Blood-borne adrenocorticotropin binds specifically to the median eminence-arcuate region of the rat hypothalamus.
The quantitative light microscope radioautographic approach was utilized to locate specific binding sites for blood-borne 125I-labeled ACTH1-24 in the rat brain. Specific binding occurred exclusively in the external zone of the median eminence, adjacent to the primary portal plexus, and to a lesser extent in the ventral arcuate nucleus. This localization may indicate that the hypophysiotropic median eminence is a new target site for circulating adrenocorticotropin. Alternatively, ACTH binding sites in the median eminence-arcuate region may provide the hypothalamus with a hormone-selective capacity to concentrate pituitary ACTH for possible retrograde transport and redistribution within the central nervous system.
D000302:Adrenal Cortex / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000818:Animals; D001665:Binding Sites; D005934:Glucagon / Q000494:pharmacology; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism*; D008473:Median Eminence / Q000378:metabolism*; D011388:Prolactin / Q000494:pharmacology; D051381:Rats
D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D005934:Glucagon