Hyperlipidemia in streptozocin-diabetic hamsters as a model for human insulin-deficient diabetes: comparison to streptozocin-diabetic rats

Dietary nitrate improves glucose tolerance and lipid profile in an animal model of hyperglycemia

Reduction in nitric oxide (NO) production and bioavailability contribute to the pathogenesis of type 2 diabetes. Administration of nitrate has strong NO-like outcomes in both animals and humans. In this study, we examined the effects of dietary nitrate on glucose tolerance and lipid profile in type 2 diabetic rats. Type 2 diabetes was induced by injection of streptozotocin and nicotinamide. Thirty-two male Wistar rats were divided into 4 groups: controls (C), control+nitrate (CN), diabetes (D), and diabetes+nitrate (DN). For 8 weeks, the CN and DN groups consumed sodium nitrate (100 mg/L in drinking water) while the C and D groups consumed tap water. Serum nitrate+nitrite (NOx), glucose, lipid profile, total antioxidant capacity (TAC), and catalase (CAT) activity were measured before and at the end of the study. Systolic blood pressure (SBP) was measured every 10 days. Intravenous glucose tolerance test (IVGTT) was performed at the end of the study. Serum NOx decreased in diabetic rats and dietary nitrate restored it to normal values. Increases in serum glucose levels was significantly lower in the DN group compared to the D group (24.1% vs. 90.2%; p < 0.05). Nitrate therapy in diabetic rats significantly improved lipid profile, glucose tolerance (AUC: 20264 ± 659 vs. 17923 ± 523; p < 0.05 for D and DN groups respectively) and restored elevated SBP to normal values. Diabetic rats had lower TAC and CAT activity and dietary nitrate restored these to normal status. In conclusion, dietary nitrate prevented increase in SBP and serum glucose, improved glucose tolerance and restored dyslipidemia in an animal model of hyperglycemia.

The Experimental Use of Syrian Hamsters

The Syrian hamster (Mesocricetus auratus) is a widely used experimental animal model. This chapter focuses primarily on the most current research uses of the hamster. More classical uses are covered only as they pertain to these current uses. Hamsters possess unique anatomical and physiological features, which make them desirable research models. Unlike other commonly used laboratory rodents, hamsters possess a cheek pouch, which can be easily everted and examined at both the gross and microscopic level. The hamster's relative size also allows for better visualization of certain biological systems including the respiratory and reproductive systems when compared to the mouse. Further, laboratory hamsters develop a variety of inherited diseases, which display similarities to human conditions. Hamsters possessing some of these inherited traits are commercially available. They are susceptible to a variety of carcinogens and develop tumors that other research animals less commonly develop. Also they are susceptible to the induction of a variety of metabolic disorders through the use of dietary manipulations. The antagonistic nature of hamsters is used to study the effect of treatment on male aggressive and defensive behaviors. Syrian hamsters display several unique characteristics that make them desired models for carcinogenesis studies.

[Effect of streptozotocin on the glycemic and lipid profiles and oxidative stress in hamsters]

OBJECTIVE

This study evaluated the effects of streptozotocin on glycemic and lipid profiles and oxidative stress status in hamsters.

MATERIALS AND METHODS

Male Golden Syrian hamsters were divided in diabetic group (D) which received a streptozotocin single injection (STZ - 50 mg/kg), and control group (C) which received a single injection of the vehicle citrate buffer. Animals were euthanized after 10 days of experiment and blood, liver and kidneys were collected.

RESULTS

The diabetic group had higher levels of glucose, triacylglycerols and cholesterol in serum and thiobarbituric acid reactive substances (TBARS) concentration increased in the liver and kidneys. Diabetes induced a significant increase in glutathione concentration in the liver and decreased paraoxonase and superoxide dismutase activities.

CONCLUSION

Hamsters provide a novel animal model for diabetes mellitus and oxidative stress, similar to the human syndrome, which may be suitable for the testing of antidiabetic compounds.

