Intragastric infusion of a liquid diet with low-methoxyl pectin alleviates fecal inconsistency and local proinflammatory cytokine expression in lipopolysaccharide-septic rats.

OBJECTIVE: Diarrhea interrupts enteral nutrition management in hospitalized patients with severe illnesses, such as sepsis. Pectin, a water-soluble dietary fiber, has the potential to maintain intestinal function and may reduce inflammatory reactions. The aim of this study was to demonstrate that the addition of low-methoxyl (LM) pectin to a liquid diet suppresses softening of stool texture and reduces tissue inflammatory responses in enteral nutrition management during sepsis. METHODS: A fat-enriched liquid diet with LM pectin (P-EN) or a liquid diet without dietary fiber (FF-EN) was given continuously to rats through a gastric catheter. Lipopolysaccharide (LPS; 10 mg/kg) was injected intraperitoneally 24 h (study 1) and 7 h (study 2) before sacrifice. RESULTS: LPS injection significantly worsened fecal property scores in rats infused with FF-EN compared with the rats given P-EN in study 1. Whereas many myeloperoxidase-positive cells infiltrated the liver, and the hepatic expressions of chemokine genes were markedly elevated 24 h after LPS administration, these findings were clearly alleviated in the LM pectin-containing liquid diet group. In study 2, protein expressions of proinflammatory cytokines, such as small intestinal tumor necrosis factor-α and hepatic interleukin-1ß, and interleukin-6, were significantly downregulated in the P-EN LPS group compared with the FF-EN LPS group. CONCLUSIONS: A liquid diet containing LM pectin allows enteral nutrition management with a low risk for diarrhea and reduces local inflammation under septic conditions.

Fluorescence imaging around the abdomen allows evaluation of gastrointestinal retention of various forms of diet in mice.

OBJECTIVES: The aims of this study were to evaluate gastrointestinal (GI) retention of an ingested meal by fluorescence imaging and compare how retention is affected by differences in the physical characteristics of meals. METHODS: Mice were given an oral fluorescent indocyanine green (ICG) probe enclosed in a liposome. We evaluated the correlation between abdominal and GI fluorescence signals. ICG was administered to mice treated with atropine, and abdominal fluorescence was observed repeatedly. Mice were continuously given a regular chow or a liquid diet containing a low or high methoxyl (LM or HM)-pectin through a catheter placed in the stomach for 2 d, after which the mice were given ICG. In all studies, the mice's abdominal and GI fluorescence signals were observed with in vivo imaging equipment. RESULTS: The fluorescence intensities (FIs) of the abdomen and the excised GI tract correlated strongly. Attenuation of the abdominal FI was delayed in the atropine-treatment group compared with the non-treated group. The attenuation of abdominal FI 8 to 24 h after ICG administration was significantly weakened in the HM group compared with the regular chow and LM groups. CONCLUSIONS: Observing FI attenuation around the abdomen allows for the evaluation of GI tract retention of an ingested meal. Compared with a solid meal, a liquid meal stays longer in the digestive tract, whereas a liquid meal in which the viscosity increases in the stomach is retained like a solid meal.

A comparison of the effects of pulsatile and bolus flushing methods on lipid emulsion residues that lead to bacterial growth in intravenous catheters.

INTRODUCTION: The aim of this study was to compare the efficacies of pulsatile and bolus flushing methods for removing residual parenteral nutrients in common shapes of central venous (CV) and peripheral venous (PV) catheters. METHODS: Straight or looped tubes filled with parenteral nutrients containing indocyanine green (ICG) were flushed with 10 mL of saline at various speeds with several pulsatile intervals. Pseudomonas aeruginosa engineered with a luciferase gene was inoculated in the flushed CV catheters. The imaging technique detected the ICG remaining and the bacterial growth in the flushed catheters. RESULTS: In the CV catheter, the residue was greater with pulsatile flushing with longer intervals than with bolus flushing at a relatively high flushing speed. In the PV catheter, the flushing speed with any pulsatile intervals did not affect the residue. A looped catheter showed less residue than the straight catheter regardless of the flushing condition. Bacterial growth occurred in the nutrient residue in the flushed tubes. CONCLUSION: Speed of flushing and the shape of catheters, but not pulsatile flow generation, are essential components for the efficacious removal of parenteral nutrients in the catheter. Moreover, the slight differences in remaining nutrients inside the catheter affected subsequent bacterial growth.

