Laboratory Rat Chow Research Articles

Rosmarinic acid alleviates the cardiac abnormalities in high fat diet induced hypercholesterolemic rats

Hyperlipidemia is a well-known risk factor for atherosclerosis and subsequent atherosclerotic cardiovascular diseases that are associated with high morbidity and mortality in obese and diabetic patients worldwide. The current study looked on rosmarinic acid's cadioprotective effects in rats fed a high-fat diet as there was no study on this aspect. The rats were given a high-fat diet comprising of 84.3 % conventional laboratory rat chow, 5 % lard, 10 % egg yolk powder, 0.2 % cholesterol, and 0.5 % bile salt to produce hypercholesterolemia. Over a span of eight weeks. The plasma lipid profile, cardiac marker enzymes, membrane bound ATPases, lysosomal enzymes, CRP, fibrinogen, proinflammatory cytokines (IL-1β, IL-6,TNF-α, NF-κB),anti-inflammatory cytokine(IL-10) lipid peroxidation markers, enzymatic and non-enzymatic antioxidant enzymes activity were examined. The thoracic aorta's histopathology was also analyzed. It was discovered that the rats fed a high-fat diet had hypercholesterolemia and showed aberrant values in the aforementioned parameters. However, rats given rosmarinic acid (100 mg/kg b.w.) had these anomalies reversed to near-normal levels. The biochemical investigation was corroborated by enhanced histological examination of the thoracic aorta in rats suffering from hypercholestolemia. The effects of rosmarinic acid on a number of measures were similar to those of the prescription medication simvastatin. These findings revealed that rosmarinic acid is an important component in the cardiovascular system's defence against a high-fat diet induced hypercholesterolemia

Chebulagic acid attenuates HFD/streptozotocin induced impaired glucose metabolism and insulin resistance via up regulations of PPAR γ and GLUT 4 in type 2 diabetic rats

The aim of the present study was to evaluate the effects of chebulagic acid on enzymes involved in carbohydrate metabolism in high-fat diet/streptozotocin-induced diabetic rats. Diabetes was induced in albino male Wistar rats by feeding them with a high-fat diet comprising of 84.3% standard laboratory rat chow, 5% lard, 10% yolk powder, 0.2% cholesterol, and 5% bile salt for 2 weeks. After 2 weeks, the animals were kept in an overnight fast and injected with a low dose of streptozotocin (35 mg/kg, dissolved in 0.1 M sodium citrate buffer, pH 4.5). At the end of the experimental periods, the blood glucose, plasma insulin, hemoglobin, glycated hemoglobin levels, homeostatic model of insulin resistance, glycogen content, glycogen synthase, glycogen phosphorylase were measured in high-fat diet and streptozotocin-induced diabetic rats whereas the glucose metabolic enzymes such as hexokinase, glucose 6 phosphate dehydrogenase, glucose 6 phosphatase, fructose 1,6 bisphosphatase and protein expression of peroxisome proliferator-activated receptor–γ (PPAR-γ) and Glucose transporter 4 (GLUT4) were analyzed. Administration of chebulagic acid to HFD/STZ -induced diabetic rats for 30 days significantly decreased the levels of plasma glucose, homeostatic model assessment of insulin resistance, glycogen phosphorylase and glycosylated hemoglobin and increased the levels of insulin, glycogen content and glycogen synthase. On the other hand, the altered activity of carbohydrate metabolic enzymes, PPAR-γ and GLUT4 were brought back to near-normal levels on treatment with chebulagic acid. The effect produced by chebulagic acid on various parameters was comparable to that of metformin.

Antioxidant potential of theaflavin ameliorates the activities of key enzymes of glucose metabolism in high fat diet and streptozotocin – induced diabetic rats

