PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Trimethyltin Compounds”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
PubMedDate not supplied

Fetal Ammon's horn transplants improve acquisition of a radial arm maze and a low-rate operant schedule in trimethyltin-treated rats.

The results of previous studies indicated that block grafts of fetal hippocampal tissue made into cavities produced by aspiration lesions of the hippocampus in rats given the neurotoxin trimethyltin (TMT) significantly worsened the TMT-induced deficit in water maze acquisition. The purpose of the present study was to test the hypothesis that a procedure for transplantation that produced less destruction to the host brain and resulted in transplants with less mass might produce recovery in a spatial learning task in TMT-exposed rats. Acquisition of an externally cued (spatial) version of the radial arm maze (RAM), an internally cued version of the RAM, and of a differential reinforcement of low rate (DRL) operant schedule was assessed in normal rats, rats given TMT, and rats given TMT and stereotaxic implants of either fetal Ammon's horn or entorhinal cortex. The rats receiving Ammon's horn transplants made significantly fewer reentries into the baited arms in both maze configurations and fewer reentries into the nonbaited arms in the spatial RAM than rats in the TMT-only and TMT/entorhinal cortex transplant groups. The rats receiving transplants of Ammon's horn made significantly fewer responses and received more reinforcements during training on the DRL-20 schedule than rats receiving just TMT or rats receiving TMT and transplants of fetal entorhinal cortex. These results support the proposal that transplantation procedures that cause less damage to the host brain and result in transplants that do not occupy a large extent of the ventricular space increase the probability of behavioral recovery.

Animals↗
PubMed2006

Lack of trimethyltin (TMT)-induced elevation of plasma corticosterone in PACAP-deficient mice.

Accumulating evidence implicates pituitary adenylate cyclase-activating polypeptide (PACAP) in a number of stress responses. By using PACAP-deficient mice, PACAP has been shown to have an in vivo role in the regulation of the sympathoadrenal axis, but a role in regulating the hypothalamo-pituitary-adrenal (HPA) axis has not been fully addressed. To elucidate the role of endogenous PACAP in HPA axis regulation during pathological conditions, mice lacking the Adcyap1 gene encoding the neuropeptide PACAP (Adcyap1-/-) were injected with trimethyltin (TMT), a neurotoxin known to induce neuronal damage and several systemic responses including elevated plasma corticosterone levels. In wild-type controls, TMT induced transient decreases in water and food intake, with a concomitant decrease in body weight; however, no significant changes were observed in Adcyap1-/- mice. Basal corticosterone levels were not significantly different between the mutant and wild-type mice. TMT induced a marked elevation of plasma corticosterone above basal levels in wild-type mice but no significant increase was seen in Adcyap1-/- mice. The present article suggests that PACAP is involved in the corticosterone release in some pathological conditions but not in the basal state.

Animals↗
PubMed1995

[Three simple maze tests employing mice housed in maze apparatuses].

This report deals with three different maze methods using spontaneous learning behavior. Forty-eight mice housed in an apparatus with a multiple maze mastered the maze task on the 5th day after the start of housing. Then they were divided into four groups, and two of the groups were treated with AF64A (3.5 nmol, i.c.v.) or trimethyltin (TMT, 3 mg/kg, p.o.), and the other two groups were treated with the vehicle as the respective control. Seven days after the treatment, their memory retrieval was tested. Subsequently, the same mice were housed in the apparatus with a T-maze. After the finish of the experiment using the T-maze, they were housed in the apparatus with an eight arm radial maze. The control groups mastered the T-maze task with a 3-sec delay on the 4th day after the start of housing and the radial maze task on the 10th day after the start of housing. Both the treatments lowered the performance in all maze tasks. These results show that the mice housed in the apparatus with maze learned to negotiate the maze spontaneously, and the apparatuses are useful for estimating memory in mice with little effort.

Animals↗
PubMed1987

Risk assessment for neurobehavioral toxicity.

