Electrical Stimulation of the Insular Region Attenuates Nicotine-Taking and Nicotine-Seeking Behaviors

Pharmacological inactivation of the granular insular cortex is able to block nicotine-taking and -seeking behaviors in rats. In this study, we explored the potential of modulating activity in the insular region using electrical stimulation. Animals were trained to self-administer nicotine (0.03 mg/kg per infusion) under a fixed ratio-5 (FR-5) schedule of reinforcement followed by a progressive ratio (PR) schedule. Evaluation of the effect of stimulation in the insular region was performed on nicotine self-administration under FR-5 and PR schedules, as well on reinstatement of nicotine-seeking behavior induced by nicotine-associated cues or nicotine-priming injections. The effect of stimulation was also examined in brain slices containing insular neurons. Stimulation significantly attenuated nicotine-taking, under both schedules of reinforcement, as well as nicotine-seeking behavior induced by cues and priming. These effects appear to be specific to nicotine-associated behaviors, as stimulation did not have any effect on food-taking behavior. They appear to be anatomically specific, as stimulation surrounding the insular region had no effect on behavior. Stimulation of brain slices containing the insular region was found to inactivate insular neurons. Our results suggest that deep brain stimulation to modulate insular activity should be further explored.     

Blockade of Dopamine D4 Receptors Attenuates Reinstatement of Extinguished Nicotine-Seeking Behavior in Rats

Since cloning of the dopamine receptor D4 (DRD4), its role in the brain has remained unclear. It has been reported that polymorphism of the DRD4 gene in humans is associated with reactivity to cues related to tobacco smoking. However, the role of DRD4 in animal models of nicotine addiction has seldom been explored. In our study, male Long-Evans rats learned to intravenously self-administer nicotine under a fixed-ratio (FR) schedule of reinforcement. Effects of the selective DRD4 antagonist L-745,870 were evaluated on nicotine self-administration behavior and on reinstatement of extinguished nicotine-seeking behavior induced by nicotine-associated cues or by priming injections of nicotine. L-745,870 was also tested on reinstatement of extinguished food-seeking behavior as a control. In addition, the selective DRD4 agonist PD 168,077 was tested for its ability to reinstate extinguished nicotine-seeking behavior. Finally, L-745,870 was tested in Sprague Dawley rats trained to discriminate administration of 0.4 mg/kg nicotine from vehicle under an FR schedule of food delivery. L-745,870 significantly attenuated reinstatement of nicotine-seeking induced by both nicotine-associated cues and nicotine priming. In contrast, L-745,870 did not affect established nicotine self-administration behavior or reinstatement of food-seeking behavior induced by food cues or food priming. L-745,870 did not produce nicotine-like discriminative-stimulus effects and did not alter discriminative-stimulus effects of nicotine. PD 168,077 did not reinstate extinguished nicotine-seeking behavior. As DRD4 blockade by L-745,870 selectively attenuated both cue- and nicotine-induced reinstatement of nicotine-seeking behavior, without affecting cue- or food-induced reinstatement of food-seeking behavior, DRD4 antagonists are potential therapeutic agents against tobacco smoking relapse.     

A Conjugate Vaccine Attenuates Morphine- and Heroin-Induced Behavior in Rats

Background:

Currently approved medications for opioid addiction have shown clinical efficacy, but undesired side effects, dependence induced by the medications themselves, and low treatment compliance necessitate the need for novel therapies.

Methods:

A novel morphine-keyhole limpet hemocyanin conjugate vaccine was synthesized with 6-glutarylmorphine as the hapten and a lengthened linker of 6 carbon atoms. The titer and specificity of the triggered antibody were assessed by enzyme-linked immunosorbent assay. The effects of the vaccine on the morphine-induced elevation of dopamine levels in the nucleus accumbens were determined by high-performance liquid chromatography. The effects of the vaccine on morphine-induced locomotor sensitization and heroin-primed reinstatement of heroin self-administration were also assessed.

