Repetitive ritalin treatment modulates the diurnal activity pattern of young SD male rats.
Attention Deficit Hyperactivity Disorder (ADHD) is a common behavioral disorder of children and is treated by psychostimulants. Psychostimulant exposure to children at the time of neuronal development can cause behavioral and physiological changes continuing during adulthood. Most of the studies on psychostimulants investigate the acute effects of the drug. The objective of this study was to investigate whether acute or chronic exposure to methylphenidate (MPD), the drug most often used to treat ADHD in children, will modulate the diurnal activity pattern of young rats. Maintaining the diurnal activity pattern is a physiological process that regulates the internal homeostasis. Dose response protocol was used to study the effect of acute and chronic MPD in four young post natal day 40 (P 40) rat groups, (each N=8), as follows: saline (control) group, and 0.6, 2.5, or 10.0 mg/kg i.p. MPD groups, respectively. The experiment was performed over 11 consecutive days of continuous locomotor activity recording using the open field assay. The data evaluation was divided into four phases as follows: acute, induction, washout and expression phases. There was a dose-dependent increase in the average locomotor activity in the first few hours post-injection. Analysis of the diurnal rhythmic pattern of locomotion in the three dose groups compared to control demonstrated that only the 10.0 mg/kg MPD elicited significant changes in diurnal pattern activity in the washout and the expression phase. In addition, this study indicated that chronic MPD treatment elicits dose dependent anticipation and/or withdrawal and behavioral sensitization.
Algahim
Mohame Fodhl
MF
Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston, Houston, Texas 77225, USA.
Yang
Pamela Boi
PB
Burau
Keith Dean
KD
Swann
Allan Craig
AC
Dafny
Nachum
N
D000818:Animals; D000697:Central Nervous System Stimulants / Q000009:adverse effects / Q000494:pharmacology*; D002940:Circadian Rhythm / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D008297:Male; D008774:Methylphenidate / Q000009:adverse effects / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013375:Substance Withdrawal Syndrome / Q000523:psychology
D000697:Central Nervous System Stimulants; D008774:Methylphenidate