Characterization and determination of neuropeptides by high-performance liquid chromatography and radioimmunoassay.

A method is described for the separation and analysis of a variety of neuropeptides using reversed-phase high-performance liquid chromatography coupled with radioimmunoassay. The solvent system (an acetonitrile gradient containing 0.08% trifluoroacetic acid) allows UV detection at 206 nm, gives good resolution and, by being volatile, is readily compatible with radioimmunoassay. Three applications of the method are described: (a) thyrotropin releasing hormone immunoreactivity in the rat brain has been characterized; (b) ACTH immunoreactivity in the rat pituitary pars intermedia has been resolved into its component peptides; (c) degradation of luteinizing hormone releasing hormone in vitro has been followed.