Long-Term Ethanol Alcoholization Decreases Levodopa- Induced Aggressive Behavior in Rats

One of the old but still unsolved problems in psychiatry is the treatment of patients with a dual diagnosis of schizophrenia and alcoholism. Numerous clinical studies failed to explain unambiguously the mechanisms of formation of these comorbid disorders. Experimental modeling of dual disorders was carried out using a model of schizophrenia based on the impaired development and dopamine hypothesis of schizophrenia. To model comorbid experimental schizophrenia and alcohol abuse, the dopamine precursors, Levodopa/Carbidopa (LC), were used in combination with 15% ethanol. The aim of this study was to investigate social behavior of rats receiving LC and exposed to intermittent semi-compulsory alcoholization. After three months of the experiment, there were significantly more interactions (including aggressive–attacks, fights, bites) and submissive postures in the group of rats that received LC. Combined LC/ethanol administration did not alter rat social behavior in contrast to ethanol administered alone.     

Genetic predisposition to catatonic behaviour and methylphenidate sensitivity in rats

To study the relationship between three animal models of schizophrenia, i.e. genetically determined akinetic catatonia, stereotypies induced by amphetamine-like psychostimulators, and behavioural changes in chronic intoxication with such stimulators, the frequency of different types of reactions to a functional amphetamine analogue, methylphenidate, was studied in wild Norway rats, non-selected Wistar rats, and Wistar rats bred for predisposition to akinetic catatonia. A positive relationship between the predisposition to catatonia and the level of stereotypies in a single methylphenidate administration was found in wild rats, but not in Wistar bred for catatonia (the latter differed from the non-selected rats in a higher frequency of “hyperactive” reactions). A closer study of catatonia in laboratory rats permitted subdivision into several types—occurring in selected and non-selected rats both naturally and as a result of chronic intoxication with amphetamines. It was found in non-selected Wistar rats that there is a positive relationship between some of these types and an increased stereotypy level in repeated methylphenidate administration. It is concluded that the natural akinetic catatonia and the chronic intoxication with amphetamines are two homologous varieties of the same model of schizophrenia, while the stereotypies are characteristics of this model. Studies of monoamine oxidase (MAO) activity imply a cortical component in the predisposition to akinetic catatonia.     

Increased neuronal activity in locus coeruleus from adult rats undernourished at perinatal age: its reversal by desipramine.

The spontaneous activity of locus coeruleus (LC) noradrenergic neurons was assessed by single unit recording in adult recovered rats undernourished at perinatal age as compared with wellnourished animals. Locus coeruleus activity, measured by the firing rate of noradrenergic neurons and the number of spontaneously active cells/track was significantly higher in deprived rats than in controls. In addition, dose-response curves for the inhibitory LC activity of clonidine showed a shift to the right in deprived animals indicating a subsensitivity of alpha2-adrenergic autoreceptors. This fact suggests an alteration in the negative feedback mechanism mediated by somatodentritic alpha2 autoreceptors that modulate the activity of LC neurons, and may account for the behavioral alterations attributed to early undernutrition. Repeated desipramine (DMI) administration to deprived rats reduced LC activity to values comparable to controls, which were not affected after a similar treatment. These data extend to previous reports on long-lasting or permanent plastic changes in the CNS induced by early undernutrition, which may be reverted by pharmacological manipulations. In addition, these results support the hypothesis that alterations induced by early undernutrition are in the same direction as and resemble those described for patients with panic disorders. Furthermore, together with behavioral alterations and selective anxiolytic effect of DMI and other drugs with antipanic effects described in early malnourished rats, the present data support the proposal that perinatally deprived rats may be a useful model for screening drugs with potential antipanic activity.     