Methionine supplementation spares body protein by regulating the expression of mTORC1 downstream factors in rats fed a soy protein diet with sufficient sulfur amino acids: a pilot study.

Dietary supplementation with methionine and threonine spares body protein in rats fed a low protein diet, but the effect is not observed for other essential amino acids. Although the requirement for sulfur amino acids is relatively high in rodents, the precise mechanisms underlying protein retention are not fully understood. The aim of this study was to explore whether the activation of mammalian target of rapamycin complex 1 (mTORC1) downstream factors in skeletal muscle by supplementation with threonine and/or methionine contributes to protein retention under sufficient cystine requirement. Male Sprague-Dawley rats were freely fed a 0% protein diet for 2 weeks. These experimental rats were then fed a restricted diet (14.5 g/day) containing 12% soy protein supplemented with both cystine and, methionine and threonine (MT), methionine (M), threonine (T), or neither (NA) (n = 8) for an additional 12 days. Two additional groups were freely fed a diet containing 0% protein or 20% casein as controls (n = 6). Body weight and gastrocnemius muscle weight were higher, and blood urea nitrogen and urinary nitrogen excretion were lower, in the M and MT groups than in the T and NA groups, respectively. p70 S6 kinase 1 abundance was higher, and eukaryotic translation initiation factor 4E-binding protein 1 abundance and mRNA levels were lower, in the skeletal muscles of the M and MT groups. These results suggest that methionine regulates mTORC1 downstream factors in skeletal muscle, leading to spare body protein in rats fed a low protein diet meeting cystine requirements.

How to perform appropriate flushing after lipid emulsion administration using totally implantable venous access devices in long-term total parenteral nutrition and home parenteral nutrition.

BACKGROUND & AIMS: There has been no clear evidence regarding the appropriate method of flushing catheters and totally implantable venous access devices (TIVADs) after lipid emulsion (LE) administration. Therefore, the aim of the study was to identify appropriate methods of flushing to minimize residual LE when using TIVADs to ensure the safety of long-term total parenteral nutrition (TPN) and home parenteral nutrition (HPN). METHODS: A soybean oil LE containing indocyanine green (ICG) was administered from the injection site of the primary infusion set for flowing TPN, and LE dynamics were evaluated by a fluorescence imaging system. TIVADs were connected to the end of the infusion sets. After LE administration, the tubes and chambers were flushed from the injection site using saline at various speeds (20, 40, 60 mL/min), with and without pulsation. The washout effect of TPN solution after LE administration followed by flushing was examined, as was the washout effect of size differences in the infusion sets. RESULTS: When the LE was flushed with 20 mL of saline immediately after administering the LE using a standard infusion set (inner diameter 2.5 mm), the LE still remained in the tubes and chambers under any flushing condition. Flushing the LE from the injection site with 10 mL of saline and then flowing >240 mL of TPN solution were effective for minimizing residual LE inside the tubes and chambers. When using an infusion set with a small inner diameter (1.0 mm), the LE inside the tubes and chambers was almost discharged with ≥20 mL of saline immediately after administering the LE. In all settings, flushing with/without pulsation did not affect LE washout efficacy. CONCLUSIONS: Flushing immediately with saline ≥10 mL and then flowing >240 mL of primary PN solution after soybean oil LE administration using the standard infusion set or flushing with 20 mL saline immediately after administering the soybean oil LE using the infusion set with a small inner diameter are effective for minimizing the residual LE in the catheter and TIVAD, ensuring the safety of long-term TPN and HPN.

Evaluation of the amount of residual lipid emulsion in chambers of flushed totally implantable venous access devices using fluorescence imaging.

