A peptide family  is a group of peptides that share significant amino acid
sequences.  Some families are composed of peptides that differ only modestly
across widely divergent species (such as the oxytocin/vasopressin family).  Most
neuroscientists are primarily interested in those representatives of peptide
familes that exist contemporaneously in different cell types in the central or
peripheral nervous system of the same species.  Such peptide families include the
following groups:


1. Oxytocin/vasopressin *  
2. Tachykinins*                 
3. CRF-like  Peptides       
4. Glucagon -like Peptides*                    
5. Opioid Peptides*             
6. Pancreatic Polypeptide*  - like Peptides