Results:

After subcutaneous administration in rats, the vaccine triggered a high antibody titer, with comparable specificity for morphine, 6-acetylmorphine, and heroin, but no interaction with dissimilar therapeutic opioid compounds, including buprenorphine, naloxone, and nalorphine, was observed. The vaccine significantly prevented the elevation of dopamine levels in the nucleus accumbens induced by a single morphine challenge. Moreover, the vaccine prevented the expression of morphine-induced locomotor sensitization and heroin-primed reinstatement of heroin seeking, suggesting its potential for preventing relapse.

Conclusion:

These results demonstrate that active immunization with the present vaccine induces a robust morphine/heroin-specific antibody response in rats and attenuates the behavioral effects of morphine and heroin.     

Gamma-Vinyl GABA Decreases Voluntary Alcohol Consumption in Alcohol-Preferring AA Rats

The effect of a GABA transaminase inhibitor, gamma-vinyl GABA, on the voluntary alcohol consumption of alcohol-preferring AA rats produced by selective breeding for high alcohol preference, was studied. The rats were first trained to voluntarily drink 10% (v/v) ethanol solution until their ethanol consumption stabilized. Gamma-vinyl GABA (100, 200 or 500 mg/kg) was then injected intraperitoneally in three groups of rats, with saline-injected animals serving as a control group. The rats continued to have a free choice between 10% ethanol and plain tap water for five days after the injection, and their ethanol, water and food consumptions were measured daily. Gamma-vinyl GABA decreased ethanol consumption by the rats in a dose-dependent way. The consumption remained significantly decreased for three days in the two groups receiving the highest doses, with only a small concomitant tendency to decreased food intake. The results suggest that an increase in brain GABA concentration decreases alcohol drinking, possibly through potentiation of the pharmacological action of ethanol.     

Liposomal Simvastatin Attenuates Neointimal Hyperplasia in Rats

Monocytes, macrophages, and inflammation play a key role in the process of neointimal proliferation and restenosis. The present study evaluated whether systemic and transient depletion of monocytes could be obtained by a single intravenous (IV) injection of simvastatin liposomes, for the inhibition of neointima formation. Balloon-injured carotid artery rats (n = 30) were randomly assigned to treatment groups of free simvastatin, simvastatin in liposomes (3 mg/kg), and saline (control). Stenosis and neointima to media ratio (N/M) were determined 14 days following single IV injection at the time of injury by morphometric analysis. Depletion of circulating monocytes was determined by flow cytometry analyzes of blood specimens. Inhibition of RAW264.7, J774, and THP-1 proliferation by simvastatin-loaded liposomes and free simvastatin was determined by the 3-(4, 5-dimethylthiazolyl-2)-2, 5- diphenyltetrazolium bromide assay. Simvastatin liposomes were successfully formulated and were found to be 1.5-2 times more potent than the free drug in suppressing the proliferation of monocytes/macrophages in cell cultures of RAW 264.7, J774, and THP-1. IV injection of liposomal simvastatin to carotid-injured rats (3 mg/kg, n = 4) resulted in a transient depletion of circulating monocytes, significantly more prolonged than that observed following treatment with free simvastatin. Administration to balloon-injured rats suppressed neointimal growth. N/M at 14 days was 1.56 ± 0.16 and 0.90 ± 0.12, control and simvastatin liposomes, respectively. One single systemic administration of liposomal simvastatin at the time of injury significantly suppresses neointimal formation in the rat model of restenosis, mediated via a partial and transient depletion of circulating monocytes.Key words: drug delivery systems, liposomes, monocytes, restenosis, statins     

维生素C对顺铂所致大鼠肾损伤的保护作用

目的研究维生素C（Vit C）对顺铂所致肾损伤的保护作用,并探讨其可能的机制。方法将40只成年雌性SD大鼠按体重分成5组,分别为正常对照组（A组,生理盐水）、Vit C对照组（B组,500mg／kg）、顺铂化疗模型组（C组,6mg／kg）、顺铂（6mg／kg）＋Vit C（50mg／kg或500mg／kg）干预组（D1组及D2组）。腹腔注射Vit C进行前、中、后期全程保护,并于顺铂给药5d后采血处死动物,测定血清尿素氮（BUN）、肌酐（Cr）、肾皮质匀浆丙二醛（MDA）含量及谷胱甘肽过氧化物酶（GSH—Px）、超氧化物歧化酶（SOD）活力的变化。结果与C组相比,D1组及D2组的血清Cr及BUN、肾皮质匀浆MDA含量明显下降（P〈0．01或P〈0．05）,GSH—Px和SOD活力略有增加。结论Vit C可以减轻顺铂所致肾损伤,作用机制可能与其抗氧化作用和清除自由基活性密切相关。     

