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Keywords:

  • medial septal nucleus;
  • fimbria-fornix transection;
  • CNTF;
  • in situ hybridization;
  • parvalbumin;
  • saporin;
  • cholinergic neurons

Abstract

Using non-radioactive in situ hybridization we investigated the effect of fimbria-fornix transection on the expression of ciliary neurotrophic factor receptor α (CNTFRα) mRNA in axotomized septohippocampal neurons of the rat septal complex. Whereas CNTFRα expression was undetectable in the medial septal nucleus/diagonal band complex (MSDB) of control animals, specific up-regulation was observed in MSDB neurons after fimbria-fornix transection. CNTFRα expression was maximal 7–10 days after the lesion and had returned to control levels after 3 weeks. Following unilateral fimbria-fornix transection, CNTFRα up-regulation was restricted to the MSDB ipsilateral to the lesion. When cholinergic septal neurons were selectively eliminated by immunolesioning with 192 IgG-saporin prior to fimbria-fornix transection, the lesion-induced expression of CNTFRα was still observed in many medial septal nucleus neurons. These results demonstrate that after fimbria-fornix transection CNTFRα expression is transiently induced in axotomized, non-cholinergic neurons of the medial septal nucleus, suggesting a postlesion function of locally supplied CNTF.