Cyrus Jalili
Abstract
Tobacco consumption is increasing in developing countries over the same period. Each cigarette contains an average of 10–14 mg nicotine (NIC). Through pulmonary circulation, the NIC spreads rapidly across the brain tissue within 10–20 s. NIC available in the cigarette is an alkaloid agent which rapidly passes through the blood–brain barrier and stimulates the mesolimbic dopamine system. This substance reduces the activity of superoxide dismutase, glutathione peroxidase, and glutathione reductase in the hippocampus. Pathologic changes associated with neuronal apoptosis have been reported due to the use of NIC. Furthermore, NIC can induce the increased oxidative stress levels and neuronal apoptosis rate, destroy deoxyribonucleic acid (DNA), and produce reactive oxygen species (ROS). Among the brain areas where the NIC has the greatest effect, the mesocorticolimbic is a region which contains nucleus accumbens, ventral tegmental area, hippocampus, and amygdala. In this region, the structures of the amygdala and hippocampus play a crucial role in the formation of long‑term memory, whose function is associated with stimulation of the reward system. Hippocampus is a part of the limbic system and seems to be essential in the formation of different types of learning and memory. Cornu ammonis 1 (CA1) area, which belongs to the hippocampus, plays an essential role in converting short‑term memory to long term. Meanwhile, in recent years, herbal medicines have gained popularity. For centuries, India and China have been used turmeric as an anti‑inflammatory substance in the treatment of colic pain, toothache, chest pain, jaundice, anorexia, and menstrual disorders. The rhizome extract contains mainly curcumin (CUM). CUM has antioxidant and anti‑inflammatory properties. The results of a study by Jayaprakasha et al. revealed that in Alzheimer’s experimental model, the CUM could improve the memory through intravenous injection of streptozotocin. CUM can encourage the neurogenesis process in elderly female rats. The results of a study by Mashayekhi et al. on various antioxidants showed that the CUM has far more potent in breaking down of free radicals. In addition, it can protect the brain against lipid peroxidation and breaking down nitrite oxide (NO)‑induced free radicals. CUM seems to prevent the destructive effects of NIC in the brain through the inhibition of oxidative stress mechanism. According to the effects of NIC brain toxicity and the therapeutic properties of CUM, and considering that no study has evaluated the antioxidant effects of CUM on NIC‑induced CA1 damage, this experimental study was designed to evaluate the therapeutic effects of CUM against NIC injury in the hippocampus CA1 region of rats.