Vasopressin-containing and vasopressin-deficient subpopulations of corticotropin-releasing factor axons are differentially affected by adrenalectomy.
CRF-containing parvocellular axons in the external zone of the rat median eminence were classified as vasopressin-containing (CRF+/AVP+) and vasopressin-deficient (CRF+/AVP-) subpopulations based on post-embedding electron microscopic immunocytochemical staining of serial ultrathin sections for CRF, AVP and the other peptides derived from the AVP precursor: AVP-associated neurophysin (NP-AVP) and the C-terminal glycopeptide (GP). In normal animals, the CRF+/AVP+ and CRF+/AVP- subpopulations were approximately equal in terms of detectable axonal swellings. Three to 14 days after adrenalectomy (ADX), the CRF+/AVP+ and CRF+/AVP- subpopulations represented about 95% and 5%, respectively, of total CRF+ swellings. This change was due to a 90% decrease in the absolute number of detectable CRF+/AVP- swellings after ADX, whereas the absolute number of detectable CRF+/AVP+ swellings rose by less than 20%. These changes were completely blocked by administering the glucocorticoid agonist dexamethasone throughout the period after ADX. The results suggest that the CRF+/AVP+ and CRF+/AVP- subpopulations of neurosecretory axons in the external zone of the median eminence respond differently to ADX, indicating that they are independently regulated by glucocorticoids.
D000315:Adrenalectomy; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D001369:Axons / Q000378:metabolism*; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D006651:Histocytochemistry; D007118:Immunoassay; D008297:Male; D008473:Median Eminence / Q000187:drug effects / Q000648:ultrastructure*; D008854:Microscopy, Electron; D051381:Rats; D011919:Rats, Inbred Strains
D001127:Arginine Vasopressin; D003907:Dexamethasone; D003346:Corticotropin-Releasing Hormone