Differences in the elution profiles of corticotropin-Releasing activity in rat plasma and hypothalamic extracts following high performance liquid chromatography

Extracts of rat plasma and hypothalami were fractionated by reversed-phase high performance liquid chromatography (HPLC) and the fractions were assayed in an in vitro bioassay for corticotropin-releasing activity. Corticotropin releasing factor (CRF) bioactivity was found in many fractions with retention times of 20-50 min. In contrast, material derived from the plasma of rats stressed by ether anaesthesia yielded only one peak of CRF bioactivity, with a retention time of 47-48 min. These results suggest that ACTH can be released from isolated pituitary cells by a number of components derived from HPLC of extracts of rat hypothalami. It is possible, however, that some of these are artefacts of the extraction process from post-mortem material. Because the CRF activity found in plasma was homogeneous by HPLC, plasma can be used to obtain physiologically active CRF.