Anticonvulsant activity of a nonpeptide galanin receptor agonist

Proc Natl Acad Sci U S A. 2002 May 14;99(10):7136-41. doi: 10.1073/pnas.102163499.

Abstract

Galanin is a neuropeptide with a wide variety of biological functions, including that of a strong endogenous anticonvulsant. No nonpeptide ligands, capable of activating galanin receptors, are available today. Based on known pharmacophores of galanin, a combinatorial library was designed, synthesized, and screened at the rat hippocampal galanin receptor. A low molecular weight galanin receptor agonist, 7-((9-fluorenylmethoxycarbonyl)cyclohexylalanyllysyl)amino-4-methylcoumarin (galnon) was found to displace (125)I-galanin with micromolar affinity at Bowes cellular and rat hippocampal membranes. Autoradiographic binding assay on rat spinal cord sections confirmed the ability of galnon to displace (125)I-galanin from its binding sites. Galnon inhibited adenylate cyclase activity, suggesting an agonist action at galanin receptors. When injected i.p. galnon reduced the severity and increased the latency of pentylenetetrazole-induced seizures in mice and reversed the proconvulsant effects of the galanin receptor antagonist M35, injected into a lateral ventricle. Intrahippocampal injection of galnon also shortened the duration of self-sustaining status epilepticus in rats, confirming its agonist properties in vivo. Pretreatment of rats with antisense peptide nucleic acid targeted to galanin receptor type 1 mRNA abolished the effect of galnon, suggesting mediation of its anticonvulsant properties through this receptor subtype. These findings introduce a systemically active nonpeptide galanin agonist anticonvulsant.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenylyl Cyclase Inhibitors
  • Animals
  • Anticonvulsants / chemical synthesis
  • Anticonvulsants / chemistry
  • Anticonvulsants / pharmacology*
  • Coumarins / chemical synthesis
  • Coumarins / chemistry
  • Coumarins / pharmacology*
  • Disease Models, Animal
  • Hippocampus / metabolism
  • Ligands
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Molecular Structure
  • Oligodeoxyribonucleotides, Antisense
  • Peptides
  • Rats
  • Rats, Wistar
  • Receptor, Galanin, Type 1
  • Receptors, Galanin
  • Receptors, Neuropeptide / agonists*
  • Seizures / drug therapy

Substances

  • 7-((9-fluorenylmethoxycarbonyl)cyclohexylalanyllysyl)amino-4-methylcoumarin
  • Adenylyl Cyclase Inhibitors
  • Anticonvulsants
  • Coumarins
  • Ligands
  • Oligodeoxyribonucleotides, Antisense
  • Peptides
  • Receptor, Galanin, Type 1
  • Receptors, Galanin
  • Receptors, Neuropeptide