Reduction of Lactogenic Receptors in Female Hamster Liver due to the Human Growth Hormone Analog Produced by Plerocercoids of the Tapeworm, Spirometra mansonoides

The inductive effect of GH on hepatic lactogenic receptors is suspected of being due to a direct somatogenic action. Plerocercoid larvae of the tapeworm, Spirometra mansonoides, produce a factor that stimulates body growth, suppresses endogenous GH, and specifically displaces [125I] human (h) GH from hepatic receptors. Plerocercoid growth factor (PGF) mimics the growth-promoting actions of GH, but it has not been shown to duplicate all of the activities reported for GH. An important function of GH is its role in the maintenance of liver receptors for lactogenic hormones. This study was undertaken to determine if treatment of female hamsters with PGF would increase, decrease, or have no effect on liver receptors that bind hGH. Since hGH binds to somatogenic as well as lactogenic receptors, it was necessary to demonstrate the specificity of PGF's effects on [128I]hGH binding. PGF-treated (15 pleocercoids sc) hamsters had accelerated body growth, suppressed serum GH, and a marked reduction in [125I]hGH and [...