title: Cell death of adult pyramidal CA1 neurons after intraventricular injection of a novel peptide derived from trkA.
abstract: Members of the nerve growth factor (NGF) family of neurotrophins bind to the second leucine-rich motif (LRM2) within the extracellular domains of their respective receptors (trkA, trkB, trkC). Small LRM2 peptides have been recently demonstrated to selectively bind the neurotrophins revealing similar complex binding characteristics as full-length receptors. We extend our recent findings, showing that the peptides (A and C) do not block nerve fiber outgrowth through high affinity trk receptors in a ganglia bioassay. Since the highest concentration of neurotrophins [NGF, brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3)] is found in the hippocampus, the peptides were injected into the 3rd ventricle of anesthetized adult rats. The (NGF binding) LRM2-A peptide, but not the (BDNF binding) LRM2-B or the (NT-3 binding) LRM2-C peptides, caused severe apoptotic neurodegeneration of hippocampal pyramidal CA1 neurons as revealed by cresyl violet staining and the TUNEL reaction. The degeneration was protected by intrahippocampal injection of NGF-beta and by the non-N-methyl-D-aspartate (NMDA) antagonist CNQX (6-cyano-7-nitroquinoxaline-2,3-dione), indicating a glutamatergic mechanism. In situ hybridization revealed that pyramidal CA1 neurons did not express trkA and p75 receptor mRNA in sham and LRM2-A-lesioned animals. It is concluded that the LRM2-A peptide represents a novel peptide with properties to induce apoptotic cell death of pyramidal CA1 neurons and may be useful as an experimental agent.
authors.affiliation: Department of Psychiatry, University of Innsbruck, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Kadari
authors.forename: J M
authors.initials: JM
authors.lastname: Windisch
authors.forename: T
authors.initials: T
authors.lastname: Ebendal
authors.forename: R
authors.initials: R
authors.lastname: Schneider
authors.forename: C
authors.initials: C
authors.lastname: Humpel
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000008:administration & dosage / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000008:administration & dosage / Q000494:pharmacology; D000595:Amino Acid Sequence; D000704:Analysis of Variance; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D007276:Injections, Intraventricular; D008297:Male; D008845:Microinjections; D008969:Molecular Sequence Data; D009410:Nerve Degeneration; D018696:Neuroprotective Agents / Q000008:administration & dosage / Q000494:pharmacology; D010446:Peptide Fragments / Q000008:administration & dosage / Q000494:pharmacology*; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D017966:Pyramidal Cells / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis / Q000737:chemistry / Q000502:physiology*; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000032:analysis / Q000737:chemistry / Q000502:physiology*
chemical_list: D018691:Excitatory Amino Acid Antagonists; D018696:Neuroprotective Agents; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; D017475:Receptors, Nerve Growth Factor; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D015763:2-Amino-5-phosphonovalerate; D020794:Receptor Protein-Tyrosine Kinases; D020917:Receptor, trkA