Changes of blood biochemistry in the rabbit animal model in atherosclerosis research; a time- or stress-effect

Safety evaluation of saffron extracts in early and established atherosclerotic New Zealand white rabbits

Previous research has shown that natural medications pose health risks, especially in subjects with comorbidities. This study aimed to evaluate the safety of saffron ethanolic extract (SEE) administration in early and established atherosclerotic rabbits. Rabbits were given a high-cholesterol diet (HCD) for 4 and 8 weeks to induce early and established atherosclerosis respectively, and then they were treated with 50 and 100 mg/kg/day SEE. The body weight of the animals was recorded. Blood samples were collected at baseline, pre-treatment, and post-treatment for hematological studies, lipid profiles, and biochemical profiles. Tissue specimens of the vital organs were subjected to histological examination. The above parameters were significantly altered post-intervention with 4 and 8 weeks of HCD. No significant differences in body weight were observed in all the groups post-treatment with 50 and 100mg/kg of SEE compared to pre-treatment. However, low-density lipoprotein cholesterol, total cholesterol, serum urea, and glucose significantly decreased post-treatment with 50 and 100mg/kg/day SEE compared to pre-treatment in early and established atherosclerosis groups. Hematological parameters that were affected post-intervention with HCD returned to their baseline values post-treatment with 50 and 100mg/kg/day SEE. There was a significant improvement in the vital organs post-treatment with 50 and 100mg/kg SEE. SEE can safely be administered without causing harmful effects on the hematological, biochemical profiles, and vital organs. Notably, SEE exerts hypolipidemic and hypoglycemic effects on atherosclerotic conditions. Further clinical trials are warranted to ensure the safety of saffron administration in patients with atherosclerosis-related diseases.

Effect of Postbiotic Based on Lactic Acid Bacteria on Semen Quality and Health of Male Rabbits

The aim of this study was to evaluate the effect of lactic acid bacteria-based postbiotic supplementation on semen characteristics and hematological and biochemical profiles in rabbits. A total of 28 males were randomly allocated into two groups. Males received a Control diet and Enriched diet supplemented with postbiotic for 15 weeks (4 weeks of adaptation period and 11 weeks of experimental period). Body weight, feed intake and semen characteristics were recorded weekly. Hematological profile was recorded at the beginning and end of the experiment and biochemical profile at 0, 5, 10 and 15 weeks. Bayesian methodology was used for the statistical analysis. Feed intake was higher in Control diet (125.2 g) than in the Enriched diet (118.6 g, p = 1.00). The percentages of abnormal spermatozoa were higher in Control diet than in Enriched diet (30% and 22%; p = 0.93) and the acrosome integrity percentage was lower (97% and 96%; p = 0.87). The hematological profile was within the range for healthy rabbits. The plasmatic level of alanine aminotransferase was higher in Control diet than Enriched diet at 5 and 10 weeks (p = 0.93 and p = 0.94, respectively) and alkaline phosphatase was similar in Control diet throughout the experiment, but decreased in Enriched diet (p = 0.97). No difference was found in kidney parameters (uric nitrogen and creatinine). Enriched diet showed higher total protein and globulin than Control diet (p = 0.99). Phosphorus was lower (p = 0.92) in Control diet than in Enriched diet. In conclusion, the addition of the postbiotic based on lactic acid bacteria seems to improve the quality of the semen and the liver profile in rabbits.

HDL (High-Density Lipoprotein) Remodeling and Magnetic Resonance Imaging-Assessed Atherosclerotic Plaque Burden: Study in a Preclinical Experimental Model

OBJECTIVE

HDL (high-density lipoprotein) role in atherosclerosis is controversial. Clinical trials with CETP (cholesterylester transfer protein)-inhibitors have not provided benefit. We have shown that HDL remodeling in hypercholesterolemia reduces HDL cardioprotective potential. We aimed to assess whether hypercholesterolemia affects HDL-induced atherosclerotic plaque regression. Approach and Results: Atherosclerosis was induced in New Zealand White rabbits for 3-months by combining a high-fat-diet and double-balloon aortic denudation. Then, animals underwent magnetic resonance imaging (basal plaque) and randomized to receive 4 IV infusions (1 infusion/wk) of HDL isolated from normocholesterolemic (NC-HDL; 75 mg/kg; n=10), hypercholesterolemic (HC-HDL; 75 mg/Kg; n=10), or vehicle (n=10) rabbits. Then, animals underwent a second magnetic resonance imaging (end plaque). Blood, aorta, and liver samples were obtained for analyses. Follow-up magnetic resonance imaging revealed that NC-HDL administration regressed atherosclerotic lesions by 4.3%, whereas, conversely, the administration of HC-HDLs induced a further 6.5% progression (P<0.05 versus basal). Plaque characterization showed that HC-HDL administered animals had a 2-fold higher lipid and cholesterol content versus those infused NC-HDL and vehicle (P<0.05). No differences were observed among groups in CD31 levels, nor in infiltrated macrophages or smooth muscle cells. Plaques from HC-HDL administered animals exhibited higher Casp3 (caspase 3) content (P<0.05 versus vehicle and NC-HDL) whereas plaques from NC-HDL infused animals showed lower expression of Casp3, Cox1 (cyclooxygenase 1), inducible nitric oxide synthase, and MMP (metalloproteinase) activity (P<0.05 versus HC-HDL and vehicle). HDLs isolated from animals administered HC-HDL displayed lower antioxidant potential and cholesterol efflux capacity as compared with HDLs isolated from NC-HDL-infused animal and vehicle or donor HDL (P<0.05). There were no differences in HDL-ApoA1 content, ABCA1 (ATP-binding cassette transporter A1) vascular expression, and SRB1 (scavenger receptor B1) and ABCA1 liver expression.

