FD Rats Research Articles

Evaluation of the hypoglycemic, hypolipidemic and antioxidant activities of Phoenix dactylifera l. Date seeds extract in high fructose diet-induced diabetic rats

Diabetes is a growing global epidemic, necessitating effective management to prevent long-term complications. Natural substances are increasingly explored as alternatives to synthetic drugs due to their affordability and lower risk of side effects. This study investigates the qualitative composition and the hypoglycemic, hypolipidemic, and antioxidant activities of date seed extract (Phoenix dactylifera L.) in diabetic rats fed a high-fructose diet. Male rats were divided into four groups (n=6): Control (C, standard diet), Fructose Diabetic (FD, 60% fructose diet), and Control and Diabetic groups receiving daily 30 mL of aqueous date seed extract (C-aqDS, FD-aqDS). Weight gain, food and energy intake were monitored, while blood samples were analyzed for biochemical and oxidant/antioxidant markers. High-fructose consumption significantly increased body weight, energy intake, and apparent nutritional efficiency, while food intake remained unchanged. Biochemical markers, including glucose, glycated hemoglobin, uric acid, urea, creatinine, lipids, and liver enzymes, were elevated in FD rats compared to controls. Oxidative stress markers (MDA, PC) were increased, and antioxidant markers (catalase, SOD, GSH) decreased. Treatment with date seed extract significantly mitigated these abnormalities, reducing weight, biochemical parameters, and oxidative stress markers while enhancing antioxidant defenses. This study highlights the richness of date seed aqueous extract in bioactive compounds and its ability to alleviate early diabetic complications and oxidative stress in high-fructose-induced diabetic rats. These findings suggest its potential as a functional food for diabetes management.

Network pharmacology combined with experimental validation reveals the mechanism of action of erpixing granules on functional dyspepsia

Ethnopharmacological relevanceFunctional dyspepsia (FD) is a prevalent gastrointestinal disorder characterised by high incidence and recurrence rates, posing significant health risks. Erpixing Granules (EPX), approved by the National Food and Drug Administration in 2002, are known for their spleen and stomach invigorating properties, effectively treating FD. However, its mechanism of action remains unclear. Aim of the studyThis study aims to elucidate EPX's mechanism of treating FD through network pharmacology, and experimental validation using FD animal models. MethodsIn this study, the chemical composition of EPX in positive and negative ion modes was analyzed by UHPLC-Q-TOF MS. The mass spectral data were processed and analyzed using MS-DIAL software to automatically match compound fragment information and identify the known components with the compound database to obtain the active components of EPX. SwissTargetPrediction was used to obtain EPX targets, while FD-related targets were sourced from GeneCards, OMIM and DisGeNET databases. A protein-protein interaction (PPI) network was constructed using the STRING platform, and potential signalling pathways of EPX were determined through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Finally, an FD model was established in rates by administering a 0.1% iodoacetamide sucrose solution, followed by tail clamp stimulation to experimentally validate the network pharmacology findings. ResultsOur results revealed 139 effective ingredients in EPX, targeting 60 core FD-related genes. PPI network analysis identified EGFR, CTNNB1 and NFκB1 as core target genes. The KEGG pathway analysis indicated that EPX can modulate FD progression through the PI3K/AKT signalling pathway. Animal experiments demonstrated EPX's capacity to increase body mass, food intake and food utilisation efficiency in FD rats, alongside increased gastric juice secretion, pepsin activity, trypsin activity, cholesterol, bile acid and bilirubin activity. HE examination revealed that EPX improved the inflammatory infiltration of gastric mucosal cells in rats. Furthermore, EPX also promoted gastric emptying and intestinal propulsion in mice. These results suggest that EPX improves spleen and stomach function, enhances the protective effect on the spleen and stomach and promotes food digestion and absorption. Immunofluorescence studies revealed upregulated expression of PI3K, AKT and ANO1 proteins in gastric tissue following EPX administration, while Western blotting indicated increased expression of SCF and C-kit proteins. ConclusionSuggesting EPX's anti-FD effect may involve the regulation of the SCF/C-kit signalling pathway and activation of downstream PI3K/AKT signalling pathway, thereby promoting gastrointestinal motility and improving FD symptoms.

