en Behavioral Neuroscience Behavioral Neuroscience Original Original <div style="text-align: justify;"><strong>Introduction</strong>: Alzheimer disease (AD) is a neurodegenerative disorder characterized by the progressive loss of memory and other cognitive functions. Protein kinase C&epsilon; (PKC&epsilon;) is an isoform that most effectively suppresses amyloid beta (A&beta;) production and synaptic loss.<br> <strong>Methods</strong>: In this study, spatial learning and memory for treated rats were evaluated by the Morris water maze test. The activity (total PKC), mRNA expression, and protein level of PKC&epsilon; in the platelet and hippocampal tissue were evaluated using immunosorbent assay, real-time qPCR, and western blotting analysis, respectively.&nbsp;<br> <strong>Results</strong>: The traveled distance was significantly prolonged, and escape latency significantly increased in A&beta;-treated groups. PKC activity assay showed that there was a remarkable difference between the A&beta;-treated and sham-operated groups on days 10 and 30 in the hippocampus and also day 30 in platelet after the injection of A&beta;. A significant effect in PKC activity was observed between days 0 and 10, days 0 and 30, as well as days 5 and 30. A&beta; significantly downregulated the PKC&epsilon; mRNA expression in the hippocampus of rats on day 30; however, no significant difference was observed in platelet. Western blot analysis demonstrated that A&beta; significantly reduced PKC&epsilon; protein expression in the hippocampus of treated groups on day 30.&nbsp;<br> <strong>Conclusion</strong>: The expression level of PKC&epsilon; was downregulated following the injection of A&beta; in the hippocampus, but no significant difference was observed between the AD and sham groups in platelet that may be due to the low concentration of PKC&epsilon; or duration of A&beta; exposure in the rat brain.</div> Alzheimer disease, PKCε, Platelet, Hippocampus, Amyloid beta 545 556 http://bcn.iums.ac.ir/browse.php?a_code=A-10-80-1&slc_lang=en&sid=1 Sara Amiri sara_am57@yahoo.com 13700319475328460025334 13700319475328460025334 No Department of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran, Iran. Kayhan Azadmaneshb azadmanesh@pasteur.ac.ir 13700319475328460025335 13700319475328460025335 No Department of Virology, Pasteur Institute of Iran, Tehran, Iran. Marzieh Dehghan Shasaltaneh M_deghan1361@ut.ac.ir 13700319475328460025336 13700319475328460025336 No Department of Biology, Faculty of Sciences, University of Zanjan, Zanjan, Iran. Baharak Khoshkholgh-Sima khoshkholghh@yahoo.com 13700319475328460025337 13700319475328460025337 No Department of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran, Iran. Nasser Naghdi naghdi@pasteur.ac.ir 13700319475328460025338 13700319475328460025338 Yes Department of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran, Iran.