Oxidized LDL Is Strictly Limited to Hyperthyroidism Irrespective of Fat Feeding in Female Sprague Dawley Rats

Abstract

Metabolic dysfunctions might play a crucial role in the pathophysiology of thyroid dysfunctions. This study aimed to investigate the impact of a controlled diet (normal versus high fat feeding) on hypothyroid and hyperthyroid Sprague Dawley rats. Female Sprague Dawley rats (n = 66) were grouped into normal diet (n = 30) and high-fat diet (n = 36) groups and subdivided into controls, hypothyroid and hyperthyroid groups, induced through propylthiouracil or triiodothyronine (T3) treatment, respectively. After 12 weeks of treatment metabolic parameters, such as oxidized LDL (oxLDL), malondialdehyde (MDA), 4-hydroxynonenal (HNE), the lipid profile, body weight and food intake parameters were analyzed. Successfully induced thyroid dysfunctions were shown by T3 levels, both under normal and high fat diet. Thyroid dysfunctions were accompanied by changes in calorie intake and body weight as well as in the lipid profile. In detail, hypothyroid rats showed significantly decreased oxLDL levels, whereas hyperthyroid rats showed significantly increased oxLDL levels. These effects were seen under high fat diet and were less pronounced with normal feeding. Taken together, we showed for the first time in female SD rats that only hyper-, but not hypothyroidism, is associated with high atherogenic oxidized LDL irrespective of normal or high-fat diet in Sprague Dawley rats.

The effects of long-term moderate exercise and Western-type diet on oxidative/nitrosative stress, serum lipids and cytokines in female Sprague Dawley rats

“…*p < 0.05, **p < 0.01 compared to appropriate sedentary control group; # p < 0.05 compared to appropriate normal diet control group. £ p < 0.05, ££ p < 0.01, £££ p < 0.001 compared to baseline control group we obtained in young and old control animals are in line with a previous study in SD rats [11].…”

“…In our laboratory, all methods are strictly controlled by internal and external quality controls. Furthermore, the lipid concentrations that we obtained in young and old control animals are in line with a previous study in SD rats [ 11 ].…”

“…Previous studies that treated rodents with HFD reported mixed results. While some studies found increasing concentrations of TC, TG and LDL-C [ 2 , 25 , 41 , 44 ] others did not [ 11 ]. However, a direct comparison of these studies is limited due to differences in study design and composition of the diets.…”

“…The modification of LDL-C by oxidation promotes the receptor-mediated uptake of oxLDL by macrophages, thereby causing cholesterol accumulation in the vasculature. Previous studies in humans and animals indicate that Western diet and physical inactivity induce free radical production, which may enhance the susceptibility of LDL to oxidation [ 3 , 4 , 11 ]. One of the principal pathways involved in the adaptation to exercise is nitric oxide (NO) signalling.…”

Preliminary Analysis of Modified Low-Density Lipoproteins in the Serum of Healthy and Obese Dogs and Cats

“…Previous studies have shown that thyroid dysfunction is accompanied by changes in caloric intake and body weight, as well as changes in the lipid profile. Hypothyroid rats showed significantly decreased oxidized LDL levels, whereas hyperthyroid rats showed significantly increased oxidized LDL levels ( 30 ). Another report showed that oxidized LDL levels in 125 obese human patients were positively correlated with body mass index and T-Cho concentration ( 31 ).…”