en تخصصي Special پژوهشي Research <strong>Objective:</strong> Alteration in the basement membrane proteins maybe associated with diabetic neuropathy. Fibronectin is one of the most important components of peripheral nerves basement membrane. In this study we investigated the effects of insulin administration on prevention of alteration in fibronectin contents of sciatic nerve in diabetic rats.<br> <strong>Materials and Methods</strong><strong>:</strong> Twenty-four wistar rats were divided into control, diabetic and diabetic with insulin treatment groups. Three months after diabetes induction, we measured blood glucose level, body weight and then expression of fibronectin in sciatic nerves of rats were evaluated by real time polymerase chain reaction (PCR) and immunohistochemical study.<br> <strong>Results:</strong> Intensity of fibronectin immunoreactivity in the perineurium and endoneurium of sciatic nerves significantly increased in diabetic without treatment group compared to control group (<em>P</em>-value< 0.001).&nbsp;<br> <strong>Conclusion</strong><strong>:</strong> This finding suggested that diabetic neuropathy resulted in increased of fibronectin contents in sciatic nerves of rats. Diabetes, Sciatic nerve, Basement membrane proteins, Fibronectin 54 57 http://ijdo.ssu.ac.ir/browse.php?a_code=A-10-30-271&slc_lang=en&sid=1 Manochehr Safari 0000-0001-6975-7747 No Department of Anatomical Sciences, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran. Niloofar Aldaghi 0000-0002-0592-120X No Department of Biology, School of Biology, Damghan University, Damghan, Iran. Hamid Reza Sameni 0000-0002-2669-6697 No Department of Anatomical Sciences, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran. Mohammad Reza Aldaghi 0000-0001-8715-6099 Yes Department of Anatomical Sciences, School of Medicine, Semnan University of Medical Sciences, Semnan, Iran.