In vivo biosynthesis of arginine vasopressin and oxytocin in hypothalami from intact and hypophysectomized rats.

Published

Journal Article

The rates of incorporation of [35S]cysteine into arginine vasopressin (AVP) and oxytocin (OXT) were studied concurrently in hypothalami from intact and hypophysectomized male rats. After label injection into the third ventricle, rats were killed 0.5, 1, 2, 4, or 8 h later. The hypothalamic peptides were quantitated by specific RIA and separated by HPLC to allow quantitation of label incorporation into each peptide. In intact rats, labeling of both OXT and AVP rose rapidly to peak at 2 h; thereafter, radioactivity in both peptides declined slowly to 8 h. In hypophysectomized rats, labeling of AVP fell below that in intact animals at all time points. Labeling of OXT was somewhat below normal 2 h after label injection, but considerably above normal at 4 and 8 h. For comparison, label incorporation into somatostatin-14 (SRIF-14) and somatostatin-28 (SRIF-28) was also studied in the same animals. In intact rats, labeling of both SRIF peptides rose slowly to maximal values at 8 h. In hypophysectomized animals, labeling of each peptide was reduced substantially at all times tested. Endogenous cysteine specific activity and protein specific activity did not differ between intact and hypophysectomized animals. Immunoreactive levels of AVP and OXT in the hypothalamus were unaffected by hypophysectomy, though total SRIF-like immunoreactivity was depressed. Together these results suggest that hypothalamic neurons synthesize OXT and AVP at rates much faster than those for the SRIF peptides, and that hypophysectomy has differential effects on the syntheses of cysteine-containing peptides in the hypothalamus. Specifically, the syntheses of SRIF-14 and SRIF-28 appear to be sizeably reduced in hypophysectomized rats, while that of AVP only modestly diminished. OXT synthesis may be increased.

Full Text

Duke Authors

Cited Authors

  • Wetsel, WC; Fernstrom, JD

Published Date

  • June 1, 1987

Published In

Volume / Issue

  • 120 / 6

Start / End Page

  • 2562 - 2568

PubMed ID

  • 2883002

Pubmed Central ID

  • 2883002

International Standard Serial Number (ISSN)

  • 0013-7227

Digital Object Identifier (DOI)

  • 10.1210/endo-120-6-2562

Language

  • eng

Conference Location

  • United States