Marijuana Research Today is a free monthly online journal that collates and summarizes the latest research about Marijuana, including details on benefits, cancer, effects, uses, addiction. | ||||||||
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Prenatal cannabis exposure increases heroin seeking with allostatic changes in limbic enkephalin systems in adulthood.Spano MS, Ellgren M, Wang X, Hurd YL Karolinska Institute, Department of Clinical Neuroscience, Psychiatry Section, S-17176 Stockholm, Sweden. BACKGROUND: Prenatal cannabis exposure is a growing concern with little known about the long-term consequences on behavior and neural systems relevant for reward and emotional processing. METHODS: We used an animal model to study the effects of prenatal exposure to Delta(9)-tetrahydrocannabinol (THC) on heroin self-administration behavior and opioid neural systems in adult males (postnatal day 62). Rats were exposed to THC (.15 mg/kg) or vehicle from gestational day 5 to postnatal day 2. RESULTS: Both pretreatment groups showed similar heroin intake, but THC-exposed rats exhibited shorter latency to the first active lever press, responded more for low heroin doses, and had higher heroin-seeking during mild stress and drug extinction. THC exposure reduced preproenkephalin (PENK) mRNA expression in the nucleus accumbens during early development, but was elevated in adulthood; no adult striatal changes on preprodynorphin mRNA or PENK in caudate-putamen. PENK mRNA was also increased in the central and medial amygdala in adult THC-exposed animals. THC animals had reduced heroin-induced locomotor activity and nucleus accumbens mu opioid receptor coupling. CONCLUSIONS: This study demonstrates enduring effects of prenatal THC exposure into adulthood that is evident on heroin-seeking behavior during extinction and allostatic changes in mesocorticolimbic PENK systems relevant to drug motivation/reward and stress response. Published 5 February 2007 in Biol Psychiatry, 61(4): 554-63.
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