Effects of long-term moderate ethanol and cholesterol on cognition, cholinergic neurons, inflammation, and vascular impairment in rats

There is strong evidence that vascular risk factors play a role in the development of Alzheimer's disease (AD) or vascular dementia (vaD). Ethanol (EtOH) and cholesterol are such vascular risk factors, and we recently showed that hypercholesterolemia causes pathologies similar to AD [Ullrich et al. (2010) Mol Cell Neurosci 45, 408–417]. The aim of this study was to investigate the effects of long-term (12 months) EtOH treatment (20% v/v in drinking water) alone or long-term 5% cholesterol diet alone or a combination (mix) in adult Sprague–Dawley rats. Long-term EtOH treatment (plasma EtOH levels 58±23 mg/dl) caused significant impairment of spatial memory, reduced the number of choline acetyltransferase- and p75 neurotrophin receptor-positive nucleus basalis of Meynert neurons, decreased cortical acetylcholine, elevated cortical monocyte chemoattractant protein-1 and tissue-type plasminogen activator, enhanced microglia, and markedly induced anti-rat immunoglobulin G-positive blood–brain barrier leakage. The effect of long-term hypercholesterolemia was similar. Combined long-term treatment of rats with 20% EtOH and 5% cholesterol (mix) did not potentiate treatment with EtOH alone, but instead counteracted some of the EtOH-associated effects. In conclusion, our data show that vascular risk factors EtOH and cholesterol play a role in cognitive impairment and possibly vaD.

Hypercholesterolemia in rats impairs the cholinergic system and leads to memory deficits

Alzheimer's disease (AD) is a chronic brain disorder characterized by cognitive impairment, cholinergic dysfunction, inflammation, tau and beta-amyloid pathology and vascular damage. Recent studies have shown, that high cholesterol levels are linked to the pathology of AD. The aim of our present work was to study the effects of hypercholesterolemia in adult rats. Five months after 5% cholesterol-enriched diet plasma cholesterol levels and total weight were significantly enhanced compared to controls. Spatial memory was studied in an 8-arm radial maze and cholesterol-treated rats showed an impaired learning and long-term memory. Hypercholesterolemia significantly reduced the number of cholinergic neurons in the basal nucleus of Meynert and decreased acetylcholine levels in the cortex. Nerve growth factor was only slightly enhanced in the cortex of cholesterol-treated animals. Levels of amyloid precursor protein, beta-amyloid(1–42), as well as tau and phospho-tau 181 were significantly enhanced in the cortex of cholesterol-fed rats. Hypercholesterolemia markedly increased several cerebral inflammatory markers and enhanced microglial CD11b-like immunoreactivity. Vascular density, stained by RECA-1 was not changed. However, cholesterol induced cortical microbleedings illustrated by intensive anti-rat IgG-positive spots in the cortex. In conclusion, our data demonstrate that hypercholesterolemia in rats caused memory impairment, cholinergic dysfunction, inflammation, enhanced cortical beta-amyloid and tau and microbleedings, all indications, which resemble an AD-like pathology.

Dietary diacylglycerol oil has no effect on hypertriacylglycerolaemia in lipoprotein lipase-deficient cats

A commercially available vegetable oil containing a high concentration (87 %, w/w) of diacylglycerol (DAG) has been investigated in humans and animals for potential beneficial effects in reducing serum TAG concentrations in fasting and postprandial states. Effects of DAG oil as a sole dietary fat source (25 % metabolisable energy) were evaluated in a feline model of hypertriacylglycerolaemia. Eleven adult (1.5 (sem 0.1) years) male cats deficient of lipoprotein lipase (LPL) catalytic activity from a heritable point mutation of the LPL gene were acclimatised to a semi-purified diet containing TAG oil for 21 d. After assignment into two groups, pair-matched by serum TAG concentrations (range 6.1-31.6 mmol/l), the cats were fed the diet with either TAG or DAG oil for 8 d. The dietary fat source was crossed-over and presented for 8 d more. Non-fasting serum concentrations of TAG, cholesterol and NEFA were measured on days 6-8 and days 14-16. Dietary fat source (DAG v. TAG) did not significantly affect food intake (491 (sem 16) v. 486 (sem 14) kJ/kg0.67), body weight or serum concentrations (mmol/l) of TAG (37.1 (sem 4.5) v. 33.9 (sem 3.4)), cholesterol (4.8 (sem 0.3) v. 4.8 (sem 0.2)) and NEFA (1.4 (sem 0.2) v. 1.4 (sem 0.2)). The results show that for a feeding trial of 8 d, DAG oil was well accepted and tolerated by cats but did not reduce hypertriacylglycerolaemia resulting from a deficiency of LPL catalytic activity.

Gallbladder stones classified by chemical analysis of cholesterol content. Frederiksberg, 1987-1988

Gallstones from 80 cholecystectomies and 81 autopsies were chemically analysed and showed a trend of decreasing cholesterol content with increasing age (p = 0.00009). The frequency of cholesterol stones (cholesterol content greater than 70%) was higher in operated women (81%) than in operated men (33%) (p = 0.0006) and in the total autopsy material (42%). The study supports the theory that the predominance of gallstone disease in women is an effect of the preponderance of cholesterol stones. The accuracy of estimates of cholesterol content of gallstones from the appearance of the cut surface was low. When the chemical analysis was used as a key, only one in three was correct. There was a tendency to underestimate cholesterol content.

Problems with measurements caused by high concentrations of serum solids

There have been numerous reports of spectrophotometric and volume problems caused by elevated levels of lipids in blood. The offending lipids, primarily triglycerides, not only cause turbidity leading to optical aberrations when added to analytical reagents, but also result in short-sampling errors leading to the measurement of inaccurate volumes of sample. Numerous methods have been developed to clear the lipemia, including ultracentrifugation organic solvent extraction, chemical precipitation and, most recently, enzymic hydrolysis. Although the latter procedures eliminate the optical problems, they do not deal with the volume dilution error created by the triglycerides. In turn, corrective mathematics have been developed to compensate for the inaccurate pipetting caused by the elevated lipids in a sample; however, these empirical calculations are not truly accurate at high concentrations of total lipids. This monograph will describe the problems caused by the presence of elevated lipids and the means available for treating them.