Insulin-dependent diabetes mellitus in mice does not alter liver heparan sulfate

Diabetes -associated hyperlipidemia is generally attributed to reduced clearance of plasma lipoproteins, especially remnant lipoproteins enriched in cholesterol and triglycerides. Hepatic clearance of remnants occurs via low density lipoprotein receptors and the heparan sulfate proteoglycan, syndecan-1. Previous studies have suggested alterations in heparan sulfate proteoglycan metabolism in rat and mouse diabetic models, consistent with the idea that diabetic dyslipidemia might be caused by alterations in proteoglycan expression in the liver. In this study we analyzed the content and composition of liver heparan sulfate in streptozotocin-induced insulin-deficient diabetic mice that displayed fasting hypertriglyceridemia and delayed clearance of dietary triglyceride-rich lipoproteins. No differences between normal and diabetic littermates in liver heparan sulfate content, sulfation, syndecan-1 protein levels, or affinity for heparin-binding ligands, such as apolipoprotein E or fibroblast growth factor-2, were noted. Decreased incorporation of [(35)S]sulfate in insulin-deficient mice in vivo was observed, but the decrease was due to increased plasma inorganic sulfate, which reduced the efficiency of labeling of liver heparan sulfate. These results show that hyperlipidemia in insulin-deficient mice is not due to changes in hepatic heparan sulfate composition.

A high-cholesterol, n-3 polyunsaturated fatty acid diet causes different responses in rats and hamsters

This study was designed to investigate the response to a high-cholesterol, n-3 polyunsaturated fatty acid (PUFA) or n-6 PUFA diet in rats and hamsters. Animals were fed n-3 or n-6 PUFA with a cholesterol-free diet, or with a diet enriched with cholesterol (0.5%, w/w) for 2 weeks. In rats and hamsters fed a cholesterol-free diet, plasma cholesterol, triglycerides and very-low-density lipoprotein (VLDL)-triglyceride levels in n-3 PUFA group were significantly lower than those in n-6 PUFA group. In contrast, when diets were supplemented with 0.5% cholesterol, the plasma cholesterol- and triglyceride-lowering effect of dietary n-3 PUFA disappeared. In hamsters fed with the atherogenic diet (0.5% dietary cholesterol) for 2 weeks, n-3 PUFA induced hypercholesterolemia more than n-6 PUFA, the increase being in the VLDL and low-density lipoprotein (LDL) fractions. Our data thus indicate that elevation of VLDL- and LDL-cholesterol in hamsters by n-3 PUFA, compared with n-6 PUFA, is dependent on 0.5% dietary cholesterol supplementation. In rats, on the other hand, dietary n-3 PUFA did not induce hypercholesterolemia more than n-6 PUFA when 0.5% cholesterol was supplemented. Although the effects of n-3 PUFA on plasma cholesterol, triglycerides and VLDL-triglycerides were similar in hamsters and rats, the interactive effects of n-3 PUFA and cholesterol on plasma and lipoprotein cholesterol levels differed in the two species. It was also found that plasma triglycerides, cholesterol and lipoprotein cholesterol levels in hamsters are higher than in rats in the presence and absence of dietary cholesterol. In addition, cholesterol feeding induces hypertriglyceridemia and hypercholesterolemia only in hamsters. Moreover, liver triglyceride concentrations increased in rats fed a cholesterol-rich diet and hepatic triglyceride levels of the n-3 PUFA-fed rats were significantly lower than those in the n-6 PUFA-fed rats in the presence and absence of dietary cholesterol. However, triglycerides did not accumulate in the liver in hamsters fed a cholesterol-rich diet and hepatic triglyceride levels of the n-3 PUFA-fed hamsters were not significantly different from those in the n-6 PUFA-fed hamsters in the presence and absence of dietary cholesterol. Therefore, these studies confirm marked species differences in response to the interactive effects of dietary n-3 PUFA and cholesterol.

