Excitochemical-induced trophic bridging directs axonal growth of transplanted neurons to distal target

Feng C. Zhou, Yung H. Chiang

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Brain grafts directly placed in their target regions often lack proper connections and normal regulation. When brain grafts are placed in their ontogenetic normal area, the axonal outgrowth of grafts to distal target regions is a major obstacle. We previously demonstrated that directional axonal growth of grafts can be facilitated by laminin. In this study we demonstrated that excitochemicals induced trophic environment can be strategically used as a bridge to guide transplanted neurons to innervate a distal target of millimeter distance, and has a unique effect on fiber expansion in the target region. To distinguish dopamine (DA) growth from that of transplants, 6-hydroxydopamine was unilaterally injected into medial forebrain bundle to remove dopamine innervation to the striatum. Ibotenic acid (IB), kainic acid (KA), or phosphate buffer (vehicle) were microinjected through a glass-pipet to make a 7 mm long tract between the substantia nigra and the striatum in Sprague-Dawley rats. Gestational 14-15 days brainstem slurry was transplanted either in the same or a separate tract into nigra at the bottom of the bridge. All transplants survived with abundant serotonin (5-HT) and DA neurons. Traceable DA fibers formed distinct bundles from grafts along the length of IB/KA tracts. Upon arrival at their major target regions, fibers from bundles were capable of leaving the tracts, and reinnervating the DA-vacated striatum. The 5-HT fibers formed bundles similar to DA fibers but left the tract earlier upon arrival at their major target the globus pallidus and when arriving at the striatum and cortex. Fibers from grafts with vehicle tracts grew randomly and not into the tract. These results indicate that the trophic effects of chemical lesioning serves as a remarkably effective axonal guidance for more than one type of fetal neuron to innervate distal brain regions. This method has great potential in directing fibers in many transplant models.

Original languageEnglish
Pages (from-to)103-112
Number of pages10
JournalCell Transplantation
Volume4
Issue number1
DOIs
Publication statusPublished - 1995
Externally publishedYes

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Keywords

  • Axonal guidance
  • Brain graft
  • Ibotenic acid
  • Kainic acid
  • Neural bridging
  • Neurotrophic factor
  • Parkinsonism
  • Striatum
  • Substantia nigra

ASJC Scopus subject areas

  • Cell Biology
  • Biomedical Engineering
  • Transplantation

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