Simple Peptides In Brain

Abstract

Although polypeptides such as substance P and related compounds, neurohypophyseal hormones, and the releasing factors of the anterior hypothalamus have been the subjects of extensive studies in the past decade, relatively few studies have been made of the occurrence of smaller oligopeptides in the brain and of their possible function. Automatic amino acid analysis of protein-free extracts of mammalian brain demonstrated the presence of unknown ninhydrin-positive compounds, which disappeared after acid hydrolysis. The nomenclature of the di- and tripeptides is ambiguous. Their classification as di- or tripeptides as a group may be justified because naturally occurring peptides can be separated grossly into three classes: (1) di- or tripeptides, (2) biologically active peptides having 7-15 amino acid residues, which include most peptide hormones and antibiotics, and (3) the larger polypeptides, which have very diverse biological functions. This chapter describes the occurrence, distribution, and metabolism of oligopeptides, which are found in the mammalian brain up to the present time. The physiological and pharmacological actions of some of them and of compounds related to them also arediscussed, although unfortunately there is almost nothing known about this.