Acid-treated Rats Research Articles

Vascular Alterations in the Sprague-Dawley Rat Mandible During Intravenous Bisphosphonate Therapy

Long-term use of intravenous bisphosphonates, such as zoledronic acid (zoledronate), has been linked to bisphosphonate-related osteonecrosis of the jaw (BRONJ). Invasive dental surgery seems to trigger the bone necrosis in most cases. To determine the effects of zoledronic acid on the vascular structure of the rat mandible. Extracted of the mandibular first molar in rats that received 2 IV injections of zoledronate (20 μg/kg), 4 weeks apart. Zoledronate-treated rats (n = 18) were then compared to a control group of untreated rats (n = 18). At the fourth, eighth, and 12th week after molar extraction, 8 rat mandibles from each group were perfused with 35% radiopaque triphenylbismuth in methyl methacrylate via carotid artery perfusion. Mandibles were harvested and examined by micro-CT to assess the spatial and dimensional changes of the vasculature as a result of zoledronate treatment. The micro-CT analysis showed that zoledronic acid-treated rats had blood vessels that were thicker, less connected, and less ordered than control rats that were not exposed to zoledronic acid. This study demonstrated that treatment with zoledronic acid in rats is associated with vascular changes in alveolar bone. Further studies are underway to explore whether these vascular changes contribute to the pathogenesis of BRONJ.

Autism: Metabolism, Mitochondria, and the Microbiome

New approaches are needed to examine the diverse symptoms and comorbidities of the growing family of neurodevelopmental disorders known as autism spectrum disorder (ASD). ASD originally was thought to be a static, inheritable neurodevelopmental disorder, and our understanding of it is undergoing a major shift. It is emerging as a dynamic system of metabolic and immune anomalies involving many organ systems, including the brain, and environmental exposure. The initial detailed observation and inquiry of patients with ASD and related conditions and the histories of their caregivers and families have been invaluable. How gastrointestinal (GI) factors are related to ASD is not yet clear. Nevertheless, many patients with ASD have a history of previous antibiotic exposure or hospitalization, GI symptoms, abnormal food cravings, and unique intestinal bacterial populations, which have been proposed to relate to variable symptom severity.In addition to traditional scientific inquiry, detailed clinical observation and recording of exacerbations, remissions, and comorbidities are needed. This article reviews the role that enteric short-chain fatty acids, particularly propionic (also called propanoic) acid, produced from ASD-associated GI bacteria, may play in the etiology of some forms of ASD. Human populations that are partial metabolizers of propionic acid are more common than previously thought. The results from pre-clinical laboratory studies show that propionic acid-treated rats display ASD-like repetitive, perseverative, and antisocial behaviors and seizure. Neurochemical changes, consistent and predictive with findings in ASD patients, including neuroinflammation, increased oxidative stress, mitochondrial dysfunction, glutathione depletion, and altered phospholipid/acylcarnitine profiles, have been observed. Propionic acid has bioactive effects on (1) neurotransmitter systems, (2) intracellular acidification and calcium release, (3) fatty acid metabolism, (4) gap junction gating, (5) immune function, and (6) alteration of gene expression that warrant further exploration. Traditional scientific experimentation is needed to verify the hypothesis that enteric short-chain fatty acids may be a potential environmental trigger in some forms of ASD. Novel collaborative developments in systems biology, particularly examining the role of the microbiome and its effects on host metabolism, immune and mitochondrial function, and gene expression, hold great promise in ASD.

AMPA receptor subunits expression and phosphorylation in cingulate cortex in rats following esophageal acid exposure

