RESUMO
Limited experimental models exist to assess drug toxicity in pediatric populations. We recently reported how a multi-age rat model could be used for pre-clinical studies of comparative drug toxicity in pediatric populations. The objective of this study was to expand the utility of this animal model, which previously demonstrated an age-dependent sensitivity to the classic nephrotoxic compound, gentamicin, to another nephrotoxicant, namely cisplatin (Cis). Sprague-Dawley rats (10, 25, 40 and 80 days old) were injected with a single dose of Cis (0, 1, 3 or 6 mg kg(-1) i.p.). Urine samples were collected prior and up to 72 h after treatment in animals that were >or= 25 days old. Several serum, urinary and 'omic' injury biomarkers as well as renal histopathology lesions were evaluated. Statistically significant changes were noted with different injury biomarkers in different age groups. The order of age-related Cis-induced nephrotoxicity was different than our previous study with gentamicin: 80 > 40 > 10 > 25 day-old vs 10 >or= 80 > 40 > 25-day-old rats, respectively. The increased levels of kidney injury molecule-1 (Kim-1: urinary protein/tissue mRNA) provided evidence of early Cis-induced nephrotoxicity in the most sensitive age group (80 days old). Levels of Kim-1 tissue mRNA and urinary protein were significantly correlated to each other and to the severity of renal histopathology lesions. These data indicate that the multi-age rat model can be used to demonstrate different age-related sensitivities to renal injury using mechanistically distinct nephrotoxicants, which is reflected in measurements of a variety of metabolite, gene transcript and protein biomarkers.
Assuntos
Envelhecimento/fisiologia , Cisplatino/toxicidade , Nefropatias/induzido quimicamente , Rim/metabolismo , Fatores Etários , Animais , Biomarcadores/metabolismo , Biomarcadores/urina , Criança , Suscetibilidade a Doenças/metabolismo , Suscetibilidade a Doenças/patologia , Gentamicinas/toxicidade , Humanos , Rim/patologia , Nefropatias/patologia , Nefropatias/urina , Modelos Animais , Pediatria , Ratos , Ratos Sprague-Dawley , Sensibilidade e EspecificidadeRESUMO
Exposure of the vasculature to vasodilators, pharmaceuticals and industrial chemicals may lead to injury of the blood vessel wall in animals. Vascular injury may begin with changes in the permeability of vascular endothelial cell and vessels, resulting in possible hemorrhage and edema leading subsequently to immune cell infiltration. The present study was undertaken to determine if the direct exposure of the Sprague Dawley rat mesenteric vasculature through the perfusion of aminophylline, fenoldopam, compound 48/80, histamine or serotonin has any such effects on the blood vessels, and if the two vital dyes Monastral blue B and Evans blue can be used to enhance the visualization of the vascular damage. Microscopic visualization was enhanced by the use of dyes and a variety of alterations of the perfused mesenteric vessels were detected, including varying degrees of mast cell degranulation, microvascular vasodilatation and increased vascular permeability. Macroscopic evidence of vascular damage was minimal. This study demonstrates that in situ perfusion of the rat mesentery is a simple and useful method to eliminate the influence of a variety of physiologic influences or homeostatic responses and can be used to further investigate drug-induced vascular damage.
Assuntos
Artérias Mesentéricas/efeitos dos fármacos , Veias Mesentéricas/efeitos dos fármacos , Microvasos/efeitos dos fármacos , Aminofilina/toxicidade , Animais , Permeabilidade Capilar/efeitos dos fármacos , Degranulação Celular/efeitos dos fármacos , Fenoldopam/toxicidade , Histamina/toxicidade , Técnicas In Vitro , Masculino , Mastócitos/efeitos dos fármacos , Mastócitos/fisiologia , Artérias Mesentéricas/patologia , Veias Mesentéricas/patologia , Microvasos/fisiologia , Ratos , Ratos Sprague-Dawley , Serotonina/toxicidade , Vasodilatação/efeitos dos fármacos , p-Metoxi-N-metilfenetilamina/toxicidadeRESUMO
The anesthetic gas nitrous oxide (N2O) and the volatile anesthetic isoflurane (ISO) are commonly used in surgical procedures for human infants and in veterinary and laboratory animal practice to produce loss of consciousness and analgesia. Recent reports indicate that exposure of the developing brain to general anesthetics that block N-methyl-D-aspartate (NMDA) glutamate receptors or potentiate GABA(A) receptors can trigger widespread apoptotic neurodegeneration. In the present study, the question arises whether a relatively low dose of ISO alone or its combination with N2O entails significant risk of inducing enhanced apoptosis. In addition, the role of L-carnitine to attenuate these effects was also examined. Postnatal day 7 (PND-7) rat pups were exposed to N2O (75%) or a low dose of ISO (0.55%) alone, or N2O plus ISO for 2, 4, 6 or 8 h with or without L-carnitine. The neurotoxic effects were evaluated 6 h after completion of anesthetic administration. No significant neurotoxic effects were observed for the animals exposed to N2O or ISO alone. However, enhanced apoptotic cell death was apparent when N2O was combined with ISO at exposure durations of 6 h or more. Co-administration of L-carnitine (300 or 500 mg/kg, i.p.) effectively protected neurons from the anesthetic-induced damage. These data indicate that 6 h or more of inhaled anesthetic exposure consisting of a combination of N2O and ISO results in enhanced neuronal apoptosis, and L-carnitine effectively blocks the neuronal apoptosis caused by inhalation anesthetics in the developing rat brain.