The aim of the present study was to use a quantitative fluorescence imaging technique to evaluate the invisible amount of residual lipid emulsion in port chambers flushed with various fundamental protocols. Chambers were filled with lipid emulsion containing indocyanine green and then flushed with 5-70 mL of normal saline. Chambers were flushed at various speeds (15-60 mL/min), with a time interval of 1 or 3 s between boluses, and with varying directions of flow. The slower the flushing speed, the more lipid emulsion that remained. Pulsatile flushing with either time interval did not decrease the residual amounts, and the areas well-cleansed after flushing were oriented to the bevel-opening direction. These findings suggest that to reduce the residual amount of lipid emulsion poured in a chamber, fast and furious flushing under continuous as opposed to pulsatile flushing is of paramount importance.

Fecal imaging demonstrates that low-methoxyl pectin supplementation normalizes gastro-intestinal transit in mice given a liquid diet.

This study has the following aims: (1) to confirm a methodology for a fecal indocyanine green (ICG) imaging test for measuring gastro-intestinal transit time (GITT); and (2) to compare GITT in mice given a liquid diet in which viscosity increases under acidic conditions to that in mice given stable liquid diets with comparable viscosity or regular chow. To address Aim 1, mice received ICG orally along with intraperitoneal injection of atropine in Study 1, and mice were given ICG orally with concurrent carmine red for Study 2. Fluorescence imaging of feces collected for 8 h thereafter was used to detect the first feces with fluorescence and thereby determine GITT. To address Aim 2, mice were fed ad libitum for 1 week with either liquid diet or regular chow for Study 3, or with liquid diet containing low-methoxyl (LM) pectin or high-methoxyl (HM) pectin, or regular chow for Study 4. GITT was then determined by fecal ICG imaging. Atropine delayed GITT in a dose-dependent manner. The GITT of ICG completely corresponded to that of carmine red (correlation coefficient, 1.00). The first ICG excretion in the loose/some diarrheal feces of mice given a liquid diet was seen at 170 min. Feces of mice given liquid diet were loose with LM pectin and loose/some diarrhea with HM pectin. GITT of mice given liquid diet with HM pectin was significantly delayed (280 min) compared to that of mice given liquid diet with LM pectin (111 min) or regular chow (130 min). Fecal imaging of ICG enables measurements of GITT. LM pectin supplementation in a liquid diet may normalize GITT in mice to that of a normal meal and may be associated with changes in fecal properties.

Detecting Enteral Nutrition Residues and Microorganism Proliferation in Feeding Tubes via Real-Time Imaging.

BACKGROUND: Enteral nutrition (EN) residues that persist in feeding tubes provide substrates for microorganisms to proliferate and occlude the tubes. Visible EN residues in tubes are easily identified, but smaller residues can persist. We developed a new imaging technique to visualize EN residues and proliferation of microorganisms in feeding tubes. MATERIALS AND METHODS: (1) Feeding tubes containing EN labeled with fluorescent dye and either with or without various types or amounts of thickeners were flushed once with water and then seeded with Pseudomonas aeruginosa Xen05 with recombinant luciferase DNA. (2) Because EN fluoresces intrinsically, EN in the feeding tubes without fluorescent dye was repeatedly flushed until the intrinsic fluorescence levels reached background levels. Fluorescent images of EN residues and bioluminescent images of microorganisms were acquired via an optical imaging system. RESULTS: (1) Fluorescence images showed that the amount of EN residues increased at various sites in tubes depending on EN viscosity and the thickening agent, and bioluminescence images showed that microorganism proliferation was associated with a commensurate increase in EN residues. (2) The intrinsic fluorescence of EN also enabled the detection of EN residues in tubes even in the absence of fluorescence dye. Higher EN viscosity required more flushes to reach undetectable levels. CONCLUSION: EN residues and microorganism proliferation in enteral feeding tubes were detected on fluorescence and bioluminescence images, respectively. This simplified approach allowed the real-time visualization of EN residues and microorganisms in feeding tubes.

