The Croonian Lecture The lipotropic agents in the protection of the liver, kidney, heart and other organs of experimental animals

Abstract

Our successors in medical research will read, with amused tolerance, our frequent agonized protests that the volume of literature which we should comprehend exceeds our capacity. Those of us who teach and write text-books for medical students and practitioners are forced to depend more and more upon the review journals. The number and breadth of the fields in which one can pose, even transiently, as an authority are diminishing rapidly. But if one looked only at this aspect of the picture an ageing outlook on the most fascinating of all games, medical research and teaching, might be suggested. The appearance of new authorities is most stimulating, and it is refreshingly obvious that the soaring rate of publication has not inhibited research. We must co-ordinate the abstracting services in our field, continue the struggle to eliminate unworthy papers, hope for even better colloquia and review journals, and confidently expect that the next fifty years will contribute more to medical science than has the past vigorous half-century. The award of the Croonian Lectureship has given me exceptional pleasure and a sense of great responsibility. In selecting a title I have considered the principal subjects in which I have endeavoured to keep abreast, and the choice has thus been narrowed to insulin and experimental diabetes, heparin and thrombosis, and the dietary factor choline and its precursors, which we have termed the lipotropic agents. Certain of the effects of these three substances might be discussed in a single lecture, since they all affect either the formation, distribution or the state of fat in the body. The action of a lipokinetic constituent of the anterior pituitary, first clearly demonstrated in our laboratory in 1936 (Best & Campbell), which increases the rate of mobilization of depot fat to the liver (Barrett, Best & Ridout 1938; Stetten & Salcedo 1944), might also have been included. The fat-mobilizing effect of anterior pituitary extracts may be due to Evans’s somatotropin, to the adrenocorticotropic hormone, to a more specific but as yet unidentified substance or, of course, to more than one of these. The four factors, insulin, choline, heparin and ‘adipokinin’ (Weil & Stetten 1947) have given us a measure of control over fat metabolism which our predecessors did not enjoy. There are, of course, other dietary and hormonal agents affecting these processes which one would have to discuss in a comprehensive treatment of the field. I shall not even list these and, indeed, after a very brief consideration of insulin and heparin, particularly in relation to fat metabolism, I shall limit my discussion to ‘the lipotropic agents’.