Daily Intake of Smallanthus sonchifolius (Yacon) Roots Reduces the Progression of Non-alcoholic Fatty Liver in Rats Fed a High Fructose Diet.

High-fructose diet is associated with an increased risk of dyslipidemia, metabolic syndrome, and the development of non-alcoholic fatty liver disease (NAFLD) through chronic inflammation. The present study aimed to elucidate the potential benefit of daily consumption of Smallanthus sonchifolius (yacon) roots, rich in fructooligosaccharides (FOS), on the progression to liver fibrosis, in a rat model of NAFLD induced by a high-fructose diet. Male Wistar rats were fed a standard diet (CD, n= 6) or a standard diet plus 10% fructose solution (FD; n= 18). After 20weeks, FD rats were randomly separated into the following groups (n= 6, each): FD; FD treated with yacon flour (340mg FOS/body weight; FD + Y) and FD treated with fenofibrate (30mg/kg body weight; FD + F), for 16weeks. Daily intake of yacon flour significantly reduced body weight gain, plasma lipid levels, transaminase activities, and improved systemic insulin response in FD rats. In the liver, yacon treatment decreased fructose-induced steatosis and inflammation, and reduced total collagen deposition (64%). Also, yacon decreased TGF-β1 mRNA expression (78%), followed by decreased nuclear localization of p-Smad2/3 in liver tissue. Yacon significantly reduced the expression of α-smooth muscle actin (α-SMA), Col1α1, and Col3α1 mRNAs (85, 44, and 47%, respectively), inhibiting the activation of resident hepatic stellate cells (HSCs). These results suggested that yacon roots have the potential to ameliorate liver damage caused by long-term consumption of a high-fructose diet, being a promising nutritional strategy in NAFLD management.

Eosinophil-associated microinflammation in the gastroduodenal tract contributes to gastric hypersensitivity in a rat model of early-life adversity.

Gastric hypersensitivity is a major pathophysiological feature of functional dyspepsia (FD). Recent clinical studies have shown that a large number of patients with FD present with gastroduodenal microinflammation, which may be involved in the pathophysiology of FD. However, no animal model reflecting this clinical characteristic has been established. The underlying mechanism between microinflammation and FD remains unknown. In this study, using a maternal separation (MS)-induced FD model, we aimed to reproduce the gastroduodenal microinflammation and reveal the interaction between gastroduodenal microinflammation and gastric hypersensitivity. The MS model was established by separating newborn Sprague-Dawley rats for 2 h a day from postnatal day 1 to day 10. At 7-8 wk of age, electromyography was used to determine the visceromotor response to gastric distention (GD) and immunohistochemistry was performed to detect distension-associated neuronal activation as well as immunohistological changes. Our results demonstrated that MS-induced FD rats underwent gastric hypersensitivity with GD at 60 and 80 mmHg, which are related to increased p-ERK1/2 expression in the dorsal horn of T9-T10 spinal cords. Eosinophils, but not mast cells, were significantly increased in the gastroduodenal tract, and the coexpression rate of CD11b and major basic protein significantly increased in MS rats. Treatment with dexamethasone reversed gastric hypersensitivity in MS-induced FD rats by inhibiting eosinophil infiltration. These findings indicated that neonatal MS stress induces eosinophil-associated gastroduodenal microinflammation and gastric hypersensitivity in adulthood in rats. Microinflammation contributes to gastric hypersensitivity; therefore, anti-inflammatory therapy may be effective in treating patients with FD with gastroduodenal microinflammation.NEW & NOTEWORTHY We showed for the first time that neonatal MS stress-induced FD rats undergo gastroduodenal eosinophil-associated microinflammation in adulthood. Suppression of microinflammation attenuated gastric hypersensitivity in MS rats. These findings established a functional link between microinflammation and gastric hypersensitivity, which may provide a potential clue for the clinical treatment of FD.

