Effects of smoked marijuana in experimentally induced asthma.
After experimental induction of acute bronchospasm in 8 subjects with clinically stable bronchial asthma, effects of 500 mg of smoked marijuana (2.0 per cent delta9-tetrahydrocannabinol) on specific airway conductance and thoracic gas volume were compared with those of 500 mg of smoked placebo marijuana (0.0 per cent delta9-tetrahydrocannabinol), 0.25 ml of aerosolized saline, and 0.25 ml of aerosolized isoproterenol (1,250 mug). Bronchospasm was induced on 4 separate occasions, by inhalation of methacholine and, on four other occasions, by exercise on a bicycle ergometer or treadmill. Methacholine and exercise caused average decreases in specific airway conductance of 40 to 55 per cent and 30 to 39 per cent, respectively, and average increases in thoracic gas volume of 35 to 43 per cent and 25 to 35 per cent, respectively. After methacholine-induced bronchospasm, placebo marijuana and saline inhalation produced minimal changes in specific airway conductance and thoracic gas volume, whereas 2.0 per cent marijuana and isoproterenol each caused a prompt correction of the bronchospasm and associated hyperinflation. After exercise-induced bronchospasm, placebo marijuana and saline were followed by gradual recovery during 30 to 60 min, whereas 2.0 per cent marijuana and isoproterenol caused an immediate reversal of exercise-induced asthma and hyperinflation.
Bronchodilator effect of delta1-tetrahydrocannabinol.
1 delta1-trans-tetrahydrocannabinol, (delta1-THC) produces bronchodilatation in asthmatic patients. 2 Administered in 62 microliter metered volumes containing 50–200 microgram by inhalation from an aerosol device to patients judged to be in a steady state, it increased peak expiratory flow rate (PEFR) and forced expiratory volume in 1 second (FEV1). 3 The rate of onset, magnitude, and duration of the bronchodilator effect was dose related.
Activation of cannabinoid receptors prevents antigen-induced asthma-like reaction in guinea pigs.
- Department of Preclinical and Clinical Pharmacology, University of Florence, Florence, Italy.
In this study we evaluated the effects of the CB1/CB2 cannabinoid receptor agonist CP55, 940 (CP) on antigen-induced asthma-like reaction in sensitized guinea pigs and we tested the ability of the specific CB2 receptor antagonist SR144528 (SR) and CB1 receptor antagonist AM251 (AM) to interfere with the effects of CP. Ovalbumin-sensitized guinea pigs placed in a respiratory chamber were challenged with the antigen given by aerosol. CP (0.4 mg/kg b.wt.) was given i.p. 3 hrs before ovalbumin challenge. Sixty minutes before CP administration, some animals were treated i.p. with either AM, or SR, or both (0.1 mg/kg b.wt.). Respiratory parameters were recorded and quantified. Lung tissue specimens were then taken for histopathological and morphometric analyses and for eosinophilic major basic protein immunohistochemistry. Moreover, myeloperoxidase activity, 8-hydroxy-2-deoxyguanosine, cyclic adenosine monophosphate (cAMP) and guanosine monophosphate (cGMP) levels, and CB1 and CB2 receptor protein expression by Western blotting were evaluated in lung tissue extracts. In the bronchoalveolar lavage fluid, the levels of prostaglandin D2 and tumour necrosis factor-alpha TNF-alpha were measured. Ovalbumin challenge caused marked abnormalities in the respiratory, morphological and biochemical parameters assayed. Treatment with CP significantly reduced these abnormalities. Pre-treatment with SR, AM or both reverted the protective effects of CP, indicating that both CB1 and CB2 receptors are involved in lung protection. The noted treatments did not change the expression of cannabinoid receptor proteins, as shown by Western blotting. These findings suggest that targeting cannabinoid receptors could be a novel preventative therapeutic strategy in asthmatic patients.
The role of cannabinoids in inflammatory modulation of allergic respiratory disorders, inflammatory pain and ischemic stroke.
- Department of Preclinical and Clinical Pharmacology, University of Florence, Viale G. Pieraccini 6, I- 50139 Florence, Italy.
This review is intended to offer updated information on the involvement of cannabinoids in the process of inflammation, focusing on immune/allergic reactions, inflammatory pain and neuroinflammation and discussing the interactions among endocannabinoid metabolism, prostanoids and nitric oxide. Two types of cannabinoid receptors, CB1 and CB2, which belong to the G protein-coupled receptor family, have been identified and are targeted by numerous exogenous and endogenous ligands. The activation of CB2 receptors on mast cells has direct antiinflammatory effects, causing decreased release of pro-inflammatory mediators by these cells. The activation of CB1 receptors on bronchial nerve endings has bronchodilator effects by acting on the airway smooth muscle and may be beneficial in airway hyperreactivity and asthma. Moreover, pharmacologic interference with endocannabinoid metabolism has been demonstrated to result in anti-nociceptive activity, mediated by CB1 and CB2 receptors, in animal models of inflammatory pain. The presence of endocannabinoid machinery in the central nervous system, together with high levels of CB1 expression, suggests that the endocannabinoid system is an important modulator of neuroinflammation and a possible drug target. In selected conditions, the activation of CB1 receptors in cerebral blood vessels can have beneficial antiischemic effects. However, as endocannabinoids can also bind to vanilloid receptors, they may also mediate neurotoxic effects.