By

H.Khorrami Ph.D.

http://khorrami1962.spaces.live.com khorrami4@yahoo.com

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

Prolactin

Biologically active

Immunoreactive Some patients with hi prolactin has no galactorhea

Prolactin

Little 22000mw

Big 50000mw lower activity

Big-big 100000mw lower activity

Glycosylated 25000mw

Prolactin actions

Stimulate learning

Stimulate immune responses

Reduce body temperature

Stimulate corticosteroid secretions

Testosterone productions Maintain LH receptors

Prolactin stimulate transcription of mRNA of

Casein

Lactalbumin

Beta-lactoglobulin

Galactosyl transferase

N-acetyl lactosamine synthetase

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

PIF

Dopamine

GnRH-associated peptide

Prolactin stimulators

TRH

Oxytocin

VIP

ACTH

Beta-LPH

Estrogen

GnRH

GHRH

Histamine(H1)

Cimethidine(H2antagonist)

Angiotensin II

Bombesin

Secretin

Gastrin

Galanin

Calcitonin

Melatonin

Platelet-activating F

Epidermal GF

α-MSH

Prolactin increases with

Puberty (female)

Pregnancy

Near the term 10fold

Puerperium

Nursing

In fetus higher than

mother near the term

Neonate 2-3 week after birth

Feeding

Exercise

Stress

Hypoglycemia

Surgical stress

Orgasm(10fold)

Nocturnal sleep

Plasma prolactin concentration during & after dopamine infusion in normal male/female subjects

Effect of L-dopa on PRL secretion

Serum PRL & cortisol in normal fasting volunteers before

& after regular mixed meal or sham*

*Seeing and chewing

Acute elevation of PRL after sleep

Prolactin levels in pregnant women

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

Relaxin and prolactin on myometrial activity

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)

Hyperprolactinemia

Is more frequent in girls with: Father absent

Alchoholic father

As a psychosomatic reaction

Pseudopregnancy

This is MARS

But we have one EARTH yet!