CONCLUSIONS

HDL particles isolated from a hypercholesterolemic milieu lose their ability to regress and stabilize atherosclerotic lesions. Our data suggest that HDL remodeling in patients with co-morbidities may lead to the loss of HDL atheroprotective functions.

Effect of the methanol extract of the red cultivar Allium cepa L. on the serum biochemistry and electrolytes of rats following sub-chronic oral administration

Background In traditional medicine, Allium cepa Linnaeus is used for the treatment of several disease conditions. Whilst reports abound on the effects of several cultivars of A. cepa L on biochemical parameters, similar information on the red cultivar is scarce. This study examines the effects of the methanol extract of the red cultivar A. cepa L on some serum biochemical parameters in experimental Wistar rats. Materials and methods Fifty-five Wistar rats were divided into three groups (A, B and C), which include 25, 25 and 5 rats, respectively. The rats in Groups A and B were sub-divided into 5 groups of 5 rats. Each rat was administered a certain dose of methanol extract of the red cultivar A. cepa L for 14 days (Group A) or 28 days (Group B). Group C rats served as the control and were administered with distilled water (10 mL/kg). Results A. cepa L administration resulted in dyslipidaemia, hyponatremia, hypokalaemia and hyperchloraemia; a significant (p < 0.05) decrease in hepatic enzymes and a significant (p < 0.05) increase in serum bicarbonate, bilirubin and its fractions. Conclusions These biochemical results indicate that the excessive and prolonged medicinal consumption of A. cepa L products beyond 7 days may induce moderate hepatic injury and mild renal dysfunction and may complicate disease conditions, such as hypertension and diabetes. Thus, in order to minimize its toxic effects, it is recommended that A. cepa L products should not be used for more than seven consecutive days or beyond a dosage of 90 mg/kg.

Impact of space allowance on performance traits, brain neurotransmitters and blood antioxidant activity of New Zealand White rabbits

The objective of this trial was to investigate the effect of space allowance on performance, welfare-related parameters and the levels of brain neurotransmitters in growing male rabbits. In a cage housing system, a total of 96 weaned rabbits were accommodated on three space allowance conditions (S₁ = 1425 cm²/rabbit; S₂ = 850 cm²/rabbit; S₃ = 625 cm²/rabbit), with 8 replicate cages per each group. Rabbits in the S₁ and S₂ groups showed better daily feed intake and feed conversion ratio compared with the high stocking density group (p = 0.004 and 0.018, respectively). Compared to the highest stocking density group (S₃), rabbits in the S₁ and S₂ groups showed significantly lower serum cortisol, MDA and GSSH level (p = 0.026, 0.018 and 0.009, respectively). The concentration of dopamine in brain tissues was significantly decreased in the S₃ group compared with other experimental groups (P = 0.001). However, there was no significant effect of space allowance on the brain AChE level (P = 0.277). Brain serotonin and GABA levels showed a significant decrease in rabbits reared with a limited space allowance (S₃) compared with S₁ and S₂ groups (P = 0.001 and 0.038, respectively). The level of brain MDA was significantly increased in the S₃ group compared with the S₁ group (P = 0.006). However, there were no detectable differences in the brain ATP level in rabbits reared with different space allowance (P = 0.693). In conclusion, the current study indicates that the 850 cm²/rabbit stocking density has resulted in a better feed intake, and welfare-related conditions compared with the 625 cm²/rabbit. Furthermore, the limited space allowance may impair the most important brain neurotransmitters in male rabbits.

The effects of oleanolic acid on atherosclerosis in different animal models

In the present study, three animal models, including C57BL/6J mice, low-density lipoprotein receptor knockout (LDLR-/-) mice, and rabbit that mimicked atherosclerosis, were established to investigate the inhibitory effect of oleanolic acid (OA) on atherosclerosis. In rabbit model, serum total cholesterol (TC), triglyceride, low density lipoprotein cholesterol (LDL-C), and high density lipoprotein cholesterol (HDL-C) were measured. Carotid artery lesions were isolated for histological analysis. The red oil O and hematoxylin-eosin staining in liver were examined. The messenger ribonucleicacid (mRNA) levels of PPARγ, AdipoR1, and AdipoR2 related to lipid metabolism were determined. Compared with model group, OA and atorvastatin significantly lowered the levels of TC and LDL-C. The result of red oil O staining showed that OA and atorvastatin had similar effect on reducing the accumulation of lipid. Histological result demonstrated that OA reduced the thickness of intima. AdipoR1 was markedly increased, while AdipoR2 was remarkably decreased in OA group compared with that in the control group of the rabbit model. In LDLR-/- mouse model, lipid parameters in blood and mRNA levels of PPARγ, AdipoR1, and AdipoR2 were measured. It was found that OA exhibited similar effects as atorvastatin including reduced TG, LDL-C, and enhanced HDL-C. Notably, OA elevated the levels of AdipoR1 and PPARγ. At the same time, OA decreased TC and LDL-C in C57BL/6J mice model. Our results in three different animal models all revealed that OA retarded the development of atherosclerosis by influencing serum lipid levels, lipid accumulation in liver and intimal thickening of artery. And the underlying mechanism of OA on atherosclerosis may involve in lipid metabolism genes: PPARγ, AdipoR1, and AdipoR2.

