title: Down-regulation of prolactin receptors in the liver, mammary gland and kidney of female virgin rat, infused with ovine prolactin or human growth hormone.
abstract: 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.
mesh_terms: 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
chemical_list: D011956:Receptors, Cell Surface; D011981:Receptors, Prolactin; D011388:Prolactin; D013006:Growth Hormone