The lipids present in hepatic stellate cells (HSCs) lipid droplets include retinyl ester, triglyceride, cholesteryl ester, cholesterol, phospholipids and free fatty acids. Activation of HSCs is crucial to the development of fibrosis in liver disease. During activation, HSCs transform into myofibroblasts with concomitant loss of their lipid droplets and production of excessive extracellular matrix. Release of lipid droplets containing retinyl esters and triglyceride is a defining feature of activated HSCs. Accumulating evidence supports the proposal that recovering the accumulation of lipids would inhibit the activation of HSCs. In healthy liver, quiescent HSCs store 80% of total liver retinols and release them depending on the extracellular retinol status. However, in injured liver activated HSCs lose their retinols and produce a considerable amount of extracellular matrix, subsequently leading to liver fibrosis. Further findings prove that lipid metabolism of HSCs is closely associated with its activation, yet relationship between activated HSCs and the lipid metabolism has remained mysterious.
Animals ; Cholesterol ; metabolism ; Hepatic Stellate Cells ; physiology ; Humans ; Lipid Metabolism ; Triglycerides ; metabolism ; Vitamin A ; metabolism

Human apolipoprotein A- I, the major protein component of high density lipoproteins and the main activator of the enzyme lecithin: cholesterol acyltransferase, defines the structure and stability and functions of HDL. It is clearly demonstrated that high concentration of the apoA- I not only inhibits the initiation and progression of atherosclerosis, but also makes the preexisting atherosclerotic lesions regress. This review gives an overview of the apoA- I structure, production, relation between apoA- I and HDL, and several mechanisms of the apoA-I anti-atherosclerosis. These mechanisms include directing excess celluar cholesterol from the peripheral tissues to the liver in reverse cholesterol transport, inhibiting oxidative modification of LDL, and modulating inflammatory responses to favour vasoprotection.
Animals ; Apolipoprotein A-I ; chemistry ; metabolism ; physiology ; Atherosclerosis ; metabolism ; prevention & control ; Cholesterol ; metabolism ; Humans ; Lipoproteins, HDL ; metabolism ; physiology

The steroidogenic acute regulatory (StAR) protein is an essential component in the regulation of steroid biosynthesis in adrenal and gonadal cells. The StAR protein has a high tissue specificity, located on the mitochondrial membranes of some relative cells. It regulates the transfer of cholesterin from extracellular into intracellular and plays a dominant role in steroidogenic synthesis. Recent studies have also shown that the transcription and expression of StAR are modulated not only through the cAMP-PKA dependent pathway, but also by multiple hormones and cytokines, which contributes to the regulation of cholesterin synthesis.
Animals ; Cholesterol ; metabolism ; Cholesterol Side-Chain Cleavage Enzyme ; metabolism ; Ethisterone ; metabolism ; Gene Expression Regulation ; Humans ; Mice ; Mitochondria ; metabolism ; Phosphoproteins ; genetics ; physiology ; Rats

The physiological changes that occur to sperm during the residence in the female tract are collectively referred to as "capacitation". The mechanism of action by which these compounds promote capacitation is poorly understood at the molecular level. However, some molecular events significant to the initiation of capacitation have been identified, such as the correlation of capacitation with cholesterol efflux from the sperm plasma membrane, increased membrane fluidity, modulations in intracellular ion concentrations, hyperpolarization of the sperm plasma membrane and increased protein tyrosine phosphorylation. This review discusses recent progress in elucidation mechanisms which regulate sperm capacitation.
Bicarbonates ; metabolism ; Calcium ; metabolism ; Cholesterol ; metabolism ; Cyclic AMP ; physiology ; Humans ; Ion Transport ; Male ; Membrane Potentials ; Phosphorylation ; Sperm Capacitation