We recently reported an increase in N-methyl-d-aspartate (NMDA) receptor subunit expression and CaMKII-dependent phosphorylation of NR2B in the rostral cingulate cortical (rCC) neurons following esophageal acid exposure in rats. As α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors mediate the fast excitatory transmission and play a critical role in synaptic plasticity, in this study, we investigated the effect of esophageal acid exposure in rats on the expression of AMPA receptor subunits and the involvement of these molecular alterations in acid-induced sensitization of neurons in the anterior cingulate (ACC) and midcingulate (MCC) cortices. In molecular study, we examined GluA1 and GluA2 expression and phosphorylation in membrane preparations and in the isolated postsynaptic densities (PSDs) from rats receiving acute esophageal exposure of either saline (control group) or 0.1N HCl (experimental group). In electrophysiological study, the effect of selective AMPA receptor (Ca(2+) permeable) antagonist IEM-1460 and CaMKII inhibitor KN-93 was tested on responses of cortical neurons during acid infusion to address the underlying molecular mechanism of acid-induced sensitization. The acid exposure significantly increased expression of GluA1, pGluA1Ser(831) , and phosphorylated CaMKIIThr(286) , in the cortical membrane preparations. In isolated PSDs, a significant increase in pGluA1Ser(831) was observed in acid-treated rats compared with controls. Microinjection of IEM-1460 or KN-93 near the recording site significantly attenuated acid-induced sensitization of cortical neurons. The underlying mechanism of acid-induced cortical sensitization involves upregulation and CaMKII-mediated phosphorylation of GluA1. These molecular changes of AMPA receptors subunit GluA1 in the cortical neurons might play an important role in acid-induced esophageal hypersensitivity.

Cardioprotective effects of fish omega-3 fatty acids on doxorubicin-induced cardiotoxicity in rats

The aim of this study was to investigate the protective effects of fish omega-3 (n-3) fatty acids on doxorubicin (DOX)-induced acute cardiotoxicity. A total of 24 rats were divided into three groups: control, DOX-treated, and DOX treated with fish n-3 fatty acids. Control group received 0.4ml/kg/day of saline intragastrically. The rats in the fish n-3 fatty acid-pretreated group were given 400mg/kg/day fish n-3 fatty acids for 30days by intragastric intubation. To induce acute cardiotoxicity, DOX (30mg/kg) was injected intraperitoneally by a single dose and the rats were killed after 48h. DOX treatment caused severe damage in heart tissues. Disorganization of myocardial muscle fibers, myofibrillar loss, and cardiotoxic myocardial fibers with cytoplasmic vacuoles were seen. Fish n-3 fatty acid-treated rats showed an improved histological appearance in the DOX-treated group. Our data indicate a significant reduction in the activity of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling in cardiomyocytes of the DOX-treated group with fish n-3 fatty acids therapy. The DOX-treated with fish n-3 fatty acids group showed a significant decrease in malondialdehyde levels, and an increase in superoxide dismutase and glutathione peroxidase activities in comparison with the DOX-treated group. This study showed that fish n-3 fatty acids may be a suitable cardioprotector against acute toxic effects of DOX.

Effects of sodium citrate on melamine–cyanuric acid mixture-induced urolithiasis in rats

BackgroundWhen melamine is used as an additive in infant formula, it may cause acute nephrotoxicity in humans as well as in other animals. This study was designed to examine the effects of a melamine–cyanuric acid mixture on cytotoxicity in vitro and rat-acute nephrotoxicity. MethodsIn the in vitro study, crystal formations created by the melamine–cyanuric acid mixture were evaluated in media with differing pH conditions over a 24-h period and co-treatment with sodium citrate to observe the crystal formation. In the animal study, rats were exposed to a melamine–cyanuric acid mixture (400mg/kg, 1:1) via oral gavage 14days and co-treated with sodium citrate to observe the crystal formation in rats. ResultsMelamine–cyanuric acid mixture-induced crystal was pH dependent in a conditioned medium, and sodium citrate could decrease the crystal formation. Melamine–cyanuric acid-treated rats showed marked kidney swelling, vacuolization and necrosis in the proximal tubules, and numerous polarizable crystals were located in the distal segments, causing increases in kidney weight, serum BUN and creatinine. After co-treatment with sodium citrate, these increases can all be reversed. Moreover, the degrees of nephrotoxicity, proliferating of cell nuclear antigen protein and urolithiasis-related osteopontin were also decreased in the kidneys. ConclusionSodium citrate could decrease melamine–cyanuric acid mixture-induced crystal formation that leads to urolithiasis and nephrotoxicity in rats. These results may provide a strategy for melamine–cyanuric acid-intoxication therapy in animal.