Propolis Attenuates Doxorubicin-Induced Testicular Toxicity in Rats

Doxorubicin (Dox), an effective anticancer agent, can impair testicular function leading to infertility. The present study aimed to explore the protective effect of propolis extract on Dox-induced testicular injury. Rats were divided into four groups (n = 10). Group I (normal control), group II received propolis extract (200 mg kg⁻¹; p.o.), for 3 weeks. Group III received 18 mg kg⁻¹ total cumulative dose of Dox i.p. Group IV received Dox and propolis extract. Serum and testicular samples were collected 48 h after the last treatment. In addition, the effects of propolis extract and Dox on the growth of solid Ehrlich carcinoma in mice were investigated. Dox reduced sperm count, markers of testicular function, steroidogenesis and gene expression of testicular 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD) and steroidogenic acute regulatory protein (StAR). In addition, it increased testicular oxidative stress, inflammatory and apoptotic markers. Morphometric and histopathologic studies supported the biochemical findings. Treatment with propolis extract prevented Dox-induced changes without reducing its antitumor activity. Besides, administration of propolis extract to normal rats increased serum testosterone level coupled by increased activities and gene expression of 3ß-HSD and 17ß-HSD. Propolis extract may protect the testis from Dox-induced toxicity without reducing its anticancer potential.     

A Role for Hypocretin/Orexin Receptor-1 in Cue-Induced Reinstatement of Nicotine-Seeking Behavior

Hypocretin/orexin signaling is critically involved in relapse to drug-seeking behaviors. In this study, we investigated the involvement of the hypocretin system in the reinstatement of nicotine-seeking behavior induced by nicotine-associated cues. Pretreatment with the hypocretin receptor-1 antagonist SB334867, but not with the hypocretin receptor-2 antagonist TCSOX229, attenuated cue-induced reinstatement of nicotine-seeking, which was associated with an activation of hypocretin neurons of the lateral and perifornical hypothalamic areas. In addition, relapse to nicotine-seeking increased the phosphorylation levels of GluR2-Ser880, NR1-Ser890, and p38 MAPK in the nucleus accumbens (NAc), but not in the prefrontal cortex. Notably, phosphorylation levels of NR1-Ser890 and p38 MAPK, but not GluR2-Ser880, were dependent on hypocretin receptor-1 activation. The intra-accumbens infusion of the protein kinase C (PKC) inhibitor NPC-15437 reduced nicotine-seeking behavior elicited by drug-paired cues consistent with the PKC-dependent phosphorylations of GluR2-Ser880 and NR1-Ser890. SB334867 failed to modify cue-induced reinstatement of food-seeking, which did not produce any biochemical changes in the NAc. These data identify hypocretin receptor-1 and PKC signaling as potential targets for the treatment of relapse to nicotine-seeking induced by nicotine-associated cues.     

氟比洛芬酯减轻肾缺血再灌注模型大鼠的炎症损伤研究

目的 探索氟比洛芬酯(flurbiprofen axetil,FA)减轻大鼠肾缺血再灌注炎症损伤的生物学作用及其潜在的机制.方法 将♂SD大鼠随机分为4组(每组8只):假手术组、假手术+FA(5 mg·kg-1)组、缺血再灌注损伤(ischemia-reperfusion injury,IRI)组和IRI+FA(5 m...     