Cholesterol-lowering effect of lactic acid bacteria (LAB: Streptococcus, Lactobacillus and Bifidobacterium) is well-known. Thus, we investigated LAB isolated from human intestine on the cholesterol-lowering effect in vitro. Seven Streptococcus (61.1%), 11 Lactobacillus (71.8%) and 7 Bifidobacterium (27.9%) were isolated as acid (pH 2.5 and 3.0) and bile (0.3% oxgall) tolerant strains. Streptococcus HJS-1, Lactobacillus HJL-37 and Bifidobacterium HJB-4 were finally selected as probiotic strains to use through the bile salt hydrolase (BSH) activity assay by using MRS media added taurodeoxycholic acid (TDCA) and the cholesterol-lowering test by using soluble cholesterol containing MRS broth. These studies suggested that the isolated LAB had an excellent hypocholesterolemic effect.
Amidohydrolases/metabolism ; Bifidobacterium/*isolation&purification/physiology ; Cholesterol/*metabolism ; Feces/microbiology ; Female ; Humans ; Intestines/*microbiology ; Lactobacillus/*isolation&purification/physiology ; Male ; Probiotics/*therapeutic use ; Streptococcus/*isolation&purification/physiology ; Taurodeoxycholic Acid

Resistin, a newly discovered peptide hormone mainly secreted by adipose tissues, is present at high levels in serum of obese mice and may be a potential link between obesity and insulin resistance in rodents. However, some studies of rat and mouse models have associated insulin resistance and obesity with decreased resistin expression. In humans, no relationship between resistin level and insulin resistance or adiposity was observed. This suggests that additional studies are necessary to determine the specific role of resistin in the regulation of energy metabolism and adipogenesis. In the present study, we investigated the effect of resistin in vivo on glucose and lipid metabolism by over-expressing resistin in mice by intramuscular injection of a recombinant eukaryotic expression vector pcDNA3.1-Retn encoding porcine resistin gene. After injection, serum resistin and serum glucose (GLU) levels were significantly increased in the pcDNA3.1-Retn-treated mice; there was an obvious difference in total cholesterol (TC) level between the experiment and the control groups on Day 30. In pcDNA3.1-Retn-treated mice, both free fatty acid (FFA) and high density lipoprotein (HDL) cholesterol levels were markedly lower than those of control, whereas HDL cholesterol and triglyceride (TG) levels did not differ between the two groups. Furthermore, lipase activity was expressly lower on Day 20. Our data suggest that resistin over-expressed in mice might be responsible for insulin resistance and parameters related to glucose and lipid metabolism were changed accordingly.
Animals ; Blood Glucose ; analysis ; Cholesterol, HDL ; blood ; Cholesterol, LDL ; blood ; Fatty Acids, Nonesterified ; blood ; Glucose ; metabolism ; HeLa Cells ; Humans ; Lipid Metabolism ; Male ; Mice ; Resistin ; blood ; physiology ; Triglycerides ; blood

The regulation of astroglia on synaptic plasticity in the CA1 region of rat hippocampus was examined. Rats were divided into three groups: the newly born (< 24 h), the juvenile (28-30 days) and the adult groups (90 - 100 days), with each group having 20 animals. The CA1 region of rat hippocampus was immunohistochemically and electron-microscopically examined, respectively, for the growth of astroglia and the ultrastructure of synapses. The high performance liquid chromatography was employed to determine the cholesterol content of rat hippocampus. In the newly-born rats, a large number of neurons were noted in the hippocampal CA1 region of the newly-born rats, and few astroglia and no synaptic structure were observed. In the juvenile group, a few astroglias and some immature synapses were found, which were less than those in adult rats (P < 0.01). The cholesterol content was 2.92 +/- 0.03 mg/g, 11.20 +/- 3.41 mg/g and 12.91 +/- 1.25 mg/g for newly born, the juvenile and the adult groups, respectively, with the differences among them being statistically significant (P < 0.01). Our study suggests that the astrocytes may play an important role in the synaptic formation and functional maturity of hippocampal neurons, which may be related to the secretion of cholesterol from astrocytes.
Age Factors ; Animals, Newborn ; Astrocytes/cytology ; Astrocytes/metabolism ; Astrocytes/*physiology ; CA1 Region, Hippocampal/*physiology ; CA1 Region, Hippocampal/*ultrastructure ; Cell Communication/physiology ; Cholesterol/metabolism ; Neuronal Plasticity/*physiology ; Random Allocation ; Rats, Wistar ; Synapses/*physiology ; Synapses/ultrastructure

OBJECTIVETo study the effects of high-density lipoprotein (HDL) and oxidized high-density lipoprotein (ox-HDL) on the expression of ATP-binding cassette transporter A1 (ABCAl) and cholesterol efflux in human umbilical vein endothelial cells (HUVECs).

