The comparative distribution of [Lys-Asn]-neurotensin8–13-like immunoreactivity in chicken and rat tissues

The presence of [Lys⁸-Asn⁹]-neurotensin_8–13-like immunoreactivity was studied by radioimmunoassay in chicken and rat tissues. In the chicken, [Lys⁸-Asn⁹]-neurotensin_8–13-like immunoreactivity showed a wide distribution throughout the central nervous system and the gastrointestinal tract, and the immunoreactive material co-eluted with the synthetic peptide on reverse-phase high performance liquid chromatography. In the rat, [Lys⁸-Asn⁹]-neurotensin_8–13-like immunoreactivity was widely distributed when 0.1 M HCl was used as the extraction procedure. However, the immunoreactive material did not co-elute with the synthetic peptide on reverse-phase high performance liquid chromatography; moreover, the addition of the aspartic proteinase inhibitor pepstatin to the extraction medium resulted in a large reduction in the levels of [Lys⁸-Asn⁹]-neurotensin_8–13-like immunoreactivity and no immunoreactive material could be detected when the tissues were extracted using acetone/HCl. The present results therefore indicate that [Lys⁸-Asn⁹]-neurotensin_8–13-like immunoreactivity is not present in rat tissues. That which was detected resulted from an extraction artefact.