Isolation of two lipolytic pituitary peptides

Abstract

Pig pituitary glands were extracted with 70% acetone at pH 1.1, acetone was added to a concentration of 92 %, and the resulting 70-92 % acetone precipitate was dissolved in 0.1 N acetic acid and adsorbed with oxycellulose to remove adrenocorticotropin and melanocyte-stimulating hormones. To the unadsorbed supernatant solution, trichloroacetic acid was then added to a concentration of 5%. The resulting 5 % trichloroacetic acid precipitate (labeled fraction 7) possesses lipolytic activity in vitro on rabbit, guinea pig, chicken, and pigeon adipose tissue, and raises plasma free fatty acid concentration in the anesthetized monkey. By gel filtration of fraction 7 on Sephadex G-75, followed by ionexchange chromatography on carboxymethylcellulose, two lipolytic peptides (labeled peptides 7D6 and 7D7) were isolated in homogeneous form. Peptide 7D6 in the amount recovered accounted for about 60 of the lipolytic activity of fraction 7, and peptide 7D7 for about 20%. The minimal effective dose for the lipolytic activity of 7D6 on rabbit D uring the past 10 years, three laboratories have reported on novel pituitary peptides which are highly active lipolytic agents on rabbit adipose tissue, but virtually inactive on the rat tissue. (1) This laboratory described a fraction of pig pituitary, labeled fraction H (Rudman et al., 1960), and, in more purified form, fraction L (Rudman et al., 1961), which was lipolytic in vitro and in vivo in the rabbit but not in the rat, These preparations were weakly active on guinea pig adipose tissue, but inactive on the tissues of mouse, hamster, dog, and pig (Rudman et al., 1962). (2) Astwood and collaborators (Astwood et al., 1961) isolated from pig pituitaries two peptides labeled I and 11, both of which were active on the rabbit but not on the rat tissue. Peptide I1 was found by electrophoretic and immunologic tests to be identical with the major component in fraction H (Friesen et al., 1962). (3) Li and colleagues have isolated three novel lipolytic peptides from sheep, pig, and human pituitaries, labeled fraction L' (Birk and Li, 1964), P-lipotropin (Li et al., 1965; Graf and Cseh, 1968; Cseh et al., 1968), and y-lipotropin (Chretien and Li, 1967), all highly active on rabbit adipose tissue but only weakly so on the rat tissue. 1 Abbreviations used are: ACTH, adrenocorticotropin; MSH, FR-39.adipose tissue in vitro was 0.1 pg/ml, and of 7D7 0.01 pg/ml. Both peptides were active as well on the adipose tissue of guinea pig and chicken, and inactive on that of rat, hamster, cat, and opossum. As little as 0.01 mg of 7D6 increased the plasma free fatty acid concentration in the intact rabbit, and as little as 2.5 mg had this effect in the monkey. The rise in plasma free fatty acid level was associated with an increase in blood glucose concentration and a fall in plasma total amino acid level. Molecular weight of 7D6 was estimated by sedimentation equilibrium as 8900, and that of 7D7 as 5500. The differing amino acid compositions of 7D6 and 7D7 are reported.Peptide 7D6, porcine fraction L, and ...

A Glycopeptide from the Posterior Lobe of Pig Pituitaries

“…Indeed, there are several reports, (e.g. [34,35]) that 1ipoIytic factors can be isolated from the pituitary. I n these cases the activity is considerably greater than in ours.…”

In vivo-Untersuchungen beim Miniaturschwein mit einem lipidmobilisierenden Polypeptid aus Schweinehypophysen

“…13 Versuchstiere erhielten naeh Blutentnahme je 100 ~/kg lipidmobflisierendes Peptid (gel5st in 5 ml physiologischer NaC1-LSsung) injiziert; 3 Kontrolltiere be- Ein Anstieg des Blutzuckers nach Lipotropin-Injektion wurde bisher bei Kaninchen und Affen beobachtet [7,8,11] und jetzt auch yon uns beim Schwein gefunden. Neben der initial gesteigerten Glykogenolyse w/iren als Ursachen eine Hemmung der peripheren Glucoseutilisation und eine erhShte Gluconeogenese zu diskutieren, zumal im Hinblick auf den gegenl/~ufigen Verlauf yon FFS-und Glucosekurven yon der 60. rain an.…”

Malignant disease: nutritional implications of disease and treatment

“…Yet fat mobilising peptides have been isolated from the urine of both fasted animals and humans [111,112] and in those with widespread malignant disease even when food intake is 'normal'. Peptides with lipid mobilising activity have been isolated from both pituitary [113,114] and hypothalamic [115] extracts and lipolytic activity has been reported in extracts from other parts of the brain. Such peptides could thus account for the hyperlipidaemia of malignant disease.…”