Radioimmunoassay of neurotensin and the distribution and concentration of gut neurotensin in rat and dog.

A specific radioimmunoassay (RIA) for neurotensin (NT) has been developed. Four antisera of high avidity were raised in 4 rabbits immunized with synthetic NT tridecapeptide coupled with bovine serum albumin via glutaraldehyde. NT was labeled with Na125I by means of modified Hunter-Greenwood's chloramine-T method. Sensitivity of the RIA was 100 pg/ml. Cross-reactivity of antiserum to other peptides was not observed. Using the RIA, the distribution and concentration of gastrointestinal (GI)-NT have been determined in acid-acetone extracts of rat and dog GI tissues. RIA using four kinds of antisera similarly detected higher concentrations in jejuno-ileal sections than in other regions. Although the distribution of GI-NT was quite similar between rat and dog, its concentration showed species specific difference.