Detrimental effects of fluvastatin on plasma lipid metabolism in rat breast carcinoma model

From clinical practice, obvious positive effects of statins on plasma lipid metabolism are well known. On the other hand, there are several experimental rodent studies, where these beneficial effects were not confirmed. The effects of fluvastatin on selected serum lipid parameters in a rat model of experimental breast cancer were determined. The drug was dietary administered at two concentrations of 20 and 200 mg/kg. At the end of the study (experiment duration - 18 weeks) the blood from each animal was collected and serum lipid parameters were evaluated. Fluvastatin in both treated groups significantly increased parameters of serum lipids (mostly in a dose dependent manner). Fluvastatin in both treated groups of animals significantly increased serum levels of triacylglycerols, total cholesterol, and LDL-, HDL-, VLDL-cholesterol when compared to the control group. Our results pointed out to the apparent harmful effects of fluvastatin on plasma lipid metabolism in rat mammary carcinogenesis. Based on our previous results, it seems that rats commonly used in cancer model studies are generally unresponsive to the hypocholesterolemic effects of statins

Prolonged melatonin administration in 6-month-old Sprague-Dawley rats: metabolic alterations

The aim of this work was to evaluate the effect of prolonged melatonin administration on chosen metabolic and hormonal variables in male and female Sprague-Dawley rats. Melatonin was administered in tap water (4 μg/ml) daily from the 6th month of age. Rats were fed a standard type of diet ad libitum and were kept in a light regimen L:D - 12:12h. The experiment was terminated after 12 weeks of melatonin administration. Melatonin decreased body mass during the whole experiment in females and from the 42nd day of the experiment in males. Relative heart muscle weight in females and absolute/relative thymus weight in males were increased after melatonin administration. Melatonin decreased glycaemia, heart muscle glycogen concentration in females and liver glycogen concentration in both sexes. Serum insulin concentration in males was decreased; serum corticosterone concentration was increased in both males and females. Serum triacylglycerol and heart muscle cholesterol concentration in females were decreased, however in males serum and heart muscle cholesterol concentration was increased. Liver phospholipid concentration in females was decreased and heart muscle phospholipid concentration in males was increased. Melatonin increased malondialdehyde concentration in heart muscle in males and in liver in both sexes. Melatonin induced prominent sexdependent changes in both carbohydrate and lipid metabolism