Liver-Associated Natural Killer Activity in Cirrhotic Rats

An impaired host defense mechanism is well known in patients with liver cirrhosis (LC). Using a sinusoidal lavage method, lymphocytes were obtained from LC rats that were administered thioacetamide, and natural killer (NK) activity was measured by ^5lCr-release assay. The NK cell count was measured by flow cytometric analysis using monoclonal antibody (Mab) 3.2.3 and/or CD 3-8+ as markers for NK cells, and by immunohistochemical staining using Mab 3.2.3. Furthermore, interferon (IFN) α was administered to LC rats and the subsequent changes in hepatic NK activity and NK cell count were observed. In the large granular lymphocyte (LGL)-rich fraction (Fr.1, LGLs: 60-90%), the NK activity was significantly lower in the LC rats (40.0±3.8%) compared to that in the control rats (48.4±4.3%) (P<0.005). In addition, the number of NK cells in the liver tissues of the LC rats was significantly lower compared to that in the liver tissues of the control rats by morphometric analysis (P<0.05). For LC rats, NK activity of the Fr.1 24 hr after IFNα administration (5×10⁴ IU / 100 g body weight) increased significantly (P<0.005). Hepatic NK activity and NK cell count were reduced in the LC rats, and recovered following IFNα administration. The results obtained in this study may give clues to better understanding the impaired host defense mechanism in LC patients.     

Lanthanum-Induced Mucosal Alterations in the Stomach (Lanthanum Gastropathy): a Comparative Study Using an Animal Model

Lanthanum (La) carbonate (LC) is one of the most potent phosphate binders that prevents the elevation of serum phosphate levels in patients with end-stage renal diseases undergoing dialysis. LC binds strongly to dietary phosphate and forms insoluble complexes that pass through the gastrointestinal tract. La deposition in patients treated with LC is a recently documented finding particularly observed in gastric mucosa. We herein describe the detailed gastric mucosal lesions in 45 LC-treated patients and address the potential underlying pathologic mechanism using oral LC administration in rats. Microscopically, La deposition, as shown by subepithelial collections of plump eosinophilic histiocytes or small foreign body granulomas containing coarse granular or amorphous inclusion bodies, was found in the gastric mucosa of 44 (97.8%) of the 45 dialysis patients in the study cohort, which was most frequently associated with foveolar hyperplasia (37.8%). Using oral administration of rats with 1000 mg/day LC for 2 or more weeks, La deposition was consistently detectable in the gastric mucosa but not in other organs examined. In addition, various histologic alterations such as glandular atrophy, stromal fibrosis, proliferation of mucous neck cells, intestinal metaplasia, squamous cell papilloma, erosion, and ulcer were demonstrated in the rat model. Thus, orally administered LC can induce mucosal injury, designated here as La gastropathy, which may alter the local environment and result in La deposition in the gastric mucosa, thereby potentially inducing abnormal cell proliferation or neoplastic lesions.     

Behavioral analysis of consequences of chronic blockade of NMDA-type glutamate receptors in the early postnatal period in rats

In view of the hypothesis that glutamatergic dysfunction of brain can underlie the negative symptoms of schizophrenia (including cognitive deficit), the aim of this study was to develop a model of cognitive impairment in Wistar male rats after administration of a noncompetitive NMDA-receptor antagonist in early postnatal period. Rat pups were daily subcutaneously injected with 0.05 mg/kg MK-801 on postnatal days 7-49. On the 27th and 28th days 24 h after the last previous injection, the MK-801-treated rats demonstrated lower spontaneous locomotor and exploratory activity in comparison with saline control, however, they retained the reaction of hyperlocomotion which developed immediately after the MK-801 administration. In these rats, the anxiety level in the elevated plus-maze (on the 40th postnatal day) was found to be decreased, and the spatial learning in food rewarded task was negatively affected (on the 50th-54th days). It is suggested that impairment of the input of sensory information and its correct assessment by the animals can be associated with the early neonatal blockade of NMDA glutamate receptors.     

The locus coeruleus is directly implicated in L-DOPA-induced dyskinesia in parkinsonian rats: an electrophysiological and behavioural study

Despite being the most effective treatment for Parkinson's disease, L-DOPA causes a development of dyskinetic movements in the majority of treated patients. L-DOPA-induced dyskinesia is attributed to a dysregulated dopamine transmission within the basal ganglia, but serotonergic and noradrenergic systems are believed to play an important modulatory role. In this study, we have addressed the role of the locus coeruleus nucleus (LC) in a rat model of L-DOPA-induced dyskinesia. Single-unit extracellular recordings in vivo and behavioural and immunohistochemical approaches were applied in rats rendered dyskinetic by the destruction of the nigrostriatal dopamine neurons followed by chronic treatment with L-DOPA. The results showed that L-DOPA treatment reversed the change induced by 6-hydroxydopamine lesions on LC neuronal activity. The severity of the abnormal involuntary movements induced by L-DOPA correlated with the basal firing parameters of LC neuronal activity. Systemic administration of the LC-selective noradrenergic neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine did not modify axial, limb, and orolingual dyskinesia, whereas chemical destruction of the LC with ibotenic acid significantly increased the abnormal involuntary movement scores. These results are the first to demonstrate altered LC neuronal activity in 6-OHDA lesioned rats treated with L-DOPA, and indicate that an intact noradrenergic system may limit the severity of this movement disorder.     

