lead to increased blood sodium concentration, decreased urine production, increased fluid storage which ultimately increased blood volume and arterial pressure as well.
V1 receptors, a subtype of G-protein coupled receptors, can be found at high densities on vascular smooth muscle, testis and superior cervical ganglion as well as kidneys.
V1Rs are also induced by AVP and oxytocin in the hypothalamus for use in regulating osmotic water balance regulation.
AVP is used to treat diabetes insipidus, which results in excess fluid loss and dehydration.
It can also be used to raise blood pressure among those experiencing shock due to certain medical conditions (septic or post-cardiotomy shock) who remain hypotensive even after traditional fluid resuscitation and catecholamine administration.
Corticotropin-Releasing Hormone Explanated
Corticotrophin-Releasing Hormone, or CRH, is produced by neurons located within the hypothalamic paraventricular nucleus (PVN).
CRH secretes Adrenocorticotropic Hormone (ACTH), stimulating production of adrenal glucocorticoids.
Normally its production follows a circadian rhythm: peaking early morning and gradually declining overnight; however under stress-induceed increase secretions both CRH and ACTH leading to an overproduction of cortisol which mobilizes energy reserves but eventually leads to hypercortisolism over time.
CRH plays an integral part of physiological and behavioral responses to stress. It acts through binding to two G-protein coupled receptors called CRHR1 and CRHR2.
CRH promotes adrenocorticotropic hormone production in the pituitary gland, activating the hypothalamic-pituitary-adrenal (HPA) axis; additionally it has anxiolytic properties in the brain and inhibits appetite - losing function may contribute to anxiety, depression, anorexia nervosa as well as anorexia nervosa.
Additionally, increased amounts of CRH are produced during gestation which contribute to labor starting earlier than expected.
Patients suspected of Cushing's syndrome can benefit from taking a CRH stimulation test in order to distinguish pituitary from extrapituitary sources of ACTH, and in cases when radiologic studies fail to pinpoint its source, taking a suppression test may also help.
Thyrotropin-Releasing Hormone Explained
Thyrotropin-releasing hormone (TRH), is a crucial brain hormone in controlling the hypothalamic-pituitary-thyroid axis.
It induces pituitary gland secretion of thyroid stimulating hormone, as well as secretion from thyroid gland of thyroxine and triiodothyronine that play key roles in metabolic rate, heat production and neuromuscular functioning, among many other effects.
TRH is a three amino acid peptide produced by nerve cells in the hypothalamus called the paraventricular nucleus.
Axons from these cells carry TRH into blood circulation and ultimately into the hypothalamic-pituitary axis where it triggers release of TSH from pituitary gland. TSH then stimulates production of thyroid hormone by the thyroid gland.
TRH activates several signals when it binds to its receptor, such as protein kinase C and calcium/calmodulin dependent protein kinases.
In addition to stimulating epidermal growth factor receptor (EGFR) phosphorylation, changes in its ligand binding site, paracrine effects on pancreatic b-cells via G-protein-coupled TRHR1 signaling, stimulating insulin secretion from these cells through G-protein coupled TRHR1 signaling.
Additional effects include desensitization which involves receptor phosphorylation, arrestin binding, internalization (Luo et al. 2012).
Hypothalamus and pituitary gland are controlled by hormones known as TRH that regulate thyroid hormone secretion.
A rare condition arises when an area of the hypothalamus that produces this peptide (known as median eminence) is damaged due to cancer or injury
This results in hypothyroidism - when not enough thyroid hormone is produced by gland. TRH also plays other less well-known roles; in this article we outline 13 ways that can increase or decrease its levels.
Gonadotropin-Releasing Hormone Explained
Gonadotropin-releasing hormone is a decapeptide neurohormone produced by nerve cells in the hypothalamus and secreted through nerve endings in specialized locations within it.
When produced, this neurohormone triggers production of two other hormones known as FSH and LH that stimulate the testes and ovaries to produce testosterone (in men) or oestrogen (in women).
GnRH secretion in all vertebrates is a continuous cycle, controlling both initiation and maintenance of reproduction systems.
It stimulates release of estrogen and progesterone from ovaries as well as testis-spermatogenesis (Herbison 2018).
Glucocorticoids have both positive and negative influences on gonadotropin secretion depending on their context of administration.
