Prolactin Flashcards
What kind of hormone is prolactin?
A long chain polypeptide hormone
Where is prolactin produced?
Anterior pituitary gland by the lactotrophs
Which cells produce prolactin?
Lactotrophs
Which hormones is prolactin similar to?
Growth hormone
Human placental lactogen
(These are all long chain polypeptides)
Which hormone stimulates lactotroph growth?
Oestrogen
How does the hypothalamus influence prolactin secretion?
It is predominately inhibitory
What is the main neurohormone to inhibit prolactin?
Dopamine
Which hormones inhibit prolactin?
Dopamine and somatostatin
What factors increase prolactin secretion?
Thyroid releasing hormone Oestrogen Pregnancy Lactation (suckling) Opioids Dopamine d2 antagonists Sleep stress hypoglycaemia, exercise
On which xsome is prolactin located?
Xsome 6
Primary functions of prolactin
Breast development
Lactogenesis
Which hormones does prolactin inhibit?
Testosterone and oestrogen
Which pathologies lead to an increase in prolactin?
Pituitary tumour, hypothyroidism, chronic renal and liver failiure
Which drugs inhibit prolactin secretion?
Dopamine agonists
What kind of drug is aripiprazole and how does it affect prolactin production?
Dopamine agonist used in Parkinson’s disease, it inhibits prolactin secretion
What is verapamil?
A calcium channel blocker used to control blood pressure
What does verapamil do to prolactin production?
It increases it
Which hormone causes milk ejection reflex?
Oxytocin
When do prolactin levels reach their peak in breastfeeding?
30 mins after onset of suckling
At which point of the day are prolactin levels at their highest?
Evening and sleeping
How many amino acids make up prolactin?
198
How might an epileptic seizure effect prolactin levels?
They rise
What is the molecular weight of prolactin?
24000 daltons
What is the effect of metoclopramide on prolactin secretion?
It stimulates prolactin secretion (dopamine antagonist)
What is the effect of haloperidol on prolactin secretion?
Stimulates (dopamine antagonist)
What is the effect of chlorpromazine on prolactin?
Stimulates
What is the effect of diazepam on prolactin?
Stimulates
What is the effect of domperidone on prolactin production?
Stimulates
Where is prolactin produced?
Anterior pituitary gland
Which hypothalamic nuclei influence prolactin release?
The arcuate nucleus inhibits prolactin by releasing dopamine
The paraventricular nucleus stimulates prolactin by releasing thryrotropin releasing hormone
How does the paraventricular nucleus of the hypothalamus influence prolactin release?
It releases thyrotropin releasing hormone which stimulates prolactin release from the lactotropes of the anterior pituitary gland
Impact of oestrogen on prolactin release
Inhibits arcuate nucleus release of dopamine and directly stimulates the lactotropes to release prolactin
Which cells in the breast does prolactin act on?
alveolar cells in the lobules - to stimulate formation of milk proteins and stimulation of channels for ions and electrolytes, IgA, cholesterol, vitamins etc.
Which type of immunoglobulin is found in breast milk?
IgA
Stimulants of prolactin production
Oestrogen
Breast feeding/suckling
Pregnancy
TRH
What is the impact of oestrogen on prolactin in pregnancy
Stimulates prolactin production but inhibits its effect on the aveolar cells, when oestrogen levels drop after pregnancy, the prolactin can act on the aveolar cells of the breast lobules to produce milk
What impact does bromcriptine have on prolactin production?
Inhibitory
What impact does carbergoline have on prolactin production?
Inhibitory
What impact does metoclopramide have on prolactin production?
Stimulatory
What impact does domperidone have on prolactin production?
Stimulatory
What kind of drug is bromocriptine?
A dopamine agonist
What is bromocriptine used for?
Treatment of acromegaly, hyperprolactinaemia, Parkinson’s disease
What kind of drug is carbergoline?
Dopamine receptor agonist
What is carbergoline used for?
Parkinson’s disease, lactate suppression, hyperprolactinaemia
What kind of drug is metoclopramide?
Dopamine D2 receptor antagonist
What kind of drug is domperidone?
Dopamine D2 receptor antagonist
What part of the breast does prolactin develop?
The alveolar tissue
What is the effect of prolactin on oestrogen and testosterone?
Inhibitory
Which hormone stimulates prolactin production by the anterior pituitary gland?
Thyroid releasing hormone
What is the effect of hypothyroidism on prolactin levels?
Hypothyroidism causes an increase in TRH and therefore an increase in prolactin leading to hyperprolactinaemia
