Depression is the most common mood disorder; it is the major cause of disability and premature death worldwide (Hiraki
et al., 2019, Ritter
et al., 2020, Saki
et al., 2014, Sánchez-Vidaña
et al., 2019, Shinohara
et al., 2013). According to the World Health Organization (WHO) report, approximately 450 million people suffer from a mental or behavioral disorder, and only a small minority of patients receive the basic treatment (Brundtland, 2001). Clinical depression is a brain-based illness involving the prefrontal cortex as well as other key brain regions (George
et al., 1994). Findings suggest that dietary fat type affects the behavioral signs of anxiety fairly rapidly (Mizunoya
et al., 2013). Obesity and high fat diet (HFD) have been linked to depression, with both epidemiological and clinical studies, demonstrating a positive association between these two disorders (Vagena
et al., 2019). HFD can also affect hypothalamus, neuronal plasticity and connectivity, reducing dendritic spine density and decreasing synaptic markers in the prefrontal cortex (Bocarsly
et al., 2015). Emerging research has established an association between omega-3 fatty acids (alpha-linolenic, eicosapentaenoic, and docosahexaenoic) and major depressive disorder (Freeman, 2009). Evidence from epidemiological, laboratory, and clinical studies have suggested that dietary lipids and other associated nutritional factors may affect vulnerability and outcome in depressive disorders (Logan, 2004). There are two kinds of edible oil, including vegetable oil (such as olive oil, sunflower oil, solid vegetable oil) and animal oil (such as Kermanshah animal oil).
The forced swim test (FST) was a rodent behavioral test used for evaluating depression (Yankelevitch-Yahav
et al., 2015). Mice were placed in an inescapable transparent tank filled with water and their escape related mobility behavior was measured. The FST was straight forward to conduct reliably, requiring
minimal specialized equipment. Successful implementation of the FST required adherence to certain procedural details and minimization of unwarranted stress to the mice. The protocol description explained how to conduct the mouse version of this test with emphasis on potential pitfalls that may be detrimental to the interpretation of results and how to avoid them. Additionally, the way of assessing the manifested behaviors in the test were explained (Can
et al., 2012, Hassan
et al., 2019, Ruanpang
et al., 2018, Takase
et al., 2016).
In this study, the types of liquid sunflower oil, spring frying oil, olive oil, vegetable solid oil, and animal oil of Kermanshah were separately studied.
Materials and Method
Selection of edible oil: Five types of vegetable and animal oils were selected which were among the most widely used oils in the market, including spring frying oil, Laden sunflower liquid oil, olive oil, Kermanshah Rojin animal oil , and BAHAR solid vegetable oil (Table1) (Orsavova
et al., 2015).
Animals and experimental diets: Thirty-two male and female mice (Mus musculus (BALB/c)) weighing 25-35 g were randomly divided into 8 groups (4 mice in each group, 2 male and 2 female). The mice were housed under controlled conditions of temperature (27°C), relative humidity (60–40 ± 10%), lighting (12-hour light-dark cycles), and well-ventilated. After two weeks of standardization with the same nutrition in all groups (soybeans and corn regime daily), they were fed 100 mg of cheese and 5 g of cucumber every other day. In different groups, 30 g of vegetable or animal oil was gavaged every day at 1:00 pm:
A: Laden sunflower liquid oil
B: 50% vegetable oil + 50% olive oil
C: Kermanshah Rojin animal oil
D: Spring frying oil
E: Distilled water
F: BAHAR solid vegetable oil
G: Olive oil
H: 50% Kermanshah animal oil + 50% of olive oil
Behavioral test; FST: After 6 weeks of using the oils diet, the forced swim test was conducted according to the study ethical rules, especially ethical code No. 5014/710 / D dated 11/23/2015 as a standard of FST rules. Among all animal models, the FST is one of the most widely used tools for screening antidepressants (Kulkarni and Dhir, 2007).
The forced swim aperture is a cylindrical container with a length of 25 cm and width of 12 cm and a height of 8 cm filled with 25 ͦ C water. At the beginning, the mouse was placed in the water at a height of 20 cm. Cutting off the movement of the mouse's hands and feet is typically considered the mouse immobility.
The total FST time was 10 minutes, the first two minutes was the time when the mouse adapt to the environment and no data was recorded. After two minutes of testing, the time of 10 minutes was divided into two five-minute periods and the animal's movements were recorded with an accurate chronometer.
During 5 minutes, swimming (score=1), immobilization (score=0), and trying to climb (score=2) were recorded every 15 seconds.
Ethical considerations: Ethical committee of Shahid Beheshti University of Medical Sciences approved this study (approval number: IR.SBMU.REC.1398.109).
Data analysis: The data were expressed as the mean ± standard deviation (SD). Comparisons among groups were performed by one-way ANOVA, followed by a Tukey’s HSD post-hoc and multiple comparison tests, when appropriate. A P-value of < 0.05 was considered to be significant.
Results
Latency of immobility: There was a significant difference between all the study groups (
P < 0.0001)
. Based on the results, the latency time of immobility in group A significantly decreased in comparison with groups C (
P ˂ 0.02), D (
P ˂ 0.003), and G (
P <0.001). However, it increased in groups B and C compared to group H (
P ˂ 0.02). Also, this parameter significantly increased in group D compared to groups E (
P < 0.01), F (
P < 0.05), and H (
P < 0.002). In addition, groups E and F showed a significant decrease compared to group G (
P ˂ 0.001) (
Figure 1). The highest amount of Latency of immobility was seen in the group consuming olive oil and the lowest value was seen in the group consuming Laden sunflower liquid oil.
Total immobility time: The data showed that total immobility in groups B (
P ˂ 0.004), D (
P ˂ 0.04), F (
P ˂ 0.002), G (P < 0.001), and H (
P ˂ 0.006) compared to group A decreased. There were no differences between other comparisons. The lowest amount belonged to the group receiving olive oil and the highest value was seen in the group consuming Laden sunflower liquid oil (
Figure 2).