Effect of Zinc supplementation on ethanol-mediated bone alterations

Orally administered zingerone does not mitigate alcohol-induced hepatic oxidative stress in growing Sprague Dawley rat pups

Neonatal alcohol exposure (NAE) can induce oxidative stress. We determined whether zingerone (ZO), a phytochemical with anti-oxidant activity, can mitigate the negative impact of neonatal alcohol-induced oxidative stress. Seventy ten-day-old Sprague-Dawley rat pups (35 male, 35 female) were randomly assigned and administered the following treatment regimens daily from postnatal day (PND) 12-21: group 1 - nutritive milk (NM), group 2 - NM +1 g/kg ethanol (Eth), group 3 - NM + 40 mg/kg ZO, group 4 - NM + Eth + ZO. Growth performance, blood glucose and plasma triglycerides (TGs), total cholesterol, HDL-cholesterol, leptin and insulin concentration were determined. Cytochrome p450E21(CYP2E1) and thiobarbituric acid (TBARS); markers of hepatic oxidative stress and catalase, superoxide dismutase (SOD) and total glutathione (GSH), anti-oxidant markers of the pups were determined. Oral administration of ethanol (NM + Eth), zingerone (NM + ZO) and combined ethanol and zingerone (NM + Eth + ZO) did not affect the growth performance and insulin and leptin concentration of the rats (p > 0.05). Ethanol significantly reduced plasma TGs concentration of female rats (p = 0.04 vs control). However, ethanol and/or its combination with zingerone decreased hepatic GSH (p = 0.02 vs control) and increased CYP2E1 (p = 0.0002 vs control) activity in male rat pups. Zingerone had no effect (p > 0.05 vs control) on the rats' CYP2E1, GSH, SOD and catalase activities. Neonatal alcohol administration elicited hepatic oxidative stress in male rat pups only, showing sexual dimorphism. Zingerone (NM + ZO) prevented an increase in CYP2E1 activity and a decrease in GSH concentration but did not prevent the alcohol-induced hepatic oxidative stress in the male rat pups.

Organ-organ communication: The liver's perspective

Communication between organs participates in most physiological and pathological events. Owing to the importance of precise coordination among the liver and virtually all organs in the body for the maintenance of homeostasis, many hepatic disorders originate from impaired organ-organ communication, resulting in concomitant pathological phenotypes of distant organs. Hepatokines are proteins that are predominantly secreted from the liver, and many hepatokines and several signaling proteins have been linked to diseases of other organs, such as the heart, muscle, bone, and eyes. Although liver-centered interorgan communication has been proposed in both basic and clinical studies, to date, the regulatory mechanisms of hepatokine production, secretion, and reciprocation with signaling factors from other organs are obscure. Whether other hormones and cytokines are involved in such communication also warrants investigation. Herein, we summarize the current knowledge of organ-organ communication phenotypes in a variety of diseases and the possible involvement of hepatokines and/or other important signaling factors. This provides novel insight into the underlying roles and mechanisms of liver-originated signal transduction and, more importantly, the understanding of disease in an integrative view.

Zinc deficiency as a mediator of toxic effects of alcohol abuse

OBJECTIVE

To review data on the role of ethanol-induced alteration of Zn homeostasis in mediation of adverse effects of alcohol abuse.

METHODS

The scholarly published articles on the association between Zn metabolism and alcohol-associated disorders (liver, brain, lung, gut dysfunction, and fetal alcohol syndrome) have been reviewed.

RESULTS

It is demonstrated that alcohol-induced modulation of zinc transporters results in decreased Zn levels in lungs, liver, gut, and brain. Zn deficiency in the gut results in increased gut permeability, ultimately leading to endotoxemia and systemic inflammation. Similarly, Zn deficiency in lung epithelia and alveolar macrophages decreases lung barrier function resulting in respiratory distress syndrome. In turn, increased endotoxemia significantly contributes to proinflammatory state in alcoholic liver disease. Finally, impaired gut and liver functions may play a significant role in alcoholic brain damage, being associated with both increased proinflammatory signaling and accumulation of neurotoxic metabolites. It is also hypothesized that ethanol-induced Zn deficiency may interfere with neurotransmission. Similar changes may take place in the fetus as a result of impaired placental zinc transfer, maternal zinc deficiency, or maternal Zn sequestration, resulting in fetal alcoholic syndrome. Therefore, alcoholic Zn deficiency not only mediates the adverse effects of ethanol exposure, but also provides an additional link between different alcohol-induced disorders.