Treatment with ferulic acid to rats with streptozotocin-induced diabetes: effects on oxidative stress, pro-inflammatory cytokines, and apoptosis in the pancreatic β cell

In the present study, we aimed to investigate the protective effect of ferulic acid at different doses (50 mg/kg alternative day and 50 mg/kg daily) on diabetic rats and to explore the interrelationship between oxidative stress and cytokines correlates with apoptotic events in pancreatic tissue. Male Wistar rats were rendered diabetic by a single intraperitoneal injection of streptozotocin (60 mg/kg body weight). Ferulic acid was administered orally for 8 weeks. At the end of the study, all animals were sacrificed. Blood samples were collected for the biochemical estimations and pancreas was isolated for antioxidant status, histopathological, immunohistochemical, and apoptotic studies. Treatment with ferulic acid to diabetic rats significantly improved blood glucose, serum total cholesterol, triglycerides, creatinine, urea, and albumin levels toward normal. Furthermore, decrement of the elevated lipid peroxidation levels and increment of the reduced superoxide dismutase, catalase, and reduced glutathione enzyme activities in pancreatic tissues were observed in ferulic acid-treated groups. Ferulic acid-treated rats in the diabetic group showed an improved histological appearance. Our data also revealed a significant reduction in the activity of apoptosis using terminal dUTP nick end-labeling and reduced expression of TGF-β1 and IL-1β in the pancreatic β-cell of ferulic acid-treated rats. Treatment with ferulic acid daily doses produced a significant result compared to alternative dose. Collectively our results suggested that ferulic acid acts as a protective agent in diabetic rats by altering oxidative stress, expression of pro-inflammatory cytokines and apoptosis.

Antiepileptic Effect ofUncaria rhynchophyllaandRhynchophyllineInvolved in the Initiation of c-Jun N-Terminal Kinase Phosphorylation of MAPK Signal Pathways in Acute Seizures of Kainic Acid-Treated Rats

Seizures cause inflammation of the central nervous system. The extent of the inflammation is related to the severity and recurrence of the seizures. Cell surface receptors are stimulated by stimulators such as kainic acid (KA), which causes intracellular mitogen-activated protein kinase (MAPK) signal pathway transmission to coordinate a response. It is known that Uncaria rhynchophylla (UR) and rhynchophylline (RP) have anticonvulsive effects, although the mechanisms remain unclear. Therefore, the purpose of this study is to develop a novel strategy for treating epilepsy by investigating how UR and RP initiate their anticonvulsive mechanisms. Sprague-Dawley rats were administered KA (12 mg/kg, i.p.) to induce seizure before being sacrificed. The brain was removed 3 h after KA administration. The results indicate that pretreatment with UR (1.0 g/kg), RP (0.25 mg/kg), and valproic acid (VA, 250 mg/kg) for 3 d could reduce epileptic seizures and could also reduce the expression of c-Jun aminoterminal kinase phosphorylation (JNKp) of MAPK signal pathways in the cerebral cortex and hippocampus brain tissues. Proinflammatory cytokines interleukin (IL)-1β, IL-6, and tumor necrosis factor-α remain unchanged, indicating that the anticonvulsive effect of UR and RP is initially involved in the JNKp MAPK signal pathway during the KA-induced acute seizure period.

Effects of L-Arginine on Seizure Behavior and Expression of GFAP in Kainic Acid-Treated Rats

Rats i.p. injected once with 10 mg/kg kainic acid exhibited clear seizure behavior (“wet-dog shakes,” rearing on the hindlimbs, and bilateral clonus). Pretreatment with L-arginine (L-Arg twice a day for 5 days) significantly decreased these manifestations. The medium dose of L-Arg (40 mg/kg) was found to be close to optimum; 10 and 160 mg/kg L-Arg provided much smaller positive effects. In KA-treated rats, a much higher density of GFAP-positive astrocytes was found in the hilus of the dorsal hippocampus, while 40 mg/kg L-Arg+KA-treated rats demonstrated noticeably weaker GFAP overexpression. The results of Western blotting analysis were fully comparable with those obtained in the immunostaining experiments.

Chios Mastic Fractions in Experimental Colitis: Implication of the Nuclear Factor κB Pathway in Cultured HT29 Cells

