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Acta Neuropathol (2009) 117:545555 DOI 10.1007/s00401-009-0504-5
ORIGINAL PAPER
Ultrastructural and functional characterization of satellitosis in the human lateral amygdala associatedwith Ammons horn sclerosis
Heidrun Faber-Zuschratter Kerstin Httmann Christian Steinhauser Albert Becker Johannes Schramm Uchenna Okafo Daniel Shanley Deniz M. Yilmazer-Hanke
Received: 19 September 2008 / Revised: 17 February 2009 / Accepted: 17 February 2009 / Published online: 27 February 2009 Springer-Verlag 2009
Abstract The amygdala displays neuronal cell loss and gliosis in human temporal lobe epilepsy (TLE). Therefore, we investigated a certain type of gliosis, called satellitosis, in the lateral amygdala (LA) of TLE patients with Ammons horn sclerosis (AHS, n = 15) and non-AHS (n = 12), and in autopsy controls. Satellite cells were quantied using light and electron microscopy at the somata of Nissl-stained and glutamic acid decarboxylase-negative projection neurons, and their functional properties were studied using electro-physiology. Non-AHS cases suffered from ganglioglioma, cortical dysplasia, SturgeWeber syndrome, astrocytoma WHO IIIIV, Rasmussens encephalitis, cerebral infarction and perinatal brain damage. TLE cases with AHS had a more prominent satellitosis as compared to non-AHS and/or autopsy cases, which correlated with epilepsy duration but not age. At ultrastructural level, the predominant type of satellite cells occurring in both AHS and non-AHS cases
displayed a dark cytoplasm and an irregularly shaped dark nucleus, whereas perineuronal glial cells with a light cytoplasm and light oval nucleus were much rarer. Satellite cells expressed time- and voltage-dependent transmembrane currents as revealed by patch-clamp recordings typical for complex glia, although only 44% of satellite cells were immunostained for the chondroitin sulfate proteoglycan NG2. Together, the perineuronal cells described here were a heterogenous cell population regarding their NG2 expression, although they resembled NG2 cells rather than bona de oligodendrocytes and astrocytes based on their ultra-structural and electrophysiological characteristics. Thus, perineuronal satellitosis as studied in the LA seems to be a hallmark of AHS-associated TLE pathology in patients suffering from intractable epilepsy.
Keywords Perineuronal glia Satellitosis NG-2 cells
Temporal lobe epilepsy Human amygdala
Electron microscopy
Introduction
Many patients with temporal lobe epilepsy (TLE) display histopathological abnormalities called Ammons horn sclerosis (AHS) including segmental loss of pyramidal neurons, granule cell dispersion and reactive gliosis in the hippocampal formation. However, there is some controversy on whether AHS is the cause or result of epilepsy, and it...