METHYLPHENIDATE EXPOSURE DURING PERIPUBERTAL PHASE AFFECTS LEARNING AND MEMORY OF ADULT RATS

Abstract

Methylphenidate (MPH) is the active ingredient in Ritalin, although effective in treating of
the attention deficit hyperactivity disorder (ADHD), its neurostimulation action is attractive
among students in order to increase the focus or improving student performance. In context of
the Developmental Origins of Health and Disease (DOHaD) concept, states that insults in
critical phases of development, as the peripubertal period, may program the organism to
dysfunctions in adulthood. The aim of this work was to investigate the impact of peripubertal
MPH exposure on learning and retrograde memory in adult rats. Male Wistar rats were
exposed to MPH (5 mg/kg) from post-natal day (PN) 30 until PN60 (MPH). Control animals
received 0.9% saline (Sal). At PN60, learning was evaluated true 10 days in an eight-arm
elevated maze and at PN120 retrograde memory. At PN60, MPH group showed a delay of
61% in the latency, an increase of 100% in the number of errors and 200% in the number of
repetition errors when compared to the Sal group, until the day 5 of learning period (p=0.004).
After the washout period, at PN120, the MPH group showed an increase of 37% in the
latency, 49% in the number of errors of reference and 600% in the number of repetition errors
compared with the Sal group (p=0.001, p=0.004 and p=0.01). Exposure to MPH during
peripubertal phase decreases learning and memory in adult male Wistar rats.