Role of the locus coeruleus in the mechanism of different types of analgesia

The activity of antinociceptive mechanisms during exposure to cold swim stress (CSS), inescapable foot shock (FS) and morphine administration (10 mg/kg) was studied in rats subjected to bilateral lesions of locus coeruleus (LC). It has been shown that under all types of stimulation the latent periods (LP) of nociceptive reactions of paw licking and tail flick were significantly increased, as compared to baseline level, thus suggesting suppression of the pain sensitivity. In rats subjected to CSS and morphine administration significantly shorter LP were revealed in the experimental group, compared to the control, which suggested partial inhibition of antinociceptive mechanisms activity after LC lesion. FS did not cause any differences in the experimental and control groups. It is concluded that LC lesions cannot completely inhibit the antinociceptive mechanisms activated by CSS and morphine injection. In FS monoamine mechanisms of LC do not seem to play an important role in the functioning of antinociceptive mechanisms.     

静脉注射雌二醇对不同性周期雌鼠蓝斑中去甲肾上腺素能神经元放电的影响

静脉注射雌二醇可使非发情期雌鼠蓝斑(LC)中去甲肾上腺素(NE)能神经元放电增加,发情期雌鼠LC中NE能神经元放电减少。非发情期雌鼠LC中NE能神经元自发放电频率与注射雌二醇后放电频率之间存在着正相关。摘除卵巢雌鼠LC中NE能神经元放电频率比发情期、非发情期雌鼠均显著减少,但对雌二醇的反应与非发情期雌鼠相似,仍为放电增加。结果提示:静脉注射雌二醇可改变LC中NE能神经元的放电。此效应可能反映了内源性雌激素水平及LC中NE能神经元兴奋性的密切关系。     

Molecular validation of the acute phencyclidine rat model for schizophrenia: identification of translational changes in energy metabolism and neurotransmission

Administration of the noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist phencyclidine (PCP) to rodents is widely used as preclinical model for schizophrenia. Most studies on this model employ methods investigating behavior and brain abnormalities. However, little is known about the corresponding peripheral effects. In this study, we analyzed changes in brain and serum molecular profiles, together with alterations in behavior after acute PCP treatment of rats. Furthermore, abnormalities in peripheral protein expression of first and recent onset antipsychotic free schizophrenia patients were assessed for comparison with the preclinical model. PCP treatment induced hyperlocomotion and stereotypic behavior, which have been related to positive symptoms of schizophrenia. Multiplex immunoassay profiling of serum revealed molecular abnormalities similar to those seen in first and recent onset, antipsychotic free schizophrenia patients. Also, increased insulin levels were detected after administration of a glucose tolerance test (GTT), consistent with previous studies showing changes in insulin signaling in patients with schizophrenia. Finally, schizophrenia-relevant alterations in brain molecules were found in the hippocampus and to a lesser extent in the frontal cortex using liquid-chromatography mass spectrometry and (1)H nuclear magnetic resonance spectroscopy. In conclusion, this study identified behavioral and molecular alterations in the acute PCP rat model, which are also observed in human schizophrenia. We propose that the corresponding changes in serum in both animals and patients may have utility as surrogate markers in this model to facilitate discovery and development of novel drugs for treatment of certain pathological features of schizophrenia.     

