Marijuana (cannabis sativa) use during adolescence normally predates the use of """"""""heavy"""""""" drugs such as heroin in later life, which has raised speculations as to possible """"""""gateway"""""""" effects of marijuana. Factors such as drug-associated environment and inherent individual differences (e.g., impulsivity, hyperactivity), which predates early drug use and can influence neurodevelopment during adolescence, appear to increase the risk for substance abuse disorders. The mesocorticolimbic system (MCLS) is critically involved in, e.g., emotional regulation, reward, and motivation and express significant levels of cannabinoid receptors (CB1). We have observed that cannabis-exposed human fetuses have impaired dopamine (DA)-related gene expression in the amygdala, a component of the MCLS (which also includes the nucleus accumbens (NAcc), ventral tegmental area (VTA), and medial prefrontal cortex (mPFC)). Moreover, we found that adolescent rats administered THC (the psychoactive component of cannabis) have increased heroin intake in adulthood suggesting a link between the cannabinoid and opioid systems. It is the goal of this proposal to identify neurobiological alterations in MCLS structures that can account for the effects of THC exposure during adolescence on heroin self-administration in adulthood. In vivo DA levels as well as gene expression and receptor binding linked to the CB1, opioid neuropeptides, and DA neural systems will be studied in MCLS structures in adult rats exposed to THC during adolescence. The impact of risk factors such as behavioral individual differences (e.g., high behavioral activity, high impulsivity) and the environmental context of THC exposure will also be evaluated in regard to their influence on heroin self-administration behavior and neurobiology. These studies should provide information as to whether there exist a long-term impact of THC exposure during development to substantiate a neurobiological """"""""gateway"""""""" hypothesis and, if so, help to identify potential risk factors in adolescents that can influence the risk for heroin abuse in adulthood.

Agency
National Institute of Health (NIH)
Institute
National Institute on Drug Abuse (NIDA)
Type
Research Project (R01)
Project #
5R01DA019350-04
Application #
7118794
Study Section
Special Emphasis Panel (ZDA1-MXG-S (21))
Program Officer
Lynch, Minda
Project Start
2004-09-30
Project End
2009-08-31
Budget Start
2006-09-01
Budget End
2007-08-31
Support Year
4
Fiscal Year
2006
Total Cost
$289,655
Indirect Cost
Name
Mount Sinai School of Medicine
Department
Psychiatry
Type
Schools of Medicine
DUNS #
078861598
City
New York
State
NY
Country
United States
Zip Code
10029
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Ren, Yanhua; Whittard, John; Higuera-Matas, Alejandro et al. (2009) Cannabidiol, a nonpsychotropic component of cannabis, inhibits cue-induced heroin seeking and normalizes discrete mesolimbic neuronal disturbances. J Neurosci 29:14764-9
Ellgren, M; Artmann, A; Tkalych, O et al. (2008) Dynamic changes of the endogenous cannabinoid and opioid mesocorticolimbic systems during adolescence: THC effects. Eur Neuropsychopharmacol 18:826-34
Ellgren, Maria; Spano, Sabrina M; Hurd, Yasmin L (2007) Adolescent cannabis exposure alters opiate intake and opioid limbic neuronal populations in adult rats. Neuropsychopharmacology 32:607-15