ABSTRACTObjectives: The present study was to evaluate the effect of theaflavin on the activities of key enzymes of carbohydrate metabolism in high fat diet and streptozotocin – induced diabetic rats.Methods: Diabetes was induced in male albino Wistar rats by feeding them with high fat diet comprising of standard laboratory rat chow 84.3%, lard 5%, egg yolk powder 10%, cholesterol 0.2% and bile salt 0.5% for 2 weeks. After 2 weeks, the animals were kept in an overnight fast and injected with low dose of streptozotocin (40 mg/kg b.w).Results: Theaflavin (100 mg/kg b.w /day) was administered orally to diabetic rats for 30 days. At the end of the experimental period, diabetic control rats showed significant increase in plasma glucose, homeostatic model assessment of insulin resistance (HOMA-IR), glycosylated hemoglobin (HbA1c) with concomitant decrease in plasma insulin, total hemoglobin and body weight. The activities of key enzymes of carbohydrate metabolism, lipid peroxidation markers, antioxidant enzymes, glycogen content and glycogen synthase and glycogen phosphorylase were also altered in diabetic rats.Discussion: Oral administration of theaflavin to diabetic rats significantly ameliorated all the biochemical alterations to near normal levels. The results of the present study suggest that theaflavin exhibits antidiabetic effect through its antioxidant activity.

Low dietary soy isoflavonoids increase hippocampal spine synapse density in ovariectomized rats

High dietary intake of plant estrogens (phytoestrogens) can affect brain structure and function. The effects of phytoestrogen intake within the range of normal animal and human dietary consumption, however, remain uncertain. The aim of the present study was to determine the effects of the isoflavonoids present in a standard low phytoestrogen laboratory rat chow on spine synapse density in the stratum radiatum of area CA1 of the hippocampus.Weanling rats (22days old) were fed either standard chow (Teklad 2018), a nutritionally comparable diet without soy (Teklad 2016) or a custom diet containing Teklad 2016 supplemented with the principal soy isoflavonoids, daidzein and genistein, for 40days. Rats were ovariectomized at 54days of age. Eight days later, spine synapse density on the apical dendrites of hippocampal pyramidal neurons in the stratum radiatum of area CA1 was measured by electron microscopic stereological analysis. Animals maintained on Teklad 2016 exhibited an approximately 60% lower CA1 spine synapse density than animals consuming Teklad 2018. Replacing genistein and daidzein in Teklad 2016 returned synapse density to levels indistinguishable from those in animals on Teklad 2018.These results indicate that the isoflavonoids in a standard laboratory rat diet exert significant effects on spine synapse density in the CA1 region of the hippocampus. Since changes in spine synapse density in this region of the hippocampus have been linked to cognitive performance and mood state, these data suggest that even relatively low daily consumption of soy phytoestrogens may be sufficient to influence hippocampal function.

Age-related periodontitis and alveolar bone loss in rice rats

ObjectiveTo characterize in rice rats: (a) periodontitis (PD) progress with feeding of standard laboratory rat chow (STD) during ages 4–80 weeks; and (b) PD progress with feeding of a high sucrose-casein (H-SC) diet during young adulthood. MethodsOne group (N=12) was euthanized at age 4 weeks (Baseline). Four groups (N=8-16) consumed a STD diet from baseline and were necropsied at ages 22, 30, 52, and 80 weeks. Three groups (N=10-16) consumed an H-SC diet from baseline. Two were necropsied at ages 22 and 30 weeks, respectively. The third switched to the STD diet at age 22 weeks and was necropsied at age 30 weeks. All mandibles/maxillae were assessed by histometry for degree of periodontal inflammation (PD Score), alveolar crest height (ACH, mm), and horizontal alveolar bone height (hABH, mm2). ResultsIn STD diet rats aged ≥30 weeks, all endpoints were worse (P<0.05) than at Baseline. In H-SC diet rats aged ≥22 weeks, all endpoints were worse than at Baseline (P<0.05). At age 22 weeks, all endpoints were worse in the H-SC group than in the STD group (P<0.05). By age 30 weeks, the STD and H-SC groups did not differ. Conclusions1) STD diet fed rice rats develop moderate/severe PD by age 30 weeks; 2) an H-SC diet accelerates moderate/severe PD development; and 3) switching to a STD diet does not halt/reverse PD that was accelerated by an H-SC diet. These data further clarify use of the rice rat as a PD model.

