Down-regulation of prolactin receptors in the liver, mammary gland and kidney of female virgin rat, infused with ovine prolactin or human growth hormone.
Down regulation of prolactin (PRL) receptors resulting from i.v. infusion of oPRL or human growth hormone (hGH) into female virgin rats was demonstrated. A decrease of over 85% in the number of free receptors was achieved within 15 - 30 min using infusion of oPRL or hGH at 25 micrograms/h and remained at this level until the end of infusion. Ovine growth hormone or recombinant bovine growth hormone at ten-fold higher concentration had no effect at all. The decrease in the specific binding resulted from a lower number of binding sites and not from change in the dissociation constants. The decrease in the total receptors in the liver was more gradual and leveled off at 40 - 50% of the initial value. Our results suggest that a change in blood PRL or hGH level may lead to a new steady state in the number, occupancy and distribution of prolactin receptors.
D000818:Animals; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D007668:Kidney / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000378:metabolism*; D011388:Prolactin / Q000494:pharmacology*; D051381:Rats; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D011981:Receptors, Prolactin; D012756:Sheep
D011956:Receptors, Cell Surface; D011981:Receptors, Prolactin; D011388:Prolactin; D013006:Growth Hormone