Acylated ghrelin protects hippocampal neurons in pilocarpine-induced seizures of immature rats by inhibiting cell apoptosis

Mol Biol Rep. 2013 Jan;40(1):51-8. doi: 10.1007/s11033-012-1993-1. Epub 2012 Nov 6.

Abstract

Ghrelin has two major molecular forms, acylated ghrelin (AG) and unacylated ghrelin (UAG). Only AG to bind growth hormone secretagogue receptor 1a (GHSR-1a) has central endocrine activities. An antiapoptotic effect of AG in cortical neuronal cells has recently been reported. However, whether there is a neuroprotective effect of AG in hippocampal neurons of pilocarpine-induced seizures in rats, is still unknown. Therefore, in the present study, the underlying mechanism of AG on lithium-pilocarpine-induced excitotoxicity was examined in the hippocampus of rat. The results showed that AG inhibited pilocarpine-induced apoptosis. Exposure of rats to the receptor-specific antagonist D-Lys-3-GHRH-6 abolished the protective effects of AG against epilepsy. Administration of AG resulted in increased expression of phosphor-Akt in status epilepticus model in rats, which was accompanied with the attenuation of hippocampal cell death. Furthermore, administration of AG resulted in decreased expression of phosphor-JNK in pyramidal neurons of hippocampus after status epilepsy, which was also accompanied with the attenuation of hippocampal cell death, too. In addition, AG increased the Bcl-2/Bax ratio and inhibited caspase-3 activation. The data indicate that AG can function as a neuroprotective agent that inhibits apoptotic pathways. These effects may be mediated via activation of the PI3K/Akt pathway.

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • CA3 Region, Hippocampal / drug effects
  • CA3 Region, Hippocampal / metabolism
  • Caspase 3 / metabolism
  • Gene Expression Regulation / drug effects
  • Ghrelin / pharmacology*
  • Hippocampus / drug effects*
  • Hippocampus / metabolism
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Male
  • Neurons / drug effects*
  • Neurons / metabolism*
  • Neuroprotective Agents / pharmacology*
  • Pilocarpine
  • Proto-Oncogene Proteins c-akt / metabolism
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Rats
  • Receptors, Ghrelin / genetics
  • Receptors, Ghrelin / metabolism
  • Seizures / chemically induced
  • Seizures / genetics
  • Seizures / metabolism*
  • bcl-2-Associated X Protein / metabolism

Substances

  • Ghrelin
  • Ghsr1a protein, rat
  • Neuroprotective Agents
  • Proto-Oncogene Proteins c-bcl-2
  • Receptors, Ghrelin
  • bcl-2-Associated X Protein
  • Pilocarpine
  • Proto-Oncogene Proteins c-akt
  • JNK Mitogen-Activated Protein Kinases
  • Caspase 3