A study by the National Academy of Sciences/National Research Council (NAS/NRC) found neurobehavioral toxicity to be one of the areas where almost no data are available for the assessment of toxicity. Using the NAS/NRC report and a data base from the American Conference of Government Industrial Hygienists (ACGIH), an estimate of the number of neurobehavioral toxins in commercial chemicals can be made. Although the assumption made in making such a calculation may be invalid, the exercise suggests that the number of neurobehavioral toxins may be quite large. There does seem to be general agreement as to what type of neurobehavioral test procedures are appropriate for regulatory purposes. Select committees have consistently recommended the use of test batteries that include schedule-controlled behavior, motor activity, and neuropathological examination following in vivo perfusion, for regulatory purposes. Alkyltin data developed from such a battery were applied to the risk assessment model employed by the United States Environmental Protection Agency (EPA) in their calculations of acceptable daily intake. Using this test battery and the EPA risk assessment model, the acceptable daily intake calculated is of the same order of magnitude as the total limit values established by the ACGIH. A number of special issues in neurobehavioral toxicity also are discussed, including the definition of adverse neurobehavioral toxic effects, species extrapolation, correlation of behavior and neuropathology, alternative methods, and quality of life issues.

Animal Welfare↗
PubMed1999

The activation of the tissue plasminogen activator-plasmin system induced in the mouse hippocampus after injection of trimethyltin: possible proteolysis of highly polysialylated NCAM.

Trimethyltin (TMT) is a neurotoxicant that causes the death of granule cells and degrades highly polysialylated NCAM (PSA-NCAM) in the dentate gyrus. To investigate the role of the tPA-plasmin system in the degradation of PSA-NCAM, we injected trimethyltin (TMT) into mice. As a result, tPA activity was significantly increased in CA1-CA4 and the dentate gyrus after TMT injection. These results suggest that up-regulated tPA may contribute to the degradation of PSA-NCAM.

Animals↗
PubMed1996

Comparison of the effects of trimethyltin on the intracellular calcium levels in spiral ganglion cells and outer hair cells.

Cochlear impairment by trimethyltin chloride (TMT), a potential contaminant of marine paints and polyvinyl chloride tubing, has been well demonstrated. Its toxic effect on the inner hair cells (IHC)-spiral ganglion cell (SGC) unit occurs almost immediately while disruption of outer hair cell (OHC) function does not occur until several hours after exposure. In this experiment, OHCs and SGCs from pigmented guinea pigs were tested in vitro to determine the role of enhanced intracellular calcium [Ca2+]i levels in TMT ototoxicity and to determine the sources of enhanced [Ca2+]i. The latter was determined by experiments using artificial perilymph without Ca2+ and by use of the Ca2+ channel blocker, nifedipine. The data show that TMT elevates [Ca2+]i in both OHC and SGC. The elevation of [Ca2+]i in SGC is much more rapid and larger than that in OHC. The elevation of [Ca2+]i in SGC can be attenuated by removing Ca2+ from artificial perilymph or pretreating with nifedipine, but neither of these treatments is effective in OHC. The results suggest that TMT disrupts intracellular storage of Ca2+ in OHCs and SGCs, but that is also enhancing influx of Ca2+ from extracellular sources in the SGCs.

Animals↗
PubMed1996

Trimethyltin-induced plastic neuronal changes in rat hippocampus are accompanied by astrocytic trophic activity.

Partial deafferentation of the hippocampus due to trimethyltin (TMT) intoxication has been reported to induce plastic rearrangements of neuronal elements but the factors that direct these responses are unknown. To assess the possible involvement of nerve growth factor (NGF) in the phenomenon we evaluated the presumable changes in the expression pattern of NGF immunoreactivity (NGF-IR) in rat hippocampus 21 days after administration of TMT (8 mg/kg, i.p.) when reactive changes are fully developed. Immunolabelling for TrkA known to mediate biological effects of NGF and for GFAP to identify astroglial cells as a one of presumed source of postinjury produced factors was carried out on adjacent sections to establish the relation between expression of these proteins. In control hippocampus NGF-IR and TrkA-IR were localized in neurons and/or neuropil. After exposure to TMT remarkable non-neuronal expression of both proteins was observed. The distribution pattern of NGF, TrkA and GFAP overlapped suggesting that reactive astrocytes may not only produce NGF but also may become responsive to this neurotrophin. Zones of extensive NGF and TrkA astroglial expression corresponded to areas of axonal-dendritic rearrangements reported earlier. The data suggest that astroglia-derived trophic activity may be involved in neuronal plastic events associated with treatment with TMT.

