Microtubule Dynamicity Is More Important than Stability in Memory Formation: an In Vivo Study Deyhim Atarod & Ghazaleh Eskandari-Sedighi & Farid Pazhoohi & Seyed Morteza Karimian & Mojtaba Khajeloo & Gholam Hossein Riazi Received: 13 January 2015 /Accepted: 23 February 2015 # Springer Science+Business Media New York 2015 Abstract It has been shown that microtubule (MT) activity and dynamics can have huge impacts on synaptic plasticity and memory formation. This is mainly due to various func- tions of MTs in neurons; MTs are involved in dendritic spine formation, axonal transportation, neuronal polarity, and recep- tor trafficking. Recent studies from our group and other labs have suggested the possible role of brain MT dynamicity and activity in memory; however, there is a need for more detailed studies regarding this aspect. In this study, we have tried to evaluate the importance of microtubule dynamicity rather than stability in memory formation in vivo. In order to investigate the role of MT stability in memory formation, we treated mice with paclitaxel—a classic microtubule-stabilizing agent. We then studied the behavior of treated animals using Morris wa- ter maze (MWM) test. To measure the effect of injected pac- litaxel on MT polymerization kinetics, we conducted poly- merization assays on brain extracts of the same paclitaxel- treated animals. Our results show that paclitaxel treatment affects animals’ memory in a negative way and treated ani- mals behave poorly in MWM compared to control group. In addition, our kinetics studies show that MT stability is signif- icantly increased in brain extracts from paclitaxel-treated mice, but MT dynamics is reduced. Thus, we suggest that dynamicity is a very important feature of MT protein struc- tures, and regarding memory formation, dynamicity is more important than stability and high activity. Keywords Microtubule . Microtubule dynamicity . Paclitaxel . Taxol . Memory . Synaptic plasticity Introduction Learning is defined as the acquisition of information and skills, whereby subsequent retention of this information is called memory. Neuroplasticity, which is defined as the capac- ity of neural cells in forming new connections or modifying the ones they have, plays a crucial role in memory formation (Milner et al. 1998). Numerous studies have shown that mi- crotubules (MTs) are essential for many of the neural cells’ main functions, such as axonal transportations and receptor trafficking (Paulson and McClure 1974; Kim and Lisman 2001; Malinow and Malenka 2002; Lau and Zukin 2007). MTs are also important for neural cell polarity and dendritic spine development (Arimura and Kaibuchi 2007; Gu et al. 2008). Instability of MT structure and decrease in their total mass are observed in various neurodegenerative diseases mainly referred to as tauopathies. MT instability is strongly related to the pathological features observed in molecular level in these neurodegenerative disorders (Hasegawa et al. 1998; Falnikar and Baas 2009). Moreover, It has been described that nonfatal doses of colchicine, as a microtubule depolymerizing agent, can cause amnesia in rats, and such animals can be used as a potential animal model for studying the early stages of Alzheimer’ s disease (AD) (Nakayama and Sawada 2002). D. Atarod : G. Eskandari-Sedighi : M. Khajeloo : G. H. Riazi (*) Department of Biochemistry, Institute of Biochemistry and Biophysics (IBB), University of Tehran, Qods Street, Tehran 1417614411, Iran e-mail: ghriazi@ibb.ut.ac.ir F. Pazhoohi Department of Animal Sciences, Shiraz University, Shiraz, Iran S. M. Karimian Department of Physiology, Tehran University of Medical Sciences, Tehran, Iran J Mol Neurosci DOI 10.1007/s12031-015-0535-4