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Activation of somatostatin‐synthesizing neurons in the hippocampal formation through kindling‐induced seizures
Author(s) -
Pretel S.,
Applegate C. D.,
Piekut D. T.
Publication year - 1995
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/hipo.450050106
Subject(s) - hippocampal formation , neuroscience , perforant path , kindling , perforant pathway , hippocampus , dentate gyrus , somatostatin , in situ hybridization , psychology , chemistry , epilepsy , messenger rna , biochemistry , gene
The present study was designed to determine if and to what extent somatostatin (SST) synthesizing neurons of the hippocampal formation are activated during seizures, elicited through kindling of the perforant pathway. Tissue was used and analyzed from animals which had experienced a single afterdischarge, or a stage 3 or stage 5 seizure. The protein expression of the oncogene c‐fos in activated, depolarizing neurons was utilized to identify seizure‐activated SST‐synthesizing neurons. Combined immunocytochemical and in situ hybridization methods were used to identify these double‐labeled, Fos protein, and SST mRNA‐containing neurons. The results were quantified and compared across seizure stages. The resulting data demonstrate that at every stage of seizure development, a majority of SST‐synthesizing neurons is activated, but that these activated SST mRNA‐containing neurons represent only a minority of all seizure‐activated, Fos‐expressing neurons in the hippocampal formation. The data further reveal a numerical hierarchy in which the majority of double‐labeled neurons is present in the hilus of the dentate, followed by the stratum oriens of CA1. It is concluded that SST‐synthesizing neurons represent an integral component of the kindling activated neuronal network and, since the SST synthesizing neurons represent the minority of all seizure‐activated neurons in the hippocampal formation, that this neuronal network is likely to be of considerable neurochemical complexity. & 1995 Wiley‐Liss, Inc.