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Sodium arsanilate-induced vestibular dysfunction in meadow voles (Microtus pennsylvanicus): effects on posture,
K P Ossenkopp1, L A Eckel, E L Hargreaves
1Department of Psychology, University of Western Ontario, London, Canada.
Abstract:
Vestibular dysfunction was chemically induced in male meadow voles (Microtus pennsylvanicus) by intratympanic injections (30 mg per side) of sodium arsanilate (atoxyl). The control group received intratympanic injections of isotonic saline. After a one-week recovery period the voles were behaviorally assayed for integrity of their labyrinthine systems. All subjects were tested for the presence of the air-righting reflex and body rotation-induced nystagmus. Three weeks later a multivariate assessment of spontaneous motor activity of the voles was carried out in the automated Digiscan Activity Monitor. In addition, the swimming behavior of the voles was examined. Voles with vestibular dysfunction exhibited pronounced postural abnormalities (head dorsiflexion), were not able to swim with their nose above the water for a 1 min test period, and displayed disorientation and thrashing movements. In the Digiscan activity test the atoxyl-treated voles displayed significantly more activity in the horizontal measures (Ps less than 0.01), including greater distance travelled per movement and greater speed of movements, relative to the control animals. The labyrinthectomized group also spent significantly (P less than 0.05) less time in vertical movements and exhibited significantly more time in stereotypic behavior (P less than 0.01), relative to controls. Atoxyl-treated voles also showed significantly less thigmotaxis (wall-hugging) than the control animals (P less than 0.01). In general, changes in spontaneous behavior observed in the sodium arsanilate-treated voles were consistent with the presence of postural and balance abnormalities and a redirecting of exploratory vertical movements toward horizontal locomotion to the extent that these animals were clearly hyperactive in this dimension. The multivariate behavioral assessment available in the Digiscan Activity Monitoring system, thus seems to be especially useful in the examination of behavioral components affected by vestibular dysfunction.
Insights
Chemically induced vestibular dysfunction in voles caused significant postural abnormalities and altered spontaneous motor activity. The Digiscan Activity Monitor effectively revealed hyperactivity and changes in movement patterns, confirming its utility in studying balance disorders.
Area of Science:
- Neuroscience
- Behavioral Science
- Toxicology
Background:
- Vestibular dysfunction can arise from various causes, impacting balance and motor control.
- Assessing behavioral changes is crucial for understanding the functional consequences of vestibular system impairment.
Purpose of the Study:
- To investigate the behavioral effects of chemically induced vestibular dysfunction in meadow voles.
- To evaluate the utility of the Digiscan Activity Monitor in characterizing these behavioral changes.
Main Methods:
- Vestibular dysfunction was induced using intratympanic injections of sodium arsanilate (atoxyl) in meadow voles.
- Behavioral assays included air-righting reflex, nystagmus, swimming behavior, and spontaneous motor activity using the Digiscan Activity Monitor.
Main Results:
- Atoxyl-treated voles displayed postural abnormalities, impaired swimming, and disorientation.
- Significant increases in horizontal activity, distance traveled, and speed were observed in atoxyl-treated voles.
- Reduced vertical movement and increased stereotypic behavior, along with decreased thigmotaxis, were noted in the dysfunction group.
Conclusions:
- Chemically induced vestibular dysfunction leads to distinct behavioral alterations in voles.
- The Digiscan Activity Monitor is a valuable tool for quantifying behavioral changes associated with vestibular dysfunction, highlighting hyperactivity and altered locomotion.