Assuntos
Anestésicos Inalatórios/toxicidade , Apoptose/efeitos dos fármacos , Carnitina/farmacologia , Lobo Frontal/citologia , Neurônios/efeitos dos fármacos , Complexo Vitamínico B/farmacologia , Animais , Animais Recém-Nascidos , Caspase 3/metabolismo , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Fluoresceínas , Isoflurano/toxicidade , Molécula L1 de Adesão de Célula Nervosa/metabolismo , Neurônios/citologia , Óxido Nitroso/toxicidade , Compostos Orgânicos , Ratos , Ratos Sprague-Dawley , Ácidos Siálicos/metabolismo , Fatores de Tempo , Proteína X Associada a bcl-2/metabolismo , Proteína bcl-X/metabolismoRESUMO
Recent data suggest that anesthetic drugs may cause widespread and dose-dependent apoptotic neurodegeneration during development. The window of vulnerability to this neurotoxic effect, particularly with N-methyl-D-aspartate (NMDA) antagonists such as ketamine, is restricted to the period of synaptogenesis. The purposes of this study are to determine whether treatment of forebrain cultures with ketamine results in a dose-related increase in neurotoxicity and whether upregulation of NMDA receptor subunit NR1 promotes ketamine-induced apoptosis. Forebrain cultures were treated for 12 h with 0.1, 1, 10 and 20 microM ketamine or co-incubated with NR1 antisense oligonucleotide (2 microM). After washout of the ketamine, cultures were kept in serum-containing medium (in presence of glutamate) for 24 h. Application of ketamine (10 and 20 microM) resulted in a substantial increase in DNA fragmentation as measured by cell death enzyme-linked immunosorbent assay, increased number of terminal dUTP nick-end labeling positive cells, and a reduction in mitochondrial metabolism of the dye 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide. No significant effect was seen in the release of lactate dehydrogenase, indicating that cell death presumably occurred via an apoptotic mechanism. Co-incubation of ketamine with NR1 antisense significantly reduced ketamine-induced apoptosis. Western analysis showed that neurotoxic concentrations of ketamine increased Bax and NR1 protein levels. NR1 antisense prevented this increase caused by ketamine, suggesting that ketamine-induced cell death is associated with a compensatory upregulation of the NMDA receptor. These data suggest that NR1 antisense offers neuroprotection from apoptosis in vitro, and that upregulation of the NR1 following ketamine administration is, at least, partially responsible for the observed apoptosis.
Assuntos
Anestésicos Dissociativos/toxicidade , Apoptose/efeitos dos fármacos , Ketamina/toxicidade , Prosencéfalo/efeitos dos fármacos , Prosencéfalo/patologia , Receptores de N-Metil-D-Aspartato/metabolismo , Animais , Western Blotting , Células Cultivadas , Relação Dose-Resposta a Droga , Ensaio de Imunoadsorção Enzimática , Marcação In Situ das Extremidades Cortadas , Oligonucleotídeos Antissenso/farmacologia , Prosencéfalo/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Ratos , Tionucleotídeos/farmacologia , Proteína X Associada a bcl-2RESUMO
Antinociception was assessed in male CD-1 mice by a modification of Haffner's tail-clamp procedure. The H1 blockers, including an ethylenediamine (pyrilamine), an ethanolamine (diphenhydramine), a phenothiazine (methdilazine), a piperazine (cyclizine) and an alkylamine (chlorpheniramine), all produced antinociception when given alone to mice and also caused potentiation when combined with morphine.
