Astrocytes Regulate the Expression of Insulin-Like Growth Factor 1 Receptor (IGF1-R) in Primary Cortical Neurons During In Vitro Senescence

The role of insulin-like growth factor 1 (IGF1) pathway as regulator of aging and age-related diseases is increasingly recognized. Recent evidence has been provided that neuronal IGF1-R increases during aging leading to activation of a signaling pathway that causes an increased production of amyloid beta-peptide, the principal event in the pathogenesis of Alzheimer's disease. Here, by using long-term neuronal cultures as a model of aging, we show that astroglial cells are required to upregulate the expression of IGF1-R in neurons during in vitro senescence. Moreover, evidence is provided that the cross-talk between astrocytes and neurons is independent of cell-to-cell contact, and it is mediated by low molecular weight soluble factor(s) released by astrocytes in culture medium. These results suggest that astrocytes could play an important role in aging and age-related pathological processes.