Hypothalamus and Functions

Hypothalamus and functions The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions • The hypothalamus is a section of the brain that is responsible for the production of many of the body's essential hormones, chemical substances that help control different cells and organs • Hypothalamus functions including: 1-It has many functions that maintain chemical and temperature homeostasis 2-It functions with the limbic system 3-It Controls the release of hormones from the anterior and posterior pituitary 4- It synthesizes releasing hormones in cell bodies of neurons 5-Hormones are transported down the axon and stored in the nerve endings 6-Hormones are released in pulses Hypothalamic Releasing Hormones Seven releasing hormones are made in the hypothalamus incuding: – – – – – – – Thyrotropin-releasing hormone (TRH) Corticotropin-releasing hormone (CRH) Gonadotropin-releasing hormone (GnRH) Growth hormone-releasing hormone (GHRH) Growth hormone-release inhibiting hormone (GHIH) Prolactin-releasing factor (PRF) Prolactin-inhibiting hormone (PIH) AVP (Argenin vasopersin ) and Angiotensin II • 1-Thyrotropin-releasing hormone (TRH) • TRH is consisted of 3 Amino acids and Thyrotrophic cells of Anterior Pituitary are its target tissue • TRH induces the TSH hormons synthesis releasing from anterior Pituitary in circulation and • Increased TRH releasing will be inhibited by increased TSH and Thyroid hormones • 2-Corticotropin-releasing hormone (CRH) • CRH is consisted of 41 amino acids • Corticotropic cells of interior Pituitary is target for CRH  CRH induces the ACTH ( Adernocorticotropin hormone) synthesis and releasing in circulation from Corticotropic cells interior pituitary ( Hypohpysis) 3-Gonadotropin-releasing hormone (GnRH) • GnRH is consisted of 10 amino acids • Gonadotropic cells of anterior Pituitary is target for GnRH • GnRH induces the LH ( Luteinizing ) and FSH ( Follicular stimulating) hormones synthesis and releasing from Gonadotropic cells of anterior Pituitary in circulation • GnRH concentration in circulation are regulated by Sex hormones concentration • 4-Growth Hormon Releasing Hormon=GHRH • GHRH is consisted of 44 amino acids • Somatomatropic cells of anterior Pituitary is target of GHRH • • GHRH induces the GH hormone synthesis and releasing from anterior Pituitary in circulation • Whole body is target of GH hormone • 5-Growth Hormon Releasing Inhibitory Hormon=GHRIH)= SRIF ( Somatostatin) • SRIF is consisted of 14 amino acids • SRIF inhibits the GH and TSH hormones both synthesis and releasing from anterior Pituitary 6- Prolactin Releasing Hormon=PRH PRH is consisted of 198-199 amino acids Lactotropic cells of anterior Pituitary are target for PRH  PRH induces prolactin synthesis and releasing prolactin from Lactotropic cells in circulation • Prolactin Releasing inhibitory Hormon=PRIH • PRIH is consisted of 56 amino acids • Lactotropic cells anterior Pituitary are the PRIH target • PRIH inhibits the prolactin trancription, synthesis and releasing from Lactotropic cells • Prolactin transcription, synthesis and releasing from lactotropic cells also are inhibited by dopamin • Dopamin is released from hypotalamus and inhibit the prolactin synthesis and secretion from anterior pituitary lactotrop AVP (Argenin vasopersin ) and Angiotensin II are other hypotalamus hormones • AVP consisted of 9 amino acids • AVP induces the CRH effect for ACTH realease • Angiotensin II consisted of 8 amino acids • Angiotensin II inhibites the CRH effect for ACTH release Hypothalamus Hormones Secretion is influenced by : • Is influenced by emotions • Can be influenced by the metabolic state of the individual • Their secretion are pulsatile How do Hypothalamus Hormones function in signal transducting ? They ( Hypothalamus Hormones )function via cAMP and phosphotydil inositol triphosphate pathways How do they inactivate? 1- By lysosomal hydrolysing 2-by deletion of pyroglutamic acid at C terminal of hormones