Developmental expression of insulin-like growth factor-II receptor immunoreactivity in the rat central nervous system

A polyclonal antiserum raised against the insulin-like growth factor-II (IGF-II) receptor has been used to map the distribution of this receptor in the developing rat central nervous system (CNS). Transiently high levels of receptor immunoreactivity were found in the developing brain, particularly in the cortex and hypothalamus. The amount of receptor immunostaining in these areas decreases toward the time of birth, and levels are approximately equivalent to those in the adult by postnatal day 7. The choroid plexus, cerebral vasculature, ependymal cells, retina, and pituitary contain high levels of receptor immunoreactivity throughout embryogenesis and adulthood. Some mesodermally derived tissues, such as bone, also demonstrate transient expression of IGF-II receptor during fetal development. These data are consistent with potential roles for IGF-II in CNS development, in the development of specific mesodermal tissues, and in specific regions of the postnatal CNS.