Animals↗
PubMed1999

Effect of dexamethasone on elevated cytokine mRNA levels in chemical-induced hippocampal injury.

An acute administration of the hippocampal toxicant trimethyltin (TMT) produced a specific pattern of neuronal necrosis in dentate granule cells with accompanying astrogliosis and initiation of a cytokine response within 24 hours. The purpose of this study was to examine the effects of the anti-inflammatory agent, dexamethasone (DEX), on the pattern of cytokine expression and neuronal degeneration occurring after an acute TMT injection. Dexamethasone (0.2 mg/kg or 10 mg/kg) was administered to 21-day-old male mice 1 hour prior to an injection of TMT hydroxide (2.5 mg/kg, i.p.). Mice receiving 0.2 mg/kg DEX received a second injection 6 hours after TMT. Twenty-four hours later, neuronal necrosis and astrogliosis were assessed and found to be similar in animals treated with TMT, either in the presence or absence of dexamethasone. Pretreatment with dexamethasone failed to prevent the neurodegeneration and astrogliosis. The TMT-induced injury response was represented in elevations of mRNA levels for the injury-associated host response genes glial fibrillary acidic protein (GFAP), EB22/5.3, and intercellular adhesion molecule-1 (ICAM-1). The combination of DEX and TMT produced increased elevation in mRNA levels for EB22/5.3 and ICAM, while GFAP levels remained the same as with TMT alone. The injury response from TMT was accompanied by elevations in mRNA levels for the cytokines tumor necrosis factor (TNF) alpha, TNFbeta, and interleukin (IL)-1alpha. Treatment with dexamethasone prior to TMT resulted in significantly elevated levels of TNFalpha, TNFbeta, and IL-1alpha as compared to TMT alone. These data represent the inability of glucocorticoids to downregulate the injury response in rat hippocampus following a systemic injection of TMT and suggest a stimulation and "priming" of hippocampal cells by dexamethasone.

Analysis of Variance↗
PubMed1999

Expression of AP-1 transcription factors in rat hippocampus and cerebellum after trimethyltin neurotoxicity.

Neurotoxic insult causes neurons to degenerate due to necrosis or apoptosis. After this neurodegenerative phase, gene expression in surviving neurons is altered to undergo regeneration and repair to adapt to changes in the cellular environment. In this study, we examined the expression of four AP-1 transcription factors, Jun, JunB, JunD and FRA-2, and AP-1 DNA binding activity in the rat hippocampus to examine changes during the periods of degeneration and then of regeneration and repair after TMT-induced neurotoxicity. The expression of these factors in the cerebellum was examined as a control since this brain region is not grossly affected by TMT. AP-1 DNA binding slowly increased in both the cerebellum and hippocampus from one hour to eight days after TMT exposure. Levels of Jun in the hippocampus significantly increased at 12 hours after TMT while JunB and JunD expression did not change. On the other hand, FRA-2 was induced at 8 days in the hippocampus after TMT treatment and was expressed only in hippocampi containing neurodegeneration as gauged by elevated glial fibrillary acidic protein levels. FRA-2 immunoreactivity was detected in the AP-1 DNA binding complex only in hippocampal extracts from rats after eight days post-trimethyltin administration. Thus, FRA-2 is a component of the AP-1 DNA binding complex suggesting that it is involved in regulating genes during a later stage of TMT neurotoxicity.

Animals↗
PubMed2000

Quantification of acute neurotoxic effects of trimethyltin using neuronal networks cultured on microelectrode arrays.