The offspring from rats fed a fatty diet display impairments in the activation of liver peroxisome proliferator activated receptor alpha and features of fatty liver disease

Maternal obesity programs liver derangements similar to those of NAFLD. Our main goal was to evaluate whether these liver anomalies were related to aberrant PPARα function. Obesity was induced in female Albino-Wistar rats by a fatty diet (FD rats). Several parameters related to NAFLD were evaluated in both plasma and livers from fetuses of 21 days of gestation and 140-day-old offspring. FD fetuses and offspring developed increased levels of AST and ALT, signs of inflammation and oxidative and nitrative stress-related damage. FD offspring showed dysregulation of Plin2, CD36, Cyp4A, Aco, Cpt-1, Hadha and Acaa2 mRNA levels, genes involved in lipid metabolism and no catabolic effect of the PPARα agonist clofibrate. These results suggest that the FD offspring is prone to develop fatty liver, a susceptibility that can be linked to PPARα dysfunction, and that this could in turn be related to the liver impairments programmed by maternal obesity.

Upregulation of gastric norepinephrine with beta-adrenoceptors and gastric dysmotility in a rat model of functional dyspepsia.

Disordered motility is one of the most important pathogenic characteristics of functional dyspepsia (FD), although the underlying mechanisms remain unclear. Since the sympathetic system is important to the regulation of gastrointestinal motility, the present study aimed to investigate the role of norepinephrine (NE) and adrenoceptors in disordered gastric motility in a rat model with FD. The effect of exogenous NE on gastric motility in control and FD rats was measured through an organ bath study. The expression and distribution of beta-adrenoceptors were examined by real-time PCR, Western blotting and immunofluorescence. The results showed that endogenous gastric NE was elevated in FD rats, and hyperreactivity of gastric smooth muscle to NE and delayed gastric emptying were observed in the rat model of FD. The mRNA levels of beta1-adrenoceptor and norepinephrine transporter (NET) and the protein levels of beta2-adrenoceptor and NET were increased significantly in the gastric corpus of FD rats. All three subtypes of beta-adrenoceptors were abundantly distributed in the gastric corpus of rats. In conclusion, the enhanced NE and beta-adrenoceptors and NETs may be contributed to the disordered gastric motility in FD rats.

An orally administered magnoloside A ameliorates functional dyspepsia by modulating brain-gut peptides and gut microbiota

AimsFunctional dyspepsia (FD) is very common worldwide with a high prevalence of 10%–30%, and it becomes a heavy burden to patients because of its hard to be cured. In our previous study, phenylethanoid glycosides were found to exist in Houpo, a traditional Chinese medicine commonly used for the treatment of abdominal distention, pain and dyspepsia. In the present study, the effect of magnoloside A (MA), a main phenylethanoid glycoside in Houpo, on FD was firstly evaluated and its potential mechanism was concluded. Materials and methodsMA was orally administered consequently for 3 weeks, and its effect on a FD rat model established through transient neonatal gastric irritation and mature alternate-day fasting was tested. Levels of brain-gut peptides and inflammatory factors in blood or tissues were determined by ELISA methods. Meanwhile, the gut microbiota was analyzed by 16S rRNA gene sequencing and short chain fat acids were determined by GC/MS. Key findingsMA exhibited anti-FD activities by fastening the delayed gut emptying rate of FD rat and increasing the levels of gastrin, motilin, and calcitonin gene related protein; and decreasing the levels of 5-hydroxytryptamine, nitric oxide synthase, and vasoactive intestinal peptide. On the other hand, MA can modulate the composition of gut microbiota, resulting in the variation of the short chain fat acids. SignificanceMA ameliorated FD rats by modulating of the secretion of related brain-gut peptides and altering the composition of intestinal microbiota.

Polyunsaturated Fatty Acids Attenuate Diet Induced Obesity and Insulin Resistance, Modulating Mitochondrial Respiratory Uncoupling in Rat Skeletal Muscle.

