Hormones of epiphysis

Melatonin

Melatonin is formed in epiphysis (pineal gland). It is derivative of tryptophan. (5-OH-TryàSerotoninàMelatonin). So, melatonin is acetylserotonin.

Melatonin carries out next functions:

1) promotes fast phase of sleep

2)increases the secretion of Growth hormone

3)influences on sexual function breaking secretion of gonadotropic hormes

4)stimulates immune system

5)decreases blood pressure and level of total cholesterol in blood plasma

6)stops division of tumor cells

7)promotes rejuvenation due to antioxidant action

Hypothalamic hormones

In the cells of hypothalamus neurosecretins are produced. These are liberins (releasing-factors) and statins. These hormones act on secretion of pituitary hormones: liberins enhance their secretion; statins inhibit its.

Liberins are next:

1) somatoliberinàgrowth hormone (GH)

2) corticoliberinàadrenocorticotropic hormone (ACTH)

3) lu-liberinàfollicle-stimulating hormone (FSH) and luteinizing hormone (LH)

4) prolactoliberinàprolactin

5) melanoliberinàmelanocyte-stimulating hormone (MSH)

6) thyroliberinàthyroid-stimulating hormone (TSH) and prolactin

Statins are next:

1) somatostatinàGH

2) gonadotropin-inhibiting hormoneàFSH and LH

3) prolactostatinàprolactin

4) melanostatinàMSH

all hormones of hypothalamus are peptides and act on 1-st mechanism

Vasopressin (antidiuretic hormone)

This hormone is formed in hypothalamus, but deposited in neurohypophysis.

The chemical nature:cyclic nanopeptide

Target-cells:vessels and renal tubules

The mechanism of action: there are V1 and V2 receptors. V1-receptors are located in peripheral vessels and they’re associated with phospholipase C (phosphoinositol-calcium signal system). V2-receptors are located in renal tubules and they’re associated with adenylylcyclase and specific proteins of tubules – aquaporins.

The physiologic action:

1) constriction of peripheral vessels (hence its name). This action is due to V1-receptors

2) reabsorption of water in kidneys (hence its second name – antidiuretic hormone)

Oxytocin

is formed in hypothalamus, but deposited in neurohypophysis.

The chemical nature:cyclic nanopeptide

Target-cells: smooth muscles of uterus and mammary glands

The mechanism of action:1-st, through c.AMP

The physiologic action:constriction of muscles of uterus and promote output of milk

Vasopressin and oxytocin act on mental functions, therefore they’re mention-peptides