Relationships among hypothalamic releasing and inhibiting hormones, the anterior pituitary hormones controlled by hypothalamic hormones, and their respective target organs or tissues.
Its 198 amino acid, single chain peptideMW-23000Secreted by lactotroph(mammotroph) cells
Hyperprolactinaemia
Galactorrhoea-Amenorrhoea-infertility syndrome
Causes of hyperprolactinaemia
-disorders of hypothalamus removing inhibitory control over pituitary
-Antidopamenergic and DA depleting drugs
-Prl secreting tumours
-Hypothyroidism with high TRH levels- inc. Prl secretion.
Bromocriptine
-Ergot derivative, 2-bromo-α-ergocryptine-potent dopamine agonist
Action
↓ Prl release from Pituitary
↓ GI motility
↑ GH release
HypotentionStimulate D2 receptor in
CTZ
Levodopa like action in CNS
Start at low dose 1.25 mg BD
1.Hyperprolactinemia
2.Acromegaly
3.Parkinsonism
Side effectsEarly- Nausea, vomiting, constipation etcLate- behavioral alterations, mental confusion.
Anterior pituitary secrets two Gns
FSH & LH
Function- promote gametogenesis and secretion of gonadal hormones.
FSH- in female
in male
Induces follicular growthDevelopment of ovamSecretion of estrogens
Supports spermatogenesis
Ovarian and testicular atrophy
LH
In Females-
In male-
Progesteron secretion occurs only under the influence of LH.
Induces preovulatory swelling of the ripe graafian follicle and triggers ovulation
Stimulates testosterone secretion
Disturbances of Gn secretion- Delayed puberty in girls and boys
Inadequate Gn secretion – amenorrhoea & sterility in women impotence and infertility in men
Uses1.Amenorrhoea and infertility
2.Hypogonadotrophic hypogonadism in males
3.Cryptorchism
4. To aid in vitro fertilization
Adverse effects
ovarian hyperstimulation- polycystic ovary, pain in lower abdomen
It is 210 amino acid, two chain glycoproteinMW 30000
FUNCTIONS
Stimulates thyroid to synthesize and secrete thyroxin (T4) & Triiodothyronin (T3)
-Induces hyperplasia & hypertrophy of thyroid follicles
-Promotes trapping of iodide by thyroid
-Promotes organification of trapped iodine & its incorporation into T3 & T4 By increasing Peroxidase activity
-Enhances endocytotic uptake of thyroid colloid by the follicular cells
-Proteolysis of thyroglobulin to release more T3 & T4.
39 amino acid single chain peptide
MW- 4500
Derived from larger peptide pro-opio melanocortin (MW 30,000)
Function- - promotes steriodogenesis in adrenal cortex by stimulating formation in cortical cells- Increase the availability of cholesterol for conversion to pregnenolone
Excess production- Cushing’s syndrome
USES
Diagnosis of disorders of pituitary adrenal axis
Injected 25 IU i.v. causes increase in plasma cortisol if adrenals are functional.