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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

SHR: Images showing tyrosine hydroxylase-ir fibres in the orbitofrontal cortex (OFC), prelimbic cortex (PrL; dorsal) and infralimbic cortex (IL) following chronic treatment with either methylphenidate (MPH) or distilled water (dH2O). Immunohistochemical staining was conducted in the short- and long-term groups, 1 and 12 weeks after cessation of treatment, respectively, and following behavioural testing (12 weeks post treatment) in the behavioural group. The white square represents the analysis probe in each region of interest (50,000 µm2). Images have been adjusted for presentation.
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brainsci-02-00375-f010: SHR: Images showing tyrosine hydroxylase-ir fibres in the orbitofrontal cortex (OFC), prelimbic cortex (PrL; dorsal) and infralimbic cortex (IL) following chronic treatment with either methylphenidate (MPH) or distilled water (dH2O). Immunohistochemical staining was conducted in the short- and long-term groups, 1 and 12 weeks after cessation of treatment, respectively, and following behavioural testing (12 weeks post treatment) in the behavioural group. The white square represents the analysis probe in each region of interest (50,000 µm2). Images have been adjusted for presentation.

Mentions: TH-ir fibres were seen throughout all regions of the PFC with a high density of TH staining in layers 5 and 6 of the PrL and IL (Figure 10).


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)

SHR: Images showing tyrosine hydroxylase-ir fibres in the orbitofrontal cortex (OFC), prelimbic cortex (PrL; dorsal) and infralimbic cortex (IL) following chronic treatment with either methylphenidate (MPH) or distilled water (dH2O). Immunohistochemical staining was conducted in the short- and long-term groups, 1 and 12 weeks after cessation of treatment, respectively, and following behavioural testing (12 weeks post treatment) in the behavioural group. The white square represents the analysis probe in each region of interest (50,000 µm2). Images have been adjusted for presentation.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

brainsci-02-00375-f010: SHR: Images showing tyrosine hydroxylase-ir fibres in the orbitofrontal cortex (OFC), prelimbic cortex (PrL; dorsal) and infralimbic cortex (IL) following chronic treatment with either methylphenidate (MPH) or distilled water (dH2O). Immunohistochemical staining was conducted in the short- and long-term groups, 1 and 12 weeks after cessation of treatment, respectively, and following behavioural testing (12 weeks post treatment) in the behavioural group. The white square represents the analysis probe in each region of interest (50,000 µm2). Images have been adjusted for presentation.
Mentions: TH-ir fibres were seen throughout all regions of the PFC with a high density of TH staining in layers 5 and 6 of the PrL and IL (Figure 10).

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