Chronic stress-induced oxidative damage and hyperlipidemia are accompanied by atherosclerotic development in rats

Figures & data

Figure 1.  Experimental groups showing period of stress exposure or recovery. Blood and tissue samples were collected at autopsy.

Figure 2.  Vertical bars are mean ± SEM. Percentage change in body weight compared to initial body weight (A) and relative adrenal weight (B) in control, stressed, and recovery groups, n = 5 rats per group. *p < 0.05 versus controls, ANOVA, and Duncan's test.

Table I.  Stress and adrenal 3β-HSDH activity and plasma lipid profile.

		Concentration (U/l)
Groups (n = 5)	Activity of 3β-HSDH (μmol/mg/min)	Cholesterol	LDL	TG	VLDL	HDL
Initial control	0.15 ± 0.009^a	43.1 ± 1.7^a	31.3 ± 1.8^a	58.6 ± 2.1^a	11.7 ± 0.4^a	33.4 ± 1.8^ab
2 weeks stress	0.28 ± 0.009^b	60.9 ± 2.5^b	42.3 ± 2.2^bc	92.7 ± 2.1^bc	18.5 ± 0.4^bc	28.9 ± 1.3^ac
4 weeks stress	0.39 ± 0.01^c	69.5 ± 1.6^c	50.3 ± 0.96^c	97.6 ± 3.3^c	19.5 ± 0.6^c	24.0 ± 1.2^cd
24 weeks stress	0.33 ± 0.05^bc	82.2 ± 2.6^d	60.1 ± 3.13^d	110.2 ± 14^c	22.0 ± 2.8^c	20.5 ± 0.7^d
2 weeks stress+recovery, week 24	0.12 ± 0.17^a	57.7 ± 6.8^b	42.8 ± 7.4^bc	73.5 ± 6.7^ab	14.6 ± 1.3^ab	30.0 ± 1.2^ac
4 weeks stress+recovery, week 24	0.11 ± 0.01^a	58.4 ± 1.2^b	40.4 ± 1.9^b	64.1 ± 2.4^a	12.8 ± 0.4^a	26.9 ± 4.3^ac
24 weeks no stress	0.13 ± 0.002^a	39.8 ± 1.3^a	24.7 ± 1.34^a	61.9 ± 5.1^a	12.3 ± 1^a	36.7 ± 2.9^b
F values (df = 6,34)	17.02	32.84	18.84	7.61	8.710	7.861
p value	p < 0.05	p < 0.05	p < 0.05	p < 0.05	p < 0.05	p < 0.05

Notes: All values are mean ± SEM; values with same superscript letters in a column are not significantly different; values with different superscript letters are significantly (p < 0.05) different by Duncan's multiple post hoc test. LDL, low-density lipoproteins; TG, triglycerides; VLDL, very-low-density lipoproteins; HDL, high-density lipoproteins.

Table II.  Stress and activities of hepatic antioxidant enzymes and GGT.

		Activity (μmol/mg/min)
Groups (n = 5)	CAT activity (nmol/mg/min)	GPx	GST	GR activity (U/ml)	SOD activity (U/mg protein)	GGT activity (U/l)
Initial control	24.3 ± 1.3^a	0.15 ± 0.006^a	68.1 ± 2.2^a	46.9 ± 0.66^a	20.3 ± 0.2^a	47.6 ± 9.31^a
2 weeks stress	13.4 ± 1.5^b	0.13 ± 0.006^ab	43.3 ± 3^b	14.8 ± 0.1^b	18.1 ± 1.08^ab	60.9 ± 6.7^b
4 weeks stress	0.6 ± 0.004^c	0.094 ± 0.003^ab	29.8 ± 3.1^c	15.8 ± 4.2^b	14.9 ± 0.4^bc	65.5 ± 7.7^b
24 weeks stress	0.4 ± 0.008^c	0.027 ± 0.02^b	8.95 ± 1^d	14.2 ± 0.9^b	10.9 ± 0.4^d	84.2 ± 3.3^c
2 weeks stress+recovery, week 24	18.0 ± 1.1^bd	0.21 ± 0.04^a	68.3 ± 11^a	39.6 ± 4.9^a	12.6 ± 1.2^cd	59.6 ± 5.08^b
24 weeks stress+recovery, week 24	23.3 ± 3.0^a	0.19 ± 0.13^a	74.7 ± 5.1^a	61.5 ± 8.0^c	14.7 ± 0.7^bc	48.0 ± 3.1^a
24 weeks no stress	20 ± 1.8^ad	0.14 ± 0.02^ab	64.1 ± 3.5^a	43.2 ± 2.0^a	20.8 ± 2.7^a	46.7 ± 6.1^a
F values (df = 6, 34)	62.5	2.566	39.46	34.12	10.92	5.811
p value	p < 0.05	p < 0.05	p < 0.05	p < 0.05	p < 0.05	p < 0.05

Notes: All values are mean ± SEM; values with same superscript letters in a column are not significantly different; values with different superscript letters are significantly (p < 0.05) different by Duncan's multiple post hoc test. CAT, catalase; GPx, glutathione peroxidase; GST, glutathione-S-transferase; GR, glutathione reductase; SOD, superoxide dismutase, GGT, γ-glutamyl transferase.

