Mechanisms of cannabidiol neuroprotection in hypoxic-ischemic newborn pigs: role of 5HT(1A) and CB2 receptors

• Published in: Neuropharmacology 2013-08, Vol.71, p.282-291
• Main Authors: Pazos, M Ruth, Mohammed, Nagat, Lafuente, Hector, Santos, Martin, Martínez-Pinilla, Eva, Moreno, Estefania, Valdizan, Elsa, Romero, Julián, Pazos, Angel, Franco, Rafael, Hillard, Cecilia J, Alvarez, Francisco J, Martínez-Orgado, Jose
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn; Brain - drug effects; Brain - immunology; Brain - metabolism; Brain - pathology; Brain Injuries - physiopathology; Cannabidiol - antagonists & inhibitors; Cannabidiol - pharmacokinetics; Cannabidiol - pharmacology; Cannabidiol - therapeutic use; Cannabinoid Receptor Antagonists - pharmacology; Cannabinoids - metabolism; Cannabinoids - pharmacokinetics; Cannabinoids - therapeutic use; Disease Models, Animal; HEK293 Cells; Humans; Hypoxia-Ischemia, Brain - drug therapy; Hypoxia-Ischemia, Brain - etiology; Hypoxia-Ischemia, Brain - metabolism; Hypoxia-Ischemia, Brain - pathology; Male; Nerve Tissue Proteins - antagonists & inhibitors; Nerve Tissue Proteins - metabolism; Neurons - drug effects; Neurons - immunology; Neurons - metabolism; Neurons - pathology; Neuroprotective Agents - antagonists & inhibitors; Neuroprotective Agents - pharmacokinetics; Neuroprotective Agents - pharmacology; Neuroprotective Agents - therapeutic use; Protein Multimerization; Random Allocation; Receptor, Cannabinoid, CB2 - antagonists & inhibitors; Receptor, Cannabinoid, CB2 - genetics; Receptor, Cannabinoid, CB2 - metabolism; Receptor, Serotonin, 5-HT1A - chemistry; Receptor, Serotonin, 5-HT1A - genetics; Receptor, Serotonin, 5-HT1A - metabolism; Recombinant Fusion Proteins - metabolism; Reperfusion Injury - prevention & control; Serotonin 5-HT1 Receptor Antagonists - pharmacology; Sus scrofa
• ISSN: 1873-7064
• DOI: 10.1016/j.neuropharm.2013.03.027

The mechanisms underlying the neuroprotective effects of cannabidiol (CBD) were studied in vivo using a hypoxic-ischemic (HI) brain injury model in newborn pigs. One- to two-day-old piglets were exposed to HI for 30 min by interrupting carotid blood flow and reducing the fraction of inspired oxygen to 10%. Thirty minutes after HI, the piglets were treated with vehicle (HV) or 1 mg/kg CBD, alone (HC) or in combination with 1 mg/kg of a CB₂ receptor antagonist (AM630) or a serotonin 5HT(1A) receptor antagonist (WAY100635). HI decreased the number of viable neurons and affected the amplitude-integrated EEG background activity as well as different prognostic proton-magnetic-resonance-spectroscopy (H(±)-MRS)-detectable biomarkers (lactate/N-acetylaspartate and N-acetylaspartate/choline ratios). HI brain damage was also associated with increases in excitotoxicity (increased glutamate/N-acetylaspartate ratio), oxidative stress (decreased glutathione/creatine ratio and increased protein carbonylation) and inflammation (increased brain IL-1 levels). CBD administration after HI prevented all these alterations, although this CBD-mediated neuroprotection was reversed by co-administration of either WAY100635 or AM630, suggesting the involvement of CB₂ and 5HT(1A) receptors. The involvement of CB₂ receptors was not dependent on a CBD-mediated increase in endocannabinoids. Finally, bioluminescence resonance energy transfer studies indicated that CB₂ and 5HT(1A) receptors may form heteromers in living HEK-293T cells. In conclusion, our findings demonstrate that CBD exerts robust neuroprotective effects in vivo in HI piglets, modulating excitotoxicity, oxidative stress and inflammation, and that both CB₂ and 5HT(1A) receptors are implicated in these effects.