New evidence that demonstrates that L-pro-L-leu-L-gly-NH2 might be the natural MIF.
A wide range of doses was used to study the effect of Pro-Leu-Gly-NH2 (MIF) on the MSH release in rat pituitaries incubated in vitro. The Pro-Leu-Gly-NH2 was added to one half of the gland, and the other was used as control. The MSH released into the medium was measured by a bioassay and the activity of the samples referred to a standard of synthetic alpha-MSH. Pro-Leu-Gly-NH2 in doses of 10 to 30 ng/ml inhibited the MSH release in about 60%. Doses between 10(3) to 10(4) ng/ml induced neither release nor inhibition of the release of MSH. Dose of 10(5) ng/ml clearly induced release of MSH. The results of the additional experiments presented, although they represent no proof, are in line with the contention that Pro-Ley-Gly-NH2 in the natural MIF.
D000818:Animals; D005260:Female; D009075:MSH Release-Inhibiting Hormone / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008263:Macrophage Migration-Inhibitory Factors; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010455:Peptides / Q000494:pharmacology; D010902:Pituitary Gland / Q000502:physiology; D051381:Rats; D013268:Stimulation, Chemical
D008263:Macrophage Migration-Inhibitory Factors; D010455:Peptides; D009074:Melanocyte-Stimulating Hormones; D009075:MSH Release-Inhibiting Hormone