Abstract Title

Assessment of Cognitive Deficits and Sex Differences in Adult Rats after Adolescent Methylphenidate Exposure

Abstract

Methylphenidate (MPD), commonly known as Ritalin, is considered the gold standard in treating Attention Deficit Hyperactivity Disorder (ADHD), but there is still a lack of knowledge regarding the effect of early exposure to MPD on adult brain structure and function (Grund et al., 2006). Serial pattern learning is a behavioral task that depends on multiple learning and cognitive systems. Rowan et al. (2015) found in a previous study with male rats that adolescent exposure to MPD caused cognitive impairments in serial pattern learning in adulthood long after MPD exposure ended. However, no study has yet examined sex differences in the effects of early exposure to MPD on adult cognitive capacity. In this study, 12 male and 12 female rats received the same exposures via intraperitoneal injections as in the Rowan et al. (2015) study, namely, 20.0 mg/kg/day MPD, and an equal number of male and female control rats received vehicle for 5 days/week for 7 weeks. MPD-exposed and control rats learned to perform the same 24-element serial pattern used by Rowan et al. (2015), but the rats differed in that they were from different breeding stock and they experienced twice as many serial patterns per day in training. A significant sex difference was observed for one measure of serial pattern learning. However, we did not observe any effects of adolescent MPD for either sex in this paradigm. Our results suggest that differences in rat strain or training procedures may affect the ability to measure adolescent MPD-induced impairments of adult cognition.

Modified Abstract

Adolescent methylphenidate (MPD) exposure in male rats causes cognitive impairments in adult serial pattern learning long after MPD exposure ends (Rowan et al., 2015). We examined effects of adolescent MPD on adult cognitive capacity using 12 male and 12 female rats receiving 20.0 mg/kg/day MPD, and an equal number of male and female control rats received vehicle for 5 days/week for 7 weeks. MPD-exposed and control rats also learned the same 24-element serial pattern used previously, but rats were from different breeding stock and experienced twice as many patterns per day in training. A significant sex difference was observed but with no effects of adolescent MPD. Differences in rat strain or training procedures may affect the ability to measure adolescent MPD-induced impairments of adult cognition.

Research Category

Psychology

Primary Author's Major

Psychology

Mentor #1 Information

Dr. Stephen B. Fountain

Presentation Format

Poster

Start Date

March 2016

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Research Area

Biological Psychology

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Mar 15th, 1:00 PM

Assessment of Cognitive Deficits and Sex Differences in Adult Rats after Adolescent Methylphenidate Exposure

Methylphenidate (MPD), commonly known as Ritalin, is considered the gold standard in treating Attention Deficit Hyperactivity Disorder (ADHD), but there is still a lack of knowledge regarding the effect of early exposure to MPD on adult brain structure and function (Grund et al., 2006). Serial pattern learning is a behavioral task that depends on multiple learning and cognitive systems. Rowan et al. (2015) found in a previous study with male rats that adolescent exposure to MPD caused cognitive impairments in serial pattern learning in adulthood long after MPD exposure ended. However, no study has yet examined sex differences in the effects of early exposure to MPD on adult cognitive capacity. In this study, 12 male and 12 female rats received the same exposures via intraperitoneal injections as in the Rowan et al. (2015) study, namely, 20.0 mg/kg/day MPD, and an equal number of male and female control rats received vehicle for 5 days/week for 7 weeks. MPD-exposed and control rats learned to perform the same 24-element serial pattern used by Rowan et al. (2015), but the rats differed in that they were from different breeding stock and they experienced twice as many serial patterns per day in training. A significant sex difference was observed for one measure of serial pattern learning. However, we did not observe any effects of adolescent MPD for either sex in this paradigm. Our results suggest that differences in rat strain or training procedures may affect the ability to measure adolescent MPD-induced impairments of adult cognition.