Satietin: a centrally acting potent anorectic substance with a long-lasting effect in human and mammalian blood

An anorectic substance in human, mammalian (rat, guinea pig, rabbit, cat, dog, horse, cattle) and poultry (goose) serum, named satietin, was discovered recently. The substance was extracted and purified by gelchromatographic techniques. With an improved technique, a highly purified glycopeptide fraction, containing 87% carbohydrates (fucose, mannose, glucose and galactose) and 12.5% amino acids, was prepared from human serum and its anorectic effect was measured in fasting rats. A biological assay for satietin, expressing activity in units, was developed. The unit is equivalent to the anorectic activity of the amount of a sample which, when given intracerebroventricularly (icvtr) decreases the chow pellet consumption of rats deprived of food for 96 h, during the first day of feeding, from 24.04 +/- 0.76 g to 10 g. With higher icvtr doses of satietin (2-3 units/rat) the 24 h consumption of the fasting rats can be reduced below 4-5 g and the animals begin to eat on the second day of feeding only. With samples containing 100 units/mg, the anorectic effect was checked at various routes of administration. Satietin acts icvtr, proving that its site of effect is in the brain. A significant decrease in food intake was also observed in the deprived rats 1 h after the oral administration of satietin (100 units/100 g), 1 h after the intravenous or subcutaneous administration of satietin (40 units/100 g), the first hour consumption of food was completely blocked. The anorectic effect of satietin was compared to the endogenous peptides (CCK, calcitonin, pGlu-His-GlyOH), proved or claimed to have anorectic effect, and to the drug-pair, amphetamine and fenfluramine, which represent the two main types of anti-obesity agents. Satietin proved to be a highly specific anorectic substance different in its spectrum from hitherto known compounds inhibiting food intake.