Effects of α2-Adrenergic Drugs on the Alcohol Consumption of Alcohol-Preferring Rats

The effects of seven-day subcutaneous infusion of an α₂-adrenoceptor agonist, medetomidine, and an α₂-adrenoceptor antagonist, atipamezole, on the voluntary alcohol consumption of alcohol-preferring rats were studied. The drugs were administered by means of implanted osmotic minipumps. Sham-operated control rats had no pumps implanted. The rats had a free choice between 10% alcohol and plain water for 30 days before pump implantation and again for six days starting 24 hr after the operation. Atipamezole increased the alcohol consumption during the first day of free choice. Medetomidine had no significant effect. During the remaining period of infusion, the alcohol consumption did not differ from that preceding the pump implantation in each treatment group. Animals in the atipamezole group gained more weight during the seven-day trial than did those in the medetomidine and control groups. The amine changes in different regions of the brain were consistent with medetomidine decreasing and atipamezole increasing the noradrenaline turnover. The present results indicate that specific drugs acting on the α₂-adrenoceptors produce only minor changes in the voluntary alcohol drinking of alcohol-preferring rats.     

肾安胶囊对5/6肾大部切除大鼠肾脏的保护作用

目的探讨肾安胶囊对肾大部切除大鼠肾脏功能的影响。方法将大鼠随机分为假手术组和手术组,术后3天再将手术组大鼠随机分为肾安胶囊组和Nx组。8周后测尿蛋白和血肌酐;取肾组织做病理检查;用免疫组织化学检查肌成纤维细胞标志抗原(α-平滑肌肌动蛋白α-SMA)。结果Nx组大鼠肾脏出现肾小球硬化和肾间质纤维化;和Sham组相比α-SMA表达明显升高;肾安胶囊组肾脏纤维化明显减轻(P<0.05),α-SMA表达比Nx组明显下降。结论肾安胶囊可抑制肌成纤维细胞增殖和浸润,减轻肾脏纤维化从而保护肾功能。     

Curcumin Attenuates Oxidative Stress and Activation of Redox-Sensitive Kinases in High Fructose- and High-Fat-Fed Male Wistar Rats

The present study was carried out to investigate the effects of curcumin on oxidative stress and redox-sensitive kinases in high fructose- and high-fat-fed rats. Sixty rats were randomly divided into six groups with ten animals each. Rats were fed with a standard rodent diet, high fructose diet (60%), and high-fat diet (30%). Curcumin was administered to control, high fructose and high fat diet groups for ten weeks. At the end of the study, body weight and blood glucose levels were measured. The antioxidant enzymes GSH (reduced glutathione), GPx (glutathione peroxidase), and catalase activities were estimated in the blood. MDA, TAS, and TOS were estimated in the plasma, liver, and kidney. Curcumin treatment decreased body weight and blood glucose levels in the rats fed with fructose and high-fat diet. Antioxidant enzymes and plasma TAS were significantly improved by curcumin treatment in high fructose-fed rats, whereas in high-fat-fed rats, there was an increase only in the GPx activity. Curcumin significantly attenuated the elevation of plasma MDA and TOS in both diet groups. Hepatic MDA and TOS were found to be decreased upon curcumin supplementation in both diet groups, whereas a decrease in the renal MDA levels was observed only in fructose-treated rats, not in fat-fed rats. Curcumin treatment elevated liver TAS in rats fed only with the fructose-rich diet. Curcumin showed a significant decrease in the oxidative stress index (OSI) in plasma, liver, and kidney tissues in both diet groups. ERK phosphorylation was significantly decreased in both diet groups by curcumin treatment. Similarly, curcumin reduced the phosphorylation of p38 MAPK only in the high fructose-fed rats, not in the high-fat-fed rats. No significant changes were found in JNK phosphorylation in both diet groups. Thus, curcumin may be effective in the management of diet-induced oxidative stress and could be explored as a therapeutic adjuvant against complications associated with obesity and diabetes.     

GDF11 Treatment Attenuates the Recovery of Skeletal Muscle Function After Injury in Older Rats

Loss of skeletal muscle mass and function results in loss of mobility for elderly patients. Novel therapies that can protect and/or restore muscle function during aging would have profound effects on the quality of life for this population. Growth differentiation factor 11 (GDF11) has been proposed as a “youthful” circulating factor that can restore cardiac, neural, and skeletal muscle functions in aging animals. However, conflicting data has been recently published that casts doubt on these assertions. We used a complex rat model of skeletal muscle injury that physiologically mimics injuries seen in patients; to investigate the ability of GDF11 and to enhance skeletal muscle regeneration after injury in older rats. Our data showed that GDF11 treatment resulted in a significant increase in tissue fibrosis, accompanied by attenuated functional recovery, as compared to animals treated with vehicle alone. GDF11 impaired the recovery of skeletal muscle function in older rats after injury.     