Impaired glucose tolerance (IGT) to frank diabetes: Dietary manipulations in WNIN/GR-Ob rats

Background: Several rodent models are available to study obesity and obesity associated diabetic problems. We developed an obese mutant rat model viz., WNIN/GR-Ob from our existing WNIN (Inbred Wistar) stock of rats, which exhibit hyperglycemia on challenge with oral glucose. Since such impaired glucose tolerance (IGT) is a fore runner to frank diabetes status, we carried out a study to challenge the animals with different purified carbohydrate sources (glucose, sucrose, starch) and see the outcome. Methods: 48 obese rats of both genders and equal number of lean littermates of 35 days of age were taken for the study and were divided in to four groups, A, B, C, and D. A group received purified glucose based diet, B, received purified sucrose, C, received purified starch and the D, served as the control, receiving standard laboratory rat chow developed at our centre, containing roasted bengal gram as the source of carbohydrate. All diets were isocaloric in nature and contained 56 % carbohydrate in principle. Animals were fed for 8 weeks and parameters like food intake, body weights, and plasma glucose and insulin levels were measured in experimental and control rats at initial, 4 weeks and 8 weeks. Results: As expected, food intake, body weight and feed efficiency ratio were significantly higher in obese rats of all groups as compared to their lean littermate controls and also higher in stock diet, compared to purified diets. Both lean and obese animals showed higher values of glucose and insulin on purified diets compared to control diet. But amongst lean and obese animals, the latter showed sexual dimorphism in their response, the situation being worse in starch fed (C) group. Amongst the obese animals, the males seem to suffer more, compared to females, in starch fed group, followed by glucose and sucrose fed in that order. Conclusions: WNIN/ GR-Ob rats thus seem to be a useful animal model, vulnerable to diet manipulations, especially to carbohydrates. This has the potential to be used as a diabetic model, more akin to human systems, where diet is the major trigger for precipitating diabetes.

Switching control of sympathetic activity from forebrain to hindbrain in chronic dehydration

We investigated the mechanisms responsible for increased blood pressure and sympathetic nerve activity (SNA) caused by 2-3 days dehydration (DH) both in vivo and in situ preparations. In euhydrated (EH) rats, systemic application of the AT(1) receptor antagonist Losartan and subsequent pre-collicular transection (to remove the hypothalamus) significantly reduced thoracic (t)SNA. In contrast, in DH rats, Losartan, followed by pre-collicular and pontine transections, failed to reduce tSNA, whereas transection at the medulla-spinal cord junction massively reduced tSNA. In DH but not EH rats, selective inhibition of the commissural nucleus tractus solitarii (cNTS) significantly reduced tSNA. Comparable data were obtained in both in situ and in vivo (anaesthetized/conscious) rats and suggest that following chronic dehydration, the control of tSNA transfers from supra-brainstem structures (e.g. hypothalamus) to the medulla oblongata, particularly the cNTS. As microarray analysis revealed up-regulation of AP1 transcription factor JunD in the dehydrated cNTS, we tested the hypothesis that AP1 transcription factor activity is responsible for dehydration-induced functional plasticity. When AP1 activity was blocked in the cNTS using a viral vector expressing a dominant negative FosB, cNTS inactivation was ineffective. However, tSNA was decreased after pre-collicular transection, a response similar to that seen in EH rats. Thus, the dehydration-induced switch in control of tSNA from hypothalamus to cNTS seems to be mediated via activation of AP1 transcription factors in the cNTS. If AP1 activity is blocked in the cNTS during dehydration, sympathetic activity control reverts back to forebrain regions. This unique reciprocating neural structure-switching plasticity between brain centres emphasizes the multiple mechanisms available for the adaptive response to dehydration.

Skeletal muscle lipid metabolism changes in mice selected for high maximal metabolic rate

Exercise and fasting both increase free fatty acids, and elevated unsaturated free fatty acids are up‐regulators of lipid metabolism in skeletal muscles. We examined fatty acids in skeletal muscles in lines of Mus musculus artificially selected for high maximal metabolic rate (high‐MMR). These mice were not exercised and standard laboratory rat chow was available ad libitum. After 7 generations of directional selection for increased mass‐independent MMR, high‐MMR mice showed a 10.2% increase in mass‐independent MMR and a concomitant 2.8% increase in mass‐independent basal metabolic rate compared to control mice. Free fatty acids in the gastrocnemius muscle differed significantly between high‐MMR and control mice. For mice selected for high‐MMR, there was a significant increase in linoleic and oleic acids—consistent with elevated fatty acid oxidation in the skeletal muscle. There was no difference in muscle phospholipid fatty acid composition between high‐MMR and control mice. These findings suggest that selection for high‐MMR resulted in elevated fatty acid oxidation in the skeletal muscles. Most importantly, the results suggest that there is a genetic component to elevated unsaturated free fatty acids in skeletal muscles. Supported by NSF IOS 0344994.