Secretions of glucocorticoids increase among women suffering from hypothalamic amenorrhea while exogenous administration of glucocorticoids reduce LH and increase FSH pulse frequencies in eugonadal subjects.
Sex steroids were observed to impact GnRH neurons and gonadotropes serially blood sampling women through each phase of menstruation cycle with mid cycle surges in LH and FSH, leading to speculations that hypothalamic secretions regulates human ovulation processes.
Kisspeptin directly activates GnRH neurons to enhance LH release. Kisspeptin also prevents development of an LH response in rhesus monkeys after continued GnRH administration, suggesting desensitization of their HPG axis.
Continuous infusion of Kiss1r receptor-containing Kisspeptin increases serum LH levels temporarily but this reverts upon stoppage indicating it directly regulates gonadotropes through this pathway.
Somatostatin is a polypeptide hormone produced by cells of the gastrointestinal tract and pancreatic islets, and released by them to control absorption, utilization, storage and secretion of sugar, amino acids, fatty acids and water by intestinal tissues.
Somatostatin also regulates secretion of insulin and glucagon from pancreatic islets of Langerhans; further inhibiting secretion from prolactin production from hypothalamus or exocrine glands such as salivary and sweat glands.
Somatostatin exerts neuroendocrine inhibitory effects throughout the body, specifically inhibiting GI, endocrine, and exocrine secretions and cell division at an accelerated pace, while acting directly antiproliferative against Hepatocellular Carcinoma cells in culture.
Somatostatin exerts its antitumor activity by blocking the growth hormone-insulin-like factor 1 axis via central mechanisms and by restricting IGF-1 release from proliferating endothelial cells via peripheral pathways (sst2 and sst5).
Furthermore, Somatostatin and its synthetic analogs (lanreotide, octreotide and seglitide) have demonstrated antitumor activity against several tumor types including pituitary adenomas, gastroenteropancreatic NETs, paragangliomas carcinoids and breast cancers.
Somatostatin has a short half-life and must therefore be tightly managed in order to remain therapeutically effective.
As such, longer half-lives have been developed such as lanreotide and octreotide to relieve symptoms associated with uncommon gastrointestinal endocrine tumors like esophageal varices, pylorus obstruction, pancreatic endocrine tumors (including acromegaly), as well as pancreatic cancers like acromegaly.
Octreotide also serves as an effective therapy option in cases intolerant of other somatostatin analogs.
Your brain's dopamine system provides pleasure and motivation while helping you learn and remember things.
Many activities can cause the release of dopamine, such as eating food, exercising, playing a game or having sex; alcohol and some illegal drugs also produce dopamine-boosting effects, leading some people to become dependent upon them.
This natural reward system may become corrupted by addictions and compulsive behaviors causing people to engage in harmful or inappropriate behaviors and substances for a rush of dopamine while overlooking more pleasurable activities which would otherwise bring pleasure - this natural reward system needs protecting.
Dopamine is part of a group of chemicals called neurotransmitters that transmit signals between brain cells.
Other examples of this class of neurotransmitter are serotonin, which affects mood and other aspects of behavior; and dopamine, which allows neurons to communicate between themselves and control movement.
Dopamine deficiency can lead to depression and other mental health problems. Dopamine also plays a vital role in diseases not limited to the brain, such as Parkinson's disease and obesity.
Mutations in SLC6A3 may disrupt dopamine signaling, leading to dopamine transporter deficiency syndrome or infantile parkinsonism-dystonia which manifests itself with symptoms including tremor, stiffness and slow movement; doctors treat this with levodopa which crosses blood-brain barrier.
Role of Hypothalamic Hormones in Regulating Body Temperature
One of the key functions of the hypothalamus is to regulate body temperature. The hypothalamus acts as a thermostat, constantly monitoring the temperature of the blood and surrounding tissues.
When the body temperature deviates from the desired range, the hypothalamus initiates appropriate responses to bring it back to normal.
When the body is too warm, the hypothalamus triggers mechanisms to cool it down. Blood vessels near the skin dilate, allowing more blood to flow near the surface and dissipate heat.
Sweating is also initiated, which helps cool the body as the sweat evaporates from the skin. On the other hand, when the body is too cold, the hypothalamus activates mechanisms to generate heat.