METHODSIn vitro cultured HUVECs were incubated in the presence of 100 microg/ml HDL or 100 microg/ml ox-HDL for 24 h, using PBS as the negative control. ABCA1 mRNA level and cholesterol efflux rate were determined using RT-PCR and a liquid scintillator, respectively.

RESULTSHDL and ox-HDL significantly elevated the level of ABCA1 mRNA by 58% and 23% relative to the control level, respectively (P<0.05). The cholesterol efflux rate in ox-HDL group was significantly lower than that in HDL group (P<0.01).

CONCLUSIONHDL increases ABCAl expression and cholesterol efflux in HUVECs. Oxidative modification of HDL decrease cholesterol efflux by inhibiting the expression of ABCAl, suggesting a possible mechanism of ox-HDL in the pathogenesis of atherosclerosis.

ATP Binding Cassette Transporter 1 ; ATP-Binding Cassette Transporters ; genetics ; metabolism ; Cells, Cultured ; Cholesterol ; metabolism ; Endothelial Cells ; metabolism ; Humans ; Lipoproteins, HDL ; metabolism ; physiology ; Umbilical Veins ; cytology

OBJECTIVETo investigate the effects of different electromagnetic fields on some haematochemical parameters of circadian rhythms in Sprague-Dawley rats.

METHODSThe study was carried out in 18 male and 18 female rats in good health conditions exposed to 50 Hz magnetic sinusoid fields at the intensity of 1000 microT, 100 microT, and 0 microT (control group) respectively, and in 18 male and 18 female rats in good health conditions exposed to 1.8 GHz electromagnetic fields at the intensity of 50 V/m, 25 V/m and 0 V/m (control group), respectively. Following haematochemical parameters for glucose, triglycerides, and total cholesterol were measured.

RESULTSDifferent effects of electromagnetic fields on circadian rhythms of both male and female rats were observed. Different changes occurred in some haematochemical parameters for glucose, triglycerides, and total cholesterol (P < 0.05).

CONCLUSIONExposure to different electromagnetic fields is responsible for the variations of some haematochemical parameters in rats.

Animals ; Blood Glucose ; metabolism ; Cholesterol ; blood ; Circadian Rhythm ; physiology ; Electromagnetic Fields ; Female ; Male ; Rats ; Rats, Sprague-Dawley ; Triglycerides ; blood

Atherosclerosis is a chronic, inflammatory disorder characterized by the deposition of excess lipids in the arterial intima. The formation of macrophage-derived foam cells in a plaque is a hallmark of the development of atherosclerosis. Lipid homeostasis, especially cholesterol homeostasis, plays a crucial role during the formation of foam cells. Recently, lipid droplet-associated proteins, including PAT and CIDE family proteins, have been shown to control the development of atherosclerosis by regulating the formation, growth, stabilization and functions of lipid droplets in macrophage-derived foam cells. This review focuses on the potential mechanisms of formation of macrophage-derived foam cells in atherosclerosis with particular emphasis on the role of lipid homeostasis and lipid droplet-associated proteins. Understanding the process of foam cell formation will aid in the future discovery of novel therapeutic interventions for atherosclerosis.
Acyltransferases ; metabolism ; Apoptosis Regulatory Proteins ; metabolism ; Atherosclerosis ; metabolism ; pathology ; Cholesterol ; metabolism ; Foam Cells ; cytology ; metabolism ; Humans ; Lipid Metabolism ; physiology ; Macrophages ; cytology ; immunology ; Membrane Proteins ; metabolism ; Perilipin-2 ; Peroxisome Proliferator-Activated Receptors ; metabolism ; Sterol Regulatory Element Binding Proteins ; metabolism