Chronic neurotrophin-3 strengthens synaptic connections to motoneurons in the neonatal rat. Academic Article uri icon

Overview

abstract

  • We report that neurotrophin-3 (NT-3), delivered chronically via fibroblasts implanted intrathecally into neonatal rats, can facilitate synaptic transmission in the spinal cord. A small collagen plug containing NT-3-secreting fibroblasts was placed on the exposed dorsal surface of the spinal cord (L1) of 2-d-old rats; controls received beta-galactosidase-secreting fibroblasts. After 6 hr to 12 d of survival, synaptic potentials (EPSP) elicited by two synaptic inputs, L5 dorsal root and ventrolateral funiculus (VLF), were recorded intracellularly in L5 motoneurons in vitro. Preparations treated with NT-3 implants exhibited enhanced monosynaptic synaptic transmission from both inputs, which persisted over the entire testing period. Unlike acute enhancement of transmission by NT-3 (Arvanian and Mendell, 2001a), the chronic effect could occur at connections not normally eliciting an NMDA receptor-mediated response at the time of NT-3 exposure. Using susceptibility to blockade of the NMDA receptor by Mg2+ and APV, we confirmed that chronic treatment with NT-3 did not enhance NMDA receptor activity at these connections. Cords treated with chronic NT-3 also transiently displayed polysynaptic components activated by VLF that were blocked by the NMDA receptor antagonist APV. These novel NMDA receptor-mediated potentials may reflect changes in interneurons near the site of fibroblast implantation. We conclude that chronic NT-3 enhances the potency of segmental and descending projections via mechanisms different from those underlying acute changes.

publication date

  • September 24, 2003

Research

keywords

  • Fibroblasts
  • Motor Neurons
  • Neurotrophin 3
  • Synapses

Identity

PubMed Central ID

  • PMC6740423

Scopus Document Identifier

  • 0141535172

Digital Object Identifier (DOI)

  • 10.1523/JNEUROSCI.23-25-08706.2003

PubMed ID

  • 14507970

Additional Document Info

volume

  • 23

issue

  • 25