class anterior pituitary hormones 15 th march 2014 2
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Dr. RAGHU PRASADA M SMBBS,MDASSISTANT PROFESSOR
DEPT. OF PHARMACOLOGYSSIMS & RC.
ANTERIOR PITUITARY HORMONES
Regulation of anterior pituitary function
Hormones are chemical substances which are synthesized by specific endogenous glands and secreted internally, directly into the blood stream, to act far away from the site of their production and release on the specific target organs. Ex- TSH
Tropic hormones-- target other endocrine glands to release their own hormones. Ex TRH
1. Hypophysiotropic hormones (Neuro-secretions) into the hypothalamo-hypophyseal portal system—
2. Include TRH, GnRH3. These hormones are clustered in discrete hypothalamic
nuclei4. Hypothalamic hormones travel in portal system from
hypothalamus to anterior pituitary5. Hypothalamic hormones regulate hormones secretion
by anterior pituitary
Hypophysiotropic Hormones
Hypothalamopituitary axis Hypothalamic releasing factors Somatotrophs Lactotrophs Gonadotrophs Luteinizing hormone corticotrophs
Regulation of anterior pituitary function
Primarily by the CNS– All pituitary hormones except PRL would decline in the absence of the hypothalamus
By hormones produced in peripheral target glands Example– inhibin secreted from gonads All anterior pituitary hormones secreted in a diurnal
pattern.
Regulation of anterior pituitary function
Short negetive feed back
Long negetive feed back
1. 3.
2.
hormonal families of the anterior lobe:
Glycoprotein hormone family– TSH, FSH, LH
TSH– to stimulate the secretion of thyroid hormone 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
Anterior Pituitary or Adenohypophysis
Hypo-secretion:During childhood causes
Dwarfism Hyper-secretion:
During childhood causesGigantism (up to 8 – 9 ft.)
During Adulthood causesAcromegaly:
Enlargement of the small bones of the hand and feetEnlargement of the cranium, nose, and lower jawTongue, liver, and kidneys become enlarged
Control of GH secretion
By both Growth hormone releasing hormone (GHRH; from arcuate nuclei mainly); its gene is expressed in the GI tract and the pancreas
and by somatostatin (Growth hormone release inhibiting hormone) (from preoptic periventricular and paraventricular nuclei); its gene is expressed in GI tract and the pancreas
Ghrelin (a peptide from the Arcuate Nuclei) also increase GH secretion via GHRH
Ghrelin is also synthesized in the stomach and is thought to signal feeding behavior
Growth hormone analogues and GHRIH
SERMORELIN-Synthetic analogue of GnRHSOMATOSTATIN-GHRIHOCTREOTIDE-long acting analogue of somatostatinDose-20-200mg sc TDS-carcinoid syndromeBleeding oesophageal varicesTreatment of AIDS associated diarrhoeaInsulinomasSANDOSTATIN-slow release formulation
ADR-steatorrrhoea, gall stones
LANREOTIDE
GHRIH -thyroid tumours Acromegaly
PEGVISOMANT-sc New GH-receptor antagonist-acromegaly Suppress IGF-1 levels -allows dimerisation and blocks the ongoing
conformational changes Demerit- formation of antibodies
Pharmacological actions
Protein synthesis Anabolic effects Somatomedins –IGF1, IGF2 Metabolic consequence insulin like effect
antagonistic to ILEeffect antagonistic to insulin IGF1-released from liverpositive feedback on
hypothalamusGHRIH Increase-GH- sleep, exercise Decrease-L-dopa
Somatotropin
-t1/2-25 minSc-0.2mg/kgAIDSBurn injuriesAnt agingADR-insulin resistanceArthralgia
MECASERMIN
Recombinant human IGF1+ recombinant human IGFBP-3
Maintain desired t1/2 of IGF -short statured children Dose-0.04-0.08 mg/kg ADR-hypoglycemia
Gonadotropins
GnRH-LHFSH-inhibin, activinFSH in females, LH in females
Feed backGonadorelin- synthetic
GnRH agonists
Leuprolide Nafarelin Buserelin Dosrelin Goserelin Triptorelin
GnRH antagonist
Cetrorelix Ganirelix AbarelixDegarelixUses -advanced prostate caUterine fibroids and endometriosisIVF
Natural gonadotropins
From post menopausal womenMenotropinUrofollitropinRecombinant FSHHCGUSES
-infertilityCryptorchismIVFKaposi sarcomaDiagnostic use
Adrenocorticotropin family ACTH (adrenal corticotropic hormone) regulates
hormone secretion by the cortex of the adrenal glands.
ACTH- stimulates –Glucocorticoids, mineralocorticoid and androgens
ACTH-stimulated by trauma and stress
Melanocytes and keratinocytes pigmentation by MSH
(Melanotrope in arcuate neurons)– food intake
Adrenocorticotropin family
Hypo-secretionAddison’s disease –
Simmond’s disease, hypo pituitary cachexia
Hyper-secretion:Cushing’s Syndromemobilization of fat from lower body to the thoracic and upper abdominal regions giving raise to “Buffalo Torso”
COSYNTROPIN
Is a synthetic human ACTH Diagnosis of pituitary adrenal axis ADR- similar to corticosteroids Allergic reactions
Prolactin
Peptide hormone PRIH-PRL release inhibitory hormone-D2 Stimulus for prolactin-suckling mammotropic and lactogenic
Hyperprolactinemia-galactorrhoea, amenorrhea , infertility
Treatment of hyperprolactinemia
Bromocriptine -2.5mg orally-15days Cabergoline-0.25mg orally -BD Pergolide- Quinagolide-0.2-0.6mg/day
OT (oxytocin) and ADH produced in hypothalamus transported by hypothalamo-hypophyseal tract to
posterior lobe (stores/releases hormones)
Posterior Pituitary Hormones