Oral Glutamine Attenuates Cyclophosphamide-Induced Oxidative Stress in the Bladder but Does Not Prevent Hemorrhagic Cystitis in Rats

Cyclophosphamide (CP) is widely used in the treatment of cancer and non-malignant disease states such as rheumatoid arthritis. Hemorrhagic cystitis is a major dose-limiting side effect of CP. The incidence of this side effect is related to the dosage and can be as high as 75%. Elimination of the side effects of CP can lead to better tolerance of the drug, and a more efficient therapy can be achieved for patients in need of CP treatment. Several studies have demonstrated that oxidative stress and neutrophil infiltration play important roles in CP-induced bladder damage. Glutamine is utilized under clinical conditions for preventing chemotherapeutic drug-induced side effects, based on its ability to attenuate oxidative stress. The aim of the study is to verify whether glutamine prevents CP-induced oxidative stress and bladder damage using a rat model. Adult male rats were administered 150 mg/kg body weight of CP intraperitoneally. Glutamine pretreated rats were administered 1 g/kg body weight of glutamine orally 2 h before the administration of CP. Vehicle/glutamine-treated rats served as controls. All the rats were killed 16 h after the dose of CP/vehicle. The urinary bladders were removed and used for light microscopic and biochemical studies. The markers of oxidative stress including malondialdehyde content, protein carbonyl content, protein thiol, and myeloperoxidase activity, a marker of neutrophil infiltration, were measured in bladder homogenates. CP treatment induced hemorrhagic cystitis in the rats. Pretreatment with glutamine significantly reduced CP-induced lipid peroxidation (p < 0.01), protein oxidation (p < 0.01), and increase in myeloperoxidase activity (p < 0.05). However, it did not prevent CP-induced bladder damage. The results of the present study show that glutamine pretreatment does not attenuate CP-induced hemorrhagic cystitis, although it prevents CP-induced oxidative stress and neutrophil infiltration significantly. It is therefore necessary to clarify the utility of glutamine as a chemoprotective agent before it is recommended in the market as a nutrient supplement.     

Thyroxine Replacement Attenuates Hypothyroxinemia, Hearing Loss, and Motor Deficits Following Developmental Exposure to Aroclor 1254 in Rats

The nervous system is dependent upon thyroid hormones for normaldevelopment, and we previously reported that developmental Aroclor1254 (A1254) exposure caused hypothyroxinemia, hearing lossand other behavioral changes in rats. (Goldey et al, 1995a;Herr et al, 1996). The hypothesis that A1254-induced hypothyroxinemiamay have contributed to the observed functional changes wastested in primiparous Long-Evans rats given daily oral dosesof corn oil (control) or 8 mg/kg of Aroclor 1254 from gestationday (GD) 6 through postnatal day (PND) 21. In addition, fromPND 4 to PND 21, all pups in one-half of the litters receiveddaily, subcutaneous injections of saline or 100 µg/kgthyroxine (T4), to yield four groups of litters: corn oil phissaline (CO-S), corn oil plus T4 (CO-T4), Aroclor 1254 plus saline(PCB-S), and Aroclor 1254 plus T4 (PCB-T4). We measured thyroidhormone concentrations (T4 and T3) in serum collected from 7-,14-, and 21-day-old pups. The kinetics of the injected T4 werealso monitored in the CO-T4 and PCB-T4 groups on PND 7 and 21by measuring T4 and T3 at 1, 3, 5, 8, and 24 h after injection.Circulating T4 concentrations were dramatically depleted inthe PCB-S group relative to CO-S. The kinetics study indicatedthat T4 therapy raised circulating T4 concentrations followingin the PCB-T4 pups to near CO-S concentrations, but only forapproximately 6 h postinjection, and T4 concentrations fellprecipitously thereafter to near PCB-S concentrations. In accordwith previous studies, PCB-S pups showed early eye opening,an effect which was exacerbated by T4 injection (in both theCO-T4 and the PCB-T4 groups). Motor activity (figure-eight maze)testing also replicated our finding of an age-dependent, transientreduction in motor activity on PND 15 that was significantlyattenuated in the PCB-T4 group. Similarly, we again found reducedacoustic startle amplitudes on PND 23 and low-frequency (1 kHz)hearing loss in animals tested as adults (the latter derterminedby reflex modification audiometry Importantly, the hearing lossat 1kHz in PCB-exposed animals was significantly attenuatedby T4 replacement therapy. These data suggest the hypothesisthat hypothyroxinemia is involved in PCB-induced alterationsin motor and auditory function, while other effects (e.g., eyeopening) appear to have a different mechanism of action.     

