CCK-8 induces NGF and BDNF synthesis and modulates TrkA and TrkB expression in the rat hippocampus and septum: Effects on kindling development

Neurochem Int. 2007 Jan;50(1):130-8. doi: 10.1016/j.neuint.2006.07.008. Epub 2006 Sep 11.

Abstract

In our previous studies, we demonstrated that intraperitoneal (i.p.) injections with the neurotransmitter/neuromodulatory peptide Cholecystokinin-8 (CCK-8) stimulate the synthesis of the neurotrophin nerve growth factor (NGF) resulting in the structural and functional recovery of neuronal damage. This neurotrophin-mediated neuroprotective action of CCK-8 has opened a new perspective for a better understanding of the CCK neurobiological and pharmacological properties. To explore the possible beneficial effects of the CCK-induced increase of neurotrophin availability in brain, we compared the effects of i.p. CCK-8 in healthy rats and in a chemical kindling model using a subconvulsive dose of pentylenetetrazol (PTZ). Behavioural changes were monitored during treatment and classified according to a six-point scale. After 3 weeks of treatment (12 trials), the PTZ group of rats manifested generalized clonic-tonic seizures (Class 5 behaviour). For this reason, this time point was chosen to compare the effects of CCK-8 treatment on the expression of NGF, the brain derived neurotrophin factor (BDNF) and their receptors in the septum and hippocampus. We found that repeated i.p. injections with CCK-8 in adult rats result in: (1) an increase of NGF and BDNF protein and mRNA levels in the septum and hippocampus; (2) a down-regulation of TrkA and p75NTR and an up-regulation of TrkB; (3) reduced susceptibility to develop chemical kindling; (4) recovery of the PTZ-induced changes in the expression of neurotrophin receptors in the septal and hippocampal tissues. This data clearly indicates that CCK-induced variation of neurotrophin synthesis in brain is able to influence the susceptibility to develop seizures in adult rats most probably by counteracting the progressive neuronal dysfunction and/or damage.

MeSH terms

  • Animals
  • Base Sequence
  • Behavior, Animal / drug effects
  • Brain-Derived Neurotrophic Factor / biosynthesis*
  • Cholecystokinin / pharmacology*
  • DNA Primers
  • Hippocampus / drug effects*
  • Hippocampus / metabolism
  • Hippocampus / physiology
  • Kindling, Neurologic*
  • Male
  • Nerve Growth Factor / biosynthesis*
  • Peptide Fragments / pharmacology*
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, trkA / metabolism*
  • Receptor, trkB / metabolism*

Substances

  • Brain-Derived Neurotrophic Factor
  • DNA Primers
  • Peptide Fragments
  • cholecystokinin 8
  • Cholecystokinin
  • Nerve Growth Factor
  • Receptor, trkA
  • Receptor, trkB