Effect of aqueous extract of Vernonia amygdalina on atherosclerosis in rabbits

BACKGROUND

Extracts of Vernonia amygdalina (V. amygdalina) have been shown to affect the serum lipid profile of some laboratory animals in previous studies. Its impact on serum lipid profile and the histological changes in atherosclerosis has not been studied. Our aim was to determine the effects of V. amygdalina on atherosclerotic lesions induced in rabbits on high-cholesterol diet.

METHODS

18 male rabbits were randomly divided into three groups of control, atherogenic diet, and atherogenic diet + 200 mg/kg of V. amygdalina. The rabbits were fed a normal diet (control group) or a diet supplemented by 0.5% cholesterol and 1% methionine (second and third groups, respectively) for 12 weeks. The fasting sera of all animals were collected at baseline and at the end of the 12 weeks, to determine the levels of lipid profile and the aortas underwent pathomorphological examination.

RESULTS

The two groups on the atherogenic diet had significantly increased serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) compared to the control group. The serum triglyceride (TG) was not statistically different in all three groups. High-density lipoprotein cholesterol (HDL-C) was significantly increased in the V. amygdalina group, compared to the control group but there was no statistically significant difference between the two groups on atherogenic diet. The two groups of rabbits that were on high-cholesterol diet (atherogenic diet group, as well as the atherogenic diet + 200 mg/kg of V. amygdalina) developed histological evidence of atherosclerosis. However, there was no histological difference between the lesions observed in these two groups.

CONCLUSION

The use of 200 mg/kg of aqueous extract of V. amygdalina in rabbits did not appear to exert a significant effect on the serum lipid profile. It also did not appear to have any beneficial effect on the development of atherosclerotic lesions.

Chronic unpredictable mild stress combined with a high-fat diets aggravates atherosclerosis in rats

Background

Depression and high-fat diet are both known as independent risk factors for atherosclerosis and other cardiovascular diseases, suggesting the interaction of psychological and physiological factors in the development of these diseases. The liver is a crucial organ that facilitate lipid metabolism especially in reverse cholesterol transport (RCT), while according to the theory of Traditional Chinese Medicine, depression as a kind of psychological stress has an influence on hepatic function. So there seem to be some links between depression and lipid metabolic disorders.

Methods

To investigate these links, we separately treated rats with chronic unpredictable mild stress (CMS) and/or a high-fat diet (HD) to evaluate the development of atherosclerosis and the expression of hepatic ABCG8, ABCG5, SR-BI, CYP7A1, LXRα, and LCAT which were associated with reverse cholesterol transport.

Results

This study provided evidence that high-fat diet greatly decreased these genes expression related to RCT while chronic stress alone tended to promote RCT. Chronic unpredictable mild stress combined with a high-fat diet attenuated RCT and aggravated atherogenesis.

Conclusions

These observations suggested that chronic psychological stress alone is virtually propitious to lipid metabolism, however when under a condition of high-fat diet, it deteriorated atherosclerotic plague and did harm to RCT.

Characterization of blood biochemical markers during aging in the Grey Mouse Lemur (Microcebus murinus): impact of gender and season

BACKGROUND

Hematologic and biochemical data are needed to characterize the health status of animal populations over time to determine the habitat quality and captivity conditions. Blood components and the chemical entities that they transport change predominantly with sex and age. The aim of this study was to utilize blood chemistry monitoring to establish the reference levels in a small prosimian primate, the Grey Mouse Lemur (Microcebus murinus).

METHOD

In the captive colony, mouse lemurs may live 10-12 years, and three age groups for both males and females were studied: young (1-3 years), middle-aged (4-5 years) and old (6-10 years). Blood biochemical markers were measured using the VetScan Comprehensive Diagnostic Profile. Because many life history traits of this primate are highly dependent on the photoperiod (body mass and reproduction), the effect of season was also assessed.

RESULTS

The main effect of age was observed in blood markers of renal functions such as creatinine, which was higher among females. Additionally, blood urea nitrogen significantly increased with age and is potentially linked to chronic renal insufficiency, which has been described in captive mouse lemurs. The results demonstrated significant effects related to season, especially in blood protein levels and glucose rates; these effects were observed regardless of gender or age and were likely due to seasonal variations in food intake, which is very marked in this species.

CONCLUSION

These results were highly similar with those obtained in other primate species and can serve as references for future research of the Grey Mouse Lemur.