Northern Kentucky University
Adolescent Methylphenidate Treatment: Effects on Methamphetamine Relapse-Like Behavior During Adulthood
Grade Level at Time of Presentation
Senior
Major
Neuroscience
Minor
Psychology
KY House District #
67
KY Senate District #
24
Faculty Advisor/ Mentor
Justin R. Yates, PhD
Department
Dept. of Psychology
Abstract
Methylphenidate (Ritalin®) is commonly prescribed to treat attention-deficit/hyperactivity disorder (ADHD) in children and adolescents. Considering methylphenidate is a psychostimulant with a chemical structure similar to cocaine, there are concerns about its misuse potential, and there are concerns that long-term methylphenidate treatment can increase addiction-like behaviors to other psychostimulant drugs such as cocaine or methamphetamine. In the current experiment, we tested the hypothesis that early-life methylphenidate exposure would increase methamphetamine relapse-like behavior. We first administered either methylphenidate (1.5 mg/kg) or apple juice (control group) to Spontaneously Hypertensive Rats (SHRs), an animal model of ADHD, during adolescence and early adulthood. We then tested SHRs for their preference for methamphetamine (1.0 mg/kg) using the conditioned place preference (CPP) paradigm. During CPP, rats learned to associate one environmental context with methamphetamine and a different environmental context with saline (i.e., salt water). The contexts differed in color (black vs. white) and in flooring (wire mesh vs. steel rod). After eight days of conditioning, rats were given a preference test in which they could freely explore each environmental context. Spending more time in the methamphetamine-paired compartment reflected enhanced CPP (i.e., preference for methamphetamine). Following the preference test, rats were given extinction training, in which they were allowed to explore each compartment. During extinction, rats never received methamphetamine. This is analogous to someone that is attempting to abstain from drug use. Once the time spent in the methamphetamine-paired compartment decreased by at least 20%, rats were given a reinstatement test, a model of relapse. Rats were injected with a low dose of methamphetamine (0.25 mg/kg) before being placed into the CPP chamber. Our hypothesis was not supported as early-life administration of methylphenidate failed to increase reinstatement of methamphetamine seeking in SHRs. These results suggest that long-term treatment of methylphenidate does not increase relapse vulnerability later in life.
Adolescent Methylphenidate Treatment: Effects on Methamphetamine Relapse-Like Behavior During Adulthood
Methylphenidate (Ritalin®) is commonly prescribed to treat attention-deficit/hyperactivity disorder (ADHD) in children and adolescents. Considering methylphenidate is a psychostimulant with a chemical structure similar to cocaine, there are concerns about its misuse potential, and there are concerns that long-term methylphenidate treatment can increase addiction-like behaviors to other psychostimulant drugs such as cocaine or methamphetamine. In the current experiment, we tested the hypothesis that early-life methylphenidate exposure would increase methamphetamine relapse-like behavior. We first administered either methylphenidate (1.5 mg/kg) or apple juice (control group) to Spontaneously Hypertensive Rats (SHRs), an animal model of ADHD, during adolescence and early adulthood. We then tested SHRs for their preference for methamphetamine (1.0 mg/kg) using the conditioned place preference (CPP) paradigm. During CPP, rats learned to associate one environmental context with methamphetamine and a different environmental context with saline (i.e., salt water). The contexts differed in color (black vs. white) and in flooring (wire mesh vs. steel rod). After eight days of conditioning, rats were given a preference test in which they could freely explore each environmental context. Spending more time in the methamphetamine-paired compartment reflected enhanced CPP (i.e., preference for methamphetamine). Following the preference test, rats were given extinction training, in which they were allowed to explore each compartment. During extinction, rats never received methamphetamine. This is analogous to someone that is attempting to abstain from drug use. Once the time spent in the methamphetamine-paired compartment decreased by at least 20%, rats were given a reinstatement test, a model of relapse. Rats were injected with a low dose of methamphetamine (0.25 mg/kg) before being placed into the CPP chamber. Our hypothesis was not supported as early-life administration of methylphenidate failed to increase reinstatement of methamphetamine seeking in SHRs. These results suggest that long-term treatment of methylphenidate does not increase relapse vulnerability later in life.