ObjectivesOmega (ω)-3 polyunsaturated fatty acids (PUFA) are dietary compounds able to attenuate insulin resistance. Anyway, the precise actions of ω-3PUFAs in skeletal muscle are overlooked. We hypothesized that PUFAs, modulating mitochondrial function and efficiency, would ameliorate pro-inflammatory and pro-oxidant signs of nutritionally induced obesity.Study DesignTo this aim, rats were fed a control diet (CD) or isocaloric high fat diets containing either ω-3 PUFA (FD) or lard (LD) for 6 weeks.ResultsFD rats showed lower weight, lipid gain and energy efficiency compared to LD-fed animals, showing higher energy expenditure and O2 consumption/CO2 production. Serum lipid profile and pro-inflammatory parameters in FD-fed animals were reduced compared to LD. Accordingly, FD rats exhibited a higher glucose tolerance revealed by an improved glucose and insulin tolerance tests compared to LD, accompanied by a restoration of insulin signalling in skeletal muscle. PUFAs increased lipid oxidation and reduced energy efficiency in subsarcolemmal mitochondria, and increase AMPK activation, reducing both endoplasmic reticulum and oxidative stress. Increased mitochondrial respiration was related to an increased mitochondriogenesis in FD skeletal muscle, as shown by the increase in PGC1-α and -β.Conclusionsour data strengthened the association of high dietary ω3-PUFA intake with reduced mitochondrial energy efficiency in the skeletal muscle.

Diabetes-Induced Gastric Visceral Hypersensitivity is Mediated by Activation of MAP Kinase That Modulates Transient K + Current in Rat Dorsal Root Ganglia Neurons

intact rats and on fundic muscularis externa from both groups of rats. Results: Neonatal inflammatory insult significantly suppressed the contractile response of circular muscle strips from the fundus of rats to ACh (10-6 to 10-2 M) in adulthood vs. controls. The gastric emptying of a solid meal in FD rats in 90 minutes (57±6 %) was slower than in controls (66±9 %, p<0.05). Similar induction of colonic inflammation by TNBS in 6-week-old adult rats did not show these effects 6 to 8 weeks later, compared with age-matched controls. Real time PCR and western blotting showed that the expression of MLCK mRNA (31± 9 % of control, p<0.01) and protein (51+7 % of control, p<0.01), were significantly suppressed in FD rats. The protein and mRNA expressions of other cell signaling proteins α1C-subunit of L-type Ca2+ channels, Gαq and 20 kDa regulatory light chain (RLC20) were not affected in FD rats. The intensity of phosphorylation of RLC20 by the activation of MLCK determines the amplitude of smooth muscle contraction. The intensity of phosphorylation of RLC20 in response to ACh was lower in FD vs. controls. The analysis of MLCK promoter showed no CpG islands. However, we found six regions in the mylk1 promoter (-3460/-3408; -3180/3141; -2156/-2101; -1176/-1136; -890/-831; -436/-366) that contain more than 5% of 5'CG-3' content, which may serve as methylation targets. One of these regions (-3,180/-3,141) contains the binding motifs of the SRF and SP1 transcription factors, while another region (-890/-831) contains the binding motif of the CREB transcription factor. Methylation-specific PCR showed significantly increased methylation of the DNA segment -890/-831 containing the recognition sequence of CREB transcription factor 1-week after the neonatal inflammatory insult, which persisted into adulthood. Conclusions: Neonatal inflammatory insult during the vulnerable stage of neonatal development methylates a specific region of the mlck1 gene promoter to suppress the critical cell signaling protein MLCK, which reduces the reactivity of gastric fundus smooth muscle cells to ACh, resulting in delayed gastric emptying of solid meals in adulthood.

Bacterial Lipopolysaccharides Interact With Oral Ovalbumin to Induce Food-Antigen-Related IBS-Like Alterations of Colonic Motility in Rats

G A A b st ra ct s showed a 2-fold (p<0.05) increase in Brain-derived neurotrophic factor (BDNF) mRNA and a 50% decrease in the mRNA of Kv1.1 channels, compared with controls. BDNF protein was increased 50% (p<0.05) in the thoracic spinal cord. Intrathecal administration of Kv1.1 siRNA in naive rats significantly increased sensitivity to gastric distention, suggesting that the suppression of Kv1.1 contributes to GHS. Intrathecal treatment with a BDNF antagonist, trkB-Fc, significantly reduced gastric hypersensitivity in FD rats. Nerve growth factor (NGF) protein expression was 75% (p<0.05) greater in fundic muscularis externa of FD rats. Systemic treatment with an NGF antibody significantly attenuated gastric hypersensitivity. The plasma concentration of norepinephrine was significantly greater in FD rats, compared with control rats. Treatment of fundic muscularis externa In Vitro with norepinephrine produced a 50% (p<0.05) increase in NGF expression. Sodium butyrate, a histone deacetylase inhibitor, treatment in sensitized FD rats significantly reduced both gastric hypersensitivity and NGF expression in the fundus. Conclusions: Neonatal inflammatory insult induces persistent gastric hypersensitivity in adulthood. A persistent increase in plasma norepinephrine mediates GHS by elevating NGF in muscularis externa, which suppresses Kv1.1 channels in DRGs and enhances BDNF in DRGs and thoracic spinal cord. The normalization of gastric hypersensitivity by sodium butyrate suggests epigenetic dysregulation of genes.

