Prolactin

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Prolactin

  1. 1. By H.Khorrami Ph.D. http://khorrami1962.spaces.live.com khorrami4@yahoo.com
  2. 2. Prolactin  By lactotrop cells (20% in both sexes)  A single chain polypeptide hormone  199 AA  3 disulphide bridges  Half life:20-30min  Single gene on chromosome 6  More than 300 effects  Mostly by modulation
  3. 3. Prolactin  Biologically active  Immunoreactive  Some patients with hi prolactin has no galactorhea
  4. 4. Prolactin  Little 22000mw  Big 50000mw lower activity  Big-big 100000mw lower activity  Glycosylated 25000mw
  5. 5. Prolactin actions  Stimulate learning  Stimulate immune responses  Reduce body temperature  Stimulate corticosteroid secretions  Testosterone productions  Maintain LH receptors
  6. 6. Prolactin stimulate transcription of mRNA of  Casein  Lactalbumin  Beta-lactoglobulin  Galactosyl transferase  N-acetyl lactosamine synthetase
  7. 7. Prolactin inhibitors  Dopamine from arcuate nucleus & VMN  On D2 receptor  Decrease cAMP  Blocked by estrogen  Blocked by phenothiazine or metoclopramide  GnRH-associated peptide  Histamine(H2)  Diphenhydramine((H1blocker)  GABA  SST  Ach  Bromocryptine
  8. 8. PIF  Dopamine  GnRH-associated peptide
  9. 9. Prolactin stimulators  TRH  Angiotensin II  Oxytocin  Bombesin  VIP  Secretin  ACTH  Gastrin  Beta-LPH  Galanin  Estrogen  Calcitonin  GnRH  Melatonin  GHRH  Platelet-activating F  Histamine(H1)  Epidermal GF  Cimethidine(H2antagonist)  α-MSH
  10. 10. Prolactin increases with  Puberty (female)  Feeding  Pregnancy  Exercise  Near the term 10fold  Stress  Puerperium  Hypoglycemia  Nursing  Surgical stress  In fetus higher than  Orgasm(10fold) mother near the term  Nocturnal sleep  Neonate 2-3 week after birth
  11. 11. Plasma prolactin concentration during & after dopamine infusion in normal male/female subjects
  12. 12. Effect of L-dopa on PRL secretion
  13. 13. Serum PRL & cortisol in normal fasting volunteers before & after regular mixed meal or sham* *Seeing and chewing
  14. 14. Acute elevation of PRL after sleep
  15. 15. Prolactin levels in pregnant women
  16. 16. Lactation 1. Mammogenesis  Estrogen, Progesterone 2. Lactogenesis  Estrogen, Progesterone, prolactin, Placental lactogen, Growth hormone, Insulin, Cortisol, T3, T4 3. Galactopoiesis  Prolactin, oxytocin  Estrogen increase the number of lactotropes
  17. 17. Relaxin and prolactin on myometrial activity
  18. 18. Hyperprolactinemia effects  Stimulate dopamine turnover in some brain areas  Nucleus accumbens  Decrease dopamine turnover in some brain areas  Substantia nigra  Stimulate learning  Stimulate immune response  Stimulate oxytocin  Stimulate opioidergic system  Decrease gonadotropins  Decrease testosterone in male(indirect)  Decrease libido in both sex (impotence)  Reduce bone mineral density (osteoporosis)
  19. 19. Hyperprolactinemia  Is more frequent in girls with:  Father absent  Alchoholic father  As a psychosomatic reaction  Pseudopregnancy
  20. 20. This is MARS But we have one EARTH yet!

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