Dietary tryptophan restriction in rats triggers astrocyte cytoskeletal hypertrophy in hippocampus and amygdala

We have previously reported that dietary tryptophan (TRP) restriction in a rat crucial postnatal developmental stage induces depression-like behavior and alters dendritic spine density in CA1 pyramidal neurons and granule cells of the hippocampus. Due to astrocyte involvement in critical brain mechanisms, it seems worth to investigate possible adaptive changes in the glial population with TRP restriction. Experimental rats were fed with low TRP diet (20% of TRP level of the laboratory rat chow) from postnatal days 30–60. Antibody against glial fibrillary acidic protein (GFAP), a principal intermediate filament in astrocytes, was used to evaluate cytoskeletal hypertrophy and glial proliferation. Our results showed an increase in size and branching of GFAP-immunoreactive (IR) cells in the dorsal hippocampus and amygdala, characteristics of an astrocytic activation. No significant differences were found regarding the number of GFAP-IR cells in both regions. These results indicate that dietary TRP restriction can induce astrocytic activation, hence, provide further evidences supporting the hypothesis that serotonin may also modulate glial morphology.

Altered ATP-sensitive potassium channels may underscore obesity-triggered increase in blood pressure1

To determine whether ATP-sensitive potassium channels are altered in VSMC from arotas and mesenteric arteries of obese rat, and their association with obesity-triggered increase in blood pressure. Obesity was induced by 24 weeks of high-fat diet feeding in male Sprague-Dawley rats. Control rats were fed with standard laboratory rat chow. Blood pressure and body weight of these rats were measured every 4 weeks. At the end of 24 weeks, K(ATP) channelmediated relaxation responses in the aortas and mesenteric arteries, K(ATP) channel current, and gene expression were examined, respectively. Blood pressure and body weight were increased in rats fed with high-fat diet. K(ATP) channelmediated relaxation responses, currents, and K(ATP) expression in VSMC of both aortas and mesenteric arteries were inhibited in these rats. Altered ATP-sensitive potassium channels in obese rats may underscore obesity-triggered increase in blood pressure.

Uptake and metabolism of plasma-derived erucic acid by rat brain

We examined the ability of erucic acid (22:1n-9) to cross the blood-brain barrier (BBB) by infusing [14-14C]22:1n-9 (170 microCi/kg, iv and icv) into awake, male rats. [1-14C]arachidonic acid (20:4n-6) [intravenous (i.v.)] was the positive control. After i.v. infusion, 0.011% of the plasma [14-14C]22:1n-9 was extracted by the brain, compared with 0.055% of the plasma [1-14C]20:4n-6. The [14-14C]22:1n-9 was extensively beta-oxidized (60%), compared with 30% for [1-14C]20:4n-6. Although 20:4n-6 was targeted primarily to phospholipid pools, 22:1n-9 was targeted to cholesteryl esters, triglycerides, and phospholipids. When [14-14C]22:1n-9 was infused directly into the fourth ventricle of the brain [intracerebroventricular (i.c.v.)] for 7 days, 60% of the tracer entered the phospholipid pools, similar to the distribution observed for [1-14C]20:4n-6. This demonstrates plasticity in the ability of the brain to esterify 22:1n-9 in an exposure-dependent manner. In i.v. and i.c.v. infused rats, a significant amount of tracer found in the phospholipid pools underwent sequential rounds of chain shortening and was found as [12-14C]20:1n-9 and [10-14C]oleic acid. These results demonstrate for the first time that intact 22:1n-9 crosses the BBB, is incorporated into specific lipid pools, and is chain-shortened.