CONCLUSIONS

Generally, current findings suggest that assessment of Zn status could be used as a diagnostic marker of metabolic disturbances in alcohol abuse, whereas modulation of Zn metabolism may be a potential tool in the treatment of alcohol-associated disorders.

Trace elements have beneficial, as well as detrimental effects on bone homeostasis

The protective role of nutrition factors such as calcium, vitamin D and vitamin K for the integrity of the skeleton is well understood. In addition, integrity of the skeleton is positively influenced by certain trace elements (e.g. zinc, copper, manganese, magnesium, iron, selenium, boron and fluoride) and negatively by others (lead, cadmium, cobalt). Deficiency or excess of these elements influence bone mass and bone quality in adulthood as well as in childhood and adolescence. However, some protective elements may become toxic under certain conditions, depending on dosage (serum concentration), duration of treatment and interactions among individual elements. We review the beneficial and toxic effects of key elements on bone homeostasis.

Bone health and vitamin D status in alcoholic liver disease

Alcohol consumption is harmful to many organs and tissues, including bones, and it leads to osteoporosis. Hepatic osteodystrophy is abnormal bone metabolism that has been defined in patients with chronic liver disease (CLD), including osteopenia, osteoporosis, and osteomalacia. Decreased bone density in patients with CLD results from decreased bone formation or increased bone resorption. The prevalence of osteopenia in alcoholic liver disease (ALD) patients is between 34 % and 48 %, and the prevalence of osteoporosis is between 11 % and 36 %. Cirrhosis is also a risk factor for osteoporosis. The liver has an important role in vitamin D metabolism. Ninety percent of patients with alcoholic liver cirrhosis have vitamin D inadequacy (<80 nmol/L). The lowest serum vitamin D levels were observed in patients with Child-Pugh class C. Bone densitometry is used for the definitive diagnosis of osteoporosis in ALD. There are no specific controlled clinical studies on the treatment of osteoporosis in patients with ALD. Alcohol cessation and abstinence are principal for the prevention and treatment of osteoporosis in ALD patients, and the progression of osteopenia can be stopped in this way. Calcium and vitamin D supplementation is recommended, and associated nutritional deficiencies should also be corrected. The treatment recommendations of osteoporosis in CLD tend to be extended to ALD. Bisphosphonates have been proven to be effective in increasing bone mineral density (BMD) in chronic cholestatic disease and post-transplant patients, and they can be used in ALD patients. Randomized studies assessing the management of CLD-associated osteoporosis and the development of new drugs for osteoporosis may change the future. Here, we will discuss bone quality, vitamin D status, mechanism of bone effects, and diagnosis and treatment of osteoporosis in ALD.

Bone changes in alcoholic liver disease

Alcoholism has been associated with growth impairment, osteomalacia, delayed fracture healing, and aseptic necrosis (primarily necrosis of the femoral head), but the main alterations observed in the bones of alcoholic patients are osteoporosis and an increased risk of fractures. Decreased bone mass is a hallmark of osteoporosis, and it may be due either to decreased bone synthesis and/or to increased bone breakdown. Ethanol may affect both mechanisms. It is generally accepted that ethanol decreases bone synthesis, and most authors have reported decreased osteocalcin levels (a “marker” of bone synthesis), but some controversy exists regarding the effect of alcohol on bone breakdown, and, indeed, disparate results have been reported for telopeptide and other biochemical markers of bone resorption. In addition to the direct effect of ethanol, systemic alterations such as malnutrition, malabsorption, liver disease, increased levels of proinflammatory cytokines, alcoholic myopathy and neuropathy, low testosterone levels, and an increased risk of trauma, play contributory roles. The treatment of alcoholic bone disease should be aimed towards increasing bone formation and decreasing bone degradation. In this sense, vitamin D and calcium supplementation, together with biphosphonates are essential, but alcohol abstinence and nutritional improvement are equally important. In this review we study the pathogenesis of bone changes in alcoholic liver disease and discuss potential therapies.

