This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by BACHA, P. Articles by REICHLIN, S. Search for Related Content PubMed PubMed Citation Articles by BACHA, P. Articles by REICHLIN, S.

Organ-Specific Binding of a Thyrotropin-Releasing Hormone-Diphtheria Toxin Complex after Intravenous Administration to Rats^*

Endocrine Division, New England Medical Center Boston, Massachusetts 02111
The Department of Microbiology and Molecular Genetics, Harvard Medical School Boston, Massachusetts 02115

Address requests for reprints to: Dr. Patricia Bacha, Endocrinology Division, Department of Medicine, Box 268,275; 171 Harrison Avenue, New England Medical Center, Inc., Boston, Massachusetts 02111.

Abstract

We have previously demonstrated that a hybrid protein consisting of TRH linked to CRM45, a fragment of diphtheria toxin which lacks its native cell-binding moiety, specifically binds to TRH receptors in vitro. In this study we have examined its iin vivo binding and shown that after iv injection, this complex labeled with 128I is selectively concentrated in the normal anterior pituitary and that concomitant administration of cold TRH reduces its uptake. Displaceable uptake was also demonstrated in the hypothalamus and testis, whereas nondisplaceable binding exceeding that of CRM45 alone was shown in the ovary and the breast parenchyma of lactating rats. Similar experiments with tritiated TRH were performed. We found that although there was uptake of the material by many tissues, almost all of the radioactivity was in the form of TRH degradation products. Therefore, we conclude that TRH linked to a large carrier like CRM45 may be a more revealing indicator of in vivo binding affinities than native TRH. (Endocrinology 113: 1072,1983)

Footnotes

^* This work was supported by grants from the American Cancer Society (BC-377) and the NIH (AM-16684).

Received February 24, 1983.

This article has been cited by other articles:

				L. Gnessi, A. Fabbri, and G. Spera Gonadal Peptides as Mediators of Development and Functional Control of the Testis: An Integrated System with Hormones and Local Environment Endocr. Rev., August 1, 1997; 18(4): 541 - 609. [Abstract] [Full Text] [PDF]