Smooth endoplasmic reticulum dilation and degeneration in Purkinje neuron dendrites of aging ethanol-fed female rats

The effects of chronic ethanol consumption on the extensive Purkinje neuron (PN) dendritic arbor of male rats include dilation of the smooth endoplasmic reticulum (SER) and dendritic regression. The purpose of the present study was to examine the molecular layer of female rats for the presence of ethanol-related SER dilation and evidence of degeneration within the PN dendritic arbor. Twenty-one 12-month-old Fischer 344 female rats (n = 7/treatment group) received a liquid ethanol, liquid control, or rat chow diet for a period of 40 weeks. Ethanol-fed rats received 35% of their dietary calories as ethanol. Pair-fed rats received a liquid control diet that was isocaloric to the ethanol diet. Chow-fed rats received standard laboratory rat chow ad libitum. At the end of treatment, tissues from the anterior and posterior lobes of the cerebellar vermis were viewed and photographed with the electron microscope. The diameters of SER profiles were measured and the density of degenerating bodies within the PN dendritic arbor was quantitated. In the posterior lobe, ethanol-related SER dilation was apparent. In the anterior lobe, the density of degenerating bodies within PN dendritic shafts was significantly increased but SER dilation in PN dendritic shafts was absent. These results confirm that SER dilation and dendritic degeneration in PN dendrites may precede and contribute to ethanol-related regression in female rats. In addition, comparison of these results with data obtained in male rats from a previous study suggests that PN dendrites in females may be more sensitive to the effects of ethanol.

Inhibition of Hydrogen Sulfide Generation Contributes to Gastric Injury Caused by Anti-Inflammatory Nonsteroidal Drugs

Hydrogen sulfide (H(2)S), an endogenous gaseous mediator that causes vasodilation, is generated in mammalian tissues by cystathionine beta-synthase (CBS) and cystathionine-gamma-lyase (CSE). Here, we have investigated the role of H(2)S in a rodent model of nonsteroidal anti-inflammatory drug (NSAID) gastropathy. Rats were given acetyl salycilic acid (ASA) or an NSAID alone or in combination with NaHS, an H(2)S donor, and killed 3 hours later. Gastric blood flow was measured by laser-Doppler flowmetry, whereas intravital microscopy was used to quantify adhesion of leukocytes to mesenteric postcapillary endothelium. At a dose of 100 micromol/kg, NaHS attenuated by 60%-70% the gastric mucosal injury, and tumor necrosis factor (TNF)-alpha, intercellular adhesion molecule (ICAM)-1, and lymphocyte function-associated antigen (LFA)-1 mRNA up-regulation induced by NSAIDs (P < .05) NaHS administration prevented the associated reduction of gastric mucosal blood flow (P < .05) and reduced ASA-induced leukocyte adherence in mesenteric venules. NaHS did not affect suppression of prostaglandin E(2) (PGE(2)) synthesis by NSAIDs. Glibenclamide, a K(ATP) channel inhibitor, and DL-propargylglycine, a CSE inhibitor, exacerbated, whereas pinacidil, a K(ATP) opener, attenuated gastric injury caused by ASA. Exposure to NSAIDs reduced H(2)S formation and CSE expression (mRNA and protein) and activity by 60%-70%. By promoter deletion and mutation analysis, an Sp1 consensus site was identified in the CSE promoter. Exposure to NSAIDs inhibits Sp1 binding to its promoter and abrogates CSE expression in HEK-293 cells transfected with a vector containing the core CSE promoter. Exposure to NSAIDs inhibits Sp1 and ERK phosphorylation. These data establish a physiologic role for H(2)S in regulating the gastric microcirculation and identify CSE as a novel target for ASA/NSAIDs.

Pharmacokinetics of trimethylamine in rats, including the effects of a synthetic diet

1. The pharmacokinetic profile of trimethylamine (TMA) was examined in the male Wistar rat and the effects of a synthetic diet on TMA pharmacokinetics were also evaluated. 2. The concentrations of TMA and its N -oxide in blood were analysed by a sensitive headspace gas chromatographic assay. 3. The pharmacokinetics of TMA were essentially linear for intravenous (i.v.) bolus doses of 10-40 mg kg -1. Over the range of administered i.v. doses, the concentrations of TMA in blood declined approximately monoexponentially with half-lives of 2.03-2.48 h. The V d of TMA ranged from 3.2 to 4.39 l kg -1 and clearance ranged from 18.78 to 23.92ml min -1 kg -1. The peak concentration of TMA in blood occurred at 1 h after oral administration of a 20 mg kg -1 dose and the bioavailability for the oral dose averaged 81%. 4. Peak concentrations of trimethylamine N -oxide (TMAO) in blood were attained at 0.75 and 1 h after i.v and oral administration of TMA (20mg kg -1), respectively. 5. Feeding the male Wistar rat with a synthetic diet resulted in a twofold decrease in the clearance of TMA. Furthermore, the concentration of TMAO in blood after i.v. administration of TMA peaked at 1.25 h in rat placed on the synthetic diet as opposed to 0.75 h in rat placed on normal laboratory rat chow. The altered pharmacokinetic profile of TMA and its N -oxide suggest a diminished drug-elimination capacity in rat placed on the synthetic diet. 6. Dietary modulation of flavin-containing monooxygenase (FMO) activity may explain the effects of diet on the pharmacokinetics of TMA and its N -oxide.

