GH, IGF-I, IGFBP-3 and IGFBP-2 in cerebrospinal fluid of infants, during puberty and in adults.

During diagnostic lumbar punctions cerbrospinal fluid (CSF) was collected for the determination of GH, IGF-I, IGFBP-3 and IGFBP-2. The patients were 0.3 to 68 years od and suffered from viral infections, leukemias, M. Hodgkin or multiple sclerosis. Only CSF samples without any pathological alterations were analysed. In infants and adults CSF GH concentrations significantly declined with age, while IGF-I and the two binding proteins were unrelated to age. GH was not correlated to IGF-I, IGFBP-3 or IGFBP-2. However, IGF-I was strongly related to IGFBP-3 (r = 0.529; < 0.001) and IGFBP-2 (r = 0.796; < 0.001) as was IGFBP-3 to IGFBP-2 (r = 0.685; < 0.001), suggesting dependence of the three variables. With IGFBP-3 or IGFBP-2 as control variables (partial correlation) IGF-I was no longer related to the binding proteins, while the relation of IGFBP-3 to IGFBP-2 remained unchanged with IGF-I as the control variable (r = 0.687; < 0.001). The results suggest that the age-related decrease of CSF GH may contribute to the age-dependent decline of GH receptors in brain, which are up-regulated by GH. Furthermore, in CSF IGF-I concentrations were determined by the two binding proteins. It may be speculated that the transfer of IGF-I through the blood CSF barrier or its production in brain may be closely related to the IGF-binding proteins.