Abstract
Methylphenidate (MPD) is considered as the first-line pharmacotherapy to treat ADHD. More recently, MPD has also been used as a cognitive enhancement recreationally. Its therapeutic effects are not fully understood, nor are the long term effects of the drug on brain development. The ventral tegmental area (VTA) neuronal activity was recorded from freely behaving adolescent rats using a wireless recording system. Five groups were used: saline, 0.6, 2.5, 5.0 and 10.0 mg/kg MPD. The experiment lasted for 10 days. This study demonstrated that VTA neurons respond to MPD in a dose response characteristic and the same dose of MPD can cause both behavioral sensitization and behavioral tolerance. The neuronal unit activity was evaluated based on the animals’ behavioral activity following chronic MPD administration. The study showed that the animals’ behavioral response to different acute MPD of 0.6, 2.5 and 10.0 mg/kg doses responded in a dose response characteristics. Moreover, the same chronic dose of 0.6, 2.5, and 10.0 mg/kg MPD elicits in some animals’ behavioral sensitization and in some others behavioral tolerance. Therefore, the neuronal activity recorded from animals expressing behavioral sensitization was analyzed separately from the neuronal activity recorded from of behaviorally tolerant animals and it was found that the VTA units of the behaviorally sensitization animals responded significantly different to the drug than those VTA units recorded from animals expressing behavioral tolerance.
Highlights
Methylphenidate (Ritalin, MPD) is a psychostimulant most commonly used to treat attention deficit hyperactivity disorder (ADHD) [1]-[3]
A total of 142 rats with electrodes confirmed to be in the ventral tegmental area (VTA) (Figure 1) were used in this experiment; 11, 28, 31, 29, and 43 rats were treated with saline, 0.6, 2.5, 5.0, or 10.0 mg/kg MPD respectively and 336VTA units were recorded, 26, 81, 99, 29, and 101 after saline, 0.6, 2.5, 5.0, and 10.0 mg/kg MPD respectively
The locomotor activity (HA, total distance (TD) and number of stereotypic movements (NSM)) from ED10 compared to experimental day 1 (ED1) following chronic injection of saline exhibited similar locomotor activities with minor non-significant fluctuations following single and multiple saline injections. This showed that neither saline, needle injectionnor handling had any effect on behavioral activity (Figure 2)
Summary
Methylphenidate (Ritalin, MPD) is a psychostimulant most commonly used to treat attention deficit hyperactivity disorder (ADHD) [1]-[3]. Due to its similarities to these well-known drugs of abuse, the increased use of MPD by adolescents and young adults is potentially dangerous since its use could lead to possible liability to drug dependency later in life or unknown developmental disorders. It is still unclear how psychostimulants such as MPD affect the adolescent brain and whether it can alter the neuropil formations occurring during neurodevelopment or not
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