Blood vessels near the skin constrict, reducing heat loss, and shivering is triggered to generate additional warmth through muscle contractions.
This intricate temperature regulation system is controlled by the hypothalamus hormones.
For example, when the body is too warm, the hypothalamus releases hormones that stimulate sweating and vasodilation.
These hormones act on the sweat glands and blood vessels to initiate the necessary responses.
Conversely, when the body is too cold, the hypothalamus releases hormones that promote vasoconstriction and shivering, helping the body conserve heat and generate additional warmth.
The hypothalamus is constantly monitoring the body's temperature and adjusting its responses accordingly to maintain homeostasis. This ensures that our body functions optimally regardless of external temperature fluctuations.
Impact of Hypothalamic Hormones on Appetite and Metabolism
The hypothalamus plays a crucial role in regulating our appetite and metabolism, helping to maintain a healthy body weight.
It produces hormones that interact with various parts of the body to influence our eating behavior and energy expenditure.
One such hormone is neuropeptide Y (NPY), which is produced by the hypothalamus and stimulates appetite. NPY acts on receptors in the brain, increasing hunger and promoting food intake.
On the other hand, the hypothalamus also produces hormones such as melanocortin, which suppress appetite and promote satiety. These hormones act as a balance, ensuring that we eat when we need fuel and feel satisfied when we've consumed enough.
Additionally, the hypothalamus plays a role in regulating metabolism, the process by which our body converts food into energy.
It produces hormones that influence energy expenditure and storage. For example, the hypothalamus produces thyroid-releasing hormone (TRH), which stimulates the release of thyroid-stimulating hormone (TSH) from the pituitary gland.
TSH, in turn, stimulates the thyroid gland to produce thyroid hormones, which play a crucial role in regulating metabolism.
Dysfunction in the hypothalamic control of appetite and metabolism can lead to conditions such as obesity or eating disorders.
For example, an imbalance in the production of neuropeptide Y and melanocortin can result in overeating and weight gain.
Understanding the role of hypothalamic hormones in appetite and metabolism can help us develop strategies to promote healthy eating habits and maintain a balanced weight.
Hypothalamic Hormones and the Sleep-Wake Cycle
The hypothalamus is closely involved in regulating our sleep-wake cycle, also known as the circadian rhythm. It produces hormones that help regulate our sleep patterns and ensure that we get the rest we need.
One such hormone is melatonin, which is produced by the pineal gland under the control of the hypothalamus.
Melatonin plays a crucial role in promoting sleep and regulating our internal body clock. It is released in response to darkness, signaling to the body that it's time to sleep.
Melatonin levels increase in the evening, peak during the night, and gradually decrease in the morning, helping us maintain a regular sleep schedule.
The hypothalamus also interacts with other systems in the body to regulate the sleep-wake cycle. For example, it receives input from the eyes, which detect light and send signals to the hypothalamus.
This information helps synchronize our internal body clock with the external environment, allowing us to adapt to changes in daylight and darkness.
Disruptions in the hypothalamic control of the sleep-wake cycle can lead to sleep disorders such as insomnia or narcolepsy.
For example, an imbalance in melatonin production or a disturbance in the input from the eyes can disrupt the timing and quality of sleep.
Understanding the role of hypothalamic hormones in the sleep-wake cycle can help us develop strategies to promote healthy sleep habits and address sleep disorders.
Influence of Hypothalamic Hormones on Stress Response
The hypothalamus is closely involved in the body's response to stress. It produces hormones that trigger a cascade of reactions, helping us cope with and adapt to stressful situations.
One of the key hormones involved in the stress response is corticotropin-releasing hormone (CRH).
When the hypothalamus detects a stressful stimulus, it releases CRH, which then stimulates the pituitary gland to release adrenocorticotropic hormone (ACTH).
ACTH, in turn, stimulates the adrenal glands to release cortisol, a stress hormone that helps mobilize energy and suppress the immune system.
Cortisol plays a crucial role in the body's response to stress. It increases blood sugar levels, providing a quick source of energy to deal with the stressful situation.
It also suppresses the immune system, temporarily reducing inflammation and allowing the body to prioritize immediate survival over long-term health.
