Selective loss and axonal sprouting of GABAergic interneurons in the sclerotic hippocampus induced by LiCl-pilocarpine

Int J Neurosci. 2011 Feb;121(2):69-85. doi: 10.3109/00207454.2010.530007. Epub 2010 Dec 13.

Abstract

In this study, we performed immunohistochemistry for somatostatin (SS), neuropeptide Y (NPY), and parvalbumin (PV) in LiCl-pilocarpine-treated rats to observe quantitative changes and axonal sprouting of GABAergic interneurons in the hippocampus, especially in the sclerotic hippocampus. Fluoro-Jade B (FJB) was performed to detect the specific degeneration of GABAergic interneurons. Compared with age-matched control rats, there were fewer SS/NPY/PV-immunoreactive (IR) interneurons in the hilus of the sclerotic hippocampus in pilocarpine-treated rats; hilar dentritic inhibitory interneurons were most vulnerable. FJB stain revealed degeneration was evident at 2 months after status epilepticus. Some SS-IR and NPY-IR interneurons were also stained for FJB, but there was no evidence of degeneration of PV-IR interneurons. Axonal sprouting of GABAergic interneurons was present in the hippocampus of epileptic rats, and a dramatic increase of SS-IR fibers was observed throughout all layers of CA1 region in the sclerotic hippocampus. These results confirm selective loss and degeneration of a specific subset of GABAergic interneurons in specific subfields of the hippocampus. Axonal sprouting of inhibitory GABAergic interneurons, especially numerous increase of SS-IR neutrophils within CA1 region of the sclerotic hippocampus, may constitute the aberrant inhibitory circum and play a significant role in the generation and compensation of temporal lobe epilepsy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Axons / pathology*
  • Disease Models, Animal
  • Hippocampus / drug effects
  • Hippocampus / metabolism
  • Hippocampus / pathology*
  • Interneurons / metabolism
  • Interneurons / pathology*
  • Lithium Chloride
  • Male
  • Nerve Degeneration / metabolism*
  • Neuropeptide Y / metabolism
  • Parvalbumins / metabolism
  • Pilocarpine
  • Rats
  • Rats, Sprague-Dawley
  • Sclerosis / chemically induced
  • Sclerosis / metabolism
  • Sclerosis / pathology*
  • Somatostatin / metabolism
  • Status Epilepticus / chemically induced
  • Status Epilepticus / metabolism
  • Status Epilepticus / mortality
  • Status Epilepticus / pathology*
  • gamma-Aminobutyric Acid / metabolism*

Substances

  • Neuropeptide Y
  • Parvalbumins
  • Pilocarpine
  • Somatostatin
  • gamma-Aminobutyric Acid
  • Lithium Chloride