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Effect of Intracerebroventricular Injection of TiO2 Nanoparticles on Complex Behaviour in the Rat
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There are no data available on the behavioural effects of centrally administered nanoparticles in freely moving intact mammals. Consequently, in the current study male Sprague-Dawley rats were trained to respond under an alternating-lever cyclic-ratio (ALCR) schedule of food reinforcement. Under this schedule, ascending and descending sequences of fixed-ratio (FR) lever press requirements for food reinforcement were presented over six cycles, with each discrete FR component completed on the alternate lever to the previous component. The final version of the schedule was comprised of an ascending followed by a descending sequence of the ratio values 2, 6, 12, 20, 30, 42 and 56, repeated over six cycles. When the rats were able to complete this version of the ALCR schedule in 40 min, each was implanted with a permanently indwelling ICV cannula aimed at the lateral ventricle of the brain, and allowed to recover for 7 days. On the first day of the experiment, all rats were injected with either titanium dioxide (TiO2, 9 nm, stabilised with gallic acid, 10 ěl volume, 2 mg/ml) nanoparticles, or 10 ěl saline (control). Two-hours after the ICV injections, the behaviour of all rats was measured using the ALCR schedule, and their behaviour was also measured (no ICV injection) for the next 7 days. Under the ALCR schedule, the number of lever-switching errors and incorrect lever perseverations significantly increased in the TiO2 group (p < 0.05). Other parameters of the ALCR schedule (RRRs and PRPs), which indicate the induction of malaise or general motor retardation, were not altered following ICV TiO2 injection. The findings of the current study indicate that central administration of TiO2 nanoparticles induced behavioural deterioration in freely moving intact animals, that the induced behavioural deterioration was a result of central rather than peripheral outcomes, and that this effect was chronic rather than acute.
This study used an operant schedule of food reinforced lever press responding, the alternating-lever cyclic ratio (ALCR) schedule, to assess behaviour following intracerebroventricular (ICV) TiO2 nanoparticle administration in the rat. Data from the ALCR schedule allows several features of behaviour to be assessed. Using
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Journal of Nanoscience and Nanotechnology, 13(12): 8325-8330 (December 2013)
Journal of Nanoscience and Nanotechnology
Kim EM, Palmer P, Howard V, Elsaesser A, Taylor A, Staats G, O'Hare E
Last updated on January 23, 2014
This work is supported in part by the Nanoscale Science and Engineering Initiative of the National Science Foundation
under NSF Award Number EEC-0118007.
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