Insulin-like growth factor 1-induced alterations in lumbospinal monoamine dynamics

Milad Sami Bitar, I. M. Francis, C. W.T. Pilcher

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


A wealth of evidence indicates that insulin-like growth factor (IGF-1) is involved in neurotransmitter release, synaptic plasticity, morphogenesis and regulation of gene expression. RTPCR and immunocytochemical-based techniques revealed that IGF-1 and its receptor are highly expressed by different neuronal elements of the spinal cord lumbar enlargement. Accordingly, the present study intended to examine lumbospinal monoamine dynamics in the context of the neurotrophic factor IGF-1. Spinal release of norepinephrine (NE) represented by 3-methoxy-4-hydroxyphenylglycol (MHPG)/NE ratio was enhanced by IGF-1. This action of IGF-1 was associated with a similar increase in both tyrosine hydroxylase (TH) immunoreactivity and the level of its mRNA. In contrast, neuronal contents of serotonin and its metabolite 5-hydroxyindoleacetic acid in IGF-1-treated animals remained at control level. Genistein, a tyrosine kinase inhibitor, which by itself had no effect on NE metabolism, abolished the induction effect of IGF-1 on TH and MHPG/NE ratio. Our results suggest that IGF-1 augments the lumbospinal noradrenergic system by an intracellular mechanism involving a receptor- linked tyrosine kinase. The physiological consequences of the IGF-1 actions are discussed in terms of neuroprotection and nociception.

Original languageEnglish
Pages (from-to)207-215
Number of pages9
JournalHormone and Metabolic Research
Issue number6
Publication statusPublished - 1 Jan 2000


  • Insulin-Like Growth Factor 1
  • Monoamines
  • Spinal Cord
  • Tyrosine Hydroxylase


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