Cerebellar Ataxia Produced by 3-Acetyl Pyridine in Rat

3-acetylpyridine induced behavioral dysfunction and neuronal loss in the striatum and hippocampus of adult male rats

3-acetylpyridine (3-AP) is a neurotoxin that is known to mainly affect the inferior olivary nucleus (ION) in the brain stem. Although several studies have explored the effect of this neurotoxin, still further investigation is required to understand the impact of this toxin on different parts of the brain. In this research, two groups of rats were studied, the 3-AP-treated and the control groups. Behavioral, stereological, and immunohistochemical analyses were performed. The locomotor activity of the 3-AP-treated rats decreased whereas their anxiety levels were higher than in normal controls. Also, memory performance was impaired in animals in the 3-AP group. Microscopic observations showed a decline in the numerical density of neurons in the hippocampus and striatum along with gliosis. Although this toxin is used to affect the ION, it exerts a neurotoxic effect on different brain regions.

Hericium erinaceus potentially rescues behavioural motor deficits through ERK-CREB-PSD95 neuroprotective mechanisms in rat model of 3-acetylpyridine-induced cerebellar ataxia

Cerebellar ataxia is a neurodegenerative disorder with no definitive treatment. Although several studies have demonstrated the neuroprotective effects of Hericium erinaceus (H.E.), its mechanisms in cerebellar ataxia remain largely unknown. Here, we investigated the neuroprotective effects of H.E. treatment in an animal model of 3-acetylpyridine (3-AP)-induced cerebellar ataxia. Animals administered 3-AP injection exhibited remarkable impairments in motor coordination and balance. There were no significant effects of 25 mg/kg H.E. on the 3-AP treatment group compared to the 3-AP saline group. Interestingly, there was also no significant difference in the 3-AP treatment group compared to the non-3-AP control, indicating a potential rescue of motor deficits. Our results revealed that 25 mg/kg H.E. normalised the neuroplasticity-related gene expression to the level of non-3-AP control. These findings were further supported by increased protein expressions of pERK1/2-pCREB-PSD95 as well as neuroprotective effects on cerebellar Purkinje cells in the 3-AP treatment group compared to the 3-AP saline group. In conclusion, our findings suggest that H.E. potentially rescued behavioural motor deficits through the neuroprotective mechanisms of ERK-CREB-PSD95 in an animal model of 3-AP-induced cerebellar ataxia.

Functional assays for neurotoxicity testing

Neurobehavioral and pathological evaluations of the nervous system are complementary components of basic research and toxicity testing of pharmaceutical and environmental chemicals. While neuropathological assessments provide insight as to cellular changes in neurons, behavioral and physiological methods evaluate the functional consequences of disruption of neuronal communications. The underlying causes of certain behavioral alterations may be understood, but many do not have known direct associations with specific brain pathologies. In some cases, however, rapidly expanding mouse models (transgenic, knock-out) are providing considerable information on behavioral phenotypes of altered pathology. Behavior represents the integrated sum of activities mediated by the nervous system, and functional tests used for neurotoxicity testing tap different behavioral repertoires. These tests have an advantage over pathologic measures in that they permit repeated evaluation of a single animal over time to determine the onset, progression, duration, and reversibility of a neurotoxic injury. Functional assays range from a screening-level battery of tests to refined procedures to tap specific forms of learning and/or memory. This article reviews common procedures for behavioral toxicity testing and provides examples of chemical-specific neurobehavioral-pathological correlations in order to inform interpretation and integration of neuropathological and behavioral outcomes.

Effects of 4-acetylpyridine on stress ulcer formation in mice

4-Acetylpyridine, earlier reported by us to be an anticonvulsant, offers long-lasting protection after a single administration against hypothermic restraint stress-induced gastric ulceration in mice. Electroshock convulsions, marginally but not significantly protective against such ulcers themselves, when coupled with 4-acetylpyridine administration fully prevented gastric ulcers from occurring in this murine model of experimentally induced stress.

Amino acid changes in the mouse mutant dystonia musculorum similar to those in Friedreich's ataxia

An autosomal recessive mutant strain of mouse with a progressive neurological disorder is described. Histopathology is dramatic in the sensory afferents and in the red nucleus. In the cerebellar vermis the concentrations of glutamate, aspartate, glycine and GABA are significantly reduced, and in the cerebellar hemispheres the taurine/glutamate ratio is elevated. These mice may provide a useful experimental model of Friedreich's ataxia.

Effects of glutamate and aspartate on ataxic gait induced by 3-acetyl pyridine in rats

The main purpose of this study was to examine the effects of intraventricular injections of glutamate and aspartate on the walking gait of rendered ataxic by the administration of 3-acetyl pyridine. Both amino acids significantly improved the walking gait of these animals. The effects of other substances known to have a stimulatory influence on locomotor activity in rats were also investigated. Amphetamine, apomorphine and thyrotropin releasing hormone (TRH) had no effect on the ataxic gait of 3-AP treated animals. Substance P significantly improved the gait of ataxic animals, but to a lesser extent than that seen with glutamate and aspartate.