Effects of Great Lakes Fish Consumption on Brain PCB Pattern, Concentration, and Progressive-Ratio Performance

This study investigated the effects of consumption of Great Lakes fish on progressive ratio performance, and on the pattern and concentrations of brain polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethene (DDE), and mirex in the rat. Adult, male Sprague–Dawley rats were fed a 30% diet of either Lake Ontario salmon (LAKE), Pacific Ocean salmon, or lab chow control for 20 or 65 days. Following the treatment regimen, half the rats from each group were sacrificed immediately for gas chromatographic analysis of organochlorine contaminants, and the other half were tested on a multiple fixed-ratio–progressive–ratio reinforcement schedule and then sacrificed for analysis. Consumption of Lake Ontario fish resulted in significantly higher levels of brain PCBs, DDE, and mirex relative to controls, but still well within human exposure ranges (<1 μg/g fat). Consumption of Lake Ontario fish for 20 or 65 days produced an average brain PCB concentration of 457 and 934 ng/g fat, respectively. Consumption of laboratory rat chow or Pacific Ocean salmon for 20 or 65 days produced an average brain PCB concentration of 240, 464, and 441 ng/g fat, respectively. Moreover, both LAKE-fed groups showed a much more heavily chlorinated pattern of brain PCBs than all control groups, as evidenced by both significant increases in the most heavily chlorinated PCB congeners and significant increases in the average chlorine biphenyl. All LAKE brains contained significant concentrations of DDE and mirex, whereas no control brains contained any detectable quantities. Analysis of progressive-ratio performance indicated that LAKE rats responded normally during fixed-ratio schedules but quit significantly sooner than control rats on a progressive-ratio 5 (PR5) schedule, indicating reduced persistence on progressively leaner reinforcement schedules. Analysis of brain PCBs indicated that total PCBs were most strongly related to PR5 performance. These data indicate that consumption by rats of contaminated Lake Ontario fish produces (1) increased concentrations of PCBs, DDE, and mirex in the brain, (2) a more heavily chlorinated distribution of PCBs in the brain, and (3) reduced persistence of progressive-ratio reinforcement schedules. While these behavioral changes are related to brain PCB level, more work is necessary before the effects can be directly attributed to PCBs.

Eastern Woodrat (Neotoma floridana) Consumption of Northern Bobwhite (Colinus virginianus)

The eastern woodrat (Neotoma floridana) is considered a generalist herbivore. Only anecdotal evidence suggests that eastern woodrats eat meat given the opportunity. We conducted trials to test whether the eastern woodrat would consume northern bobwhite (Colinus virginianus) under experimental conditions. We live trapped 27 eastern woodrats in the Flint Hills region of Kansas during Nov. and Dec. 1997. We assigned woodrats to either a control or one of two 108 h experimental treatments. We provided 9 control animals with laboratory rat chow ad libitum, 9 woodrats in treatment 1 with laboratory rat pellets ad lib. and a wild northern bobwhite carcass and 9 woodrats in treatment 2 with a bobwhite carcass only. Woodrats willingly consumed quail in both treatments. Control and treatment 1 woodrats maintained body mass, whereas animals in treatment 2 lost 17% of body mass. Consumption preferences changed temporally. Head and leg/feet of quail were consumed first, muscle second and organs last. We observed no difference in consumption preferences between treatments. We suggest the eastern woodrat may include meat in its food selection when seasonal food resources are limited.