Fluorescence imaging in vivo visualizes delayed gastric emptying of liquid enteral nutrition containing pectin.

BACKGROUND: Semi-solidification by gelation or increased viscosity could slow the influx of liquid enteral nutrition (EN) into the small intestine. A liquid EN formula containing pectin that gels under acidic conditions such as those found in the stomach has been developed. A new near-infrared fluorescent imaging reagent was used to non-invasively acquire real time images of gastric emptying in a murine model in vivo. We postulated that the EN formula delays gastric emptying and tested this hypothesis using imaging in vivo. METHODS: Male BALB/c mice were given an oral bolus injection of a liquid EN containing the fluorescence reagent GastroSense750 with or without pectin. The EN in the stomach was visualized in vivo at various intervals using a non-invasive live imaging system and fluorescent signals were monitored from the stomach, which was removed at 60 min after EN ingestion. RESULTS: The fluorescence intensity of signals in stomachs in vivo and in resected stomachs was lower and attenuated over time in mice given EN without, than with pectin. CONCLUSIONS: Adding a gelling agent such as pectin delayed the transit of liquid EN from the stomach. Fluorescence imaging can visualize the delayed gastric emptying of EN containing pectin.

Organ preservation using a photosynthetic solution.

BACKGROUND: Organs harvested from a body lapsing into circulatory deficit are exposed to low O2/high CO2, and reach a critical point where original functionality after transplantation is unlikely. The present study evaluates the effect of respiratory assistance using Chlorella photosynthesis on preservation of the rat pancreas from the viewpoint of donation after cardiac death (DCD). METHODS: Gas was exchanged through the peritoneum of rats under controlled ventilation with or without Chlorella photosynthetic respiratory assistance. A gas permeable pouch containing Chlorella in solution was placed in the peritoneum and then the space between the pouch and the peritoneum was filled with an emulsified perfluorocarbon gas carrier. Rat DCD pancreases procured 3 h after cardiac arrest were preserved for 30 min in a cold or mildly hypothermic environment or in a mildly hypothermic environment with photosynthetic respiratory support. The pancreases were then heterotopically transplanted into rats with STZ-induced diabetes. RESULTS: Levels of blood oxygen (PaO2) and carbon dioxide (PaCO2) increased and significantly decreased, respectively, in rats with mechanically reduced ventilation and rats given intraperitoneal photosynthetic respiratory support when compared with those without such support. Transplantation with DCD pancreases that had been stored under photosynthetic respiratory support resulted in the survival of all rats, which is impossible to achieve using pancreases that have been maintained statically in cold storage. CONCLUSION: Respiratory assistance using photosynthesis helps to improve not only blood gas status in the event of respiratory insufficiency, but also graft recovery after pancreas transplantation with a DCD pancreas that has been damaged by prolonged warm ischemia.

Ethionine-induced ATP depletion represses mTOR signaling in the absence of increases in AMP-activated protein kinase activity in the rat liver.

Administration of ethionine to female rats caused a rapid and severe decline in liver ATP and inhibited hepatic protein synthesis in association with hypophosphorylation of eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) and 70-kDa ribosomal protein S6 kinase (S6K1), two key regulatory proteins involved in initiation of mRNA translation. Phosphorylation of both regulatory proteins is mediated through a signaling pathway that involves the mammalian target of rapamycin (mTOR). Recent studies indicate that AMP-activated protein kinase (AMPK) plays a role in the cellular response to environmental stresses, which deplete ATP, and suppresses protein synthesis through downregulated mTOR signaling. We investigated the possible involvement of AMPK in the ethionine-induced inhibition of protein synthesis. The administration of ethionine surprisingly decreased AMPK activity compared with controls despite ATP depletion. We conclude that inhibition of protein synthesis by ethionine is due to AMPK-independent inhibition of mTOR signaling following ATP depletion.

Insulin mediates the linkage acceleration of muscle protein synthesis, thermogenesis, and heat storage by amino acids.