The Pistacia lentiscus tree gives a resinous exudate called Chios mastic (CM) rich in triterpenoids. CM can be fractionated into acidic and neutral fractions (AF and NF, respectively). Oleanolic acid (OA) is a major triterpenic acid in CM with several antioxidant and anti-inflammatory properties. We have recently shown that CM is beneficial in experimental colitis in the form of powder mixture with inulin, as supplied commercially. However, the bioactive fraction or compound of CM is unidentified. Thus, based on the hypothesis that terpenoids exhibit functional activities via distinguishable pathways, we fractionated CM and applied different fractions or individual OA in experimental colitis. Furthermore, we investigated the mechanism underlying this effect in human colon epithelial cells. CM powder mixture (100 mg/kg of body weight) or the respective CM powder mixture components (i.e., inulin, AF, NF, or OA) were individually administered in trinitrobenzene sulfonic acid-treated rats. Colonic damage was assessed microscopically, and levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-8, and intercellular adhesion molecule-1were measured. A model of inflammation in co-cultured human colon epithelial HT29 cells and monocytes/macrophages was established. Lactate dehydrogenase release and levels of TNF-α, IL-8, and nuclear factor-κB (NF-κB) p65 were measured. In vivo, histological amelioration of colitis and significant regulation in inflammation occurred with CM powder mixture, even at the mRNA level. Although no histological improvement was observed, AF and NF reduced levels of inflammatory markers. Inulin was ineffective. In vitro, CM treatment down-regulated IL-8 and NF-κB p65. Neither fractions nor OA was the bioactive component solely. Most probably, the entire CM rather than its individual fractions reduces inflammation via NF-κB regulation.

Gastroprotective activities of a polysaccharide from the fruiting bodies of Pleurotus ostreatus in rats

In this study, a water-soluble polysaccharide (POPw) was successfully purified and identified from the fruiting bodies of Pleurotus ostreatus, with a molecular weight of 2.3×104Da. POPw contained 97.1% total sugar, 0.3% uronic acid and 0.2% protein. Gas chromatography (GC) analysis suggested that POPw was composed of Glc (52.3%), Gal (25.8%), Man (10.0%), Rha (6.1%), and Ara (5.2%). Animal experiments showed that oral administration with POPw significantly inhibited acetic acid-induced gastric lesions in rats, accompanied with a significant increase in mucus synthesis and the prostaglandin production. In addition, POPw could significantly increase the level of glutathione (GSH) and the activity of superoxide dismutase (SOD), as well as decreasing the content of thiobarbituric acid-reactive substances (TBARS) in acetic acid-treated rats with gastric ulcer. These results suggested that the gastroprotective effects of POPw on mice ulcer models can be attributed to its ameliorating effect on oxidative damage and reinforcing effect of gastric mucosal resistance.

Effects of oxcarbazepine on monoamines content in hippocampus and head and body shakes and sleep patterns in kainic acid-treated rats

The aim of this work was to analyze the effect of oxcarbazepine (OXC) on sleep patterns, "head and body shakes" and monoamine neurotransmitters level in a model of kainic-induced seizures. Adult Wistar rats were administered kainic acid (KA), OXC or OXC + KA. A polysomnographic study showed that KA induced animals to stay awake for the whole initial 10h. OXC administration 30min prior to KA diminished the effect of KA on the sleep parameters. As a measure of the effects of the drug treatments on behavior, head and body shakes were visually recorded for 4h after administration of KA, OXC + KA or saline. The presence of OXC diminished the shakes frequency. 4h after drug application, the hippocampus was dissected out, and the content of monoamines was analyzed. The presence of OXC still more increased serotonin, 5-hidroxyindole acetic acid, dopamine, and homovanilic acid, induced by KA.

Effects of pioglitazone and retinoic acid in a rotenone model of Parkinson's disease

Parkinson's disease (PD) is a late-onset, progressive and neurodegenerative disorder of unknown etiology. Besides the other therapeutic approaches, new drug options in pharmacotherapy of PD are important. The aim of the present study was to investigate the effects of pioglitazone and retinoic acid, antioxidant and neuroprotective agents, on rotenone-induced model of PD in rats. Adult male Wistar rats (260–373g) were subjects. Rotenone (2.5mg/kg, sc) was injected to rats for 70 days. At the end of rotenone administration, rats were treated with pioglitazone (10mg/kg, ip) and retinoic acid (1mg/kg, ip) or vehicles for 15 days. Then, rats were tested for evaluation of Parkinson signs by measurement of locomotor activity. In addition, dopamine levels were detected in striatum, hippocampus and hypothalamus in individual groups of control, rotenone and pioglitazone or retinoic acid-treated rats. Rotenone significantly reduced locomotor activity of the rats. It also significantly reduced dopamine levels in striatum and hippocampus, but not hypothalamus. Pioglitazone and retinoic acid reversed in reduction of locomotor activity significantly. Pioglitazone, but not retinoic acid, significantly reversed the reduced striatal dopamine level. Both drugs were ineffective on reduced levels of dopamine in hippocampus. Our results suggest that pioglitazone and retinoic acid have some beneficial effects on rotenone-induced model of PD in rats. Pioglitazone seems to be more effective than retinoic acid. These agents may be helpful for preventing or controlling of some signs of PD.

