Hypothalamic–pituitary hormone

Hypothalamic–pituitary hormones are hormones that are produced by the hypothalamus and pituitary gland. Although these organs are relatively small, the hormones have effects throughout the body. They can be classified as a hypothalamic–pituitary axis (HP axis) of which the adrenal (HPATooltip hypothalamic–pituitary–adrenal axis), gonadal (HPGTooltip hypothalamic–pituitary–gonadal axis), thyroid (HPTTooltip hypothalamic–pituitary–thyroid axis), somatotropic (HPSTooltip hypothalamic–pituitary–somatotropic axis), and prolactin (HPPTooltip hypothalamic–pituitary–prolactin axis) axes are branches.

Illustrative diagram — The Hypothalamus-Pituitary Complex

*Hormones of the hypothalamic-pituitary-end organ axis*^[1]
	HPT axis	HPA axis	HPG axis	HPS axis	HPP axis
Hypothalamic hormone	TRHTooltip Thyrotropin-releasing hormone	CRHTooltip Corticotropin-releasing hormone	GnRHTooltip Gonadotropin-releasing hormone	GHRHTooltip Growth hormone-releasing hormone	Dopamine (inhibitor)
Pituitary cells	Thyrotrope	Corticotrope	Gonadotrope	Somatotrope	Lactotrope
Pituitary hormone	TSHTooltip Thyroid-stimulating hormone	ACTHTooltip Adrenocorticotropic hormone	LHTooltip Luteinizing hormone and FSHTooltip Follicle-stimulating hormone	GHTooltip Growth hormone	Prolactin
End organ	Thyroid	Adrenal	Gonads (testes or ovaries)	Liver	Mammary gland
Product	Thyroxine	Cortisol	Testosterone, estradiol	IGF-1Tooltip Insulin-like growth factor 1	Milk (no feedback)

The function of these hormones may be altered by physical activity.^[2]

Details

ADH (vasopressin) and oxytocin are stored and released by the posterior pituitary.

The anterior pituitary is an amalgam of hormone-producing glandular cells. Unlike the posterior, the neurosecretory cells in the anterior pituitary synthesize their own hormones, which are transported through the pituitary portal system. These hormones are prolactin, growth hormone, TSH, adrenocorticotropic hormone, FSH and LH. Some have targets in glands and some have direct function.

Conditions related to the limbic system regulate hormone release. The thalamus may also, with pain. Many of these stimuli come from the senses. Temperature control can be found in the hypothalamus. These hormones also regulate water balance and hunger, and are associated with water balance control (ADH). Other examples:

Corticotropic releasing hormone CRH: stimulates ACTH secretion
Thyrotropin releasing hormone (TRH): stimulates TSH and prolactin secretion
Growth hormone releasing hormone (GHRH): stimulates GH secretion
Somatostatin: inhibits GH (and other hormone) secretion
Gonadotropin releasing hormone (GnRH): stimulates FSH and LH secretion
Prolactin releasing hormone (PRH): stimulates PRL secretion
Prolactin inhibiting hormone (dopamine): inhibits PRL secretion

These hypothalamic hormones are secreted in pulse. They act on specific membrane receptors. They are also glycoproteins. They stimulate

release of pituitary hormones
synthesis of pituitary hormones
release of stored pituitary hormones
hyperplasia
hypertrophy

The anterior pituitary produces prolactin, GH, TSH, ACTH, FSH, and LH. 15–20% of corticotroph cells, produce ACTH. The targets are the adrenal glands, adipocytes and melanocytes. 3–5% thyrotroph cells, produce TSH. 10–15%, Gonadotroph, produce LH and FSH, 40–50% somatotroph, produce GH in particular in childhood. 10–15% are lactotrophic and produce prolactin.

References

↑ Melmed S, Jameson JL (2005). "Disorders of the anterior pituitary and hypothalamus". In Kasper DL, Braunwald E, Fauci AS, et al. (eds.). Harrison's Principles of Internal Medicine (16th ed.). New York, NY: McGraw-Hill. pp. 2076–97. ISBN 0-07-139140-1.
↑ Bobbert T, Brechtel L, Mai K, et al. (November 2005). "Adaptation of the hypothalamic-pituitary hormones during intensive endurance training". Clinical Endocrinology. 63 (5): 530–6. doi:10.1111/j.1365-2265.2005.02377.x. PMID 16268805.

[MelmedJameson-1] Melmed S, Jameson JL (2005). "Disorders of the anterior pituitary and hypothalamus". In Kasper DL, Braunwald E, Fauci AS, et al. (eds.). Harrison's Principles of Internal Medicine (16th ed.). New York, NY: McGraw-Hill. pp. 2076–97. ISBN 0-07-139140-1.

[pmid16268805-2] Bobbert T, Brechtel L, Mai K, et al. (November 2005). "Adaptation of the hypothalamic-pituitary hormones during intensive endurance training". Clinical Endocrinology. 63 (5): 530–6. doi:10.1111/j.1365-2265.2005.02377.x. PMID 16268805.

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