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Structural changes at synapses after delayed perfusion fixation in different regions of the mouse brain
Author(s) -
TaoCheng JungHwa,
Gallant Paul E.,
Brightman Milton W.,
Dosemeci Ayse,
Reese Thomas S.
Publication year - 2007
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.21276
Subject(s) - hippocampal formation , fixation (population genetics) , perfusion , biology , postsynaptic potential , neuroscience , cerebral cortex , cerebellar cortex , biophysics , dendritic spine , hippocampus , anatomy , cerebellum , receptor , medicine , biochemistry , gene
We recently showed by electron microscopy that the postsynaptic density (PSD) from hippocampal cultures undergoes rapid structural changes after ischemia‐like conditions. Here we report that similar structural changes occur after delay in transcardial perfusion fixation of the mouse brain. Delay in perfusion fixation, a condition that mimics ischemic stress, resulted in 70%, 90%, and 23% increases in the thickness of PSDs from the hippocampus (CA1), cerebral cortex (layer III), and cerebellar cortex (Purkinje spines), respectively. In step with PSD thickening, the amount of PSD‐associated α‐calcium calmodulin‐dependent protein kinase II (α‐ CaMKII) label increased more in cerebral cortical spines than in Purkinje spines. Although the Purkinje PSDs thickened only slightly after delayed fixation, they became highly curved, and many formed sub‐PSD spheres ∼80 nm in diameter that labeled for CaMKII. Delayed perfusion fixation also produced more cytoplamic CaMKII clusters (∼110 nm in diameter) in the somas of pyramidal cells (from hippocampus and cerebral cortex) than in Purkinje cells. Thus a short delay in perfusion fixation produces cell‐specific structural changes at PSDs and neuronal somas. Purkinje cells respond somewhat differently to delayed perfusion fixation, perhaps owing to their lower levels of CaMKII, and CaMKII binding proteins at PSDs. We present here a catalogue of structural changes that signal a perfusion fixation delay, thereby providing criteria by which to assess perfusion fixation quality in experimental structural studies of brain and to shed light on the subtle changes that occur in intact brain following metabolic stress. J. Comp. Neurol. 501:731–740, 2007. © 2007 Wiley‐Liss, Inc.