We used spontaneously active monolayer networks in vitro, cultured on thin film microelectrode arrays as experimental platforms for the determination of trimethyltin chloride (TMT) toxicity. Two different tissues of the mouse CNS (spinal cord and auditory cortex) exhibited characteristic and dose-dependent changes of their electrophysiological activity patterns after treatment with TMT, a standard neurotoxicant. Spinal cord networks began to respond to TMT at 1-2 microM and shut off activity at 4-7 microM. Auditory cortex cultures started to respond at 2-3 microM and shut off activity at 7-8 microM. Repeated applications of low doses of TMT always influenced the electrical activity in a reversible manner, with no overt cytotoxic effects. The inhibitory concentrations for a 50% reduction of activity (IC ) were 1.5+/-0.5 microM (spinal cord) and 4.3+/-0.9 microM (auditory cortex) indicating a relatively low interculture variability within one tissue type. The non-overlapping IC50 range for cortical and spinal cord cultures may suggest tissue specificity for network responses to TMT. Shut-off concentrations were found to be within a factor of two of the lethal concentrations reported for mice in vivo. Action potential amplitude and shape did not change even when complete cessation of activity was approached, suggesting that acute TMT applications did not affect neuronal metabolism that would lead to a lowering of membrane potentials. Our results suggest that spontaneously active monolayer networks in vitro are suitable for toxicological investigations since network activity can be influenced in a dose-dependent manner. These properties allow the development of neurotoxicity biosensors based on physiological responses of spontaneously active networks.

Action Potentials↗
PubMed2000

Trimethyltin reduces ATP levels and MTT reduction in the LRM55 rat astrocytoma cell line.

The LRM55 rat astrocytoma cell line was used to study the time and concentration effects of trimethyltin (TMT) exposure on intracellular adenosine triphosphate (ATP) levels, formazan production from (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), and lactate dehydrogenase (LDH) release. TMT concentrations of > or =50 microM produced a delayed increase in extracellular LDH from approximately 20% at 24 h to almost 70%, at 72 h. Twenty-four hours before cell lysis was detectable ATP levels decreased to less than 30% and formazan production declined to 70% (50 microM), 31% (100 microM), and 21% (200 microM) of control values. Concentrations of TMT (5 and 10 microM) that produced little or no LDH release also decreased ATP levels (62 and 49% of control, respectively) and formazan production (63 and 52% of control, respectively) by 48 h. These data support the hypothesis that TMT exposure interferes with energy production and that this event likely contributes to the delayed cell death seen in this cell line. Moreover, the declines in ATP and formazan production can occur at subtoxic concentrations in LRM55 cells.

Adenosine Triphosphate↗
PubMed2002

Studies on hypokalemia induced by trimethyltin chloride.

OBJECTIVES: To determine the possible relationship between plasma potassium concentration and severity of acute trimethyltin chloride (TMT) poisoning and to assess the mechanism of TMT induced hypokalemia. METHODS: SD rats were treated with various dosages of TMT (i.p.). All the indices were measured and analysed for determining their possible relations with plasma K+. RESULTS: With increase of dosage, the plasma K+ level dropped rapidly, and deaths appeared more quickly. The LD50 of TMT (i.p.) was 14.7 mg/kgbw. In the low dosage group (10 mg/kgbw), the plasma K+ level dropped slowly with the lowest dosage on day 6 (4.85 mmol/L). It rose again on day 11 (5.06 mmol/L), and recovered on day 28. The poisoning signs corresponded with decline of the span of K+ level. The plasma Na+ level dropped half an hour after TMT treatment, but recovered 24 h later. In the high dosage group (46.4 mg/kgbw), the levels of plasma K+ and Na+ fell rapidly within half an hour (P < 0.05), the intracellular potassium concentration of RBC did not decrease obviously (P > 0.05), the activities of Na(+)-K(+)-ATPase and Mg(2+)-ATPase in RBC membrane were depressed remarkably (P < 0.01, P < 0.05, respectively), the plasma aldosterone concentrations rose as high as tenfold (P < 0.01), the arterial blood pH fell from 7.434 to 7.258 (P < 0.01), pCO2 was raised from 29.62 to 45.33 mmHg (P < 0.01). In the 24 h urine test, when rats were treated with TMT (21.5 mg/kgbw, i.p.), urine volume, urinary potassium, sodium and chloride increased significantly in comparison with those in the controls (P < 0.01). CONCLUSION: TMT could induce hypokalemia in SD rats. The available evidence suggests that TMT can induce acute renal leakage of potassium. At the same time, a significant rise of plasma aldosterone may play an important role in promoting potassium leakage from kidney to result in severe hypokalemia with inhaling acid-base abnormalities produced, which aggravate the poisoning symptoms. In the end the rats would die of respiratory failure.