Changes in dietary folate intake differentially affect oxidised lipid and mitochondrial DNA damage in various brain regions of rats in the absence/presence of intracerebroventricularly injected amyloid β-peptide challenge

Accumulating evidence suggests that changes in dietary folate intake may modulate the risks of Alzheimer's disease (AD) through as yet unknown mechanisms. The aims of the present study were to investigate how dietary folate affects the brain folate distribution, levels of oxidised lipid and DNA damage in the absence/presence of β-amyloid(25-35) (Aβ) peptide challenge, a pathogenic hallmark of AD. Male Wistar rats were assigned to diets with folic acid at 0 (folate deprivation; FD), 8 (moderate folate; MF) and 8 mg folic acid/kg diet+0·003 % in drinking-water (folate supplementation; FS) for 4 weeks. A single injection of Aβ peptide (1 mg/ml) or the vehicle solution was intracerebroventricularly (icv) administrated to rats a week before killing. Brain folate, a marker of oxidative injury, and neuronal death were assayed. In the absence of an Aβ injection, FD rats showed reduced folate levels, and increased 2-thiobarbituric acid-reactive substances and a mitochondrial (mt)DNA 4834 bp large deletion (mtDNA4834 deletion) in the hippocampus compared with the counterpart brains of control rats (P < 0·05). A single icv injection of Aβ peptide potentiated lipid peroxidation in the medulla of FD rats, which was ameliorated by feeding FD rats with the MF and FS diets (P < 0·05). Feeding the FS diet to Aβ-injected rats enriched brain folate levels and reduced mtDNA4834 deletion in the hippocampal and medullary regions compared with corresponding tissues of Aβ+FD rats (P < 0·05). Aβ+FS rats had reduced rates of neuronal death in the frontal cortex compared with Aβ+FD rats (P < 0·05). Taken together, our data revealed that folate deprivation differentially depleted brain folate levels, and increased lipid peroxidation and mtDNA4834 deletions, particularly, in the hippocampus. Upon Aβ challenge, the FS diet may protect various brain regions against lipid peroxidation, mitochondrial genotoxicity and neural death associated with folate deprivation.

Effects of diabetes and food deprivation on shivering activity during progressive hypothermia in the rat

Diabetes mellitus and food deprivation are two conditions known to significantly reduce the ability to generate body heat during periods of acute cold stress. The purpose of this study was to determine if shivering is attenuated in the urethane-anesthetized (1.5 g/kg; i.p.), streptozotocin-induced diabetic (STZ; n = 10) and food-deprived (12-hour nocturnal fast) rat (FD; n = 11) as colonic temperature (T col) declined from baseline (36°C) to 28°C. Shivering was assessed using the mean rectified electromyographic (EMG) signal obtained from indwelling bipolar electrodes placed in the gluteus superficialis muscle. Although the mean rectified EMG progressively increased ( P ≤ 0.05) between T col of 33°C to 28°C and achieved peak activity (7.89 ± 1.80 μV) at 29°C in non-diabetic rats, shivering activity was virtually absent in the STZ group throughout cooling ( e.g. peak EMG = 0.49 ± 0.09 μV). The lack of shivering activity in STZ could partially explain the shorter time to reach 28°C (STZ, 48.5 ± 1.5 vs CON, 136.5 ± 23.0 min; P ≤ 0.05) and the divergent trends in oxygen consumption (ΔVO 2) between STZ and non-diabetic rats. In the FD group, the mean peak rectified EMG activity (3.09 ± 1.35 μV) was significantly lower ( P ≤ 0.05) than the fed group. The peak ΔVO 2 from baseline (FD, +2.11 ± 0.36 vs. CON, +4.51 ± 0.50 mlO 2/min) and the time taken to reach 28°C (FD, 73.4 ± 4.2 vs CON, 136.5 ± 23.0 min) were statistically different ( P ≤ 0.05) between groups. The results indicate that: 1) shivering thermogenesis is severely depressed and hypothermia accelerated in experimental diabetic animals as evidenced by the attenuation in mean rectified EMG and ΔVO 2, and 2) FD rats experienced a faster decline in colonic temperature than the fed group due, in part, to the relatively greater decline in shivering activity and oxygen consumption.

