The Effect of Administration of an Equal Dose of Different Classes of Phytochemicals on Heme Oxygenase-1 Gene and Protein Expression in Mice Liver

Abstract

Objective: Heme oxygenase-1 (HO-1) is enzyme that possesses antioxidant, anti-inflammatory, and cytoprotective functions. Induction of HO-1 occurs as an adaptive and beneficial response to various injurious stimuli such as oxidative stress. This study is aimed at monitoring the effects of administration of equal doses (50 mg/kg) of sulforaphane (SFN), curcumin, quercetin, indole-3-carbinol, and butylated hydroxyanisole (BHA) for 14 days on the levels of liver HO-1 gene and protein expression in mice.
 Method: A total of 48 adult male ICR white mice (25–30 g) were divided into eight groups: Normal control group (n=6), SFN-treated group (n=6), quercetin-treated group (n=6), curcumin-treated group (n=6), BHA-treated group (n=6), indole-3-carbinol treated group (n=6), vehicle 1 control group (n=6), and vehicle 2 control group (n=6). All chemicals were administered intraperitoneally at a dose of 50 mg/kg for 14 days. Vehicle 1 (dimethyl sulfoxide, TweenTM 20, and normal saline at a ratio of 0.05:0.1:0.85) was used to dissolve SFN, quercetin, and curcumin. Vehicle 2 (corn oil) was used to dissolve indole-3-carbinol and BHA. At day 15, the animals were sacrificed and their livers were isolated. From the liver, total RNA was extracted, reverse transcribed and subjected to quantitative real‐time polymerase chain reaction to detect HO-1 gene expression. Agarose gel electrophoresis was also performed to verify the specificity of the amplification. HO-1 protein expression was determined by Western blotting.
 Results: HO-1 gene expression showed significant increase of 4.6±0.3, 3.6±0.2, 3.6±0.4, 3.3±0.3, and 3.0±0.4-fold and HO-1 protein expression showed significant increase of 2.3±0.2, 2.2±0.2, 2.2±0.1, 1.8±0.1, and 1.7±0.2-fold following treatment with 50 mg/kg of SFN, indole-3-carbinol, BHA, curcumin, and quercetin, respectively, compared to controls (p<0.05).
 Conclusion: At a dose of 50 mg/kg, SFN administration for 14 days resulted in the highest induction of HO-1 gene and protein expression level in mice liver, and quercetin the lowest.

Effect of Administration of an Equal Dose of Selected Dietary Chemicals on Nrf2 Nuclear Translocation in the Mouse Liver

“…Furthermore, male mice are not subjected to oestrous cycles that can complicate the pharmacological studies of rodents. Most animal pharmacology/toxicology studies have been performed with male mice due to the fact that female mice undergo oestrous cycles that could create a tremendous amount of variability in experimental results [ 22 ]. The animals were treated after a period acclimatization of seven days at room temperature and relative humidity of 28.5°C and 50%, respectively.…”

“…at a dose of 50 mg/kg body weight for 14 consecutive days. In many previous studies (cited in Reference [ 22 ]), the dose of 50 mg/kg of several phytochemicals (SFN, indole-3-carbinol, quercetin, and curcumin) was effective in inducing several important antioxidant enzyme expressions. In a number of studies [ 21 , 22 , 48 – 50 ], two or more phytochemicals were given at a dose of 50 mg/kg in order to compare which phytochemical is more potent in producing positive health-protective effects.…”

“…Phytochemicals such as sulforaphane (SUL), curcumin (CUR), quercetin (QRC), and indole 3 carbinol (I3C) have been shown to activate the Nrf2 pathway in the livers of animals such as rats and mice [15][16][17][18][19][20] (Table 1). We have previously shown that the treatment of mice with equal dose (50 mg/kg body weight) of SUL, CUR, QRC, I3C, and BHA for 14 days resulted in different patterns of expression of phase II enzymes regulated by Nrf2 such as NQO1 and HO-1 in the liver [21,22]. At a dose of 50 mg/kg body weight for 14 days, administration of SUL resulted in the highest NQO1 expressional level in the liver, followed by I3C and BHA (equal expression level), QRC, and CUR [21].…”

“…However, the reasons behind the difference in expressions are not clear. Therefore, this study is aimed at investigating whether the difference in phase II enzymes expression pattern is due to the difference in Nrf2 translocation into the nuclear fraction of the liver, despite the same dose of chemicals being administered to the animals [21,22]. It would also be pertinent to investigate whether the different patterns of expression of phase II enzymes are influenced by the difference in the intensity of Nrf2 expression levels in the nuclear fractions of the liver induced by equal doses of dietary chemicals with different structural properties.…”

“…At a dose of 50 mg/kg body weight for 14 days, administration of SUL resulted in the highest NQO1 expressional level in the liver, followed by I3C and BHA (equal expression level), QRC, and CUR [ 21 ]. Also, at the same dose of 50 mg/kg, SUL administration resulted in the highest level of expression of HO-1 in the mouse liver, followed by I3C and BHA (equal expression level), CUR, and QRC (lowest expression) [ 22 ].…”