Associations of the T329S Polymorphism in Flavin-Containing Monooxygenase 3 With Atherosclerosis and Fatty Liver Syndrome in 90-Week-Old Hens

Abstract

This study aimed to evaluate the effects of the spontaneous genetic mutation T329S in flavin-containing monooxygenase 3 (FMO3) on atherosclerosis (AS), fatty liver syndrome (FLS), and adiposity in 90-week-old layers. At 90 weeks of age, 27 FMO3 genotyped Rhode Island White chickens (consisting of nine AA hens, nine AT hens, and nine TT hens) with normal laying performance were selected. The AS lesions, incidence of FLS, fat deposition, metabolic characteristics, and production performance of these egg-layers with different FMO3 genotypes were assessed. The T329S mutation in TT hens reduced the AS lesions (P < 0.01) and altered the plasma metabolic indices more than it did in the AA and AT hens. Furthermore, it reduced the incidence of FLS, hepatic triglyceride deposition (P < 0.05), liver indices (P < 0.05), and fat deposition (P < 0.05) in the subcutis and abdomen of TT hens compared to those of AA and AT hens. Moreover, as an effect of T329S, TT hens laid a higher than average number of eggs and maintained a higher egg-laying rate from 68 to 90 weeks than AA and AT hens. Our study confirmed that the T329S mutation in FMO3 could reduce the development of AS lesions, the incidence of FLS, and fat deposition, which are associated with changes in plasma and hepatic metabolic indices and improvements in the laying performance of older layers. Our results may provide a new strategy for using the T329S mutation to improve the health status and production performance of layers during the late laying period.

Keywords: adiposity; atherosclerosis; fatty liver syndrome; flavin-containing monooxygenase 3; old hen.

Figure 1

Pathological observations of lipid deposition in the aortic wall in different genotyped layers. (A) Oil Red O staining of the whole aorta with aortic lesions (black dashed lines). (B) Quantification of staining results (% of the total area) of the aorta. (C) Oil Red O and hematoxylin staining of aortic arch cross-sections with local tissue magnification (blue squares). Quantification of staining results (% of the total area) of the aortic arch cross-section (D) and its local tissue magnification (blue squares) (E). (B,D,E) Box plot lower extreme is first quartile; box plot upper extreme is third quartile. AA, AA genotype hens; AT, AT genotype hens; TT, TT genotype hens. n = 9 hens with each genotype. ^A,BMeans within a histogram with no common superscripts differ significantly (P < 0.01).

Figure 2

(A) Histopathologic observations of chicken livers were divided into five grades representing the different degrees of fatty liver syndrome (arrows point to local tissue magnification). (B) Incidence rates of different grades of fatty liver syndrome in different genotyped layers. (C) Quantification of Oil red O staining results (% of the total area) of the liver. AA, AA genotype hens; AT, AT genotype hens; TT, TT genotype hens. Values are expressed as means ± standard deviation (SD); n = 9 hens with each genotype. ^A,BMeans within a histogram with no common superscripts differ significantly (P < 0.01).

Figure 3

Hepatic pathological scores (A) and TG levels (B) in different genotyped layers. TG, triglyceride; AA, AA genotype hens; AT, AT genotype hens; TT, TT genotype hens. Values are expressed as means ± standard deviation (SD); n = 9 hens with each genotype. ^a,bMeans within a histogram with no common superscripts differ significantly (P < 0.05).

Figure 4

Hepatic antioxidant indices in different genotyped layers. (A) Glutathione peroxidase (GSH-Px) activity; (B) Total superoxide dismutase (T-SOD) activity; (C) Catalase (CAT) activity; (D) Hepatic malondialdehyde (MDA) levels. AA, AA genotype hens; AT, AT genotype hens; TT, TT genotype hens. Values are expressed as means ± SD, n = 9 hens each genotype. ^{a, b}Means within a histogram with no common superscripts differ significantly (P < 0.05).

Figure 5

The average number of eggs (A) and the egg-laying rate (B) of sample layers with different FMO3 genotypes from 19 to 90 weeks. FMO3, flavin-containing monooxygenase 3. AA, AA genotype hens; AT, AT genotype hens; TT, TT genotype hens. Values are expressed as means ± standard deviation (SD); n = 9 hens with each genotype. Mean values with (*) differ significantly between the AA and TT hens (P < 0.05).

Figure 6

Heat map based on Pearson's correlations for the relationships among metabolic indices and phenotypic traits (fat deposition characteristics in the aorta, liver, subcutis, and abdomen, organ indices, and production performance) of the 27 selected hens at 90 weeks. (A) Correlations between plasma metabolic indices and phenotypic traits. (B) Correlations between hepatic metabolic indices and phenotypic traits. (A) Correlations between plasma metabolic indices and phenotypic traits. (B) Correlations between hepatic metabolic indices and phenotypic traits. The color scale represents Pearson's correlation coefficients, with red and bluish violet representing positive and negative correlations, respectively. Ranging from 1.0 (maximum positive correlation) to −1.0 (maximum anti-correlation), with 0 indicating no correlation. TC, total cholesterol; LDL-C, low-density lipoprotein cholesterol; VLDL, very low-density lipoprotein; TG, triglyceride; FFAs, free fatty acids; INS, insulin; Glu, glucose; IL-1β, interleukin-1β; IL-6, interleukin-6; IL-8, interleukin-8; ALT, alanine aminotransferase; AST, aspartate aminotransferase; CRE, creatinine; EN90, average number of eggs laid by layers from 19 to 90 weeks; OI, ovarian index; SFT, subcutaneous fat thickness; AFR, abdominal fat rate; LI, liver index; HLD, hepatic lipid deposition; AL, aortic lesion; GSH-Px, glutathione peroxidase; T-SOD, total superoxide dismutase; CAT, catalase; MDA, malondialdehyde; HTG, hepatic triglyceride. *P < 0.05, **P < 0.01.