Alterations in the lenticular protein profile in experimental selenite-induced cataractogenesis and prevention by ellagic acid

Accumulating evidence suggests that oxidative stress underlies age-related formation of cataract, and that antioxidants retard cataractogenesis. This study aimed to evaluate whether ellagic acid, a natural polyphenol with antioxidant properties, prevents alterations in the lenticular protein profile in an experimental model of selenite cataract. Alterations in lenticular protein were determined by two-dimensional electrophoresis (2DE) and image analysis. Eluted αA-crystallin spots were analyzed by mass spectrometry. Western blot analysis was also performed to confirm the differential expression of certain crystallins and cytoskeletal proteins. In cataractous lenses, 2DE and image analysis revealed approximately 45 and 60 prominent spots in soluble and insoluble protein fractions respectively. Analysis of the pI and molecular weight of protein spots revealed differences in the expression of crystallin proteins in soluble and insoluble fractions. Western blot analysis confirmed changes in the expression of αA- and βB1- crystallins in both soluble and insoluble protein fractions, while mass spectrometry confirmed the degradation of αA-crystallin in selenite cataractous lenses. Western blot analysis also confirmed the occurrence of altered expression of certain cytoskeletal proteins in insoluble fractions. However, the lenticular protein profile in lenses from selenite-challenged, ellagic acid-treated rats was essentially similar to that noted in lenses from normal rats. The present study confirms the importance of structural and cytoskeletal proteins in the maintenance of lenticular transparency; the results also suggest that ellagic acid prevents lenticular protein alterations induced by selenite in an experimental setting.

Lipoic acid inhibits caspase-dependent and -independent cell death pathways and is neuroprotective against hippocampal damage after pilocarpine-induced seizures

Alpha-lipoic acid has some neuroprotective properties, but this action has not been investigated in models of epilepsy. The aim of the present study was to investigate the protective efficacy of α-lipoic acid (lipoic acid) against pilocarpine-induced cell death through the caspase-dependent or -independent mitochondrial apoptotic pathways. Wistar rats were injected intraperitoneally with 0.9% saline (control group), pilocarpine (400mg/kg, pilocarpine group) alone, or α-lipoic acid (20mg/kg) in association with pilocarpine (400mg/kg) 30min before administration of α-lipoic acid. After the treatments all groups were observed for 24h. Cell death was reduced in lipoic acid-treated rats. Cytosolic translocation of cytochrome c and subsequent activation of caspase-3 were reduced by lipoic acid treatment. AIF nuclear translocation and subsequent large-scale DNA fragmentation were also decreased in lipoic acid-treated rats. Our study suggests that lipoic acid inhibits both caspase-dependent and -independent apoptotic pathways and may be neuroprotective against hippocampal damage during pilocarpine-induced seizures.

Retinoic acid attenuates lipopolysaccharide-induced inflammatory responses by suppressing TLR4/NF-κB expression in rat mammary tissue

The retinoids, a group of natural or synthetic derivatives of vitamin A, exert various anti-neoplastic and immunomodulatory actions. Recent studies have demonstrated that retinoic acid protects rats against lipopolysaccharide (LPS)-induced mastitis, but the mechanism of action is unclear. In the present study, an LPS-induced rat mastitis model and primary cultures of rat mammary epithelial cells were used to investigate the effect of retinoic acid on the TLR4/NF-κB signaling pathway. The data indicated that toll-like receptor 4 (TLR4) gene expression reached its peak value earlier in retinoic acid-treated rats than in the control group, and that retinoic acid significantly decreased NF-κB DNA binding activity and the level of IL-1β in the mammary gland. The animal study result was confirmed by an in vitro cell culture system trial. TLR4 protein expression and NF-κB DNA binding activity were significantly decreased in primary rat mammary epithelial cells pretreated with 1 μmol/l retinoic acid at 1 h post-LPS stimulation. IL-1β gene expression was also significantly decreased at 2, 4 and 8 h post-LPS stimulation. These findings demonstrate that direct action by retinoic acid leads to attenuation of the LPS-induced inflammatory response by suppression of the TLR4/NF-κB signalling system, thereby providing a novel explanation for the underlying effect proposed for retinoic acid in the protection of mammary tissue during LPS-induced acute mastitis.