Amelioration of diabetic dyslipidemia by macrocyclic binuclear oxovanadium complex on streptozotocin induced diabetic rats

Diabetic dyslipidemia, the main causative factor for the progression of vascular complications in diabetes, is caused due to hyperglycemia and excess mobilisation of fatty acids. Recently we have reported on a novel macrocyclic binuclear oxovanadium (MBOV) complex synthesized by us with significant hypoglycemic efficacy and without any apparent toxicity on streptozotocin induced diabetic rats. In the present study, streptozotocin induced diabetic rats were treated with the vanadium complex (5 mg/kg body weight/day) for a period of 30 days and at the end of the treatment period the status of the lipid profile in the plasma, liver and kidney was evaluated. Also the fatty acid composition of liver and kidney were analysed by gas chromatography. The increased levels of lipid contents in plasma and tissues observed in diabetic rats were reverted back to near normal levels by the administration of the vanadium complex. Also the decreased levels of HDL cholesterol and increased levels of LDL cholesterol in plasma of diabetic rats were restored to near normal levels by the treatment with the vanadium complex. The altered fatty acid composition in liver and kidney were restored by the treatment. The results enhance the claim for the macrocyclic binuclear oxovanadium complex as a potent anti-diabetogenic drug.

Apolipoprotein CIII deficiency prevents the development of hypertriglyceridemia in streptozotocin-induced diabetic mice

To explore the role of apolipoprotein (apo) CIII in the development of hypertriglyceridemia associated with diabetes mellitus, we examined triglyceride (TG) kinetics in apo CIII - deficient mice (apo CIII - null) and wild-type (WT) (C57BL/6J) mice with diabetes induced by the injection of streptozotocin (STZ). Plasma TG levels increased significantly in WT mice after diabetes was induced (102 +/- 29 v 65 +/- 33 mg/dL, P <.01). Apo CIII-null mice had a significantly lower TG level (35 +/- 9 mg/dL) that remained unchanged even when diabetes was induced (35 +/- 8 mg/dL). The TG secretion rate (TGSR) measured by the Triton WR1339 method tended to decrease in diabetic WT, indicating that catabolism of TG was impaired. Apo CIII-null mice showed 2-fold higher TG production than WT mice, indicating markedly faster clearance of TG. The high TGSR was halved when diabetes was induced in apo CIII-null mice, and the fractional catabolic rate (FCR) of TG was also halved, although it was still significantly higher than in WT mice. Lipoprotein lipase (LPL) activity in postheparin plasma was not significantly altered in WT or apo CIII-null mice regardless of the presence or absence of diabetes. [(3)H] very-low-density lipoprotein (VLDL)-TG from WT or apo CIII-null mice showed similar clearance by WT recipients, and this was also observed when VLDL was obtained from diabetic counterparts. In contrast, VLDL-TG was cleared faster by apo CIII-null recipients compared with WT recipients, regardless of the VLDL donors. These results suggest that apo CIII deficiency prevents the development of hypertriglyceridemia associated with diabetes by stimulating TG removal, possibly by promoting the interaction of VLDL with the TG removal system.

The effects of diabetes with hyperlipidemia on P450 expression in APA hamster livers

The effect of chronic hyperglycemia and hyperlipidemia induced by streptozotocin (SZ) on the expression of P450 in the liver of APA hamsters was studied in this experiment. No effect on the total activity of P450 was seen in SZ-induced diabetic hamsters throughout the experimental period. At 1 and 6 months after SZ-injection, the levels of CYP1A, 2C6, and 3A of SZ-injected hamsters were much lower than those of age-matched control hamsters. CYP2B expression tended to decrease and CYP2E1 and 4A expression tended to increase in SZ-injected hamsters, although the results were not significant. At 3 months after SZ-injection, however, no significant difference between SZ-injected and normal hamsters was seen in these P450 isozymes. On the other hand, CYP2C11 expression was slightly depressed in SZ1M and SZ6M, and almost equivalent to control hamsters in SZ3M. Immunohistochemistry by the use of each isozyme antibody revealed that SZ-induced diabetes affected the localization of CYP2C6, 3A, and 4A in the hepatic acinus. The expression of CYP2C6 and 3A was depressed mainly in the periportal region of the acinus, and CYP4A expression was induced mainly in the perivenous region by SZ-induced diabetes. On the other hand, the expression pattern of CYP1A, 2B, 2C11, and 2E1 were not affected. These results demonstrate that the effects of SZ-induced diabetes on hepatic P450 differ for each isozyme in APA hamsters and also differ from those of other experimental diabetic animals, including golden hamsters.