Assuntos
Analgésicos , Antagonistas dos Receptores Histamínicos H1/farmacologia , Morfina/farmacologia , Animais , Clorfeniramina/farmacologia , Ciclizina/farmacologia , Difenidramina/farmacologia , Sinergismo Farmacológico , Masculino , Camundongos , Fenotiazinas/farmacologia , Pirilamina/farmacologiaRESUMO
Ketamine is a widely used pediatric anesthetic recently reported (C. Ikonomidou et al., 1999, Science 283, 70-74) to enhance neuronal death in neonatal rats. To confirm and extend these results, we treated four groups of PND 7 rats with seven sc doses, one every 90 min, of either saline, 10 mg/kg ketamine, 20 mg/kg ketamine, or a single dose of 20 mg/kg ketamine. The repeated doses of 20 mg/kg ketamine increased the number of silver-positive (degenerating) neurons in the dorsolateral thalamus to a degree comparable to previous results (Ikonomidou et al., 1999, Science 283, 70-74), i.e., 28-fold vs. 31-fold respectively. However, blood levels of ketamine immediately after the repeated 20 mg/kg doses were about 14 micrograms/ml, about seven-fold greater than anesthetic blood levels in humans (J. M. Malinovsky et al., 1996, Br. J. Anaesth. 77, 203-207; R. A. Mueller and R. Hunt, 1998, Pharmacol. Biochem. Behav. 60, 15-22). Levels of ketamine in blood following exposure to the multiple 10 mg/kg doses of ketamine or to a single 20 mg/kg dose ranged around 2-5 micrograms/ml; although these blood levels are close to an anesthetic level in humans, they failed to produce neurodegeneration. To investigate the mode of ketamine-induced neuronal death, coronal sections were stained with both Fluoro-Jade B (a green fluorescent stain selective for neurodegeneration) and DAPI (a blue DNA stain), as well as for caspase-3 (using an antisera labeled red with rhodamine). These histochemical results confirmed the developmental neurotoxicity of ketamine, demonstrated that Fluoro-Jade B (FJ-B), like silver methods, successfully stained degenerating neurons in neonatal rats, and indicated that ketamine acts by increasing the rate of neuronal apoptosis.
Assuntos
Apoptose/efeitos dos fármacos , Antagonistas de Aminoácidos Excitatórios/toxicidade , Ketamina/toxicidade , Sistema Nervoso/crescimento & desenvolvimento , Sistema Nervoso/patologia , Neurônios/patologia , Síndromes Neurotóxicas/patologia , Animais , Animais Recém-Nascidos , Encéfalo/patologia , Química Encefálica/efeitos dos fármacos , Relação Dose-Resposta a Droga , Antagonistas de Aminoácidos Excitatórios/sangue , Feminino , Fluoresceínas , Corantes Fluorescentes , Ketamina/sangue , Masculino , Sistema Nervoso/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Compostos Orgânicos , Ratos , Ratos Sprague-Dawley , Coloração pela Prata , Tálamo/patologiaRESUMO
Antinociception (ANTI) was assessed in male CD-1 mice by a modification of Haffner's tail clamp procedure. Studies revealed that tripelennamine (Tp) alone produced antinociception (ANTI) in mice and also caused potentiation when combined with morphine (M) or nalbuphene (NB). Naloxone (Nx) only partially blocked the effect of Tp, but fully blocked M. Although atropine (At) had no intrinsic ANTI activity, it enhanced that of Tp but not M. Histamine (Hm) had no intrinsic ANTI activity, nor did it interact with either Tp or M. The partial abolition of Tp ANTI, in contrast to complete blockade of M effects with Nx, appears to indicate that Tp can stimulate the opiate receptor as well as another receptor for ANTI at a different locus. The combination of Tp with various opiates may have considerable abuse potential.
Assuntos
Analgesia , Entorpecentes/farmacologia , Tripelenamina/farmacologia , Animais , Atropina/farmacologia , Relação Dose-Resposta a Droga , Interações Medicamentosas , Histamina/farmacologia , Masculino , Camundongos , Morfina/farmacologia , Nalbufina/farmacologia , Naloxona/farmacologiaRESUMO
Influence of protein deficiency on the neurobehavioral toxicity of styrene during gestation and early infancy was studied in rats. Eye opening and fur growth were delayed in rat pups born to dams receiving a low protein diet. These pups also showed a delay in the development of surface and air righting reflexes and cliff avoidance response and a marginal increase in the levels of dopamine and serotonin receptors in comparison to those born to dams receiving a normal protein diet. Alterations in these parameters were more marked in pups born to dams exposed to styrene and receiving a low protein diet. In addition, these pups also showed a significant decrease in the activity of monoamine oxidase, Na+, K(+)-ATPase and succinic dehydrogenase as well as significant increases in motor activity and receptor sensitivity when compared to rat pups born to dams receiving a low protein diet. No significant alterations in behavioral and biochemical parameters were observed in the pups born to dams exposed to styrene and receiving a normal protein diet at this dose level. These results suggest that protein deficiency during early life renders the animals more susceptible to styrene.
