The effect of ghrelin on spatial memory and apoptosis pathway in the hippocampus of the methamphetamine received male rats

Abstract

This study aimed to investigate the effects of ghrelin, as a neuroprotective agent, on cognitive impairment and apoptosis pathway in methamphetamine-treated male rats. Sixty adult male Wistar rats were randomly divided into six groups (n=10): Saline/Saline (S-S), Saline/Ghrelin (S-G), Methamphetamine/Simultaneous Saline (M-SS), Methamphetamine/Simultaneous Ghrelin (M-SG), Methamphetamine/Delayed Saline (M-DS), and Methamphetamine/Delayed Ghrelin (M-DG). Methamphetamine (5 mg/kg) and ghrelin (5 nM/kg) were injected intraperitoneally. Spatial and passive avoidance memories were evaluated by Morris water maze (MWM) and Shuttle box, respectively. Hippocampal expression levels of Cytochrome-C, Caspase 3, and Bax/Bcl-2 ratio were evaluated by Western blotting. TUNEL assay was performed to detect hippocampal neuronal apoptosis. Our results showed that time spent in the target quadrant in M-SS group was less than the control group. However, simultaneous ghrelin treatment could increase it. Ghrelin treatment reversed methamphetamine effects on hippocampal protein expression of Caspase 3 and Cytochrome-C, and BAX/Bcl-2 ratio. TUNEL assay showed an increase in the number of apoptotic cells in methamphetamine-treated animals, while ghrelin treatment decreased apoptosis. These results indicate that ghrelin treatment could improve spatial memory and reduce neuronal apoptosis in the hippocampus of methamphetamine-treated animals.