Functional and histochemical analysis on pancreatic islets of APA hamsters with SZ-induced hyperglycemia and hyperlipidemia

To clarify how Syrian hamsters of the APA strain (APA hamsters) keep a diabetic condition for a long period, the functional and histochemical changes in the pancreatic islets of diabetic APA hamsters were examined. By glucose tolerance test, no glucose-induced insulin secretion was seen in the diabetic APA hamsters. By immunohistochemistry, it was revealed that at 24 hr after SZ-injection, the number of islets had decreased and that remnant islets had become markedly smaller. The islets had hardly any insulin-immunoreactive cells and consisted of cells stained by anti-glucagon and somatostatin antibodies. One, three and six months after SZ-injection, a small number of cells with vacuolative changes, which were positive for PAS staining, were observed in most islets and the vacuolated cells were stained mainly by anti-insulin antibody. In addition, a number of PCNA-positive cells were observed, especially in the periphery of the vacuolated cells, while TUNEL-positive cells were not detected. This data suggests that beta-cells proliferating as a result of the replication of the resident beta-cells in islets had fallen into degeneration and necrosis by a stress, such as the glycogen deposition in hyperglycemia and hyperlipidemia. Consequently, secretion of insulin was maintained at low levels, which allowed the hamsters to live without insulin therapy in the diabetic condition for over 6 months.

Effects of dietary fish oil on survival rate, plasma amino acid pattern, and inflammatory-related mediators in diabetic rats with sepsis

This study was designed to investigate the effects of dietary fish oil on survival rates, plasma amino acid profiles, and inflammatory-related mediators in diabetic rats with sepsis. Diabetes mellitus (DM) was induced in rats by streptozotocin. The DM rats were maintained for 4 weeks on medium fat (10%, w/w) diets containing either fish oil or safflower oil. After that, sepsis was induced by cecal ligation and puncture (CLP). There were 2 groups in this study: fish oil sepsis group (FOS) and safflower oil sepsis group (SOS). The survival rate was observed after CLP. Also, changes of the amino acid pattern as well as interleukin (IL)-1 beta, tumor necrosis factor (TNF)-alpha, prostaglandin (PG) E(2)at 6, 12, and 24 h after CLP were investigated. The results demonstrated that survival rates were not significantly different between the 2 groups. Plasma arginine levels were significantly lower in sepsis groups than that in the DM-chow group, regardless of whether the diabetic rats were fed fish oil or safflower oil. No significant differences were observed in plasma valine, leucine, isoleucine, glutamine, or arginine concentrations between the FOS and SOS groups at different time points. Concentrations of IL-1 beta in peritoneal lavage fluid (PLF) at 6 h and TNF-alpha at 6 h as well as at 12 h after CLP in the FOS group were significantly higher than those in the SOS group. PGE(2)levels in PLF, by contrast, were lower in the FOS group at 6 and 12 h after CLP than in the SOS group. These results suggest that differences in IL-1 beta, TNF-alpha, and PGE(2)levels in PLF in the early period of sepsis did not influence the survival rates and plasma amino acid profiles of the FOS and SOS groups. Compared with safflower oil, feeding diabetic rats with fish oil had no beneficial effects on survival rates and muscle protein breakdown. The immunologic impact of dietary n-3 polyunsaturated fatty acids on diabetic rats with sepsis requires further investigation.

