Hypothalamus and Pituitary Gland Hormones

What sample is needed for the hormones of the hypothalamus and pituitary glands?

1. The most commonly used sample is serum.
2. In some cases, 24 hours urine sample is collected.

What are the indications for hypothalamus and pituitary gland hormones?

1. These hormones are estimated for:
   1. Diagnostic purposes.
   2. For a therapeutic reason.
   3. To evaluate ovulation.
   4. To evaluate spermatogenesis.
   5. To treat endometriosis and uterine fibroids.
   6. To evaluate precocious puberty.
   7. To treat prostatic carcinoma.
   8. To find GH deficiency.

Hypothalamus:

How will you discuss the pathophysiology of the Hypothalamus?

1. The hypothalamus is a very important organ for the body.
   1. It is located below the thalamus and above the pituitary gland.
   2. It is the floor and part of the third ventricle.
   3. It is connected to the pituitary gland through the infundibulum.  (pituitary stalk).
   4. It is the main organ linking the nervous and endocrine systems.
2. Hormones communicate between cells and depend upon neuronal and endocrine signals to regulate body functions.
3. Hormones are chemical substances that are formed in various glands.
4. These hormones stimulate or inhibit the growth or function of other tissues and organs.

What are the Hypothalamus Hormones?

1.  Corticotropin-releasing hormone (CRH).
   1. This hormone will stimulate the production and secretion of ACTH by the anterior pituitary gland.
2.  Thyrotropin Releasing Hormone (TRH).
   1. This hormone stimulates the anterior pituitary gland to produce and secrete TSH and prolactin.
3. Gonadotropin-releasing hormone (GnRH).
   1. This hormone stimulates the anterior pituitary gland to produce and secrete FSH and LH.
4. Growth hormone-releasing hormone  (GRH).
   1. This hormone stimulates the anterior pituitary gland to produce and secrete GH.
5. Growth hormone inhibiting hormone (GIH).
   1. This hormone inhibits the anterior pituitary gland’s production and secretion of GH and TSH.
6. Prolactin inhibiting factor (PIF).
   1. This neurotransmitter inhibits the production and secretion of prolactin, TSH, FSH, LH, and GH by the anterior pituitary gland.

What are the functions of the hypothalamus?

1. It controls the autonomic nervous system and regulates:
   1. Heart rate.
   2. Blood pressure.
   3. Digestion.
   4. Temperature.
   5. Sweating.
2. It regulates the endocrine system through the hypothalamic-pituitary axis.
3. The hypothalamus acts as a thermostat.
   1. The anterior hypothalamus leads to heat loss.
   2. The posterior hypothalamus leads to heat conservation.
4. The hypothalamus regulates the sleep cycle.
   1. It functions like a biological clock.
5. When it is damaged by any means leads to:
   1. Diabetes inspidus.
   2. Sleep disorder.
   3. Obesity.
   4. Hormonal abnormalities.
   5. Temperature variations.

What are the functions of the pituitary gland hormones?

1. Hypophysis regulates the endocrine system. The pituitary gland is called the master endocrine organ.
2. It occurs by integrating signals from the brain with feedback from blood hormone concentrations, leading to intermittent hormone release from the target endocrine glands.
3. These hormones regulate:
   1. Growth.
   2. Thyroid functions.
   3. Adrenal gland functions.
   4. Gonadal functions.
   5. Water and salt homeostasis.
4. Vasopressin (an antidiuretic hormone,  ADH) and oxytocin are produced in the hypothalamus and stored in the posterior pituitary lobes.
   1. So, the posterior pituitary gland (neurohypophysis) is not a gland but a storage site for ADH and oxytocin.

How would you describe the Anterior Pituitary Gland?

1. The pituitary gland consists of three lobes:
   1. The anterior lobe is called the adenohypophysis.
   2. The posterior lobe is called the neurohypophysis.
   3. There is a middle lobe as well.
2. This gland is present at the base of the skull in a bone cavity called the sella turcica.
3. The gland is small, measuring 1 cm or less in width/height and weighing 500 mg.
4. Most pituitary gland hormones are proteins (consisting of peptides) or peptides (short chains).

5. The cells of the anterior lobes of the pituitary glands are divided into:
   1. Acidophilic cells that stain with acidic stains are around 40%.
   2. Basophilic cells stain with basic dyes and account for around 10%.
   3. Chromophobic cells do not stain with either acid or basic dyes and are around 50%.

How will you divide cells by Immunohistochemistry and hormones secreted?

6. Secretion of the hormones from the anterior pituitary glands is controlled by the hypothalamus.
7. The hypothalamus secretes small peptides that are known as releasing or inhibitory factors.

What are the inhibitory chemicals for the hormones?

What are the Anterior pituitary hormones?

1. Adrenocorticotropic hormone (ACTH).
   1. This hormone stimulates cortisol secretion by the adrenal gland.
2. Growth Hormone (GH).
   1. This hormone promotes growth in soft tissue, cartilage, and bone.
3. Thyroid-stimulating hormone (TSH).
   1. This hormone stimulates the secretion of the thyroid hormones T3 and T4 by the thyroid gland.
4. Prolactin Hormone (PRL).
   1. This hormone’s main role is in the initiation and maintenance of lactation.
   2. Prolactin induces ductal growth, the lobular alveolar system, and the synthesis of milk production.
5. Follicle-stimulating hormone (FSH).
   1. This hormone controls the functional activity of the gonads.
   2. In males, this stimulates spermatogenesis.
   3. Females stimulate the growth of ovarian follicles in the presence of LH. This promotes estrogen secretion by the mature follicle.
6. Luteinizing hormone (LH).
   1. This hormone controls the functional activity of the gonads.
   2. Males produce testosterone through the Leydig cells of the testes.
   3. In females, it leads to the release of the ovum from the ovarian follicle, in which FSH ripens.
   4. It transforms the follicle into a corpus luteum that secretes progesterone.

What are the Posterior Pituitary Gland hormones?

1. Antidiuretic Hormone (ADH):

1. This maintains water homeostasis.
2. It increases water reabsorption by the distal tubules and collecting ducts of the kidneys, increasing urine concentration.
3. This also leads to vasoconstriction, which increases blood pressure.

2. Oxytocin:

1. This will stimulate uterine contraction during labor.
2. This may be used to induce labor.
3. It helps the breasts to release milk from the mammary ducts.