Endocrine 3: Prolactin Hormone (PRL) + Panhypopituitarism Flashcards
Cells secreting PRL
Mammotrophic acidophilic cells of Anterior pituitary gland
Nature of PRL hormone
Polypeptide (199aa), similar in structure to GH
Normal levels of PRL
- Male: 5ng/ml
- Female: 8ng/ml
Mechanism of Action of PRL hormone
Similar the GH:
* Homodimer receptor complex
* Activates JAK-STAT pathway
Enummerate Functions of PRL in females
- increases Caesin & lactalbumin proteins in milk secretion
- inhibit ovulation
Describe how prolactin (PRL) inhibits ovulation
it inhibts the effect on gonadotrophic hormones (LH & FSH) on the ovaries
Effect of lactation (PRL) on menstural cycle
- Inhibit ovulation = (temporary) Infertility
- therefore no menses =amenorrhea
excessive prolactin in males causes
sterility
factors causing Variations in PRL plasma levels
- Sleep: rises during sleep then plateaus when waking up
- Pregnency: rises gradully and reaches maximum during partrurition
- Suckling: produces sharp rises in prolactin (gradullay decreases after the first 3 months
- Stress: increases secretion
effect of stimulating nipple in non-pregnent females on PRL plasma levels
Mild increase by the stimulus
Prolactin inhibiting hormone is also known as ____
Dopamine
Explain indirect negative feedback mechanism of Prolactin secretion
- Prolactin secretion facilitates dopamine secretion from hypothalamus
- this then reduced prolactin secretion
Medications used in hyperprolactinemia
Dopamine agonists= bromocriptine
Medications used in hypoprolactinemia
Dopamine receptor blockers= Chlorpromazine
main cause of hyperprolactinemia
Adenoma
Effect of hyperprolactinemia in females
- amenorrhea (absence of mensturation)
- galactorrhea during non lactation periods
Effect of hyperprolactinemia in males
may produce sterility
Effect of hyperprolactinemia in both sexes
Decrease Libido
Sheehan syndrome in females is caused by ____
severe postpartum hemorrhage
other names for Panhypopituitarism
- Simmond’s disease
- Sheehan’s syndrome (in females after sever pph)
cause of Panhypopituitarism
Atrophy of all pituitary gland cells
effect of Panhypopituitarism
No GH,thyroid, Suprarenal, gonadal, prolactin
* Decreased GH function:
- progeria (premature greying of hair)
- severe decrease in bodyweight (emaciation)
- Dry wrinkled skin
- Shrunken hands & feet
* Decreased thyroid function: decrease BEE + anemia
* Decreased cortical functions:
- Hypoglycemia
- Hypotention
- weakness
* Decreased Gondatrophic function: amenorrhea & Sterility
