Downregulation of adrenocortical cyclo (His-Pro)-binding sites by cyclo (His-Pro) administration to neonatal but not adult rats.
The specific binding of [3H-Pro]cyclo (His-Pro) to a 27,000 g pellet fraction from rat adrenal gland was studied. Binding sites were exclusively localized in the cortical region of the adrenal gland and exhibited a binding affinity (Kd) of 1.79 +/- 0.21 microM and maximal binding capacity (Bmax) of 123.4 +/- 10.2 pmol/mg protein. In vivo administration of cyclo (His-Pro) to neonatal rats led to the downregulation of cyclo (His-Pro)-binding sites with a decrease in Bmax but not Kd. Such changes were not observed after similar treatments of adult rats. These data suggest a receptor-like characteristic of cyclo (His-Pro) binding sites.
D000302:Adrenal Cortex / Q000032:analysis*; D000313:Adrenal Medulla / Q000032:analysis; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D008297:Male; D009928:Organ Specificity; D010456:Peptides, Cyclic / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000032:analysis*; D018025:Receptors, Thyrotropin-Releasing Hormone
D010456:Peptides, Cyclic; D010879:Piperazines; D011956:Receptors, Cell Surface; D018025:Receptors, Thyrotropin-Releasing Hormone; C015924:histidyl-proline diketopiperazine