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Keywords:

  • TGF-β;
  • rat astrocytes;
  • neuron–glia interactions;
  • neurons;
  • RT PCR;
  • binding

Abstract

We examined the effect of neurons on oxytocin (OT) receptors (OTR) and OTR gene expression in cultured astrocytes. The addition of neuron-conditioned medium induced an increase of both OTR binding and OTR mRNA level. This effect was enhanced after the medium was boiled or acidified. As it is known that transforming growth factor-β (TGF-β) can be released from carrier proteins by acid or heat, TGF-β1 and 2 were tested and found to induce an increase of OTR binding. Furthermore, TGF-β antibody abolished the stimulatory effect of normal or acidified neuron-conditioned medium. Neurons added to cultured astrocytes without contact mimicked the stimulatory effect of the conditioned medium. In contrast, neurons added with contact, induced a decrease in OTR binding and an increase of mRNA level, whereas neuronal membranes induced a decrease of both OTR binding and mRNA levels. In conclusion, the present data demonstrate that in vitro, neurons are able to modulate astrocytic OTR expression at the level of both protein and mRNA. They stimulate this expression through their release of TGF-β and inhibit it by the action of unknown membrane components. GLIA 37:169–177, 2002. © 2002 Wiley-Liss, Inc.