Regulation of hypothalamic preprogrowth hormone-releasing factor messenger ribonucleic acid expression in food-deprived rats: a role for histaminergic neurotransmission.

To determine the component(s) of dietary protein that regulates GH-releasing factor (GRF) synthesis, we measured hypothalamic prepro-GRF mRNA by solution hybridization/nuclease protection analysis in food-deprived rats refed protein-free diets (PF) supplemented with individual amino acids. Adult male Sprague-Dawley rats were allowed free access to food (Fed), food deprived for 72 h (FD), or FD then refed for 72 h with a normal (NF) diet, a protein-free (PF) diet, or PF diets containing tyrosine, tryptophan (Trp), glutamic acid, or histidine (His). Food-deprived rats displayed the expected 80% reduction in hypothalamic prepro-GRF mRNA. Upon refeeding, levels were normalized in rats refed a normal diet, but not in those refed a PF diet alone or with tyrosine, Trp, or glutamic acid. In contrast, prepro-GRF mRNA was restored to 70% of Fed values by a PF diet with His. Supplementing a PF diet with His was sufficient to maintain hypothalamic prepro-GRF mRNA expression, as 3 days of feeding replete rats with PF diet or PF diet with added Trp resulted in a 50% reduction in prepro-GRF mRNA, whereas levels were reduced 25% by feeding animals a PF diet with His. Groups of rats allowed free access to food were treated for 72 h with two daily injections of 100 mg/kg alpha-fluoremethylhistidine, a specific irreversible inhibitor of histidine decarboxylase, to determine if the effect of His on prepro-GRF mRNA depended on neural conversion to histamine. alpha-Fluoremethylhistidine-treated rats showed a 40% reduction in hypothalamic prepro-GRF mRNA, with no concomitant change in preproneuropeptide-Y or preprosomatostatin. These data indicate that decreased hypothalamic prepro-GRF mRNA in FD rats is due in part to the lack of dietary and provide clear evidence for a role of the histaminergic neural system in the regulation of hypothalamic GRF expression.

Regulation of Rat Hypothalamic PreproGrowth Hormone-Releasing Factor Messenger Ribonucleic Acid by Dietary Protein

To further evaluate nutrient regulation of GRF synthesis, we measured hypothalamic preproGRF messenger (m) RNA in food-deprived rats refed diets varying in nutrient composition by nuclease protection analysis. Adult male Sprague-Dawley rats were allowed free access to food (Fed), food deprived for 72 h (72-h FD), or 72 h FD then refed for 72 h with either a normal (NF) diet or isocaloric diets containing no protein (PF), carbohydrate (CF), or fat (FF). Seventy-two-hour FD rats displayed the expected 80% reduction in hypothalamic preproGRF mRNA. Upon refeeding, levels were normalized in rats refed NF, CF, or FF diets. In contrast, preproGRF mRNA in rats refed a PF diet was similar to that in 72-h FD rats. Rats refed a PF diet failed to gain weight and consumed less food than animals refed NF, CF, or FF diets. However, the lack of the GRF response to the PF diet was due to protein deprivation rather than caloric restriction, since hypothalamic preproGRF mRNA returned to 66% of Fed values in rats refed an equivalent amount (grams per day) of a NF diet. In 72-h FD rats refed isocaloric diets containing 4%, 8%, or 12% protein, preproGRF mRNA was restored to Fed values in a protein concentration-dependent manner being completely restored by the 12% diet. A lack of dietary protein was sufficient to regulate hypothalamic preproGRF mRNA since feeding rats a PF diet without prior food deprivation resulted in 70% reduction in preproGRF mRNA, whereas CF and FF diets were without effect. These data indicate that decreased hypothalamic preproGRF mRNA expression in 72-h FD rats occurs as a result of dietary protein deprivation.

