Regulation of the growth hormone (GH) receptor and GH-binding protein by GH pulsatility

Growth hormone (GH) secretion is pulsatile in man and every other mammalian species that has been studied. The magnitude of pulses, their frequency, and their regularity vary. The receptor, on its part, undergoes cycles of internalization and recycling that are in synchrony with the frequency of GH pulses. This sequence of events has been shown to be advantageous to growth. It is suggested that changes in GH secretion dynamics secondarily lead to most of the changes in GH receptor abundance and GH-binding protein (GH-BP) abundance. Across a wide scope of comparative studies, ontogenesis data, experimental systems, physiologic conditions, nutritional states, and disease situations, the pulsatility of serum GH is negatively correlated with cell membrane GH receptors and serum levels of GH-BP. It is suggested that these conditions regulate primarily the pattern of GH pulsatility, which in turn regulates the GH receptor/GH-BP, and thereby exert the specific effects on target cells to promote or suppress growth or to express distinct metabolic actions.