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Schizophrenia manifests itself primarily with positive symptoms, negative symptoms and cognitive disorders. Animal models of mental diseases seem to be an important tool in understanding key theories related with pathophysiology of the disorder and are used to assess efficacy of new drugs. References describe four basic groups of animal models of schizophrenia, such as: models created by pharmacological intervention, genetic models, lesion models and models of developmental disorders of primary brain structures. Of the models referred to above, the group of developmental disorder models is particularly noteworthy, as they are primarily easy to use, and the methods are highly sensitive. High scientific value of these models is associated with the neurodevelopmental theory which stipulates that at an early stage of body development, a number of interactions between genetic and environmental factors may affect the development of neurons which may cause disorders of brain cytoarchitecture development.We review six developmental models of schizophrenia in rats (MAM - methylooxymethanol acetate, prenatal stress, maternal deprivation, isolation rearing, prenatal immune challenge and maternal malnutrition) that are all validated by disruption in PPI.
Introduction. The standard porcine-derived pancreatic enzyme replacement therapy (PERT) is a lifesaving treatment for patients with diseases causing exocrine pancreatic insufficiency (EPI). An attempt to replace PERT with microbial enzymes were undertaken. The aim was to highlight whether the mode of application, mixed with food or applied directly to the stomach, of pancreatic-like enzymes of microbial origin (PLEM) can affect their activity along the gastrointestinal tract. Materials and method. The activity of amylase, lipase and proteinase in the stomach, duodenum and ileum were tested in EPI pigs (n=6) after supplementation of PLEM, either orally – before and during feed consumption – or via the stomach – before and during feed consumption. Healthy pigs not treated with PLEM (n=3) served as controls. Activity of the enzymes measured in the chyme were obtained together with the digesta pH. Activity of the enzymatic residues in the stool samples was also checked. Results. The highest pancreatic enzyme activities were found in the duodenum of the healthy pigs (amylase 162,68 kU/ mL, lipase 507,34 kU/mL and protolitic (trypsin) activity 357,60 kU/mL). Nevertheless, the microbial enzymes remained also active along the entire length of the GIT – including stomach in EPI pigs, regardless of their route of administration. However, activity level was significantly lower. Discussion. Results indicate that the activity pattern of PLEM in the small intestine mimics the activity of the natural endogenous pancreatic enzymes in healthy pigs. The most physiological features of PLEM were observed when enzymes were offered orally. The magnitude of PLEM activity in the stomach of EPI pigs was essential and significantly higher than that measured in healthy pigs, thus being somewhat not physiological, and for health reasons of the patients should be further explored. Interestingly, specific trypsin-like activity was measured in all parts of the GIT after PLEM application. However, proteolytic activity of the experimental proteaze in in vitro studies did not exhibit trypsin-like activity.
Evidence suggests that maternal immune activation (MIA) during pregnancy is a risk factor for neurodevelopmental disturbances including autism spectrum disorders (ASDs). Animal models support this linkage and demonstrate that MIA in rodents leads to behavioral alterations in offspring that are characteristic of autism. However, the mechanism by which MIA causes long‑term behavioral deficits is unknown. Investigation of the links between maternal infection during pregnancy, mitochondrial dysfunction, and behavioral alterations in offspring. To induce MIA, pregnant Wistar rats were injected with lipopolysaccharide (LPS; 0.1mg/kg, intraperitoneally) on gestational day 9.5, a time point analogous to the first trimester of human gestation. Brains from adolescent offspring were evaluated for mitochondrial outcomes. Prenatal exposure to MIA led to anxiety and repetitive behavior. Adolescent offspring of MIA dams exhibited up-regulation of pro-inflammatory cytokines, oxidative stress, and disturbances in redox homoeostasis. Moreover, substantial mitochondrial abnormalities were observed. A significant decrease in mitochondrial membrane potential and changes in ATP production could be attributed to a downregulation of complex I and IV. Deregulated bioenergetics of mitochondria were accompanied by impaired mitochondrial dynamics, altered expression of fusion/fission machinery proteins including mitofusin 1 and 2 (Mfn1, Mfn2), Opa1, dynamin related protein‑1 (Drp1), and fission protein 1 (Fis1). We also demonstrated lower expression of the genes coding for PGC1α and TFAM (PPARGC1A and TFAM, respectively) that are responsible for mitochondrial biogenesis. MIA at early gestation leads to long-lasting effects on the mitochondrial bioenergetics, dynamics, and biogenesis in the offspring which can lead to synaptic dysfunction and behavioral abnormalities similar to ASD. FINANCIAL SUPPORT: Supported by the NSC grant 2016/23/D/NZ4/03572.