Physiological and Histopathological Investigations on the Effects of-Lipoic Acid in Rats Exposed to Malathion

The present study was designed to evaluate the influence of α-lipoic acid treatment in rats exposed to malathion. Forty adult male rats were used in this study and distributed into four groups. Animals of group 1 were untreated and served as control. Rats of group 2 were orally given malathion at a dose level of 100 mg/kg body weight (BW) for a period of one month. Experimental animals of group 3 were orally given α-lipoic acid at a dose level of 20 mg/kg BW and after 3 hours exposed to malathion at the same dose given to group 2. Rats of group 4 were supplemented with α-lipoic acid at the same dose given to group 3. The activities of serum glutamic oxaloacetic acid transaminase (GOT), glutamic pyruvic acid transaminase (GPT), alkaline phosphatase (ALP), and acid phosphatase (ACP), and the values of creatinine, urea, and uric acid were statistically increased, while the values of total protein and total albumin were significantly decreased in rats exposed to malathion. Moreover, administration of malathion for one month resulted in damage of liver and kidney structures. Administration of α-lipoic acid before malathion exposure to rat can prevent severe alterations of hematobiochemical parameters and disruptions of liver and kidney structures. In conclusion, this study obviously demonstrated that pretreatment with α-lipoic acid significantly attenuated the physiological and histopathological alterations induced by malathion. Also, the present study identifies new areas of research for development of better therapeutic agents for liver, kidney, and other organs' dysfunctions and diseases.

Effects of olive oil and its fractions on oxidative stress and the liver's fatty acid composition in 2,4-Dichlorophenoxyacetic acid-treated rats

BackgroundOlive oil's beneficial effects are not only related to its high content of oleic acid, but also to the antioxidant potential of its polyphenols. In this study, we assess the effects of virgin olive oil and its fractions on 2,4-D- induced oxidative damage in the liver of rats.MethodsMale Wistar rats were randomly divided into eight groups of ten each: (C) a control group, (D) group that received 2,4-D (5 mg/kg b.w.), (D/EVOO) group treated with 2,4-D plus extra virgin olive oil, (D/OOHF) group that received 2,4-D plus hydrophilic fraction, (D/OOLF) group treated with 2,4-D plus lipophilic fraction, (EVOO) group that received only extra virgin olive oil, (OOHF) group given hydrophilic fraction and (OOLF) group treated with lipophilic fraction. These components were daily administered by gavage for 4 weeks.ResultsA significant liver damage was observed in rats treated with 2,4-D via increased serum levels of transaminases and alkaline phosphatase, hepatic lipid peroxidation and decreased hepatic antioxidant enzyme activities, namely, superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. The liver's fatty acid composition was also significantly modified with 2,4-D exposure. However, extra virgin olive oil and hydrophilic fraction intake during 2,4-D treatment induced a significant increase in the antioxidant enzyme activities and a decrease in the conjugated dienes (CD) and thiobarbituric acid-reactive substances (TBARs) levels in the liver. The lipophilic fraction supplemented to 2,4-D- treated rats did not show any improvement in the liver oxidative status while a marked improvement was detected in the hepatic fatty acid composition of rats supplemented with olive oil and the two fractions.ConclusionWe concluded that the protective effect of olive oil against oxidative damage induced by 2,4-D is mainly related to the antioxidant potential of its hydrophilic fraction.

The microtubule interacting drug candidate NAP protects against kainic acid toxicity in a rat model of epilepsy

NAP (NAPVSIPQ, generic name, davunetide), a neuroprotective peptide in clinical development for neuroprotection against Alzheimer's disease and other neurodegenerative indications, has been recently shown to provide protection against kainic acid excitotoxicity in hippocampal neuronal cultures. In vivo, kainic acid toxicity models status epilepticus that is associated with hippocampal cell death. Kainic acid toxicity has been previously suggested to involve the microtubule cytoskeleton and NAP is a microtubule-interacting drug candidate. In the current study, kainic acid-treated rats showed epileptic seizures and neuronal death. Injection of NAP into the dentate gyrus partially protected against kainic acid-induced CA3 neuron death. Microarray analysis (composed of > 31 000 probe sets, analyzing over 30 000 transcripts and variants from over 25 000 well-substantiated rat genes) in the kainic acid-injured rat brain revealed multiple changes in gene expression, which were prevented, in part, by NAP treatment. Selected transcripts were further verified by reverse transcription coupled with quantitative real-time polymerase chain reaction. Importantly, among the transcripts regulated by NAP were key genes associated with proconvulsant properties and with long-lasting changes that underlie the epileptic state, including activin A receptor (associated with apoptosis), neurotensin (associated with proper neurotransmission) and the Wolfram syndrome 1 homolog (human, associated with neurodegeneration). These data suggest that NAP may provide neuroprotection in one of the most serious neurological conditions, epilepsy.

