pituitary hormones. turkish saddle intermediate lobe
TRANSCRIPT
Pituitary Hormones
Turkish saddle
Intermediate Lobe
(I) somatotropes that secrete GH (2) mammotropes that secrete PRL (3) thyrotrophs that secrete TSH (4)gonadotropes, single cells that
secrete both gonadotropins LH and FSH (5) corticotropes that secrete both ACTH and ß-LPH
1- Growth Hormone Family (GH, PRL, CS)
2- Glycoprotein Family(TSH,LH,FSH,HCG)
3- POMC Family (ACTH,ß-LPH, Endorphins)
GH Receptor and jak2
From: Herrington & Carter-Su (2001)
GH signalling
From: Herrington & Carter-Su (2001)
GHIH (or)
SST (somatostatin)
(-)
Anterior Pituitary:
Hypothalamus: GHRH
(+)
GH(somatotropin)
Liver: IGF (somatomedins)
(+)
(-)
GROWTH HORMONE
direct effectsindirect effects
lipolysis in fat cells
+
carbohydratemetabolism
+
Insulin-like Growth Factor
+
muscle
chondrocytes
Protein synthesis
cartilage formation
Increases FFA, glycerol, and sugars in circulation
BrainPituitary
Liver
IGF
IGF binding proteins (IGFBPs)
Growth
Growth Hormone (GH)
IGFBPs bind circulating IGF with high affinity & specificity
Functions:1. act as carriers of IGF in plasma2. prolong the half-life of IGF in circulation3. regulate IGF access to receptor in
extracellular fluid (!)
1. IGFBP-3most abundant form of IGFBPmain carrier of IGF in circulationpromotes IGF mediated somatic growthhigh IGFBP-3 associated growth stimulation
2. IGFBP-1typically present in small amountshigh IGFBP-1 associated growth inhibition
IGFBP-3
IGF
IGF receptor
LIVER
Cell
Growth Functions
Growth Functions
Cell
IGF receptor
LIVER
IGFBP-1
IGF
Growth Hormone Direct effects:
Lipolysis Carbohydrate metabolism Increase IGF secretion from liver
Indirect effects through IGF Increase protein synthesis in muscle Increase cartilage formation and growth in bone
IGFBPs IGFBP3 enhances growth IGFBP1 inhibits growth
Overproduction of GH Underproduction of GH End-organ resistance
Overproduction of GH Acromegaly gigantism
Underproduction of GH panhypopituitarism
Stress-induced dwarfism End-organ resistance
BrainPituitary
Liver
IGF
IGF binding proteins (IGFBPs)
Growth
Growth Hormone (GH)
GCs
Defective GH receptor recessive gene Lethal in males
Pygmy
GAP
Hyperprolactinemia
chronic renal failure, hypothyroidism, polycystic ovary syndrome .
prolactinoma
Galactorrhea, irregular menses or infertility
headaches
1. TSH– to stimulate the secretion of thyroid hormone
2. FSH & LH– important for the function of the testes and the ovaries
FSH– growth of ovarian follicles and formation of sperm
LH (in women)– induce ovulation and the formation of the corpus luteum; stimulate the ovarian production of estrogen and progesterone
LH (in men)– stimulates the production of Testosterone;
1. 2 peptide subunits– alpha + beta2. The three glycoprotein hormones and
hCG (Human chorionic gonadotropin; a placental hormone) all share the same alpha subunit.
3. Both subunits need to be present to be functional.
4. Beta subunits are encoded in separate genes located on different chromosomes.
4 Glycoproteins– all of them share a common alpha subunit
Pro-opiomelanocortin (POMC), a gene, products
Melanocyte-stimulating hormone (MSH)Corticotropin-like intermediate lobe peptide (CLIP)
P. convertases