Pituitary
And it's hormones.
Introduction
The hormones produced by the Pituitary include the following.
(The ones produced in the anterior pituitary)
Adrenocorticotropic hormone (ACTH)
Follicle-Stimulating Hormone (FSH)
Growth Hormone (GH)
Luteinizing Hormone (LH)
Prolactin
Thyroid Stimulating Hormone (TSH)
(The ones produced in the posterior pituitary)
Antidiuretic hormone (ADH, or vasopressin)
Oxytocin
What is the pituitary, where is it located, and what hormones does it produce?
Located in the brain, this is usually referred to as the “master” gland of the endocrine system because it works to control the functions of most of the endocrine glands. It is no larger than a pea and is attached to the hypothalamus at the base of the brain. It consists of two main structures: an anterior lobe and a posterior lobe.
The anterior pituitary communicates directly with the hypothalamus and the hypothalamus exerts a regulatory effect through the secretion of somatostatin and dopamine. These hormones either stimulate or prevent the creation/release of the hormones produced by the anterior pituitary.
Through the hormones released by the anterior pituitary, this gland is in direct contact with various tissues and structures within the body. Below, we look at them one-by-one.
Anterior Pituitary Hormones
Adrenocorticotropic Hormone (ACTH): ACTH is a hormone released by the anterior pituitary that plays a critical role in how the body responds to stress. ACTH being released triggers the adrenal glands to produce cortisol (the stress hormone), androgens (sex hormones), and simulates the production of chemical substances that increases the presence of other hormones like adrenaline and noradrenaline. Cortisol is essential and affects almost every tissue in the body. While it is known as the “stress” hormone, it does play many important functions. We’ll look at those later when we take a look at the Adrenal glands.
ACTH is controlled via the HPA (hypothalamic-pituitary-adrenal) axis. When cortisol is low it triggers the hypothalamus to release corticotrophin-releasing hormone (CRH). This is what stimulates the anterior pituitary to release ACTH. ACTH then triggers the adrenal glands to release cortisol and androgens. The resulting release of cortisol then triggers the hypothalamus to decrease its CRH levels, therefore closing the loop and turning the signal off. Stress alone can also stimulate the release of ACTH. If there are issues with your hypothalamus, pituitary, or adrenal glands it may affect the balance of ACTH within your body.
We’ll get into it more in the adrenal gland section however because ACTH stimulates the release of Cortisol, it indirectly can have a very large, and maybe even negative, impact on the health of the gut.
Follicle-Stimulating Hormone (FSH): This hormone plays a role in sexual development and function and affects the operation of both the ovaries and testicles. Specifically, in the second and third trimesters of pregnancy this hormone, along with Luteinizing Hormone, enables the sex organs of the fetus to begin to mature. These hormones spike in children as they begin to go through puberty. Lastly, in people who menstruate, FSH helps to regulate the menstrual cycle, and prepare eggs for ovulation; and in people assigned male at birth, FSH stimulates sperm production.
Growth Hormone (HGH): Growth Hormone is also known as Human Growth Hormone. It is a natural hormone that helps to promote growth in children, maintain normal body structure post childhood growth, and metabolism, including keeping blood sugar within a healthy range. HGH impacts glucose in the body because it increases the production of insulin-like growth factor-1 (IGF-1), which has glucose lowering effects on the body. HGH can contribute to increasing blood glucose levels if they get too low, however if you have too much HGH in your body it can also counteract insulin causing an elevation in blood glucose.
Luteinizing Hormone (LH): LH stimulates actions in the body that are important for reproduction, development, and sexual health. It works very closely with FSH. It is the surge in LH that causes the ovaries to release a mature egg during approximately the second week of a menstrual cycle. LH also stimulates the production of progesterone, a hormone that’s important for supporting early stages of pregnancy. LH also stimulates the testes to make testosterone and produce sperm. The ovaries can convert testosterone to estrogen. It is these hormones that contribute to sexual development as we grow.
Prolactin: This is the hormone that contributes to many bodily functions however its primary action is on certain breast tissue development and lactation. The central nervous system, uterus, mammary glands, and immune system are also capable of producing prolactin. Factors that can contribute to increased prolactin within these tissues include stress, exercise, and nipple stimulation.
Thyroid Stimulating Hormone (TSH): TSH is a hormone that triggers the Thyroid gland to produce and release its own hormones – thyroxine (T4) and triiodothyronine (T3). Together these hormones help to maintain the body’s metabolic rate, digestive functions, heart function, muscle control, bone maintenance, and brain development. We’ll cover these hormones in more depth when we cover the Thyroid gland.
Posterior Pituitary Hormones
Antidiuretic Hormone (ADH, or vasopressin): this is a hormone that helps regulate the balance of water in the body, and the amount of urine the body makes. It does so by controlling the amount of water the Kidney’s reabsorb while they do their job of filtering waste from the blood. It also helps to control the amount of salt (or sodium) within the blood; therefore, it helps to control blood pressure.
Oxytocin: this hormone is made in the hypothalamus but stored and released within the pituitary. It manages aspects of male and female reproduction, can stimulate uterine contractions for childbirth and lactation following childbirth, and manages aspects of behavior. It’s associated with trust, recognition, relationships, sexual arousal, romantic attachment, and the bonding between parents and their infants. It is one of the few hormones that has a positive feedback loop, meaning that once it’s released it leads to the pituitary being stimulated to release even more.
Summary
The Hypothalamus and Pituitary arguably produce and regulate the majority of hormones within the body, many of which have the potential to affect overall health.
References:
Cleveland Clinic. (2022). Adrenocorticotrophic Releasing Hormone (ACTH). Retrieved from https://my.clevelandclinic.org/health/articles/23151-adrenocorticotropic-hormone-acth
Cleveland Clinic. (2023). Follicle-Stimulating Hormone (FSH). Retrieved from https://my.clevelandclinic.org/health/articles/24638-follicle-stimulating-hormone-fsh
Cleveland Clinic. (2022). Hormones. Retrieved from https://my.clevelandclinic.org/health/articles/22464-hormones
Cleveland Clinic. (2022). Human Growth Hormone (HGH). Retrieved from https://my.clevelandclinic.org/health/articles/23309-human-growth-hormone-hgh
Cleveland Clinic. (2022). Luteinizing Hormone. Retrieved from https://my.clevelandclinic.org/health/body/22255-luteinizing-hormone
Johns Hopkins Medicine. (n.d.). Pituitary Gland. Retrieved from https://www.hopkinsmedicine.org/health/conditions-and-diseases/the-pituitary-gland
Cleveland Clinic. (2022). Prolactin. Retrieved from https://my.clevelandclinic.org/health/articles/22429-prolactin
Cleveland Clinic. (2022). Oxytocin. Retrieved from https://my.clevelandclinic.org/health/articles/22618-oxytocin
Cleveland Clinic. (2022). Thyroid-Stimulating Hormone (TSH) Levels. Retrieved from https://my.clevelandclinic.org/health/articles/23524-thyroid-stimulating-hormone-tsh-levels