Effects of Pituitary Peptides on Fat Mobilisation

No reliable answer can yet be given whether the pituitary gland is physiologically involved in the process of fat mobilization. The reasons are, for example, different test systems and criteria of lipolytic activity as well as variable criteria of purity of the peptides tested. Under comparable test conditions MSH, beta-endorphin, ACTH and beta-lipotropin turned out to be the most lipolytically active peptides. There is also increasing evidence that these peptides are involved in metabolic processes especially in glucose metabolism. The lipolytic activity of beta-lipoprotein, ACTH and MSH is mediated by a common heptapeptide (beta-LPH 47-53) furthermore, beta-lipotropin has a second message sequence in the C-terminal part of its molecule (beta-endorphin). This second message sequence is located in the amino acid sequence beta-LPH 77-86. The lipolytic effect of all these peptides is accompanied by an activation of adenylate cyclase. The effect of beta-endorphin is not mediated by an opiate receptor. The further elucidation of the lipolytic activity of these peptides investigations were necessary on the degradation of the peptides at the site of action as well as the use of test systems nearer to physiological conditions for example perifused fat cells. In conclusion, there are condensing data on the possible physiological role of brain and pituitary peptides in metabolic regulation.