Background. To compare the anticonvulsant potency of 10 various p-isopropoxyphenylsuccinimide (IPPS) derivatives [i.e., IPPS (IPPS); N-(morpholinomethyl)-IPPS (MM-IPPS); N-(anilinomethyl)-IPPS (AM-IPPS); N-hydroxymethyl-IPPS (HM-IPPS); N-(p-acetylphenyl)-IPPS (AP-IPPS); N-(p-ethoxycarbonylphenylmethyl)-IPPS (ECPM-IPPS); N-(m-bromoanilinomethyl)-IPPS (BAM-IPPS); N-(o-carboxyanilinomethyl)-IPPS (o-CAMIPPS); N-(m-carboxyanilinomethyl)-IPPS (m-CAM-IPPS); N-(p-carboxyanilinomethyl)-IPPS (p-CAM-IPPS)] in the maximal electroshock-induced seizure threshold (MEST) test in mice. Material and methods. Linear regression analysis of doses of IPPS derivatives and their threshold increases in the MEST test in mice allowed to calculate TID20 values i.e., doses of the tested IPPS derivatives that elevate by 20% the seizure threshold in IPPS-treated mice over the threshold in control animals. Results. A ll t he studied IPPS derivatives (i.e., IPPS, MMIPPS, HM-IPPS, AP-IPPS, AM-IPPS, ECPM-IPPS, o-CAM-IPPS, m-CAM-IPPS, p-CAM-IPPS and BAM-IPPS) increased in a dose dependent manner the threshold for maximal electroshockinduced seizures in mice. The TID20 values in the MEST test for IPPS, AP-IPPS, AM-IPPS, BAMIPPS, o-CAM-IPPS, m-CAM-IPPS, p-CAM-IPPS, ECPM-IPPS, HM-IPPS, and MM-IPPS were 60.44 mg/kg, 86.30 mg/kg, 44.69 mg/kg, 103.34 mg/kg, 22.43 mg/kg, 52.84 mg/kg, 80.85 mg/kg, 109.75 mg/kg, 32.62 mg/kg and 53.50 mg/kg, respectively. Conclusions. The studied IPPS derivatives with respect to their anticonvulsant potency in the MEST test can be arranged as follows: o-CAM-IPPS > HM-IPPS > AM-IPPS > m-CAM-IPPS > MM-IPPS > IPPS > p-CAM-IPPS >AP-IPPS > BAM-IPPS > ECPM-IPPS.
Decades of studies on alcohol dependence showed that it is a very complex and multifactorial disorder. Several receptor systems are involved in development and susceptibility to alcohol abuse; however, there are some which play a crucial role in its pathogenesis, e.g. dopaminergic or opioid system. In this paper, an effort is made to explain the role of endogenous opioid system activity in alcohol dependence. To achieve the goal, we use a unique model is used which shows mice lines that are divergently selected for high (HA) and low (LA) stress-induced analgesia. This process allowed for selecting individuals characterised by hyperactive (HA) or hypoactive (LA) opioid system. Basing on the performed experiments, we proved that delta opioid receptors play a critical role in the development of addiction. The most notable achievement is an unspecific reaction of mice with the hyperactive opioid system to naloxone – an unspecific opioid system antagonist, which is currently approved in the pharmacotherapy of dependent patients.
Animal models based on N-methyl-d-aspartate (NMDA) receptor blockade have been widely reported. Ketamine and MK- 801, the two noncompetitive antagonists of NMDA receptors, produce behaviors related to schizophrenia and exacerbated symptoms in patients with schizophrenia. The study presented here investigated the effect of subchronic dosing (once-daily, 7 day) of histamine H3 receptor (H3R) antagonists, ciproxifan (CPX) (3 mg/kg, i.p.) and clobenpropit (CBP) (15 mg/kg, i.p) including clozapine (CLZ) (3.0 mg/kg, i.p.) and chlorpromazine (CPZ) (3.0 mg/kg, i.p.), the atypical and typical antipsychotic, respectively, on MK-801(0.2 mg/kg, i.p.)-induced locomotor activity, and dopamine and histamine levels in rats. Atypical and typical antipsychotic was used to serve as clinically relevant reference agents to compare the effects of the H3R antagonists. MK-801 significantly increased horizontal activity which was reduced with CPX and CBP. The attenuation of MK-801-induced locomotor hyperactivity produced CPX and CBP were comparable to CLZ and CPZ. Dopamine and histamine levels were measured in striatum and hypothalamus, respectively, of rat brain. The MK-801 induced increase of the striatal dopamine level was reduced in rats pretreated with CPX and CBP including CLZ. CPZ also significantly lowered striatal dopamine levels, though the decrease was less robust compared to CLZ, CPX and CBP. MK-801 increased histamine content although to a lesser degree. Subchronic treatment with CPX and CBP exhibited further increased histamine levels in the hypothalamus compared to MK-801 treatment alone. Histamine H3 receptor agonist, R-α methylhistamine (10 mg/kg, i.p.) counteracted the effect of CPX and CBP. The findings of the present study support our previous work showing positive effects of CPX and CBP on MK-801-induced schizophrenia like behaviors in rodents. However, clinical studies have reported no antipsychotic effects with histamine H3 receptor antagonists.
Glial pathology and energy metabolism changes in the brain precede symptoms of Parkinson’s disease (PD) and multiple other neurodegenerative diseases. Astrocytes govern and regulate a large part of the energy metabolism in the brain. Prolonged impairment of astrocytic functions could increase the vulnerability of dopaminergic neurons in the substantia nigra (SN). In this model, 40‑50% of dopaminergic neurons were selectively killed, causing transient locomotor disability compensated with time. We also induced death of astrocytes in the SN, simultaneously activating microglia but sparing the dopaminergic neurons. The astrocytes replenished after toxin withdrawal. We studied multiple markers of energy metabolism and mitochondrial oxidative phosphorylation (OxPhos) complex and supercomplex functioning during the early stages of neurodegeneration and compensation in the SN and striatum (STR). Death of astrocytes diminished the capability of the dopaminergic system to compensate for the degeneration of neurons. It caused a local energy deprivation, a shift in the usage of energy substrates, via increased glycogenolysis and glycolysis markers, ketone bodies availability, and fatty acid transport in remaining glial cells. Increased neuronal expression of CPT1c and astrocytic expression of CPT1a suggest adaptation in fatty acid use. On the other hand, lesion of dopaminergic neurons influenced OxPhos system and enhanced its functioning. Microglia activation also plays an important role in the processes of degeneration, compensation, and energy metabolism regulation. Modulation of its activation phenotypes might be beneficial towards the indicated processes. Astrocyte and microglia energetic influence is one of the factors in the neuronal compensatory mechanisms of dopaminergic system and might have a leading role in presymptomatic PD stages.
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