Preexposure to Amorphous Silica Particles Attenuates but also Enhances Allergic Reactions in Trimellitic Anhydride-Sensitized Brown Norway Rats

Irritant-induced inflammation of the airways may aggravate respiratory allergy induced by chemical respiratory allergens. Therefore, the effect of airway irritation by synthetic amorphous silica (SAS) on respiratory allergy to trimellitic anhydride (TMA) was studied. Brown Norway (BN) rats were topically sensitized on day 0 and on day 7, subsequently exposed for 6 h/day for 6 days to 27 mg/m³ SAS, and challenged by inhalation to a minimally irritating concentration of 12 mg/m³ TMA, 24 h after the last SAS exposure. An additional group was exposed to SAS before a second challenge to TMA. Control groups were treated with vehicle, and/or did not receive SAS exposure. Breathing parameters, cellular and biochemical changes in bronchoalveolar lavage (BAL) fluid, and histopathological airway changes 24 h after challenge were the main parameters studied. Exposure to SAS alone resulted in transient changes in breathing parameters during exposure, and in nasal and alveolar inflammation with neutrophils and macrophages. Exposure to SAS before a single TMA challenge resulted in a slightly irregular breathing pattern during TMA challenge. SAS also diminished the effect of TMA on tidal volume, laryngeal ulceration, laryngeal inflammation, and the number of BAL (lung) eosinophils in most animals, but aggravated laryngeal squamous metaplasia and inflammation in a single animal. The pulmonary eosinophilic infiltrate and edema induced by a second TMA challenge was diminished by the preceding SAS exposure, but the number of lymphocytes in BAL was increased. Thus, a respiratory particulate irritant like SAS can reduce as well as aggravate certain aspects of TMA-induced respiratory allergy.     

Atorvastatin Modulates Regulatory T Cells and Attenuates Cerebral Damage in a Model of Transient Middle Cerebral Artery Occlusion in Rats

Regulatory T cells (Tregs) inhibit the activation of the immune response which could down-regulate the systemic and focal activation observed during ischemic stroke. In fact, in animal models, Tregs infiltrate the infarcted brain and reduce the pro-inflammatory cytokine production and infarct volume, mainly in late stages of ischemia. Recently, an expansion and greater suppressive capacity of circulating Tregs after treatment with statins was observed, in addition to their cardio- and neuroprotective actions demonstrated previously. Thus, to determine whether Treg modulation mediated by statins can also be beneficial during stroke, cerebral ischemia was artificially induced in Wistar rats by transient middle cerebral artery occlusion (tMCAO) during 60 minutes with subsequent reperfusion for 7 days. Six hours after surgery, some animals were treated with atorvastatin (ATV, 10 mg/kg) or carboxymethylcellulose as vehicle at the same concentration every other day during 7 days. Some animals were sham operated as control group of surgery. Interestingly, ATV treatment prevented the development of infarct volume, reduced the neurological deficits, and the circulating and cervical lymph node CD25⁺FoxP3⁺ Treg population. Moreover, there was a reduction of glial cell activation, which correlated with decreased circulating Tregs. Remarkably, treatment with ATV induced an increase in the frequency of CD4⁺CD25⁺ T cells, in particular of those expressing CTLA-4, in brain samples. Together, these results suggest that ATV can modulate Tregs in peripheral tissue and favor their accumulation in the brain, where they can exert neuroprotective actions maybe by the reduction of glial cell activation.