Friedreich's ataxia 1980. An overview of the physiopathology

Phase three of the Quebec Cooperative Study of Friedreich's Ataxia was devoted to an understanding of the physiopathology of individual symptoms on the basis of previously discovered biochemical leads. The present paper attempts to pull these results together by presenting, as a hypothesis, a unifying scheme of possible interactions and relationships. The central core of this hypothesis is the demonstration in Friedreich's ataxia of a state of mitochondrial energy deprivation. This is indirectly responsible for such associated and important symptoms as muscle weakness, dying-back neuropathy, scoliosis and hypertrophic cardiomyopathy. Secondarily, and possibly as an independent but linked-event, the entry of glucose into cells and pyruvate oxidation, are slowed down, favoring the development of diabetes. As a consequence, tissue concentrations of glutamic acid and aspartic acid are decreased, particularly in more vulnerable areas such as the cerebellum, brain stem and dorsal root ganglia. This tissue deficiency in putative excitatory neurotransmitters is directly responsible for the symptom of ataxia. This conclusion is reinforced by the correction of the ataxia in experimental animals, by the intraventricular injection of the same amino acids, and not by the injection of other stimulants of motricity. The observed mitochondrial energy deprivation could be the metabolic consequence of major changes in the linoleic acid (18.2) composition of inner mitochondrial membrane phospholipids, such as cardiolipin. Such decreases in membrane 18:2 could be the result of interference with the normal incorporation of this fatty acid to lipoproteins and/or cell membranes. It is at this level that the search for the specific enzyme defect in Friedreich's ataxia is continuing.

Leucocyte glutamate dehydrogenase in various hereditary ataxias

Leucocyte Glutamate Dehydrogenase (GDH) activity was measured in 44 patients with various forms of ataxia and 44 age and sex-matched normal controls. The only significant change found was a moderate decrease in activity in Friedreich's ataxia and a few patients with OPCA. This decreased activity is not primary to the disease but probably reflects a regulatory defect affecting mitochondrial membranes in these patients.

Effect of asparagine, glutamine and insulin on cerebral amino acid neurotransmitters

Treatment of rats with asparagine or glutamine caused substantial increases in glutamine concentrations in cerebellum and medulla oblongata. Insulin treatment caused a diminution of glutamate and GABA in these regions of brain. Since it is now well-established that glutamine is a very efficient precursor of the neurotransmitter pool of glutamate in mammalian brain, treatment with asparagine or glutamine could be of therapeutic (replacement) value in the treatment of neurological disorders such as Friedreich's ataxia, in which cerebral glutamate concentrations have been found to be diminished.

A light and electron microscopic study of the effects of 3-acetylpyridine intoxication on the inferior olivary complex and cerebellar cortex

The effects of 3-acetylpyridine (3-AP) intoxication on the inferior olivary complex and cerebellar cortex of the rat were examined at both the light and electron microscopic level. Following intraperitoneal injection of 65 mg of 3-AP per kg body weight, the inferior olivary neurons were observed to undergo a rapid form of electron dense degeneration. A complete bilateral involvement of the nuclear complex was well advanced as early as 12 hours following injection. Marked astrocytic proliferation also occurred by 12 hours and appeared essential for neuronal fragmentation and disintegration. Microglial activity was prominent in the later stages, from 60 hours onwards, and participated in the phagocytic removal of degenerating neuronal fragments. By the end of the second week, all cytoplasmic and nuclear debri was removed. Concurrently, degenerative changes in the cerebellar cortex were evident from 12 hours onwards. All climbing fiber varicosities were observed to be degenerative as early as 24 hours following treatment. Electron microscopic observations revealed that these electron dense fragments were largely phagocytized and cleared by Bergmann glial cells around 7 days. The sensitivity of the olivocerebellar system to 3-AP thus provides a convenient and selective means of eliminating all of the inferior olivary neurons and their axons, the climbing fibers of the cerebellar cortex. In contrast to the more conventionally used electrolytic methods, 3-AP causes a complete bilateral ablation of all olivary neurons while avoiding the problems inherent to electrolytic procedures, such as incomplete destruction of the nucleus and involvement of fibers of passage.

Dicarboxylic amino acid uptake in normal, Friedreich's ataxia, and dicarboxylic aminoaciduria fibroblasts

Glutamic and aspartic acid uptake was measured in skin fibroblasts from patients with Friedreich's Ataxia, dicarboxylic aminoaciduria, and normal individuals. The results showed no difference in uptake kinetics of either dicarboxylic amino acids between Friedreich's Ataxia and normal cells, but reduced uptake velocities in dicarboxylic aminoaciduria fibroblasts. Friedreich's Ataxia fibroblasts were, however, less calcium-dependent and more magnesium and phosphate-dependent than controls in glucose-free incubation mixture. This difference might be related to some degree of glucose intolerance by Friedreich's Ataxia fibroblasts in culture.

Taurine and beta-alanine uptake in cultured human skin fibroblasts from patients with Friedreich's ataxia

Taurine and beta-alanine uptake kinetics were studied in cultured skin fibroblasts from 9 patients with Friedreich's Ataxia and 8 controls. No significant difference was observed. The data support the presence of normal beta-amino acid carrier protein in Friedreich's Ataxia cell membrane.

Measurement of ataxia and related neurological signs in the laboratory rat

The purpose of the present study was to design a standard battery of tests capable of quantitatively characterizing ataxia and concomitant neurological signs in the rat. In addition to a systematic analysis of the walking gait of animals, tests for activity, catalepsy, rigidity, and various reflexive responses were included in the battery. The standardization and validation of the test system was performed by determining and comparing profiles of neurobehavioral effects produced by 3-acetyl pyridine, acrylamide, pyrithiamine, and thiamine deficiency, four experimental treatments reported to induce ataxia in animals. Results indicate that profiles of neurobehavioral disturbances accompanying ataxia in animals varied distinctively with each experimental treatment.