Amino acid (AA) administration can stimulate heat accumulation in the body, as especially found under anesthetic conditions. To test our hypothesis that marked rise in plasma insulin concentrations following AA administration plays an important role in the heat storage, we intravenously administered either a balanced AA mixture or saline over 3 h, both with and without a primed-constant infusion of somatostatin in propofol-anesthetized rats. Rats on AA but lacking marked rise in plasma insulin by somatostatin treatment failed to show: attenuation of fall in core body temperature; partial increases in oxygen consumption; and stimulated muscle protein synthesis. Furthermore, the AA's stimulatory effects on phosphorylation of mTOR, 4E-BP1, and S6K1 were partially blocked by somatostatin. Our findings strongly suggest that the marked rise in insulin following AA administration promote translation initiation activities and stimulate muscle protein synthesis, which facilitates heat accumulation in the body.

Circadian changes in core body temperature, metabolic rate and locomotor activity in rats on a high-protein, carbohydrate-free diet.

Ingestion of a high-protein meal results in body weight loss due to elevated energy expenditure, while also increasing satiety and decreasing subsequent food intake. The present study aimed to clarify the effects of a high-protein, carbohydrate-free diet (HPCFD) on these physiological indicators from a circadian perspective. Rats were given HPCFD or a pair-fed normal protein content diet (20% protein; NPD) for 4 d. The HPCFD group lost more body weight than the NPD group. Oxygen consumption (VO(2)) in the HPCFD group did not change during the experimental period, and tended to be higher during the light (L) phase than in the NPD group. Carbon dioxide production (VCO(2)) during the L phase was higher in the HPCFD group than in the NPD group, where VCO(2) was gradually decreased during the last dark (D) phase and throughout the L phase. The HPCFD group exhibited higher daily core body temperature (T(b)), particularly during the late D phase and throughout the L phase when compared to the NPD group. Locomotor activities during the D phase of the NPD group tended to gradually increase and were thus significantly higher than in the HPCFD group. These results suggest that HPCFD, even if energy intake is insufficient, maintains circadian changes in metabolic rates, resulting in maintenance of elevated daily T(b) and body weight reduction without increasing activity.

Glucose infusion suppresses surgery-induced muscle protein breakdown by inhibiting ubiquitin-proteasome pathway in rats.

BACKGROUND: It appears to have been well established that after surgery, protein catabolism is accelerated and glucose infusion suppresses the catabolic reactions. However, in the early postoperative period, the effects of surgical stress and glucose infusion on muscle protein catabolism and the related mechanisms remain unclear. METHODS: Rats undergoing laparotomy were infused with acetated Ringer's solution (10 ml x kg(-1) x h(-1)) without glucose (control) or containing 1% or 5% glucose. The infusion was continued for a further 4 h after the surgical treatment. The catabolic index, excretion of urinary nitrogen and 3-methylhistidine, and release of tyrosine and 3-methylhistidine from isolated muscle were determined. Furthermore, muscular mRNA expression of proteolytic-related genes (atrogin-1/MAFbx, muscle ring finger-1, mu- and m-calpain, and cathepsin L and H) and phosphorylation of components of insulin signaling (forkhead box O3 and protein kinase B) were evaluated. RESULTS: Surgery increased the catabolic index, and this increase was suppressed by glucose infusion (both 1% and 5%). In the control group, mRNA expression of atrogin-1/MAFbx and muscle ring finger-1 was increased, and they were suppressed in the two glucose groups. Furthermore, insulin signaling (phosphorylation of protein kinase B and forkhead box O3) in muscles was stimulated by glucose infusion. CONCLUSION: The present study indicates that glucose infusion, even at a relatively low rate, suppresses muscle protein breakdown in the early postoperative period. The mechanism of this effect is related to the suppression of the ubiquitin-proteasome pathway, accompanied by activation of insulin signaling.

Modification of core body temperature by amino acid administration.

