Reference

Degradation of delta sleep inducing peptide (DSIP) and its analogs by brain extracts

Degradation of delta sleep inducing peptide (DSIP) and its analogs by brain extracts. Marks, Neville; Stern, Frederic; Kastin, Abba J.; Coy, David H. (Res. Inst. Neurochem., Rockland Res. Inst., New York, N. Y., USA). Brain Res. Bull., 2(6), 491-3 (English) 1977. CODEN: BRBUDU. ISSN: 0361-9230. DOCUMENT TYPE: Journal CA Section: 6 (General Biochemistry) Section cross-reference(s): 13 Incubation of DSIP with an ext. of mouse brain resulted in release of tryptophan (indicating rapid action by a brain aminopeptidase) and release of serine (indicating internal cleavage by a brain neutral endopeptidase at the Ala6-Ser7 bond followed by the secondary action of an aminopeptidase). This mechanism was confirmed by detection of Gly8-Glu9 as a digest product. The finding of glutamate could be attributed to cleavage of this dipeptide or direct action of a carboxypeptidase on the nonapeptide. Other products that increased with time indicated secondary action of brain exopeptidase on peptide intermediates contg. the Gly-Gly subunit. Mechanisms of breakdown were confirmed by the use of DSIP analogs. D-Alanine in positions 3 and 4 blocked internal release of amino acids and peptides at short incubation periods but not the release of tryptophan. Addn. of tyrosine to position 1 failed to affect aminopeptidase and endopeptidase actions. The low yield of glutamate in the D-alanine analogs suggests that it was derived by secondary breakdown of Gly-Glu. Thus, the nonapeptide DSIP is a substrate for brain proteolytic enzymes and is degraded with release of N-terminal tryptophan along with other residues and peptide intermediates.

Direct effect of luteinizing hormone-releasing hormone agonist on in vivo luteal progesterone secretion

Direct effect of luteinizing hormone-releasing hormone agonist on in vivo luteal progesterone secretion. Macdonald, Gordan J.; Beattie, C. W.; Raj, H. G. M. (Dep. Anat., UMDNJ-Rutgers Med. Sch., Piscataway, NJ 08854, USA). Anterior Pituitary Gland, 319-25. Edited by: Bhatnagar, Ajay S. CNRS: Paris, Fr. (English) 1983. CODEN: 50SMAN. DOCUMENT TYPE: Conference CA Section: 2 (Mammalian Hormones) 6-D-Alanine-10-deglycinamide-LH-RH ethylamide [52435-06-0] induced pregnancy failure in hypophysectomized rats, an effect that was prevented by steroid replacement therapy. Therefore, the LH-RH analog is apparently capable of inhibiting ovarian steroidogenesis by an extrapituitary mechanism. In intact animals, any direct effect of LH-RH or LH-RH agonists on luteal progesterone [57-83-0] secretion would be accompanied by ovarian receptor down-regulation as a result of the LH-RH-induced excess of circulating LH.