干酪乳杆菌LC2W菌体的抗高血压作用

为探索干酪乳杆菌LC2W抗高血压作用的活性成分,收集了采用MRS液体培养基培养的干酪乳杆菌LC2W菌体,洗涤后重悬到10%(w/w)无菌脱脂乳中,至终浓度为1010CFU/mL。将菌悬液分成两组,一组直接进行冷冻干燥(活菌组);另一组在100℃水浴10 min后再进行冷冻干燥(灭活组)。按2.0×109CFU/Kg的剂量(活菌组)或相当浓度的灭活菌体对鼠龄17~18周的自发性高血压大鼠单次或连续灌胃15日,每日一次,对照组给予同样体积的脱脂乳。采用尾环法测定大鼠的收缩压和心率。连续灌胃试验中,于灌胃后4 h测定大鼠的收缩压(Systolic blood Pressure,SBP)和心律(Heart rate,HR)。采用称重法测定大鼠第1 d和第15 d时的体重。结果表明,灌喂LC2W菌体可以显著降低SHR的收缩压,这种作用在灌胃后4 h最显著(P<0.01);在连续灌胃试验中,无论是活菌组还是灭活组在第1、4、8、11和15 d都有显著的抗高血压作用(P<0.01)。未观察到LC2W菌体对实验动物心律和体重有明显的影响。上述结果表明在干酪乳杆菌菌体中存在热稳定性、具有抗高血压作用的物质。     

L-carnitine attenuates oxidative stress in hypertensive rats

The present study aimed to investigate whether l-carnitine (LC) protects the vascular endothelium and tissues against oxidative damage in hypertension. Antioxidant enzyme activities, glutathione and lipid peroxidation were measured in the liver and heart of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. Nitrite and nitrate levels and total antioxidant status (TAS) were evaluated in plasma, and the expression of endothelial nitric oxide synthase (eNOS) and p22phox subunit of NAD(P)H oxidase was determined in aorta. Glutathione peroxidase activity was lower in SHR than in WKY rats, and LC increased this activity in SHR up to values close to those observed in normotensive animals. Glutathione reductase and catalase activities, which were higher in SHR, tended to increase after LC treatment. No differences were found in the activity of superoxide dismutase among any animal group. The ratio between reduced and oxidized glutathione and the levels of lipid peroxidation were respectively decreased and increased in hypertensive rats, and both parameters were normalized after the treatment. Similarly, LC was able to reverse the reduced plasma nitrite and nitrate levels and TAS observed in SHR. We found no alterations in the expression of aortic eNOS among any group; however, p22phox mRNA levels showed an increase in SHR that was reversed by LC. In conclusion, chronic administration of LC leads to an increase in hepatic and cardiac antioxidant defense and a reduction in the systemic oxidative process in SHR. Therefore, LC might increase NO availability in SHR aorta by a reduction in superoxide anion production.     

Autophagy Reduces Neuronal Damage and Promotes Locomotor Recovery via Inhibition of Apoptosis After Spinal Cord Injury in Rats

Autophagy is an intracellular catabolic mechanism that maintains the balance of proteins, lipids and aging organelles. 3-Methyladenine (3-MA) is a selective inhibitor of autophagy, whereas rapamycin, an antifungal agent, is a specific inducer of autophagy, inhibiting the protein mammalian target of rapamycin. In the present study, we examined the role of autophagy, inhibited by 3-MA and enhanced by rapamycin, in a model of acute spinal cord injury in rats. We found that rapamycin could significantly increase the expression of microtubule-associated protein 1 light chain 3 (LC3) and Beclin1 at the injury site. At the same time, the number of neurons and astrocytes with LC3 positive in the spinal cord was upregulated with time. In addition, administration of rapamycin produced an increase in the Basso, Beattie and Bresnahan scores of injured rats, indicating high recovery of locomotor function. Furthermore, expression of the proteins Bcl-2 and Bax was upregulated and downregulated, respectively. By contrast, the results for rats treated with 3-MA, which inhibits autophagy, were the opposite of those seen with the rapamycin-treated rats. These results show that induction of autophagy can produce neuroprotective effects in acute spinal cord injury in rats via inhibition of apoptosis.     