The feeling of warmth after a meal is caused by the ingestion of nutrients and the sensation is known as nutrition-induced thermogenesis or specific dynamic action. Core body temperature (Tb) is constantly maintained within a narrow range, but thermoregulation can become impaired by the inhalation or intravenous administration of anesthetics that inhibit hypothalamic thermoregulation. Hypothermia during surgery is directly associated with postoperative complications. Devices are available to maintain heat during surgery and thus prevent hypothermia. On the other hand, intravenous amino acid (AA) administration can attenuate hypothermia during anaesthesia, prompting many clinical trials of AA mixtures to maintain Tb. However, although the thermal effect of AA during anaesthesia is obvious, the underlying mechanism of metabolic heat production and accumulation remains obscure. A nutritional physiological approach using a rat model will be introduced in this symposium. Data from our recent studies suggest that the administration of an AA mixture during anaesthesia stimulates muscle protein synthesis via insulin-mTOR-dependent activation of the translation initiation factors, 4E-BP 1 and S6K1, as a result of increased insulin concentrations. Thus, heat accumulation in the body is facilitated. Furthermore, the content of the AA mixture applied during anaesthesia alters the thermal effect and branched chain AAs are necessary, but not sufficient, for the prevention of hypothermia.

Dietary protein modulates circadian changes in core body temperature and metabolic rate in rats.

We assessed the contribution of dietary protein to circadian changes in core body temperature (Tb) and metabolic rate in freely moving rats. Daily changes in rat intraperitoneal temperature, locomotor activity (LMA), whole-body oxygen consumption (VO2), and carbon dioxide production (VCO2) were measured before and during 4 days of consuming a 20% protein diet (20% P), a protein-free diet (0% P), or a pair-fed 20% P diet (20% P-R). Changes in Tb did not significantly differ between the 20% P and 20% P-R groups throughout the study. The Tb in the 0% P group remained elevated during the dark (D) phase throughout the study, but VO2, VCO2, and LMA increased late in the study when compared with the 20% P-R group almost in accordance with elevated Tb. By contrast, during the light (L) phase in the 0% P group, Tb became elevated early in the study and thereafter declined with a tendency to accompany significantly lower VO2 and VCO2 when compared with the 20% P group, but not the 20% P-R group. The respiratory quotient (RQ) in the 0% P group declined throughout the D phase and during the early L phase. By contrast, RQ in the 20% P-R group consistently decreased from the late D phase to the end of the L phase. Our findings suggest that dietary protein contributes to the maintenance of daily oscillations in Tb with modulating metabolic rates during the D phase. However, the underlying mechanisms of Tb control during the L phase remain obscure.

Enhancement of myofibrillar proteolysis following infusion of amino acid mixture correlates positively with elevation of core body temperature in rats.

Administration of an amino acid (AA) mixture stimulates muscle protein synthesis and elevates core body temperature (T(b)), as characteristically found under anesthetic conditions. We tested the hypothesis that not only AA given, but also AA produced by degradation of endogenous muscular protein are provided for muscle protein synthesis, which is further reflected in T(b) modifications. Rats were intravenously administered an AA mixture or saline in combination with the anesthetic propofol or lipid emulsion. We measured plasma 3-methylhistidine (MeHis) concentrations as an index of myofibrillar protein degradation, rectal temperature and mRNA expression of atrogin-1, MuRF-1 and ubiquitin in gastrocnemius and soleus muscles of rats following 3 h infusion of test solutions. T(b) did not differ significantly between conscious groups, but was higher in the AA group than in the saline group among anesthetized rats. Plasma MeHis concentrations were higher in the AA group than in the saline group under both conditions. Plasma MeHis levels correlated positively with T(b) of rats under both conditions. AA administration decreased mRNA levels of atrogin-1 and ubiquitin in gastrocnemius muscle and all mRNA levels in soleus muscle. These results suggest that AA administration enhances myofibrillar protein degradation and that the change is a determinant of T(b) modification by AA administration. However, the mechanisms underlying AA administration-associated enhancement of myofibrillar proteolysis remains yet to be determined.

Hypoglycemic effect of isoleucine involves increased muscle glucose uptake and whole body glucose oxidation and decreased hepatic gluconeogenesis.