Assuntos
Comportamento Animal/efeitos dos fármacos , Desnutrição Proteico-Calórica/psicologia , Estirenos/toxicidade , Animais , Comportamento Animal/fisiologia , Encéfalo/efeitos dos fármacos , Encéfalo/patologia , Feminino , Atividade Motora/efeitos dos fármacos , Tamanho do Órgão/efeitos dos fármacos , Gravidez , Desnutrição Proteico-Calórica/patologia , Desnutrição Proteico-Calórica/fisiopatologia , Ratos , Ratos Endogâmicos , Estireno , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologiaRESUMO
The antioxidants butylated hydroxytoluene (BHT) and ethoxyquin protected rats against intoxication and mortality normally produced by hexachlorophene (HCP, 100 mg/kg). BHT also prevented the elevation of cerebrospinal fluid pressure, a central nervous system effect of HCP poisoning. In addition, both phenobarbital and SKF-525A protected against HCP poisoning, with the barbiturate also offering significant protection against triethyltin. L-Ascorbic acid, vitamin E, N,N-diphenyl-p-phenylenediamine and reduced and oxidized glutathione over a range of doses were ineffective in preventing HCP lethality. The protective effect of phenobarbital against HCP and triethyltin intoxication further supports existing evidence of a common or similar mechanism of toxic action for these two structurally dissimilar compounds.
Assuntos
Antídotos/farmacologia , Hidroxitolueno Butilado/farmacologia , Hexaclorofeno/intoxicação , Animais , Antioxidantes/farmacologia , Edema Encefálico/prevenção & controle , Edema/prevenção & controle , Hexaclorofeno/antagonistas & inibidores , Pressão Intracraniana/efeitos dos fármacos , Masculino , Ratos , Compostos de Trietilestanho/intoxicaçãoRESUMO
Propranolol was infused in SHR subcutaneously for 7 days at two concentrations (either 3.75 or 7.5 mg kg-1 day) via a minipump. Mean blood pressure and heart rate measured under pentobarbitone anaesthesia on day 7 after implantation showed a significant dose-dependent decrease in both propranolol-treated groups. In the low-dose propranolol-treated rats, there was no change in contractile responses to phenylephrine over controls. In rats receiving the higher dose of propranolol there was a significant increase in the response to phenylephrine. There was no change in the relaxation response of any of the groups to isoprenaline. The results indicate that propranolol, while lowering blood pressure and heart rate, is also modifying the alpha-receptor response of the vascular wall in the spontaneously hypertensive rat.
Assuntos
Hemodinâmica/efeitos dos fármacos , Hipertensão/fisiopatologia , Propranolol/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Implantes de Medicamento , Frequência Cardíaca/efeitos dos fármacos , Masculino , Pressão Osmótica , Propranolol/administração & dosagem , Ratos , Ratos Endogâmicos , Vasoconstrição/efeitos dos fármacosRESUMO
Previously our laboratory has shown that ketamine exposure (24h of clinically relevant anesthesia) causes significant increases in neuronal cell death in perinatal rhesus monkeys. Sensitivity to this ketamine-induced neurotoxicity was observed on gestational days 120-123 (in utero exposure via maternal anesthesia) and on postnatal days (PNDs) 5-6, but not on PNDs 35-37. In the present study, six monkeys were exposed on PND 5 or 6 to intravenous ketamine anesthesia to maintain a light surgical plane for 24h and six control animals were unexposed. At 7 months of age all animals were weaned and began training to perform a series of cognitive function tasks as part of the National Center for Toxicological Research (NCTR) Operant Test Battery (OTB). The OTB tasks used here included those for assessing aspects of learning, motivation, color discrimination, and short-term memory. Subjects responded for banana-flavored food pellets by pressing response levers and press-plates during daily (M-F) test sessions (50 min) and were assigned training scores based upon their individual performance. As reported earlier (Paule et al., 2009) beginning around 10 months of age, control animals significantly outperformed (had higher training scores than) ketamine-exposed animals for approximately the next 10 months. For animals now over 3 and one-half years of age, the cognitive impairments continue to manifest in the ketamine-exposed group as poorer performance in the OTB learning and color and position discrimination tasks, as deficits in accuracy of task performance, but also in response speed. There are also apparent differences in the motivation of these animals which may be impacting OTB performance. These observations demonstrate that a single 24-h episode of ketamine anesthesia, occurring during a sensitive period of brain development, results in very long-lasting deficits in brain function in primates and provide proof-of-concept that general anesthesia during critical periods of brain development can result in subsequent functional deficits. Supported by NICHD, CDER/FDA and NCTR/FDA.
