STUDIES ON THE NATURE OF CORTICOTROPHIN RELEASING HORMONE AND ITS PARTIAL PURIFICATION FROM PORCINE HYPOTHALAMI

Corticotrophin releasing hormone (CRH) has proved to be one of the more elusive hypo-thalamic releasing factors. It has resisted previous purification attempts and its structure is still unknown. Progress in purifying CRH appears to have been hampered both by the difficulties associated with its assay and by its molecular nature. Previous attempts to purify CRH using gel filtration have had only limited success (Dhariwal, Antunes-Rodriguez, Resser, Chowers & McCann, 1966; Chan, Schaal & Saffran, 1969). Recent reports on its characterization suggest that the hormone may exist in two forms of different molecular weight (Gillham, Jones, Hillhouse & Burden, 1975) or that a co-factor may be required for its action (Pearlmutter, Rapino & Saffran, 1975). We have recently subjected partially purified CRH to chroma-tography on Sephadex G-50 under various conditions and our results throw some light on the nature of CRH and provide a procedure for its large scale purification. The activity of CRH was assayed by a modified Portanova & Sayers ' (1973) method using isolated pituitary cell suspensions prepared by collagenase disaggregation of rat adeno-hypophysis. In order to wash them free of endogenous stimulatory agents, broken or damaged cells and liberated corticotrophin (ACTH), the disaggregated cells were superfused for 30 mi