The Effect Of Estrogen On The Male Reproductive System Of Rats Receiving Cimetidine

To show if a small dose of estrogen can interfere with the effect of Cimetidine on male reproductive system. Five groups of five randomly selected adult male rats were utilized. Rats were given food (laboratory rat chow) and water ad libitum. Rats were treated orally with Cimetidine 50mg/kg and subcutaneous injection with estradiol 0.01µg for 60 days. The animals were grouped as: group1, treated from days 1-10. Group2, treated from days 20-30. Group3, treated from days 40-50. Group4, treated from days 50-60. Group 5 received no treatment as a control group. Blood samples were taken from the eyes (by using capillary tubes) to measure testosterone (T) and follicular stimulating hormone (FSH) levels. Measurement of weights of the reproductive organs including the testis, epididymis (head, body, and tail), seminal vesicle and prostate were done. Body weight for each animal was recorded before and after treatment. Also we counted the total sperm count and the percentage of dead and alive spermatozoa for the treated groups using Eosin–negrosin stain. The testis weight and prostate weight was significantly increased in both groups 3 and 4, while seminal vesicle weight was significantly reduced. FSH levels were significantly increased, while testosterone levels were unchanged. Total sperm count and a number of a live sperms were significantly reduced and the number of dead sperms was significantly increased among the treated groups. Cimetidine has hazards on male reproductive function while estrogen didn't play any role to abolish this action.

Vitamin E suppresses cyclosporine A–induced increase in the urinary excretion of arachidonic acid metabolites including F 2-isoprostanes in the rat model

ESPITE a large body of research, the exact mechanism by which cyclosporine (CsA) causes nephrotoxicity remains unclear. A consistent finding following CsA administration is the increase in urinary excretion of arachidonic acid metabolites. 1‐3 Although experimental studies with thromboxane synthase inhibitors suggested a role for TXA2 in CsA-induced renal dysfunction, chronic administration of thromboxane synthase inhibitors in renal transplant patients treated with CsA had little effect on improving renal function. 4,5 One possible explanation would be that arachidonic acid metabolites other than TXA2 might also be involved in the mediation of renal vasoconstriction and dysfunction. This possibility deserves consideration, because recent studies suggest that free radical-catalyzed lipid peroxidation, independent of the enzymatic pathway, may produce vasoactive prostaglandins, F2-isoprostanes and E2-isoprostanes, as well as thromboxane and isothromboxane. 6‐ 9 We have reported that dosedependent renal lipid peroxidation occurs with CsA-induced renal toxicity and that vitamin E and Lazaroid compounds suppress lipid peroxidation and protect the kidney against CsA-mediated functional and structural injury. 10,11 Recent findings from others are consistent with these observations, thus providing further support for an important role for free radical-catalyzed lipid peroxidation in the pathogenesis of CsA-induced nephrotoxicity. 12‐14 Because CsA induces lipid peroxidation and this in turn can catalyze the formation of prostaglandin- and thromboxane-like molecules, 6‐ 9 we examined whether the excessive production of arachidonic acid metabolites by CsA might be linked to heightened lipid peroxidation. Compared to vehicle, 12 weeks of CsA administration was associated with a significant reduction in renal function and an increase in urinary excretion of vasoconstrictive TBX-B2 and F2-IP and vasodilatory PGF1a. Administration of vitamin E along with CsA was accompanied by marked preservation of GFR and significant suppression of urinary TBX-B2 ,F 2-IP and PGF1a. In another experiment, vitamin E administration in normal rats did not have any effect on renal function or arachidonic acid metabolite excretion. Our new findings suggest that part of the CsA-induced increase in urinary arachidonic acid metabolites may arise from free radicalcatalyzed lipid peroxidation, and that the renoprotective effect of vitamin E may arise in part from the suppression of two potent vasoconstrictors, TBX and F2-IP. METHODS Effect of Vitamin E on CsA-Induced Increase in Urinary Excretion of Arachidonic Acid Metabolites Two weeks after subcostal right nephrectomy to simulate the single kidney model of transplant, male Sprague Dawley rats, matched for body weight and serum creatinine, were assigned to 3 groups: the control (n 5 5), CsA (n 5 6), and CsA plus vitamin E (n 5 6). The initial body weights of these rats were between 250 to 275 g. The control rats received olive oil vehicle by gavage (1 mL/kg/d) and by subcutaneous injections (0.5 mL/kg/d). The CsA group received CsA 15 mg/kg/d in olive oil subcutaneously and plain olive oil by gavage. The CsA plus vitamin E group received CsA as in the CsA group, and additionally, received vitamin E 25 mg/kg/d in olive oil by gavage. Rats were pair-fed with standard laboratory rat chow and their food intake and body weights were monitored once a week. Serial hematocrit (microcapillary method) and serum protein (refractory method) were measured from tail vein blood. Using metabolic cages, 24-hour urine was collected into containers containing antioxidant (100 mL of 2% butylated hydroxytoluene in ethanol). Urine samples were spun down and aliquots were saved at 284° until the time of assay. Creatinine in the plasma and urine were measured using an auto-analyzer based on the Jaffe reaction.

