title: Identification and localization of insulin-like growth factor receptors in human infant pituitary gland-similar distribution to somatotrophs.
abstract: Abstract Insulin-like growth factors(IGF) are involved in feedback regulation of growth hormone(GH) secretion from the pituitary. Though receptors for IGF-I and IGF-II have been identified on particulate preparations of rat pituitary, their localization and relationship to GH-secreting acidophils has not been determined. We used quantitative in vitro autoradiography and immunocytochemistry to simultaneously determine the distribution of IGF receptors and GH-secreting cells in human infant pituitary gland. Frozen or fixed post-mortem human infant pituitary glands were sectioned for binding studies, or immunocytochemistry. Binding for IGF-I and IGF-II showed characteristic specificity for respectively Type I and Type II receptors. Binding sites were visualized throughout the pituitary gland, with similar density and distribution for IGF-I and IGF-II receptor sites. Receptor density was two-fold higher in anterior than posterior pituitary, with highest density in the lateral horns of the anterior pituitary. The distribution of GH-containing cells (acidophils) was similar to IGF receptor distribution. Increased density of IGF receptors in regions of GH-secreting cells may point to the mechanism whereby IGF uniquely inhibits synthesis of human GH in contrast to its promotion of synthetic processes in other cells.
authors.affiliation: Department of Endocrinology, Royal Children's Hospital, Melbourne, Australia.
authors.forename: D A
authors.initials: DA
authors.lastname: Walker
authors.forename: A
authors.initials: A
authors.lastname: Hogg
authors.forename: K
authors.initials: K
authors.lastname: Haynes
authors.forename: A
authors.initials: A
authors.lastname: Cox
authors.forename: H
authors.initials: H
authors.lastname: Jonas
authors.forename: F A
authors.initials: FA
authors.lastname: Mendelsohn
authors.forename: G A
authors.initials: GA
authors.lastname: Werther