Proteomic Analysis of Penile Protein Alterations in a Rat Model of Cavernous Nerve Injury

ABSTRACT

PURPOSE: Cavernous nerve resection (CNR) in rats is a standard model of animal experiments on erectile dysfunction (ED) that occurs after radical prostatectomy (RP). Injured cavernous nerves after surgery can cause fibrosis and apoptosis that lead to penile structural changes that may be accompanied by alterations of protein expression. This study aimed to analyze the changes in protein after CNR in Wistar Kyoto rats. MATERIALS AND METHODS: Using 8-week-old male Wistar Kyoto rats, sham and CNR operation under a microscope were performed. Two and 8 weeks after surgery, we applied 2-DE and MALDI-TOF/TOF (AB 4700) to identify differently expressed penile proteins after CNR. 2-DE gels were stained with silver nitrate and were analyzed with PDQuest. After in-gel digestion, peptide mass spectra were obtained by MALDI-TOF/TOF mass spectrometry in the positive ion reflector mode. The obtained data were screened with a rat database from both the NCBI and the Swiss-Prot/TrFMBL home page. RESULTS: The proteins that were changed more than 1.5-fold compared with the sham group were annexin A4 and pyruvate kinase (PK). Annexin A4 was increased by 1.75-fold after 2 weeks, whereas PK was decreased by 4.16 after 8 weeks. These results were confirmed by immunohistochemistry. CONCLUSIONS: Annexin A4 in the CNR group was increased, which may be related to emiocytosis during apoptosis. The decrease in PK of the CNR group is assumed to be related to a decrease in efficacy during glycolysis. Further study will be needed to elucidate the molecular pathophysiology of ED after cavernous nerve injury.