Animals↗
PubMedDate not supplied

Trimethyltin poisoning: report of a case with postmortem examination.

A 48-year old woman died six days after intake of an unknown amount of trimethyltin (TMT). Early clinical features were tinnitus, lightheadedness, aggression and episodes of unresponsiveness. She gradually developed coma and died of multiorgan failure. The main pathologic findings were confined to the nervous system which revealed generalized chromatolysis of the neurons in the brain, spinal cord and spinal ganglia. Recent neuronal necrosis, which probably was caused by toxic effect of TMT, was present in the fascia dentata of the hippocampus and in the spinal ganglia. Recent necrosis was also present in the pyramidal cell layer of the hippocampus, cerebral cortex, basal ganglia and Purkinje cell layer of the cerebellum, but some of these changes could have been caused by an anoxic episode shortly before death. Electron microscopy revealed marked accumulation of lysosomal dense bodies and disorganization of the granular endoplasmic reticulum in the neurons. The findings were similar to those described in experimental TMT intoxications. Cytoplasmic zebra bodies, which were described in a previous human case of TMT intoxication, were not observed in the present case.

Autopsy↗
PubMed2003

Astatine-211-labeled antibodies for treatment of disseminated ovarian cancer: an overview of results in an ovarian tumor model.

PURPOSE: The aim of the study was to establish and refine a preclinical model to alpha-immunoradiotherapy of ovarian cancer. EXPERIMENTAL DESIGN: At-211 was produced by cyclotron irradiation of a bismuth-209 target and isolated using a novel dry distillation procedure. Monoclonal antibodies were radiohalogenated with the intermediate reagent N-succinimidyl 3-(trimethylstannyl)benzoate and characterized in terms of radiochemical yield and in vitro binding properties. In vitro OVCAR-3 cells were irradiated using an external Cobalt-60 beam, as reference, or At-211-albumin and labeled antibody. Growth assays were used to establish cell survival. A Monte Carlo program was developed to simulate the energy imparted and the track length distribution. Nude mice were used for studies of WBC depression, with various activities of Tc-99m antibodies, as reference, and At-211 antibodies. In efficacy studies, OVCAR-3 cells were inoculated i.p., and animals were treated 2 weeks later. The animals were either dissected 6 weeks later or followed-up for long-term survival. RESULTS: A rapid distillation procedure, as well as a rapid and high-yield, single-pot labeling procedure, was achieved. From growth inhibition data, the relative biological effectiveness of the alpha-emission for OVCAR-3 cells was estimated to be approximately 5, which is in the same range as found in vivo for hematological toxicity. At-211 MOv18 was found to effectively inhibit the development of tumors and ascites, also resulting in long-term survival without significant toxic effect. CONCLUSIONS: Use of the short-range, high-linear energy transfer alpha-emitter At-211 conjugated to a surface epitope-recognizing monoclonal antibody appears to be highly efficient without significant toxicity in a mouse peritoneal tumor model, urging a Phase I clinical trial.

Animals↗
PubMed1992

Ganglioside treatment partially counteracts neurotoxic effects of trimethyltin but may itself cause neurotoxicity in rats: experimental results and a critical review.

