# Enduring Consequences of Adolescent Cannabinoid and Methylphenidate Exposure

> **NIH NIH R01** · UNIVERSITY OF MARYLAND BALTIMORE · 2020 · $407,232

## Abstract

PROJECT SUMMARY
Adolescent marijuana use is a prominent public health concern. Indeed, exposure to marijuana during
adolescence, a developmental period characterized by impulsivity, is correlated with maladaptive decision
making in adulthood. The changing national attitudes on marijuana use and the resultant push for the reform of
marijuana laws (21 states and the District of Columbia currently have legalized marijuana in some form)
highlight a need to examine the long-term neurobiological consequences of cannabinoid exposure. Likewise,
methylphenidate (MPH, Ritalin®) prescription, a psychostimulant highly prescribed to impulsive adolescents,
has significantly risen and therefore co-exposure with marijuana is now more likely to happen than ever before.
Given that MPH interacts with the same neural substrates activated by marijuana, the question of whether
exposure to THC (the main psychoactive component in marijuana), MPH, or their combination during
adolescence promotes enduring neuroadaptations underlying compromised impulse control needs to be
addressed. We will first define adolescent impulsivity phenotypes prior to pharmacological treatments and will
utilize sophisticated microdialysis detection schemes and in vitro electrophysiology to determine whether
endocannabinoid (eCB) mobilization from dopaminergic neurons of the ventral tegmental area (VTA) differs
between impulsive and controlled animals. Next, real-time dopamine (DA) release and accumbal firing patterns
observed at precise behavioral epochs, will be optogenetically characterized with a specialized sensor during a
delay-discounting task in adult animals exposed to THC in adolescence (aim 1). Importantly, the effects of THC
treatment in adolescence will be contrasted to those occurring following adult exposure. In aim 2 we will
examine how treatment with THC in adolescence modifies eCB signaling and whether these modifications
change as a function of impulsive phenotype and age of exposure. Aim 3 will build upon the prior two aims to
determine if the effects of THC and MPH co-exposure on eCB signaling and dopaminergic encoding of
decision making are greater compared to those of either drug alone. The complementary use of innovative
recording methods is likely to elucidate changes in neural mechanisms governing DA neurotransmission and
accumbal activity patterns that may explain differences in impulse control in adulthood following exposure to
marijuana and/or Ritalin in adolescence. The proposed experiments respond to PA-14-163, “Effects of
Cannabis Use and Cannabinoids on the Developing Brain” by examining the behavioral, neurochemical and
electrophysiological mediation of eCB signaling governing the dynamic control of mesolimbic DA processing in
impulse control and its potential dysfunction following exposure to THC, MPH, or their combination in
adolescence.

## Key facts

- **NIH application ID:** 9920118
- **Project number:** 5R01DA042595-05
- **Recipient organization:** UNIVERSITY OF MARYLAND BALTIMORE
- **Principal Investigator:** Joseph F Cheer
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $407,232
- **Award type:** 5
- **Project period:** 2016-07-01 → 2022-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9920118

## Citation

> US National Institutes of Health, RePORTER application 9920118, Enduring Consequences of Adolescent Cannabinoid and Methylphenidate Exposure (5R01DA042595-05). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9920118. Licensed CC0.

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