However, chronic stress can lead to dysregulation in the hypothalamic-pituitary-adrenal (HPA) axis, which controls the stress response.
Prolonged exposure to stress can result in elevated cortisol levels, which can have detrimental effects on various systems in the body.
It can lead to immune system dysfunction, impaired memory and cognition, and increased risk of chronic diseases such as cardiovascular disease or diabetes.
Understanding the role of hypothalamic hormones in the stress response can help us develop strategies to manage and reduce stress levels.
By promoting stress management techniques such as mindfulness, exercise, and social support, we can help maintain the balance in the HPA axis and protect our overall health.
Link between Hypothalamic Hormones and Reproductive Function
The hypothalamus also plays a crucial role in regulating reproductive function. It produces hormones that act on the pituitary gland, which then releases hormones that control the reproductive system.
One such hormone is gonadotropin-releasing hormone (GnRH), which is produced by the hypothalamus and stimulates the release of gonadotropins from the pituitary gland.
These gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), act on the gonads (ovaries in females and testes in males) to regulate the production of sex hormones and gametes.
In females, the hypothalamic-pituitary-gonadal (HPG) axis plays a crucial role in the menstrual cycle. GnRH stimulates the release of LH and FSH, which then act on the ovaries to promote the maturation of follicles and the release of an egg during ovulation.
The ovaries also produce estrogen and progesterone, which play a crucial role in maintaining the uterine lining and preparing for potential pregnancy.
In males, the HPG axis regulates the production of testosterone, the primary male sex hormone. GnRH stimulates the release of LH, which acts on the testes to stimulate testosterone production.
Testosterone is responsible for the development of secondary sexual characteristics in males and plays a crucial role in sperm production.
Disorders related to hypothalamic hormone imbalance can have significant impacts on reproductive function.
For example, dysfunction in the HPG axis can lead to hormonal imbalances, irregular menstrual cycles, infertility, or sexual dysfunction.
Understanding the role of hypothalamic hormones in reproductive function can help identify and address these disorders, allowing individuals to achieve and maintain optimal reproductive health.
Disorders Related to Hypothalamic Hormone Imbalance
Imbalances in hypothalamic hormones can lead to various disorders that impact overall health and well-being.
These disorders can result from either overproduction or underproduction of specific hormones, disrupting the delicate balance in the body.
One example of a disorder related to hypothalamic hormone imbalance is diabetes insipidus.
This condition occurs when there is a deficiency of vasopressin, the "anti-diuretic hormone," produced by the hypothalamus. Without sufficient vasopressin, the body cannot properly regulate water balance, leading to excessive thirst and urine output.
Diabetes insipidus can result from damage to the hypothalamus itself or the pituitary gland, which is responsible for storing and releasing vasopressin.
Another disorder related to hypothalamic hormone imbalance is hypothalamic amenorrhea.
This condition occurs when there is a disruption in the hypothalamic-pituitary-gonadal (HPG) axis, leading to the absence or irregularity of menstrual periods.
Hypothalamic amenorrhea can be caused by factors such as excessive exercise, stress, or low body weight, which can disrupt the production of GnRH and other hormones involved in the menstrual cycle.
Understanding the disorders related to hypothalamic hormone imbalance is crucial for diagnosis and treatment.
By identifying the underlying cause of the imbalance and addressing it, healthcare professionals can help restore the body's natural balance and improve overall health outcomes.
Conclusion: The Vital Role of Hypothalamic Hormones in Maintaining Overall Health
The hypothalamus hormones are the unsung heroes of our body's regulatory system, playing a vital role in maintaining overall health and well-being.
From regulating body temperature and appetite to influencing the sleep-wake cycle and stress response, these hormones orchestrate a symphony of functions that keep our body in perfect harmony.
By understanding the intricate workings of the hypothalamus hormones, we can gain insights into the mechanisms that maintain homeostasis and address disorders that arise from hormone imbalances.
Whether it's optimizing our sleep patterns, managing stress levels, or promoting reproductive health, the knowledge of hypothalamic hormones empowers us to take control of our well-being.
So, the next time you marvel at the wonders of the human body, remember the tiny chemical messengers secreted by the hypothalamus that keep everything in check. They may be hidden deep within our brain, but their impact on our overall health is truly remarkable.