The study of microtubule dynamics and stability at the postsynaptic density in a rat pilocarpine model of temporal lobe epilepsy

Abstract

Background: The recurrence and drug resistance of temporal lobe epilepsy (TLE) has been ceaselessly challenging scientists and epilepsy experts. There has been an accumulation of evidence linking the dysregulation of postsynaptic proteins etiology and the pathology of epilepsy. For example, NMDA receptors, AMPA receptors, and metabotropic glutamate receptors (mGluRs). Furthermore, our earlier proteomic analysis proved there to be differential expressions of cytoskeletons like microtubules among rat groups. These differential expressions were shown in TLE-spontaneous recurrent seizures (TLE-SRS), TLE without SRS (TLE-NSRS) and control groups. Therefore, we aimed to understand how the microtubule system of the hippocampal postsynaptic density (PSD) regulates the development of TLE.Methods: In this study, a pilocarpine-induced Sprague-Dawley rat TLE model were used, and Western blot, Nissl staining, and the immunoelectron microscopic method were utilized to determine the dynamic change of microtubules (α-and β-tubulin) in PSD and the extent of hippocampal neuron loss respectively in acute SE, and latent and chronic (spontaneous seizures) periods. Animal models were then stereotactically treated using colchicine, a microtubule depolymerizer, and paclitaxel, a microtubule polymerization agent, after each animal's acute SE period so as to further explore the function of PSD microtubules.Results: Our study revealed 3 principal findings. One, both α-and β-tubulin were decreased from the 3 rd to the 30 th day (lowest at the 7 th day) in the seizure group compared with the controls. Two, both α-and β-tubulin were found to be more downregulated in the TLE-SRS and the TLE-NSRS group than in the control group (especially in the TLE-SRS group). The same trend was also noticed for hippocampal neuron loss. Three, the paclitaxel lowered the chronic SRS rate and increased the expression of PSD β-tubulin in the hippocampus.Conclusions: Altogether, these results indicate that the microtubule system of PSD may play an essential role in the development and recurrence of epilepsy, and it may be used as a new target for the prevention and treatment of this refractory disease.

Non-microtubule tubulin-based backbone and subordinate components of postsynaptic density lattices

“…The report suggests a higher content of tubulin in PSDs than in the spine head cytoplasm. Immunogold labeling of tubulin in the brain PSD has not been reported for a long time until recently ( Wu et al, 2020 ). The presence of tubulin in the PSD has been supported by the immunofluorescence detection of tubulin in spine heads ( Cáceres et al, 1986 ; Huang et al, 2006 ; Hu et al, 2008 ; Cheng et al, 2009a ).…”

Animal Models of Epilepsy: A Phenotype-oriented Review

“…In 1983, pilocarpine was first identified to damage extensive brain tissues, such as the amygdala and hippocampus, via intraperitoneal injection, inducing seizure attack [ 86 ]. Recently, intraperitoneal injection of pilocarpine has become a popular TLE animal model [ 105 ]. Systemic injection of pilocarpine can cause cell injury in the hilus and dentate granule, neuronal degeneration in hippocampal CA1 and CA3 regions, and nuclei injury in the thalamus and amygdala[ 86 ].…”

“…Additionally, animals with intrahippocampal or intracerebroventricular injection of pilocarpine can also present similar EEG results, behavior, and pathologic features to TLE [ 84 ]. Compared with intrahippocampal or intracerebroventricular injection, intraperitoneal injection presents a simple procedure without craniotomy, but varies in age, sex, and strain [ 86 , 105 ]. In addition, extrahippocampal lesions are commonly observed.…”

Pathological Targets for Treating Temporal Lobe Epilepsy: Discoveries From Microscale to Macroscale

“…With the confirmation of its abundant expression in the synaptic structure, MTBs are given extra attention for their promising role in the development of epilepsy (124,125). In a pilocarpine-induced TLE rat model, colchicine was used as depolymerizer and paclitaxel as a polymerizer to explore the function of MTB (126). Both α-tubulin and β-tubulin were observed to be downregulated compared to the control group in the latent and chronic period (126).…”

“…In a pilocarpine-induced TLE rat model, colchicine was used as depolymerizer and paclitaxel as a polymerizer to explore the function of MTB (126). Both α-tubulin and β-tubulin were observed to be downregulated compared to the control group in the latent and chronic period (126). Together with the downregulation of MTBs, increased hippocampal neuronal loss was reported in epileptic rats.…”