Large-Molecule Neurotransmitters Peptides

Thyrotropin-releasing hormone Vasoconstrictive intestinal polypeptide 

Corticotropin-releasing hormone Gonadotropin-releasing hormone Growth hormone-releasing hormone Somatostatin 

Galanin is a neuropeptide with widespread distribution in both the central and peripheral nervous systems. Human galanin (4.226) is a 30-amino-acid peptide that inhibits the release of other neurotransmitters and in doing so plays a role in memory acquisition, sexual behaviour modulation, gastrointestinal mobility, and the appreciation of pain. 

Over the past decade, considerable effort has been expended on the design and synthesis of nonpeptidic antagonists for the three receptors (NKl-3) to which SP, NKA, and NKB bind. These antagonists could have therapeutic use in conditions such as migraine, arthritis, inflammatory diseases such as cystitis, psoriasis, asthma, anxiety, depression, and emesis (vomiting). A variety of NKl-3 receptor antagonists have been designed and synthesized. The majority of these compounds are polyheterocyclics. 

Peptide neurotransmitters present problems for the drug designer because they are too large. Gaseous neurotransmitters likewise present problems for the dmg designer, but 

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How to synthesize biologically active polypeptides chemically has long been an important challenge for many fields in chemistry and biology. In the past, the development of solution-phase and solid-phase synthesis techniques has made it possible to synthesize large molecules like peptides with molecular weights up to 10,000. The purpose of this review is to provide an overview of how to prepare natural bioactive peptides synthetically. Because of space limitations, this review concentrates on peptide hormones and neurotransmitters. 

A vast number of hormones and neurotransmitters are synthesized from simple structural units including chains of amino acids. Among the amino acid based hormones are comparatively large protein molecules such as prolactin, growth hormone and insulin, and shorter chains of amino acids which may form peptide hormones, such as oxytocin and vasopressin. Protein based hormones are essential for metabolism, growth and some components of reproduction. However, evidence for specific influences of these compounds on human behavior is limited. 

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