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Long-term effects of chronic oral Ritalin administration on cognitive and neural development in adolescent wistar kyoto rats.

Pardey MC, Kumar NN, Goodchild AK, Clemens KJ, Homewood J, Cornish JL - Brain Sci (2012)

Bottom Line: Adolescent male animals were treated for four weeks with oral Ritalin® (2 × 2 mg/kg/day) or distilled water (dH2O).The effect of chronic treatment on delayed reinforcement tasks (DRT) and tyrosine hydroxylase immunoreactivity (TH-ir) in the prefrontal cortex was assessed.MPH treatment did not significantly alter cognitive performance in the SHR.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Macquarie University, Sydney 2109, Australia. margery.pardey@mq.edu.au.

ABSTRACT
The diagnosis of Attention Deficit Hyperactivity Disorder (ADHD) often results in chronic treatment with psychostimulants such as methylphenidate (MPH, Ritalin®). With increases in misdiagnosis of ADHD, children may be inappropriately exposed to chronic psychostimulant treatment during development. The aim of this study was to assess the effect of chronic Ritalin treatment on cognitive and neural development in misdiagnosed "normal" (Wistar Kyoto, WKY) rats and in Spontaneously Hypertensive Rats (SHR), a model of ADHD. Adolescent male animals were treated for four weeks with oral Ritalin® (2 × 2 mg/kg/day) or distilled water (dH2O). The effect of chronic treatment on delayed reinforcement tasks (DRT) and tyrosine hydroxylase immunoreactivity (TH-ir) in the prefrontal cortex was assessed. Two weeks following chronic treatment, WKY rats previously exposed to MPH chose the delayed reinforcer significantly less than the dH2O treated controls in both the DRT and extinction task. MPH treatment did not significantly alter cognitive performance in the SHR. TH-ir in the infralimbic cortex was significantly altered by age and behavioural experience in WKY and SHR, however this effect was not evident in WKY rats treated with MPH. These results suggest that chronic treatment with MPH throughout adolescence in "normal" WKY rats increased impulsive choice and altered catecholamine development when compared to vehicle controls.

No MeSH data available.


Related in: MedlinePlus

WKY rats: Mean (±SEM) number of presses on the immediate (closed) and delayed (open) levers in consecutive 20 s intervals for rats previously exposed to 4 weeks of oral methylphenidate (MPH, 2 × 2 mg/kg/day; blue diamond; n = 11) or distilled water (dH2O; red squares; n = 12), during the extinction task. There was a significant lever by time by treatment interaction, p = 0.039. The extinction task was conducted 48 h following the final DRT test.
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brainsci-02-00375-f006: WKY rats: Mean (±SEM) number of presses on the immediate (closed) and delayed (open) levers in consecutive 20 s intervals for rats previously exposed to 4 weeks of oral methylphenidate (MPH, 2 × 2 mg/kg/day; blue diamond; n = 11) or distilled water (dH2O; red squares; n = 12), during the extinction task. There was a significant lever by time by treatment interaction, p = 0.039. The extinction task was conducted 48 h following the final DRT test.

Mentions: At the commencement of the EXT task, WKYs previously treated with MPH pressed the immediate lever more than WKYs previously treated with dH2O. There was a significant main effect of lever, (Wilks’ Lambda is 0.276, F = 55.173, p < 0.001) such that WKYs pressed the immediate more than the delayed lever in the EXT task (Figure 6). There was a significant lever by time by treatment interaction (Wilks’ Lambda is 0.139, F = 3.540, p = 0.039), indicating that MPH pretreatment increased immediate lever pressing. There was no main effect of treatment and all other interactions were not significant. MPH treated WKYs continued to demonstrate sensitivity to delay.


Long-term effects of chronic oral Ritalin administration on cognitive and neural development in adolescent wistar kyoto rats.

Pardey MC, Kumar NN, Goodchild AK, Clemens KJ, Homewood J, Cornish JL - Brain Sci (2012)

WKY rats: Mean (±SEM) number of presses on the immediate (closed) and delayed (open) levers in consecutive 20 s intervals for rats previously exposed to 4 weeks of oral methylphenidate (MPH, 2 × 2 mg/kg/day; blue diamond; n = 11) or distilled water (dH2O; red squares; n = 12), during the extinction task. There was a significant lever by time by treatment interaction, p = 0.039. The extinction task was conducted 48 h following the final DRT test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4061802&req=5

brainsci-02-00375-f006: WKY rats: Mean (±SEM) number of presses on the immediate (closed) and delayed (open) levers in consecutive 20 s intervals for rats previously exposed to 4 weeks of oral methylphenidate (MPH, 2 × 2 mg/kg/day; blue diamond; n = 11) or distilled water (dH2O; red squares; n = 12), during the extinction task. There was a significant lever by time by treatment interaction, p = 0.039. The extinction task was conducted 48 h following the final DRT test.
Mentions: At the commencement of the EXT task, WKYs previously treated with MPH pressed the immediate lever more than WKYs previously treated with dH2O. There was a significant main effect of lever, (Wilks’ Lambda is 0.276, F = 55.173, p < 0.001) such that WKYs pressed the immediate more than the delayed lever in the EXT task (Figure 6). There was a significant lever by time by treatment interaction (Wilks’ Lambda is 0.139, F = 3.540, p = 0.039), indicating that MPH pretreatment increased immediate lever pressing. There was no main effect of treatment and all other interactions were not significant. MPH treated WKYs continued to demonstrate sensitivity to delay.

Bottom Line: Adolescent male animals were treated for four weeks with oral Ritalin® (2 × 2 mg/kg/day) or distilled water (dH2O).The effect of chronic treatment on delayed reinforcement tasks (DRT) and tyrosine hydroxylase immunoreactivity (TH-ir) in the prefrontal cortex was assessed.MPH treatment did not significantly alter cognitive performance in the SHR.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Macquarie University, Sydney 2109, Australia. margery.pardey@mq.edu.au.

ABSTRACT
The diagnosis of Attention Deficit Hyperactivity Disorder (ADHD) often results in chronic treatment with psychostimulants such as methylphenidate (MPH, Ritalin®). With increases in misdiagnosis of ADHD, children may be inappropriately exposed to chronic psychostimulant treatment during development. The aim of this study was to assess the effect of chronic Ritalin treatment on cognitive and neural development in misdiagnosed "normal" (Wistar Kyoto, WKY) rats and in Spontaneously Hypertensive Rats (SHR), a model of ADHD. Adolescent male animals were treated for four weeks with oral Ritalin® (2 × 2 mg/kg/day) or distilled water (dH2O). The effect of chronic treatment on delayed reinforcement tasks (DRT) and tyrosine hydroxylase immunoreactivity (TH-ir) in the prefrontal cortex was assessed. Two weeks following chronic treatment, WKY rats previously exposed to MPH chose the delayed reinforcer significantly less than the dH2O treated controls in both the DRT and extinction task. MPH treatment did not significantly alter cognitive performance in the SHR. TH-ir in the infralimbic cortex was significantly altered by age and behavioural experience in WKY and SHR, however this effect was not evident in WKY rats treated with MPH. These results suggest that chronic treatment with MPH throughout adolescence in "normal" WKY rats increased impulsive choice and altered catecholamine development when compared to vehicle controls.

No MeSH data available.


Related in: MedlinePlus