The Effect of Alpha-pinene on Amyloid-beta-induced Neuronal Death and Depression in Male Wistar Rats

Abstract

Background & objectives: The deposition of amyloid beta (Aβ) peptide in the brain is one of the most important features of Alzheimer's disease. In addition to memory loss, Aβ can lead to depression behavior. Alpha-pinene is a type of monoterpene that has antioxidant, antiinflammatory, and neuroprotective effects. Here, by using an animal model for Alzheimer's disease, we investigated the effect of alpha-pinene on neuronal cell death in the hippocampus and depression induced by Aβ1-42. Methods: Male Wistar rats weighing 240-260 g were divided into four groups including control, alpha-pinene, Aβ, and Aβ-alpha-pinene. Rats were placed in stereotaxic surgery apparatus and Aβ1-42 was injected into the hippocampus (4 μg per side) and alpha-pinene was treated intraperitoneally (50 mg/kg) for 14 consecutive days. At the end of the course, the level of depression was assessed using the forced swimming test. The animals' hippocampus was also examined microscopically after Nissl staining. Results: Intra-hippocampal injection of Aβ1-42 increased the total immobility time in the forced swimming test (p<0.01), decreased the number of pyramidal neurons in the CA1 area (p<0.001), and reduced the thickness of the neuronal layer in this region of the hippocampus. Treatment with alpha-pinene largely prevented these changes. Conclusion: It can be concluded that alpha-pinene decreased the beta-amyloid-induced depressive behavior in rats and inhibited the neuronal loss, suggesting that this neuroprotective compound may have a critical role in depression. Alpha-pinene is probably a suitable therapeutic strategy for repressing Aβ-induced neurodegeneration.