Swapnil Gupta1,2, Joao P De Aquino3,4,5, Deepak C D'Souza1,6,7, Mohini Ranganathan1,6,7. 1. Department of Psychiatry, Yale University School of Medicine, 300 George St, Suite 901, New Haven, CT, 06510, USA. 2. Connecticut Mental Health Center, 34 Park St, New Haven, CT, USA. 3. Department of Psychiatry, Yale University School of Medicine, 300 George St, Suite 901, New Haven, CT, 06510, USA. joao.deaquino@yale.edu. 4. Clinical Neuroscience Research Unit, Connecticut Mental Health Center, 34 Park St, 3rd Floor, New Haven, CT, USA. joao.deaquino@yale.edu. 5. VA Connecticut Healthcare System, Clinical Neurosciences Division, U.S. Department of Veterans Affairs, West Haven, CT, USA. joao.deaquino@yale.edu. 6. Clinical Neuroscience Research Unit, Connecticut Mental Health Center, 34 Park St, 3rd Floor, New Haven, CT, USA. 7. VA Connecticut Healthcare System, Clinical Neurosciences Division, U.S. Department of Veterans Affairs, West Haven, CT, USA.
Abstract
RATIONALE: Δ-9-Tetrahydrocannabinol (Δ-9-THC) produces psychotomimetic effects in humans. However, the role of dopamine signaling in producing such effects is unclear. We hypothesized that dopaminergic antagonism would reduce the psychotomimetic effect of Δ-9-THC. OBJECTIVE: The objective of this study was to evaluate whether pre-treatment with haloperidol would alter the psychotomimetic and perceptual-altering effects of Δ-9-THC, measured by the Positive and Negative Syndrome Scale for Schizophrenia (PANSS) and the Clinician-Administered Dissociative Symptom Scale (CADSS) in humans. METHODS: In a two-test-day double-blind study, 28 healthy individuals were administered with active (0.057 mg/kg) or placebo oral haloperidol, followed 90 and 215 min later by intravenous administration of active (0.0286 mg/kg) Δ-9-THC and placebo, respectively. This secondary analysis was conducted because of the observation in other studies and in our data that a significant proportion of individuals may not have an adequate response to THC (floor effect), thus limiting the ability to test an interaction. Therefore, this analysis was performed including only responders to THC (n = 10), defined as individuals who had an increase of at least one point on the PANSS positive scale, consistent with prior human laboratory studies. RESULTS: In the 10 responders, Δ-9-THC-induced increases in PANSS positive scores were significantly lower in the haloperidol condition (1.1 + 0.35) compared with the placebo condition (2.9 + 0.92). CONCLUSION: This responder analysis showed that haloperidol did reduce the psychotomimetic effect of Δ-9-THC, supporting the hypothesis that dopaminergic signaling may participate in the psychosis-like effects of cannabinoids.
RCT Entities:
RATIONALE: Δ-9-Tetrahydrocannabinol (Δ-9-THC) produces psychotomimetic effects in humans. However, the role of dopamine signaling in producing such effects is unclear. We hypothesized that dopaminergic antagonism would reduce the psychotomimetic effect of Δ-9-THC. OBJECTIVE: The objective of this study was to evaluate whether pre-treatment with haloperidol would alter the psychotomimetic and perceptual-altering effects of Δ-9-THC, measured by the Positive and Negative Syndrome Scale for Schizophrenia (PANSS) and the Clinician-Administered Dissociative Symptom Scale (CADSS) in humans. METHODS: In a two-test-day double-blind study, 28 healthy individuals were administered with active (0.057 mg/kg) or placebo oral haloperidol, followed 90 and 215 min later by intravenous administration of active (0.0286 mg/kg) Δ-9-THC and placebo, respectively. This secondary analysis was conducted because of the observation in other studies and in our data that a significant proportion of individuals may not have an adequate response to THC (floor effect), thus limiting the ability to test an interaction. Therefore, this analysis was performed including only responders to THC (n = 10), defined as individuals who had an increase of at least one point on the PANSS positive scale, consistent with prior human laboratory studies. RESULTS: In the 10 responders, Δ-9-THC-induced increases in PANSS positive scores were significantly lower in the haloperidol condition (1.1 + 0.35) compared with the placebo condition (2.9 + 0.92). CONCLUSION: This responder analysis showed that haloperidol did reduce the psychotomimetic effect of Δ-9-THC, supporting the hypothesis that dopaminergic signaling may participate in the psychosis-like effects of cannabinoids.
Authors: Christopher S Kearn; Katherine Blake-Palmer; Emma Daniel; Ken Mackie; Michelle Glass Journal: Mol Pharmacol Date: 2005-02-14 Impact factor: 4.436
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