Methamphetamine-Induced Depression of Monoamine Synthesis in the Rat: Development of Tolerance

Animals treated with high doses of amphetamines have been used as a model of schizophrenia due to the similarities between the psychosis associated with this mental disorder and that induced by chronic amphetamine abuse. When administered to naive rats in high doses, the amphetamine-like CNS stimulant methamphetamine produces drastic alterations in the neurochemical parameters of the neostriatal monoaminergic systems. These alterations are characterized by a decrease in the activities of the rate-limiting enzymes for dopamine and serotonin synthesis, as well as a decrease in the concentrations of both neurotransmitters and their metabolites. However, tolerance develops to these neurochemical effects when drug administration occurs in a pattern similar to that encountered during chronic amphetamine abuse. The results indicate that the neurochemical alterations produced by amphetamines in naive and tolerant animals differ widely. This suggests that the administration of high doses of amphetamine-like central stimulants to naive rats may not be an appropriate model for studying the neurochemical changes associated with psychosis and amphetamine abuse.     

损毁大鼠双侧蓝斑引起多脏器出血

目的和方法：用直流电极毁大鼠双侧蓝斑,观察膀胱及各内脏组织的出血性变化。结果：完全损毁双侧蓝斑枷恒定地引起严重的膀胱出血,并伴有其它脏器不规律性发生的充血或轻微出血。部分损毁双侧蓝斑亦可引起多脏器轻微的充血和出血,但膀胱出血不再恒定发生。切除肾上腺减轻应激反应,或应用组织按H2受体拮抗剂,对完全损毁双侧蓝斑引起的膀胱出血或其它脏器的组织学出血性变化无明显影响。结论：损毁大鼠双侧蓝斑引起的多脏器出血并非由于手术应激引起;也与组织胺H2受 体无关,其机制有待进一步研究。     

Altered Hypothalamic Signaling and Responses to Food Deprivation in Rats Fed a Low‐Carbohydrate Diet

Objective: To model how consuming a low‐carbohydrate (LC) diet influences food intake and body weight. Research Methods and Procedures: Food intake and body weight were monitored in rats with access to chow (CH), LC‐high‐fat (HF), or HF diets. After 8 weeks, rats received intracerebroventricular injections of a melanocortin agonist (melanotan‐II) and antagonist (SHU9119), and feeding responses were measured. At sacrifice, plasma hormones and hypothalamic expression of mRNA for proopiomelanocortin (POMC), melanocortin‐4 receptor, neuropeptide Y (NPY), and agouti related protein (AgRP) were assessed. A second set of rats had access to diet (chow or LC‐HF) for 4 weeks followed by 24 h food deprivation on two occasions, after which food intake and hypothalamic POMC, NPY, and AgRP mRNA expression were measured. Results: HF rats consumed more food and gained more weight than rats on CH or LC‐HF diets. Despite similar intakes and weight gains, LC‐HF rats had increased adiposity relative to CH rats. LC‐HF rats were more sensitive to melanotan‐II and less sensitive to SHU9119. LC‐HF rats had increased plasma leptin and ghrelin levels and decreased insulin levels, and patterns of NPY and POMC mRNA expression were consistent with those of food‐deprived rats. LC‐HF rats did not show rebound hyperphagia after food deprivation, and levels NPY, POMC, and AgRP mRNA expression were not affected by deprivation. Discussion: Our results demonstrate that an LC diet influences multiple systems involved in the controls of food intake and body weight. These data also suggest that maintenance on an LC‐HF diet affects food intake by reducing compensatory responses to food deprivation.     

Langerin expressing cells promote skin immune responses under defined conditions

There are conflicting data in the literature regarding the role of epidermal Langerhans cells (LC) in promoting skin immune responses. On one hand, LC can be extremely potent APCs in vitro, and are thought to be involved in contact hypersensitivity (CHS). On the other hand, it seems counterintuitive that a cell type continually exposed to pathogens at the organism's barrier surfaces should readily trigger potent T cell responses. Indeed, LC depletion in one model led to enhanced contact hypersensitivity, suggesting they play a negative regulatory role. However, apparently similar LC depletion models did not show enhanced CHS, and in one case showed reduced CHS. In this study we found that acute depletion of mouse LC reduced CHS, but the timing of toxin administration was critical: toxin administration 3 days before priming did not impair CHS, whereas toxin administration 1 day before priming did. We also show that LC elimination reduced the T cell response to epicutaneous immunization with OVA protein Ag. However, this reduction was only observed when OVA was applied on the flank skin, and not on the ear. Additionally, peptide immunization was not blocked by depletion, regardless of the site. Finally we show that conditions which eliminate epidermal LC but spare other Langerin(+) DC do not impair the epicutaneous immunization response to OVA. Overall, our results reconcile previous conflicting data in the literature, and suggest that Langerin(+) cells do promote T cell responses to skin Ags, but only under defined conditions.     