Table III.  Stress and aminotransferases and LDH activities.

	Activities (U/l)
Groups (n = 5)	Plasma LDH	Plasma GOT	Plasma GPT
Initial control	105 ± 63.8^a	226 ± 11.5^a	8.56 ± 0.6^a
2 weeks stress	184 ± 18.4^a	240 ± 27.9^a	35.3 ± 0.33^c
4 weeks stress	549 ± 37.01^b	380 ± 20.1^b	40.6 ± 0.6^c
24 weeks stress	623 ± 42.3^b	401 ± 12.1^b	58.2 ± 5.4^d
2 weeks stress+recovery, week 24	249 ± 22.7^a	244 ± 24.08^a	27.1 ± 1.5^b
4 weeks stress+recovery, week 24	236 ± 76.5^a	281 ± 37.2^a	24.2 ± 3.1^b
24 weeks no stress	240 ± 18.2^a	225 ± 12.5^a	9.4 ± 0.8^a
F values (df = 6, 34)	21.862	14.06	48.813
p value	p < 0.05	p < 0.05	p < 0.05

Notes: All values are mean ± SEM; values with same superscript letters in a column are not significantly different; values with different superscript letters are significantly (p < 0.05) different by Duncan's multiple post hoc test. LDH, lactate dehydrogenase; GOT, plasma glutamate oxaloacetate transaminase; GPT, plasma glutamate pyruvate transaminase.

Table IV.  Stress and lipid peroxidation.

	Concentration of malondialdehyde (nmol/mg protein)
Groups (n = 5)	Liver	Kidney	Heart
Initial control	23 ± 2.1^a	11.1 ± 0.9^a	11.4 ± 0.95^a
2 weeks stress	61.1 ± 1.7^b	29.2 ± 2.7^c	36 ± 2.2^c
4 weeks stress	74.2 ± 3.4^c	61.5 ± 3.09^d	64.8 ± 3.8^d
24 weeks stress	101 ± 7.09^d	81.6 ± 3.05^e	85.4 ± 6.3^e
2 weeks stress+recovery, week 24	31.1 ± 0.72^a	21.8 ± 1.6^bc	28.7 ± 1.8^c
4 weeks stress+recovery, week 24	27.4 ± 2.5^a	27.2 ± 4.4^c	25.3 ± 2.08^bc
24 weeks no stress	23.1 ± 5^a	14.3 ± 1.8^ab	14.6 ± 0.95^ab
F values (df = 6, 34)	55.94	104.3	63.83
p value	p < 0.05	p < 0.05	p < 0.05

Notes: All values are mean ± SEM. Values with same superscript letters in the given column are not significantly different; values with different superscript letters are significantly (p < 0.05) different by Duncan's multiple post hoc test.

Figure 3.  Transverse sections of similar areas of thoracic aorta of a control rat (24 weeks no stress; A and B), and a rat stressed for 24 weeks (C and D) and a part of the aorta of a stressed rat under high magnification to show a portion of an atherosclerotic plaque (E) and foam cells (arrow). Note the thickening of wall of the aorta and a fibrous layer in the vessel of the stressed rat. B and D are higher magnification images of A and C, respectively. Hematoxylin–eosin stain; AD, adventitia; EN, endothelium; FB, fibrous layer; FC, foam cells; ME, media.

Figure 4.  Transverse sections of the thoracic aorta of a control rat (24 weeks no stress; A), and a rat stressed for 24 weeks (B) stained with Oil Red O for localization of lipids. Note the Oil-Red-O-positive lipid deposition (arrow heads) in the section from a stressed rat (B). Transverse sections of the thoracic aorta of a control rat (24 weeks no stress; C), and a rat stressed for 24 weeks (D) stained with van Gieson technique to demonstrate elastic fibers (arrow head) and collagen (solid arrow). Note the presence of abundant elastic fibers in the control rat aorta (C) and depletion of elastic fibers and abundant collagen deposition in the stressed rat aorta (D).

Table V.  Stress and thickness of layers of thoracic aorta wall.

	Mean thickness (μm) ± SEM
Groups (n = 5)	Intima	Media	Total intima–media	Total aortic wall
Initial control	11.9 ± 1.1^a	67.3 ± 3.2 ^a	71.3 ± 4.2 ^a	153 ± 3.09^a
4 weeks stress	12.0 ± 0.8^a	72.6 ± 3.1^a	81.6 ± 2.4^a	160 ± 0.6^a
24 weeks stress	60.4 ± 4.6^b	202 ± 19.8^b	252 ± 18.8 ^b	322 ± 41.5^b
4 weeks stress+recovery, week 24	13.4 ± 0.8^a	78.3 ± 5.5^a	90.3 ± 7.01^a	186 ± 15.8^a
24 weeks no stress	14.6 ± 0.9^a	69.6 ± 2.3^a	73.03 ± 3.3^a	152 ± 2.1^a
F values (df = 4, 24)	80.85	34.65	66.6	11.9
p value	p < 0.05	p < 0.05	p < 0.05	p < 0.05

Notes: Values with same superscript letters in a given column are not significantly different; values with different superscript letters are significantly (p < 0.05) different by Duncan's multiple post hoc test.