Isoleucine, a branched chain amino acid, plays an important role in the improvement of glucose metabolism as evidenced by the increase of insulin-independent glucose uptake in vitro. This study evaluated the effect of isoleucine on glucose uptake and oxidation in fasted rats and on gluconeogenesis in vivo and in vitro. Oral administration of isoleucine decreased the plasma glucose level by 20% and significantly increased muscle glucose uptake by 71% without significant elevation of the plasma insulin level compared with controls at 60 min after administration. Furthermore, expiratory excretion of 14CO2 from [U-14C]glucose in isoleucine-administered rats was increased by 19% compared with controls. Meanwhile, isoleucine decreased AMP levels in the liver but did not affect hepatic glycogen synthesis. Under insulin-free conditions, isoleucine significantly inhibited glucose production when alanine was used as a glucogenic substrate in isolated hepatocytes. This inhibition by isoleucine was also associated with a decline in mRNA levels for phosphoenolpyruvate carboxykinase and glucose-6-phosphatase (G6Pase) and a decreased activity of G6Pase in isolated hepatocytes. These findings suggest that a reduction of gluconeogenesis in liver, along with an increase of glucose uptake in the muscle, is also involved in the hypoglycemic effect of isoleucine. In conclusion, isoleucine administration stimulates both glucose uptake in the muscle and whole body glucose oxidation, in addition to depressing gluconeogenesis in the liver, thereby leading to the hypoglycemic effect in rats.

Effects of chronic ethanol administration on the expression levels of neurotrophic factors in the rat hippocampus.

Chronic ethanol consumption has adverse effects on the central nervous system. Hippocampus is one of the target sites of ethanol neurotoxicity. Hippocampal damage is known to result in impairment of learning and memory. This study was aimed to determine whether chronic ethanol consumption could alter the expression levels of brain-derived neurotrophic factor (BDNF) and glial-derived neurotrophic factor (GDNF) mRNAs in the hippocampus. Male Wistar rats were given unrestricted access to a liquid diet containing 5% (v/v) ethanol as the sole fluid source for 19 weeks beginning at 10 weeks of age. The expression levels of BDNF and GDNF mRNAs in the hippocampus were analyzed by real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis. The present study revealed that chronic ethanol consumption did not result in significant changes in the expression levels of BDNF and GDNF mRNAs. Our present results showed no significant alteration in the expression of these neurotrophic factors; these results will lead to further studies to examine the possible alterations in the gene expression of various neurotrophins that are related to hippocampal functions including learning and memory.

Intravenous administration of amino acids during anesthesia stimulates muscle protein synthesis and heat accumulation in the body.

The present study was conducted to determine the contribution of muscle protein synthesis to the prevention of anesthesia-induced hypothermia by intravenous administration of an amino acid (AA) mixture. We examined the changes of intraperitoneal temperature (Tcore) and the rates of protein synthesis (K(s)) and the phosphorylation states of translation initiation regulators and their upstream signaling components in skeletal muscle in conscious (Nor) or propofol-anesthetized (Ane) rats after a 3-h intravenous administration of a balanced AA mixture or saline (Sal). Compared with Sal administration, the AA mixture administration markedly attenuated the decrease in Tcore in rats during anesthesia, whereas Tcore in the Nor-AA group became slightly elevated during treatment. Stimulation of muscle protein synthesis resulting from AA administration was observed in each case, although K(s) remained lower in the Ane-AA group than in the Nor-Sal group. AA administration during anesthesia significantly increased insulin concentrations to levels approximately 6-fold greater than in the Nor-AA group and enhanced phosphorylation of eukaryotic initiation factor 4E-binding protein-1 (4E-BP1) and ribosomal protein S6 protein kinase relative to all other groups and treatments. The alterations in the Ane-AA group were accompanied by hyperphosphorylation of protein kinase B and the mammalian target of rapamycin (mTOR). These results suggest that administration of an AA mixture during anesthesia stimulates muscle protein synthesis via insulin-mTOR-dependent activation of translation initiation regulators caused by markedly elevated insulin and, thereby, facilitates thermal accumulation in the body.