The effects of reduced body weight gain on nervous system function of young male Fischer 344 rats were examined. The rats were fed 15% ('mild') or 50% ('severe') less than the controls. Mild and severe dietary restriction resulted in 9% and 38% lower body weight compared to the controls. Mild dietary restriction caused slight changes in flash evoked potentials, auditory brainstem responses, caudal nerve action potentials, and body temperature. Severe dietary restriction increased the magnitude of the effects noted in the mild group, as well as causing a significant decrease in grip strength. Somatosensory evoked responses were not affected by either mild or severe restriction. Diet restricted rats were more excitable while restrained for testing. Thus, dietary restriction has significant effects on numerous behavioral and neurophysiological parameters that should be considered in the interpretation of neurotoxicological data when body weight differences are present.

Animals↗

PubMedDate not supplied

Effects of trialkyltins on the schedule-controlled behavior of the pigeon.

Male White Carneaux pigeons trained to respond for food under a multiple fixed-ratio fixed-interval schedule of reinforcement were given single injections of trimethyltin (TMT), or triethyltin (TET). A dose of 0.3 mg/kg TMT produced no effect on behavior, while a 1.0 mg/kg dose was a threshold dose and 1.75 mg/kg produced behavioral changes that persisted for months in some birds. TMT produced effects on responding under the multiple schedule at approximately the same doses that produce neuronal damage in the hippocampus and the brain stem of the pigeon. Higher doses given to untrained birds produced signs of extensive neurological damage. A dose of 1.0 mg/kg of TET decreased rates of responding under both schedule components three hours after administration, but behavior usually had recovered by the next day. Doses of 3.0 and 5.6 mg/kg had similar effects, but responding did not recover for several days. Some birds showed significant rate increases, especially under the fixed-interval component several days to several weeks after TET administration. Doses greater than 10 mg/kg TET were lethal. Dose-effect curves for the effects of d-amphetamine, chlorpromazine and morphine on responding under the multiple schedule were determined for some birds before and one month after 1.0 and 1.5 mg/kg of TMT. TMT shifted the dose-effect curve for d-amphetamine to the right, but it did not produce systematic changes in the dose-effect curves for morphine and chlorpromazine.

Animals↗

PubMedDate not supplied

Subchronic neurotoxicity in rats of the structural fumigant, sulfuryl fluoride.

Inhalation exposure of male and female Fischer 344 rats to sulfuryl fluoride [Vikane (Dow Chemical Company) gas fumigant] at 300 ppm for 6 hr/day, 5 days week, for 13 weeks caused diminished weight gain, dental fluorosis, a slight decrease in grooming, decreased flicker fusion threshold, slowing of flash, auditory and somatosensory evoked potentials, mild nasal and pulmonary inflammation, mild kidney effects, and mild vacuolation in the brain. Auditory brainstem responses (ABRs) and brain histology were evaluated two months postexposure in 2 male and 2 female rats. Both the ABRs and brain histology were within normal limits at this time, indicating that these treatment effects were, to at least a great extent, reversible. Exposure to 100 ppm resulted in dental fluorosis and very minor slowing of some evoked responses; all other measures, including brain histology, were normal. No treatment effects were noted at 30 ppm.

Action Potentials↗

PubMedDate not supplied

Neurotoxicological effects of trimethyltin on the stellate ganglion.

Hamsters treated with trimethyltin (TMT), 3 or 4 mg/kg IP, developed neurological symptoms, including tremor, within 24 hours. Postganglionic action potentials were recorded from isolated stellate ganglia of untreated hamsters (control ganglia) and TMT-treated hamsters (TMT ganglia). Compound action potentials (nicotinic transmission) of control and TMT ganglia were not significantly different. The afterdischarges induced by preganglionic stimulation at 30 Hz for 2 sec in the presence of 10(-3) M hexamethonium (muscarinic transmission) were significantly smaller in TMT ganglia than in control ganglia. The discharges induced by the muscarinic cholinoceptor agonist. McN-A-343, were also smaller in the TMT ganglia. Two other muscarinic processes, posttetanic potentiation and potentiation of the compound action potential by McN-A-343, were not significantly reduced in the TMT ganglia. Morphological studies of the ganglia revealed marked changes in the TMT ganglia with severe neuronal degeneration including vacuole formations and accumulations of lysosomes in the cytoplasm. These results demonstrate that TMT has marked anatomical effects on the stellate ganglion that may lead to the reduction in muscarinic cholinergic transmission.

Action Potentials↗

PubMedDate not supplied

Xenogeneic islets transplanted into primates are subject to a form of hyperacute rejection independent of anti-GAL-alpha 1-->3 gal antibody binding.

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Acute Disease↗