Trace elements and bone health

The importance of nutrition factors such as calcium, vitamin D and vitamin K for the integrity of the skeleton is well known. Moreover, bone health is positively influenced by certain elements (e.g., zinc, copper, fluorine, manganese, magnesium, iron and boron). Deficiency of these elements slows down the increase of bone mass in childhood and/or in adolescence and accelerates bone loss after menopause or in old age. Deterioration of bone quality increases the risk of fractures. Monitoring of homeostasis of the trace elements together with the measurement of bone density and biochemical markers of bone metabolism should be used to identify and treat patients at risk of non-traumatic fractures. Factors determining the effectivity of supplementation include dose, duration of treatment, serum concentrations, as well as interactions among individual elements. Here, we review the effect of the most important trace elements on the skeleton and evaluate their clinical importance.

Relative and combined effects of ethanol and protein deficiency on bone manganese and copper

Both manganese and copper may affect bone synthesis. Bone content of both metals can be altered in alcoholics, although controversy exists regarding this matter. To analyse the relative and combined effects of ethanol and a low protein diet on bone copper and manganese, and their relationships with bone structure and metabolism, including trabecular bone mass (TBM), osteoid area (OA), osteocalcin (OCN), insulin-like growth factor-1 (IGF-1), parathyroid hormone (PTH), urinary hydroxyproline (uHP) and vitamin D. Adult male Sprague-Dawley rats were divided into four groups. The control rats received a 18% protein-containing diet; a second group, an isocaloric, 2% protein-containing diet; a third one, an isocaloric, 36% ethanol-containing diet and a fourth, an isocaloric diet containing 2% protein and 36% ethanol. After sacrifice, TBM and OA were histomorphometrically assessed; bone and serum manganese and copper were determined by atomic absorption spectrophotometry, and serum OCN, IGF-1, PTH, uHP and vitamin D by radioimmunoassay. Ethanol-fed rats showed decreased TBM and bone manganese. Significant relationships existed between bone manganese and TBM, serum IGF-1 and OCN. Ethanol leads to a decrease in bone manganese, related to decreased bone mass and bone synthesis. No alterations were found in bone copper.

Impaired expansion and multipotentiality of adult stromal cells in a rat chronic alcohol abuse model

It is well established that bone maintenance and healing is compromised in alcoholics. Adult bone marrow-derived stromal cells (BMSCs) and adipose tissue-derived stromal cells (ASCs) likely contribute to bone homeostasis and formation. Direct and indirect alcohol exposure inhibits osteoprogenitor cell function through a variety of proposed mechanisms. The goal of this study was to characterize the effects of chronic alcohol ingestion on the native number and in vitro growth characteristics and multipotentiality of adult BMSCs and ASCs in a rat model. Adult male Sprague-Dawley rats received a liquid diet containing 36% ethanol or an isocaloric substitution of dextramaltose (control). After 4, 8, or 12 weeks of the diet, ASCs were harvested from epididymal adipose tissue and BMSCs from femoral and tibial bone marrow. Cell doublings (CDs) per day and doubling times (DTs) were determined for primary cells (P0) and cell passages 1 through 6 (P1-P6). Fibroblastic (CFU-F), adipogenic (CFU-Ad), and osteogenic (CFU-Ob) colony-forming unit (CFU) frequencies were assessed for P0, P3, and P6. The CDs and DTs were lower and higher, respectively, for ASCs and BMSCs harvested from ethanol versus control rats at all time points. The CFU-F, CFU-Ad, and CFU-Ob were significantly higher in ASCs harvested from control versus ethanol rats for P0, P3, and P6 at all times. Both CFU-Ad and CFU-Ob were significantly higher in P0 BMSCs harvested from control versus ethanol rats after 12 weeks of the diet. The CFU-Ob for P3 BMSCs from control rats was significantly higher than those from ethanol rats after 8 and 12 weeks on the diet. All three CFU frequencies in ASCs from ethanol rats tended to decrease with increasing diet duration. The ASC cell and colony morphology was different between control and ethanol cohorts in culture. These results emphasize the significant detrimental effects of chronic alcohol ingestion on the in vitro expansion and multipotentiality of adult mesenchymal stromal cells (MSCs). Maintenance of the effects through multiple cell passages in vitro suggests cells may be permanently compromised.

