AGE-RELATED REDUCTION OF HUMAN GROWTH HORMONE-BINDING SITES IN THE HUMAN BRAIN

Previous studies have shown that alterations in various neuroendocrine functions occur with increasing age. We here report a study of growth hormone (GH)-binding sites in different areas of post-mortem human br ains collected from individual males and females of different age. The results indicate that there exists a significant negative correlation between the density of GH-binding sites and increasing age. This phen omenon was observed in both sexes in brain areas such as choroid plexu s, hippocampus, hypothalamus, pituitary and putamen but not in e.g. th alamus. In all tissues (except for choroid plexus), the GH binding was significantly higher in those originating from females than those fro m males. This discrepancy was found likely to be associated with the a ffinity of GH to lactogenic rather than to somatogenic sites as no pro nounced sex difference in binding was observed in the presence of exce ssive amounts of human prolactin. Data also indicate that the putative GH receptors in the various brain regions differ with regard to bindi ng constants and to the estimated molecular size of the hormone-bindin g units. The loss of GH receptors in brain of elderly people may have consequences in several physiological courses. The decrease in GH bind ing at hypothalamic and pituitary levels may be of importance for the mechanisms behind the release or secretion of the hormone.