Effects of exercise on insulin-induced hypoglycemia

The purpose of this study was to determine the effect of exercise on the rate of onset of hypoglycemia induced by infusion of excess insulin (0.8 mU.min-1.100 g-1). Rats were either fasted overnight (FS) or fed ad libitum (FD). FS rats were killed after 5, 10, or 15 min of infusion at rest or after running on the treadmill at 21 m/min and 15% grade. FD rats were killed after 10, 20, or 40 min of infusion at rest or after exercise. Rats were also killed 15 min postexercise for FS and 60 or 120 min postexercise for FD with continued insulin infusion. The progressive decline in blood glucose was not altered by exercise in the FS rats. FD rats showed a significant difference due to exercise only after 40 min (rest 4.2 +/- 0.3 mM, exercise 3.2 +/- 0.2 mM). A significant postexercise repletion of glycogen was observed in red vastus and soleus muscles of FD rats despite the decreasing blood glucose values. These data indicate that exercise accelerates the rate of development of hypoglycemia in FD rats. In the FS rats, where the rate of decline in blood glucose was greater, exercise had no effect on the time course of development of hypoglycemia.

Methotrexate effects on folate status and the deoxyuridine suppression test in rats

Methotrexate (MTX) was administered to rats to produce marked folate deficiency to develop an experimental model for studying folate coenzyme abnormalities. Male Sprague-Dawley rats were fed control and experimental, folate-deficient diets, with or without MTX (0.1 mg/100 g body wt) i.p. every other day for 2 wk. The MTX-treated rats developed severe folate deficiency signs, including diarrhea and impaired growth. Cytological features of megaloblastic anemia seen in peripheral blood in the folate-deficient group (FD)+MTX rats were RBC macroovalocytosis, anisocytosis and elevated neutrophil lobe counts, in comparison to both MTX-untreated FD and control rats. Urinary formiminoglutamic acid (FIGLU) excretion was elevated and RBC folate depressed in these FD+MTX rats. The dU suppression test in isolated lymphocyte cultures showed abnormal and higher [ 3H]thymidine uptake by DNA in both MTX-treated and untreated FD groups at 11 wk, but only in FD-MTX at 5 wk; this was associated with lower plasma folate values. Thus, these results indicate that MTX-treated rats have a more severe folate deficiency than that produced by a folate-deficient diet alone.

Insulin-receptor development in normal and diabetic pregnancies. Role of membrane fluidity.

In the hyperinsulinemic offspring of the diabetic mother, both significant macrosomia and postnatal hypoglycemia are thought to be due to increased insulin sensitivity. The purpose of this study is to characterize changes in insulin-receptor development in fetal offspring of an experimental model of diabetic pregnancy. Two groups of Sprague-Dawley female rats were studied after timed mating. Both groups received injections of either vehicle (controls) or streptozocin (diabetic), 40 mg/100 g body wt, on day 7 of pregnancy and were killed at either 17, 20, or 21 days of gestation. Maternal and fetal blood were assayed for glucose and insulin, and fetal liver membranes were prepared for 125I-labeled insulin binding, lipid composition, and fluorescence polarization studies with the probe 1,6-diphenyl-1,3,5-hexatriene (DPH). Maternal and pooled fetal glucose levels were elevated in streptozocin-treated rats; however, pooled fetal insulin values were not elevated in the offspring of diabetic animals compared with controls (33 +/- 1 vs. 50 +/- 5 microU/ml). 125I-insulin binding was greater in fetal offspring of diabetic (FD) rat membranes at each gestational age studied [P less than .001 by analysis of variance (ANOVA)] due to significantly greater numbers of both high- and low-affinity receptors. The highest insulin-binding capacity was seen on membranes obtained from FD rats at day 21 (9.92 M X L-1 X 100 micrograms membranes-1 vs. 6.38 M X L-1 X 100 micrograms protein-1 in fetal control (FC) rats. At each gestational age, membranes from FDs had lower values for fluorescence polarization (using the probe DPH) than did gestational-age--matched controls.(ABSTRACT TRUNCATED AT 250 WORDS)