Astrocytes produce an insulin-like neurotrophic factor
They have previously reported that survival of dissociated neurons from fetal rat telencephalon plated at low density in serum-free, hormone-free defined medium is enhanced in the presence of insulin. In the absence of insulin a similar effect on neuronal survival is observed if cells are grown in medium conditioned by glial cells. The present study was carried out to characterize the insulin-like neurotrophic activity present in the glial conditioned medium (GLCM). Conditioned medium from confluent cultures of astrogial cells maintained in a serum free defined medium without insulin was collected every two or three days. A 5 to 30kDa fraction of this medium was obtained by filtering it sequentially through YM30 and YM5 membrane filters. Binding of /sup 125/I-insulin to high density neuronal cultures was inhibited 43% by this fraction. Radioimmunoassay for insulin indicated that 1-2 ng of immuno-reactive insulin were present per ml of GLCM. Immunosequestration of the factor by insulin antibodies bound to protein A agarose gel resulted in loss of neurotrophic activity of the 5 to 30 kDa fraction. These results indicate that cultured astrocytes produce a factor immunologically and biochemically similar to insulin. This factor enhances the survival of neurons in culture and may be important for their normal development and differentiation.
- Research Organization:
- Univ. of Iowa College of Medicine, Iowa City
- OSTI ID:
- 5022860
- Report Number(s):
- CONF-8606151-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
- Country of Publication:
- United States
- Language:
- English
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550201* - Biochemistry- Tracer Techniques