Introduction: 1. Introduction
Ethanol is a colorless, volatile, flammable, odorless, antiseptic, and psychoactive liquid that is the main ingredient of alcoholic beverages. Ethanol has many harmful effects on the brain, including memory loss, and impaired motor and cognitive function caused by neurodegeneration due to increased oxidative stress. Some of the main effects of ethanol are learning and memory impairment, anxiety, and depression.
Antioxidants are compounds with the ability to deal with oxidative stress and reduce its effects on people's health. These compounds protect the body against free radical damage. Astaxanthin (ATX) is a lipophilic terpene composed of carbon precursors and a natural red-orange oxy-carotenoid pigment, which is considered a fat-soluble xanthophyll carotenoid.
Methods: 2. Methods
Thirty five 25-30 grams mice in the weight range were purchased from Pasteur Amol Institute and were kept under standard conditions of 23 ± 2 °C and 12 hours of light and dark cycle in the animal room of the Faculty of Biology.
Mice were randomly divided into 5 groups of 7: 1- Control, did not receive any drug. 2- Positive control, received 20 mg/kg astaxanthin by gavage. 3- Ethanol, received 20% ethanol by gavage. 4- AST 10, which first received 20% ethanol and 2 hours later received 10 mg/kg astaxanthin by gavage. 5- AST 20, which first received 20% ethanol and 2 hours later received 20 mg/kg astaxanthin by gavage.
2.1. Novel Object Recognition Test (NORT)
NORT is a behavioral test that investigates different aspects of memory and learning in rodents and evaluates their ability to investigate a new object. This test is completed in three 5-minute stages: Habituation stage: the animal is placed in an empty box to get familiar with the environment. Acquaintance phase: First, two identical objects were placed on both sides of the box, and then the animal was placed inside the chamber and in the middle of the two objects to explore. Memory test phase: In this phase, one of the objects in the box was replaced with a new object with different appearance characteristics, and the animal was returned to the box to explore. Exploration was described as smelling or touching objects. Results were described as a discrimination index: the percent of novel object exploration time to the whole exploration time.
2.2. Open Field Test (OFT)
The open-field test is used to evaluate the level of anxiety and motor activity. To perform this test, we place the animal in one of the quadrants of the device so that it can move freely in the box. The duration of this test is about 5 to 10 minutes. In this test, the following parameters are evaluated and measured:
1- Movement activity measurement index 2- Anxiety measurement index
Results: 3. Result
The discrimination index in the ethanol (P < 0.001) and 10 mg/kg astaxanthin (P < 0.05) groups was significantly reduced compared to the control group. While the group treated with astaxanthin 20 mg/kg showed a significant increase (P < 0.05) compared to the ethanol group.
According to the obtained results, the duration of staying in the test center showed a significant decrease in the ethanol group (P < 0.001) compared to the control group. Also, this index was significantly increased in ethanol groups treated with 10 and 20 mg/kg of astaxanthin, respectively (P < 0.01) and (P < 0.001) compared to the ethanol group.
According to the obtained results, motor activity in the ethanol group shows a significant increase (P < 0.001) compared to the control group. While ethanol groups treated with doses of 10 and 20 mg/kg of astaxanthin showed a significant decrease (P < 0.001) compared to the ethanol group.
Conclusion: 4. Conclusion
In the present study, the protective effects of astaxanthin on behavioral indices in ethanol model mice brains were investigated. The results showed astaxanthin led to the improvement of memory and learning and anxiety-like behaviors in ethanol-induced mice.