APA hamster model for diabetic atherosclerosis. 2. Analysis of lipids and lipoproteins

Syrian hamsters of the APA strain (APA hamsters) have recently been shown to have atheromatous lesions in the aortic arches under diabetic condition induced by a single injection of streptozotocin (SZ). In that model, fatty streaks, which are the initial lesions of atherogenesis, develop by 6 weeks after the injection (WAI). In this study, we evaluated plasma lipid concentrations and lipoprotein profiles in diabetic APA hamsters at 6 WAI to reveal the early stage of atherogenesis clinicopathologically. As a result, by biochemical analysis, hyperglycemic APA hamsters showed signs of hypercholesterolemia and hypertriglyceridemia. Low-density lipoprotein (LDL) cholesterol significantly increased, but high-density lipoprotein (HDL) cholesterol significantly decreased. Agarose gel electrophoresis showed an obvious increase in the fractions of chylomicron, LDL and abnormal lipoprotein. Plasma LDL in diabetic animals was in a state more susceptible to oxidization. In addition, a significant increase in glycated LDL was also found in the diabetic animals by enzyme linked immunosorbent assay (ELISA). Moreover, lipid peroxidation product (4-hydroxynonenal (4 HNE))-adducted proteins and advanced glycation end-products (AGE) were immunohistochemically detected in the foam cells of the fatty streaks. These results revealed that diabetic APA hamsters had hyperlipidemia characterized by increases in chylomicron, LDL and abnormal lipoprotein, and suggested that oxidized LDL and/or glycated LDL might be actively uptaken by macrophages and play an important role in the initial stage of atherogenesis.

The effect of vitamin E, probucol, and lovastatin on oxidative status and aortic fatty lesions in hyperlipidemic-diabetic hamsters

Diabetes mellitus is associated with an increased risk of premature atherosclerosis, which may be due in part to an increased rate of low density lipoprotein (LDL) oxidation. Previous studies have shown that vitamin E, probucol, and lovastatin can reduce the oxidative susceptibility of LDL in normoglycemic animal models; however, few studies have investigated this in conjunction with aortic fatty streak lesion formation in diabetic hyperlipidemic models. Forty-eight Syrian hamsters were made diabetic by intraperitoneal injection of low dose streptozotocin. Diabetic animals (12 animals/groups) received a high saturated fat and cholesterol diet for 12.5 weeks. At 2.5 week of dietary treatments, the diet was supplemented with either: (1) 500 IU/day vitamin E (D+E); (2) 1% probucol w/w of the diet (D+P); (3) 25 mg/kg lovastatin (D+L); or (4) diabetic control (D). An age-matched group of hamsters (n=6) receiving the same diet but not made diabetic (ND) was used as control. At the end of the study, aortic arch foam cell-rich fatty streak lesion, plasma glucose, total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), non-HDL-C, triglycerides (TG), phospholipids, alpha-tocopherol, plasma lipid peroxide and the susceptibility of LDL to copper-catalyzed oxidation were determined. Diabetes increased plasma glucose, and when combined with an atherogenic diet resulted in a further increase of plasma lipids. Vitamin E, probucol, and lovastatin significantly reduced plasma TG in the diabetic hamsters fed the atherogenic diet. Vitamin E treatment increased TC, probucol reduced HDL-C without affecting TC; whereas lovastatin reduced TC and selectively decreased non-HDL-C, and significantly reduced fatty streak lesion formation in the aortic arch. While vitamin E and probucol were effective in reducing several indices of oxidative stress including plasma lipid peroxides, cholesterol oxidation products and in vitro LDL oxidation, they had no effect on fatty streak lesion formation. Our results indicate that the LDL in diabetic animals is more susceptible to oxidation than in non-diabetic hamsters and that not only vitamin E and probucol but also lovastatin provide antioxidant protection. It appears that in this combined model of diabetes and hypercholesterolemia, progression of fatty streak lesion formation is mainly associated with changes in TC and non-HDL-C as affected by lovastatin, and is less dependent on the extent of LDL oxidation, changes in plasma TG level and oxidative stress status.

