Effects of Δ9-Tetrahydrocannabinol and the Aminoalkylindole K2/Spice Constituent JWH-073 on Cardiac Tissue and Mesenteric Vascular Reactivity

Background: Although use of Cannabis sativa is not associated with serious adverse effects, recreational use of aminoalkylindole (AAI) cannabinoid receptor agonists found in K2/Spice herbal blends has been reported to cause adverse cardiovascular events, including angina, arrhythmia, changes in blood pressure, ischemic stroke, and myocardial infarction. Δ9-Tetrahydrocannabinol (Δ9-THC) is the primary CB1 agonist found in cannabis and JWH-073 is one of the AAI CB1 agonists found in K2/Spice brands sold to the public. Methods: This study used in vitro, in vivo, and ex vivo approaches to investigate potential differences on cardiac tissue and vascular effects betweenJWH-073 and Δ9-THC. Male C57BL/6 mice were treated with JWH-073 or Δ9-THC and cardiac injury was assessed by histology. Effects of JWH-073 and Δ9-THC on H9C2 cell viability and ex vivo mesenteric vascular reactivity were also determined. Results: JWH-073 or Δ9-THC induced typical cannabinoid effects of antinociception and hypothermia but did not promote death of cardiac myocytes. No differences in cell viability were observed in cultured H9C2 cardiac myocytes after 24 h of treatment. In isolated mesenteric arteries from drug-naive animals, JWH-073 produced significantly greater maximal relaxation (96%±2% vs. 73%±5%, p<0.05) and significantly greater inhibition of phenylephrine-mediated maximal contraction (Control 174%±11%KMAX) compared with Δ9-THC (50%±17% vs. 119%±16%KMAX, p<0.05). Discussion: These findings suggest that neither cannabinoid at the concentrations/dose studied caused cardiac cell death, but JWH-073 has the potential for greater vascular adverse events than Δ9-THC through an increased vasodilatory effect.

Comparison of the Neurotoxic and Seizure-Inducing Effects of Synthetic and Endogenous Cannabinoids with Δ9-Tetrahydrocannabinol

Introduction: Synthetic cannabinoids (SCs) are commonly found in preparations used as recreational drugs. Although severe adverse health effects are not generally associated with cannabis use, a rising number of studies document seizures and even death after SC use. In this study, a mouse model is used to investigate the hypothesis that SCs are more toxic than Δ⁹-tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis.

Materials and Methods: Beginning with the SCs, JWH-073 and AM-2201, dose–response curves were generated to find the dose of each drug that was similarly efficacious to 50 mg/kg THC. Mice were given daily intraperitoneal (IP) injections of vehicle, 50 mg/kg THC, 30 mg/kg JWH-073, or 1 mg/kg AM-2201 until tolerance to the antinociceptive and hypothermic effects was complete, and then were assessed for spontaneous and antagonist-precipitated withdrawal and potential organ damage. No differences in tolerance were noted, but AM-2201 showed more rearing in the spontaneous and antagonist-precipitated withdrawal phases than either vehicle or the other two drug treatments. Histopathological examination of these mice revealed no drug-induced lesions. In a subsequent set of experiments, various doses of THC, methanandamide (mAEA), and of a variety of SCs (HU-210, CP55940, JWH-073, AM-2201, and PB-22) were given IP, and convulsions and change in body temperature were quantified.

Discussion: The treatments yielded varying numbers of convulsions and a range of changes in body temperature. JWH-073 and AM-2201 produced significantly more convulsions than THC, HU-210, mAEA, or cannabidiol (CBD) (the latter two producing none). HU-210, CP55940, JWH-073, and mAEA produced greater hypothermia than THC or CBD. Convulsions and hypothermia induced by several agonists were prevented by pretreatment with a CB₁ antagonist, but not a CB₂ antagonist.

Conclusions: In agreement with human studies and case reports, this study found that SCs generally produced more seizures than THC. Of particular significance was the finding that mAEA produced far greater hypothermia than THC (similar to most SCs), but unlike the SCs and THC, produced no seizures.