Lipoprotein lipase expression, serum lipid and tissue lipid deposition in orally-administered glycyrrhizic acid-treated rats

BackgroundThe metabolic syndrome (MetS) is a cluster of metabolic abnormalities comprising visceral obesity, dyslipidaemia and insulin resistance (IR). With the onset of IR, the expression of lipoprotein lipase (LPL), a key regulator of lipoprotein metabolism, is reduced. Increased activation of glucocorticoid receptors results in MetS symptoms and is thus speculated to have a role in the pathophysiology of the MetS. Glycyrrhizic acid (GA), the bioactive constituent of licorice roots (Glycyrrhiza glabra) inhibits 11β-hydroxysteroid dehydrogenase type 1 that catalyzes the activation of glucocorticoids. Thus, oral administration of GA is postulated to ameliorate the MetS.ResultsIn this study, daily oral administration of 50 mg/kg of GA for one week led to significant increase in LPL expression in the quadriceps femoris (p < 0.05) but non-significant increase in the abdominal muscle, kidney, liver, heart and the subcutaneous and visceral adipose tissues (p > 0.05) of the GA-treated rats compared to the control. Decrease in adipocyte size (p > 0.05) in both the visceral and subcutaneous adipose tissue depots accompanies such selective induction of LPL expression. Consistent improvement in serum lipid parameters was also observed, with decrease in serum free fatty acid, triacylglycerol, total cholesterol and LDL-cholesterol but elevated HDL-cholesterol (p > 0.05). Histological analysis using tissue lipid staining with Oil Red O showed significant decrease in lipid deposition in the abdominal muscle and quadriceps femoris (p < 0.05) but non-significant decrease in the heart, kidney and liver (p > 0.05).ConclusionResults from this study may imply that GA could counteract the development of visceral obesity and improve dyslipidaemia via selective induction of tissue LPL expression and a positive shift in serum lipid parameters respectively, and retard the development of IR associated with tissue steatosis.

Differences in Immunolocalization of Kim-1, RPA-1, and RPA-2 in Kidneys of Gentamicin-, Cisplatin-, and Valproic Acid-Treated Rats: Potential Role of iNOS and Nitrotyrosine

The present study compared the immunolocalization of Kim-1, renal papillary antigen (RPA)-1, and RPA-2 with that of inducible nitric oxide synthase (iNOS) and nitrotyrosine in kidneys of gentamicin sulfate (Gen)- and cisplatin (Cis)-treated rats. The specificity of acute kidney injury (AKI) biomarkers, iNOS, and nitrotyrosine was evaluated by dosing rats with valproic acid (VPA). Sprague-Dawley (SD) rats were injected subcutaneously (sc) with 100 mg/kg/day of Gen for six or fourteen days; a single intraperitoneal (ip) dose of 1, 3, or 6 mg/kg of Cis; or 650 mg/kg/day of VPA (ip) for four days. In Gen-treated rats, Kim-1 was expressed in the epithelial cells, mainly in the S1/S2 segments but less so in the S3 segment, and RPA-1 was increased in the epithelial cells of collecting ducts (CD) in the cortex. Spatial expression of iNOS or nitrotyrosine with Kim-1 or RPA-1 was detected. In Cis-treated rats, Kim-1 was expressed only in the S3 segment cells, and RPA-1 and RPA-2 were increased in the epithelial cells of medullary CD or medullary loop of Henle (LH), respectively. Spatial expression of iNOS or nitrotyrosine with RPA-1 or RPA-2 was also identified. These findings suggest that peroxynitrite formation may be involved in the pathogenesis of Gen and Cis nephrotoxicity and that Kim-1, RPA-1, and RPA-2 have the potential to serve as site-specific biomarkers for Gen or Cis AKI.