Fatty liver and hyperlipidemia in IDDM (insulin-dependent diabetes mellitus) of streptozotocin-treated shrews

Severe IDDM (insulin-dependent diabetes mellitus) was produced in the musk shrew (Suncus murimus, Insectivora) by a high dose (a single intraperitoneal injection of 100 mg/kg Body Weight) of streptozotocin (STZ) injection. All shrews that were administered a high dose of STZ exhibited hyperglycemia (449 +/- 16 mg/dl vs 73 +/- 4 mg/dl in controls) and hypoinsulinemia(0.25 +/- 0.07 ng/ml vs 10.96 +/- 1.97 ng/ml in controls) with ketosuria 10 days after injection. Their livers were enlarged and exhibited ayellowish-brown color with marked triglyceride (TG) accumulation (63.25 +/- 7.10 mg/g Liver vs 2.11 +/- 0.19 mg/g Liver in controls). It is probable that the increased influx of fatty acids into the liver induced by hypoinsulinemia and the low capacity of excretion of lipoprotein secretion from liver in the musk shrew resulting from a deficiency of apolipoprotein B synthesis play important roles in fatty liver formation. Hyperlipidemia was another feature in shrews with severe IDDM. The blood TG level was especially high in these shrews (899 +/- 178 mg/dl vs 23 +/- 5 mg/dl in controls). These results indicate that the IDDM shrew, induced by high doses of STZ, is a unique model characterized by fatty liver and hyperlipidemia and may be useful for studying lipid metabolism of IDDM.

Hypotriglyceridaemic activity of Ficus carica leaves in experimental hypertriglyceridaemic rats

A model of hypertriglyceridaemia in rats is described, which was used to investigate the hypolipidaemic effect of an intraperitoneal (i./p.) administration of a Ficus carica leaf decoction. Hypertriglyceridaemia was induced in rats following the protocol: a fasting period of 22 h, 2 h of oral (p.o.) administration of 20% emulsion of longchain triglycerides (LCT emulsion), both repeated once. The plasma triglyceride and total cholesterol levels obtained 2 h after the protocol were 5.7 +/- 2.5 mmol/L (p < 0.0001 vs basal levels) and 1.7 +/- 0.3 mmol/L, respectively, n = 10. The new model was used to test the hypotriglyceridaemic effect of a single dose of Ficus carica (fig tree) leaf decoction administered i./p. (50 g dry wt/kg body wt). After the i.p. injection of serum saline (control group, n = 10) or Ficus carica extract (group A, n = 10), plasma triglyceride levels in the control group and group A were 5.9 +/- 2.9 mmol/L and 5.5 +/- 2.9 mmol/L just after the LCT emulsion protocol; 4.7 +/- 2.7 mmol/L and 0.9 +/- 0.4 mmol/L, p < 0.005, 60 min after the LCT protocol; and 3.6 +/- 2.9 mmol/L and 1.0 +/- 0.4 mmol/L, p < 0.05, 90 min after the LCT protocol. The plasma total cholesterol levels, which were not modified in our experimental model, showed no significant differences in relation to baseline levels in the presence or absence of Ficus carica treatment either. The clearly positive results suggest the presence in the fig leaf decoction of a compound or compounds that influence lipid catabolism.

MCT/LCT emulsion ameliorate liver fat deposition in insulin-treated diabetic rats receiving total parenteral nutrition