Assuntos
Anestésicos Dissociativos/efeitos adversos , Transtornos Cognitivos/induzido quimicamente , Ketamina/efeitos adversos , Anestésicos Dissociativos/administração & dosagem , Animais , Animais Recém-Nascidos , Comportamento Animal/efeitos dos fármacos , Interpretação Estatística de Dados , Aprendizagem por Discriminação/efeitos dos fármacos , Esquema de Medicação , Infusões Intravenosas , Ketamina/administração & dosagem , Macaca mulatta , Masculino , Memória de Curto Prazo/efeitos dos fármacos , Motivação/efeitos dos fármacos , Reforço Psicológico , Fatores de Tempo , DesmameRESUMO
Repeated administration of phencyclidine (PCP), an N-methyl-d-aspartate (NMDA) receptor antagonist, during development, may result in neuronal damage that leads to behavioral deficits in adulthood. The present study examined the potential neurotoxic effects of PCP exposure (10mg/kg) in rats on postnatal days (PNDs) 7, 9 and 11 and the possible underlying mechanism(s) for neurotoxicity. Brain tissue was harvested for RNA extraction and morphological assessments. RNA was collected from the frontal cortex for DNA microarray analysis and quantitative RT-PCR. Gene expression profiling was determined using Illumina Rat Ref-12 Expression BeadChips containing 22,226 probes. Based on criteria of a fold-change greater than 1.4 and a P-value less than 0.05, 19 genes including NMDAR1 (N-methyl-d-aspartate receptor) and four pro-apoptotic genes were up-regulated, and 25 genes including four anti-apoptotic genes were down-regulated, in the PCP-treated group. In addition, the schizophrenia-relevant genes, Bdnf (Brain-derived neurotrophic factor) and Bhlhb2 (basic helix-loop-helix domain containing, class B, 2), were significantly different between the PCP and the control groups. Quantitative RT-PCR confirmed the microarray results. Elevated neuronal cell death was further confirmed using Fluoro-Jade C staining. These findings support the hypothesis that neurodegeneration caused by PCP occurs, at least in part, through the up-regulation of NMDA receptors, which makes neurons possessing these receptors more vulnerable to endogenous glutamate. The changes in schizophrenia-relevant genes after repeated PCP exposure during development may provide important information concerning the validation of an animal model for this disorder.
Assuntos
Antagonistas de Aminoácidos Excitatórios/farmacologia , Expressão Gênica/efeitos dos fármacos , Fenciclidina/farmacologia , Esquizofrenia/genética , Esquizofrenia/fisiopatologia , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/patologia , Encéfalo/fisiologia , Análise por Conglomerados , Modelos Animais de Doenças , Fluoresceínas/metabolismo , Perfilação da Expressão Gênica , Análise em Microsséries , Dados de Sequência Molecular , Degeneração Neural/induzido quimicamente , Degeneração Neural/patologia , Análise de Componente Principal , Ratos , Ratos Sprague-Dawley , Esquizofrenia/induzido quimicamente , Esquizofrenia/patologiaRESUMO
Ketamine, a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist, is associated with accelerated neuronal apoptosis in the developing rodent brain. In this study, postnatal day (PND) 7 rats were treated with 20 mg/kg ketamine or saline in six successive doses (s.c.) at 2-h intervals. Brain frontal cortical areas were collected 6 h after the last dose and RNA isolated and hybridized to Illumina Rat Ref-12 Expression BeadChips containing 22,226 probes. Many of the differentially expressed genes were associated with cell death or differentiation and receptor activity. Ingenuity Pathway Analysis software identified perturbations in NMDA-type glutamate, GABA and dopamine receptor signaling. Quantitative polymerase chain reaction (Q-PCR) confirmed that NMDA receptor subunits were significantly up-regulated. Up-regulation of NMDA receptor mRNA signaling was further confirmed by in situ hybridization. These observations support our working hypothesis that prolonged ketamine exposure produces up-regulation of NMDA receptors and subsequent over-stimulation of the glutamatergic system by endogenous glutamate, triggering enhanced apoptosis in developing neurons.