We have demonstrated a deficit in working memory and/or consolidation of information in working memory into reference memory by a single oral dose of the neurotoxin trimethyltin(TMT). Moreover, TMT causes loss of hippocampal corticosterone receptors and increases brain glial fibrillary acidic protein(GFAP), an index of the astrocytic reaction to diverse types of CNS lesions. We tried to block the TMT-induced cognitive deficit and these biochemical markers by treating rats with purified mixed gangliosides (GS) for 21 days, starting 2 days before the TMT treatment. As expected, TMT decreased the number of corticosterone receptors in hippocampi and increased the GFAP concentration in hippocampi and to a lesser extent, in frontal cortices, measured more than 8 mon after treatment. The small increase in GFAP in frontal cortices was attenuated by GS but not in hippocampi. The pronounced learning deficits caused by TMT were attenuated to a small extent by GS in the TMT-GS group, when a learning criterion was used for the last session's performance of acquired lever-directed behavior. GS also delayed the appearance of significant performance differences between Controls and TMT-treated rats, when probed with a progressive fixed ratio schedule of reinforcement. However, most measures of learning and performance indicated that GS did not block the dysfunctional consequences of TMT treatment but instead caused similar functional decrements in rats treated with water instead of TMT. Corticosterone receptors in hippocampi were reduced to about 65% of Controls in the TMT-Water, TMT-GS, and Water-GS groups. A reduction in corticosterone receptors in hippocampi after TMT treatment probably reflects the loss of one or more cell types (e.g., pyramidal cells), which is supported by the increase in GFAP in this region. However, we did not observe a reciprocal relation between steroid receptors and GFAP after GS alone, indicating that GS did not cause detectable cell loss or cell damage, measured in this manner. Thus, reactive gliosis probably was not a pre-condition for the cognitive dysfunction. The fact that the cognitive deficits are probably related to hippocampal dysfunction supports the notion of a causal relationship between corticosterone receptor reduction and/or their altered function and cognitive impairment of this special type. The possibility that our results demonstrate potential neurobehavioral toxicity of GS is discussed in light of many reports which present data that can be similarly interpreted.

Animals↗
PubMed1992

Enhanced expression of glial fibrillary acidic protein and the cupric silver degeneration reaction can be used as sensitive and early indicators of neurotoxicity.

The mammalian central nervous system is composed of a large and diverse array of its two principle cell types, neurons and glia. Given this extreme cellular heterogeneity, it is not surprising that targets of neurotoxic insult often are diverse and unpredictable. In devising strategies to assess neurotoxicity, one must overcome the obstacle posed by not knowing where to look for damage. Our approach to the detection and localization of sites of toxicant-induced damage has been to take advantage of two general responses to nervous system insult, astrogliosis and argyrophilia. Assays for GFAP, the principle intermediate filament protein of astrocytes, have been devised to quantify astrogliosis and a modified cupric silver degeneration stain has been employed to examine patterns of argyrophilia. Using these methods, we found that increases in GFAP and the occurrence of argyrophilia are consistent responses to neurotoxic insults. Moreover, increments in these two indicators reveal dose-, time- and region-dependent patterns of neurotoxicity at toxicant dosages below those that cause light microscopic evidence of cell loss or damage. The rapid onset of astrogliosis and argyrophilia following specific toxicant exposures suggests that the signals underlying these events are among the earliest that can be linked to the neurotoxic state.

Animals↗
PubMed2005

NG2 expressing cells in hippocampal cultures survive neurotoxic insult and retain the ability to divide.

It has been recently proposed that NG2 proteoglycan expressing cells may stand for a unique class of glia in adult CNS referred to as oligodendrocyte progenitor cells (OPCs). These NG2 positive cells can give rise to mature oligodendrocytes, however a large number of them persists in immature stage throughout a lifetime and responds to various types of injury. In order to investigate OPCs reactivity in vitro, a model of trimethyltin evoked neurodegeneration was used. The results demonstrate that NG2 expressing cells survive treatment with the neurotoxin in a concentration that injures most of neurons in the culture. Moreover, progenitors change their morphology when treated with trimethyltin, upregulate the NG2 proteoglycan expression and retain the ability to divide.

Animals↗