This study was designed to investigate the effects of high energy infusion and insulin treatment on plasma and liver lipids in diabetic rats receiving total parenteral nutrition (TPN). Diabetes was induced in rats by streptozotocin. The diabetic rats were assigned to two TPN groups to receive either long chain triglyceride (LCT) or medium chain triglyceride (MCT)/LCT (1:1) as a fat source. The TPN solutions were isonitrogenous, isocaloric and identical in nutrient composition except for the fat emulsion. All rats received the TPN solution at an energy level of 35|kcal/100|g of body weight. The LCT and MCT/LCT groups were further divided into two subgroups, depending on whether they were treated with insulin. The results demonstrated that, between the MCT/LCT and LCT groups, no differences were observed in body weight and nitrogen retention, as well as the concentrations of plasma glucose, nonesterified fatty acids, beta-hydroxybutyrate, and total cholesterol. Diabetic TPN rats without insulin treatment had weight loss and negative nitrogen balance during the experiment. Diabetic TPN rats treated with insulin, however, demonstrated less weight loss and positive nitrogen retention. Insulin treated groups had significantly higher liver fat content than did those without insulin treatment. Furthermore, liver fat content was significantly higher in the LCT group than in the MCT/LCT group among insulin treated TPN rats. These results suggest that compared with the LCT emulsion, infusion of the MCT/LCT emulsion ameliorated liver fat deposition in insulin-treated diabetic rats receiving TPN.

Effects of soybean oil and fish oil emulsions on glucose and lipid metabolism in streptozotocin-induced diabetic rats receiving total parenteral nutrition

BACKGROUND

This study was designed to investigate the effects of fat emulsions with different fatty acid composition on plasma glucose and lipid metabolism in diabetic rats receiving total parenteral nutrition (TPN).

METHODS

Diabetes was induced in rats with streptozotocin (STZ), and the rats were fed rat chow ad libitum for 6 weeks to achieve a chronic diabetic state. Control and diabetic rats were each divided into two TPN groups. The basal solutions of the two TPN groups were isonitrogenous and identical in nutrients composition except for the fat emulsion, which was made of soybean oil (SO) or fish oil (FO). The TPN control rats (C-SO and C-FO) and diabetic rats (DM-SO and DM-FO) received solutions with 37.5% of the non-protein energy provided as fat at an energy level of 30 kcal/100 g body wt/d.

RESULTS

The results demonstrated that hyperglycemia and hypertriglyceridemia were induced by STZ in diabetic rats. There was no change in plasma glucose and insulin concentrations before and after TPN infusion in the TPN control groups, whereas plasma glucose as well as triglyceride (TG) and nonesterified fatty acid (NEFA) levels decreased significantly after TPN administration in the diabetic groups. No difference in the concentrations of plasma glucose, TGs, NEFAs, and insulin were observed between the two diabetic groups.

CONCLUSIONS

These results suggest that compared with soybean oil, TPN with fish oil emulsion did not lead to lower plasma concentrations of TGs and NEFAs in STZ-induced diabetic rats. Also, no difference in plasma glucose and insulin levels between the two groups was observed.

Effects of MCT/LCT and LCT emulsions on plasma lipids and nitrogen retention in streptozotocin-induced diabetic rats receiving total parenteral nutrition

This study was designed to investigate the effects of emulsions containing medium-chain triacylglycerols (MCT) or long-chain triacylglycerols (LCT) on plasma lipids and nitrogen retention in diabetic rats receiving total parenteral nutrition (TPN). Diabetes was induced in rats by streptozotocin (STZ). Control and diabetic rats were divided into two TPN groups. The TPN groups received solutions at an energy level of 30 kcal/100 g body weight with 37.5% of the nonprotein energy provided as fat. All TPN solutions were isonitrogenous and identical in nutrient composition except for the fat emulsion, which was composed of LCT or MCT/LCT (1:1). The results showed that plasma triacylglycerol (TG), nonesterified fatty acids (NEFA), and beta-hydroxybutyrate levels were higher in diabetic rats compared with control rats, whereas plasma insulin levels and nitrogen retention were lower. Plasma glucose levels, TG, NEFA, and beta-hydroxybutyrate levels were significantly decreased after TPN administration in diabetic groups. Plasma glucose and TG levels, however, remained higher in diabetic groups than in control groups. No difference in the concentrations of plasma TG, cholesterol, NEFA, beta-hydroxybutyrate or nitrogen retention were observed between the two diabetic groups. These results suggest that MCT/LCT infusion did not lead to hyperketonemia and hypercholesterolemia as compared with LCT infusion, and had no beneficial effect on nitrogen retention in rats with STZ-induced diabetes under the present experimental conditions.