Methyl parathion increases neuronal activities in the rat locus coeruleus

Exposure to organophosphate insecticides induces undesirable behavioral changes in humans, including anxiety and irritability, depression, cognitive disturbances and sleep disorders. Little information currently exists concerning the neural mechanisms underlying such behavioral changes. The brain stem locus coeruleus (LC) could be a mediator of organophosphate insecticide-induced behavioral toxicities since it contains high levels of acetylcholinesterase and is involved in the regulation of the sleep-wake cycle, attention, arousal, memory, and pathological processes, including anxiety and depression. In the present study, using a multi-wire recording technique, we examined the effects of methyl parathion, a commonly used organophosphate insecticide, on the firing patterns of LC neurons in rats. Systemic administration of a single dose of methyl parathion (1 mg/kg, i.v.) increased the spontaneous firing rates of LC neurons by 240% but did not change the temporal relationships among the activities of multiple LC neurons. This dose of methyl parathion induced a 50% decrease in blood acetylcholinesterase activity and a 48% decrease in LC acetylcholinesterase activity. The methyl parathion-induced excitation of LC neurons was reversed by administration of atropine sulfate, a muscarinic receptor antagonist, indicating an involvement of muscarinic receptors. The methyl parathion-induced increase in LC neuronal activity returned to normal within 30 min while the blood acetylcholinesterase activity remained inhibited for over 1 h. These data indicate that methyl parathion treatment can elicit excitation of LC neurons. Such excitation could contribute to the neuronal basis of organophosphate insecticide-induced behavioral changes in human.     

Pallidal hyperdopaminergic innervation underlying D2 receptor-dependent behavioral deficits in the schizophrenia animal model established by EGF

Epidermal growth factor (EGF) is one of the ErbB receptor ligands implicated in schizophrenia neuropathology as well as in dopaminergic development. Based on the immune inflammatory hypothesis for schizophrenia, neonatal rats are exposed to this cytokine and later develop neurobehavioral abnormality such as prepulse inhibition (PPI) deficit. Here we found that the EGF-treated rats exhibited persistent increases in tyrosine hydroxylase levels and dopamine content in the globus pallidus. Furthermore, pallidal dopamine release was elevated in EGF-treated rats, but normalized by subchronic treatment with risperidone concomitant with amelioration of their PPI deficits. To evaluate pathophysiologic roles of the dopamine abnormality, we administered reserpine bilaterally to the globus pallidus to reduce the local dopamine pool. Reserpine infusion ameliorated PPI deficits of EGF-treated rats without apparent aversive effects on locomotor activity in these rats. We also administered dopamine D1-like and D2-like receptor antagonists (SCH23390 and raclopride) and a D2-like receptor agonist (quinpirole) to the globus pallidus and measured PPI and bar-hang latencies. Raclopride (0.5 and 2.0 μg/site) significantly elevated PPI levels of EGF-treated rats, but SCH23390 (0.5 and 2.0 μg/site) had no effect. The higher dose of raclopride induced catalepsy-like changes in control animals but not in EGF-treated rats. Conversely, local quinpirole administration to EGF-untreated control rats induced PPI deficits and anti-cataleptic behaviors, confirming the pathophysiologic role of the pallidal hyperdopaminergic state. These findings suggest that the pallidal dopaminergic innervation is vulnerable to circulating EGF at perinatal and/or neonatal stages and has strong impact on the D2-like receptor-dependent behavioral deficits relevant to schizophrenia.     

Arousal effects of orexin-A correlate with GLU release from the locus coeruleus in rats

Although orexin was found to promote food intake, recent reports proposed its involvement in the regulation of vigilance. To study the mechanism of how orexin affects arousal, we analyzed glutamate (GLU) release from the locus coeruleus (LC) in rats after systemic injection of orexin-A. Baseline levels of orexin-A in the LC were significantly higher during the dark period than the light period. Intravenous administration of orexin-A increased GLU levels as well as orexin in the LC, simultaneously promoting wakefulness. These results suggest that increases in GLU release may reflect the arousal-inducing effects of orexin.