Effects of oral parenteral nutrition solution on the morphology and mechanical resistance of the small bowel in rats

The objective of this study was to investigate the effect of an elemental diet (ED) on the strength and on the morphology of the small bowel. Male Wistar rats were randomized to two groups to receive during 14 days either standard laboratory rat chow (N=16) or ED (N=16) containing total parenteral nutrition (TPN) solution. After this period they were killed and necropsied. The small bowel was measured and weighted with and without the contents. Bursting pressure (BP) was taken from the jejunum and ileum and histological sections of these two portions was performed to register the crypt depth (CD), vilus height (VH) and wall width (WW). All animals significantly gain weight. The bowel of animals fed with TPN solution had significantly less weight when compared with the controls either with (9.9 ± 1.9g x 7.8 ± 1.5g, p&lt;0.05) or without (8.3 ± 1.3g x 6.5 ± 0.8g; p&lt;0.05) the luminal contents. BP was lower in animals receiving TPN solution compared with controls in both studied segments but the difference only reached significance at the ileum (287 ± 60 x 234 ± 46 mm of Hg; p&lt;0.05). VH, CD and WW were significantly shorter at the ileum in TPN-fed animals when compared to controls (p&lt;0.05). This contrast was also seen at the jejunum though without significant difference. The small bowel looses mass and become less resistant when rats are fed with elemental diet though the nutritional state is maintained. The loss of mass appeared to be not only at the mucosa layer but through all the bowel wall. This occurs predominantly at the terminal part of the small bowel.

Paradoxical Increase in Peroxisomal Cyanide-Insensitive Respiration Following Dietary Exposure to WY-14,643 in the Perfused Liver

WY-14,643, a lipid-lowering drug, increases basal rates of oxygen uptake in perfused livers. Because peroxisomes consume oxygen for H2O2production and are induced by WY-14,643 treatment, it is possible that peroxisomal β-oxidation can account for some of this increase in cellular respiration. Therefore, cyanide, an inhibitor of mitochondrial cytochrome oxidase, was infused into livers of WY-14,643-fed rats (0.1% WY-14,643 in laboratory rat chow for 1, 21, and 105 days) to assess peroxisomal cyanide-insensitive respiration. As expected, the addition of cyanide abolished oxygen uptake nearly completely; however, after approximately 20 min oxygen consumption unexpectedly returned to basal levels in 105-day WY-14,643-treated animals but not in untreated controls. Urea synthesis, a process dependent upon ATP, was decreased and remained low during cyanide infusion in livers from both groups, indicating that mitochondria were not responsible for this unusual increase in oxygen uptake in the presence of cyanide. Methanol metabolism, which requires oxygen to form H2O2, was decreased from 37 ± 5 to 6 ± 1 μmol/g/hr in all groups treated with cyanide; however, it was increased significantly about 20 min later to 25 μmol/g/hr in livers from WY-14,643-treated rats, indicating that oxygen for peroxisomal H2O2production is involved in cellular respiration in the presence of cyanide. Fasting abolished the recovery of both oxygen uptake and methanol metabolism in WY-14,643-fed rats, suggesting that ATP for acyl CoA synthetase, an enzyme which metabolizes fatty acids to acyl CoA compounds, is provided by glycolysis. Indeed, oleate significantly increased methanol metabolism in fed control rats from 8 ± 4 to 26 ± 3 μmol/g/hr in the presence of cyanide, indicating that fatty acid supply is necessary for peroxisomal respiration. Taken together, [bnthese experiments demonstrate that when mitochondrial respiration is inhibited, livers from rats fed WY-14,643 chronically have the unique ability of metabolizing fatty acids through the peroxisome using glycolytic ATP.