High-dose dietary zinc promotes prostate intraepithelial neoplasia in a murine tumor induction model

To evaluate the role of high-dose dietary zinc in the process of prostate malignancy, 60 Sprague-Dawley rats were randomly divided into four groups: tumor induction with carcinogen and hormone (group 1), oral zinc administration without tumor induction (group 2), oral zinc administration with tumor induction (group 3) and a control without zinc administration or tumor induction (group 4). Zinc was supplied orally in the form of zinc sulfate heptahydrate dissolved in drinking water to groups 2 and 3 for 20 weeks. Although the serum level of zinc measured at 20 weeks was maintained similarly in each group (P = 0.082), intraprostatic zinc concentrations were statistically different. Group 1 prostates contained the least amount of zinc in both the dorsolateral and ventral lobes at levels of 36.3 and 4.8 microg g(-1), respectively. However, in group 3, zinc levels increased in both lobes to 59.3 and 12.1 microg g(-1), respectively, comparable with that of group 4 (54.5 +/- 14.6 and 14.1 +/- 2.4 microg g(-1)). In spite of these increases in zinc concentration, the prevalence of prostate intraepithelial neoplasm was rather increased in group 3 (53.3% and 46.7%) compared with group 1 (33.3% and 33.3%) in both dorsolateral and ventral prostate lobes. Although prostate intraepithelial neoplasm did not develop in any prostate in group 4, zinc administration did induce prostate intraepithelial neoplasm in group 2 (46.7% and 40.0%). Thus, although high dietary zinc increased intraprostatic zinc concentrations, it promoted, instead of preventing, prostate intraepithelial neoplasm in a murine prostate malignancy induction model.

Protective effect of zinc on cyclophosphamide-induced hematoxicity and urotoxicity

Cyclophosphamide (CP) is widely used for the treatment of neoplastic diseases; however, its toxicity causes dose-limiting side effects. Zinc (Zn) is an essential trace element and has important biological functions that control many cell processes including DNA synthesis, normal growth, reproduction, fetal development, bone formation, and wound healing. Therefore, the toxicity of CP and the possible protective effect of Zn on blood cells, bone marrow, and bladder of rat were investigated in this study. Intraperitoneal administration of 50, 100, or 150 mg/kg CP for 3 days caused, in a dose-dependent manner, reductions in the number of leukocytes, thrombocytes, and bone marrow nucleated cells and a serious urotoxicity. To explore whether CP-induced damages could be prevented by Zn, other groups of rats were pretreated with 4 or 8 mg/kg ZnCl2 intraperitoneally for 3 days then challenged with respective doses of CP plus ZnCl2 on day 4 for three more days. The results indicated that treatment of rats with Zn could dose-dependently alleviate CP-induced toxicities on blood cells, bone marrow cells, and urinary bladder. We suggest that Zn could be a potentially effective drug in the prevention of CP-related hematoxicity and urotoxicity.

Element analysis in femur of diabetic osteoporosis model by SRXRF microprobe

Diabetes mellitus affects bone metabolism and leads to osteopenia and osteoporosis, but its pathogenic mechanism remains unknown. To address this problem, mineral element of bone was analyzed in experimental diabetic osteoporosis model. Male Wistar rats were randomly divided into streptozotocin (STZ)-induced diabetic group (n=5) and control group (n=5). The experiment lasted 68 days and at the end of the experiment, femoral bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry and element content in femur of animals was determined by synchrotron radiation X-ray fluorescence (SRXRF) microprobe analysis technique. Results showed that femoral BMD in diabetic group was significantly lower than that in control (P<0.01). Relative mineral content of calcium (Ca), phosphorus (P) and zinc (Zn) in diabetic femurs decreased significantly compared to controls. And strontium (Sr) in diabetics reduced 11% (P=0.09). Relative content of sulfur (S) in average was statistically higher (P<0.01) in diabetics than that in controls. But no obvious difference was observed in relative content of chromium (Cr), iron (Fe), copper (Cu), and lead (Pb) between the two groups. Statistical analysis revealed that Ca correlated positively with P (R=0.85 and P<0.001), with Sr (R=0.38 and P<0.05) and with Zn (R=0.37 and P<0.05). Whereas, Zn correlated negatively with S (R=-0.40 and P<0.05). Our results reveal that loss of minerals accounts for the BMD reduction in diabetics.