The potential therapeutic use of some Cannabis sativa plant compounds has been attracting great interest, especially for managing neuropsychiatric disorders due to the relative lack of efficacy of the current treatments. Numerous studies have been carried out using the main phytocannabinoids, tetrahydrocannabinol (THC) and cannabidiol (CBD). CBD displays an interesting pharmacological profile without the potential for becoming a drug of abuse, unlike THC. In this review, we focused on the anxiolytic, antidepressant, and antipsychotic effects of CBD found in animal and human studies. In rodents, results suggest that the effects of CBD depend on the dose, the strain, the administration time course (acute vs. chronic), and the route of administration. In addition, certain key targets have been related with these CBD pharmacological actions, including cannabinoid receptors (CB₁r and CB₂r), 5-HT_1A receptor and neurogenesis factors. Preliminary clinical trials also support the efficacy of CBD as an anxiolytic, antipsychotic, and antidepressant, and more importantly, a positive risk-benefit profile. These promising results support the development of large-scale studies to further evaluate CBD as a potential new drug for the treatment of these psychiatric disorders.

In this study, we investigated the role of the endocannabinoid system (ECS) in the emotional and cognitive alterations associated with osteoarthritis pain. The monosodium iodoacetate model was used to evaluate the affective and cognitive manifestations of osteoarthritis pain in type 1 (CB1R) and type 2 (CB2R) cannabinoid receptor knockout and wild-type mice and the ability of CB1R (ACEA) and CB2R (JWH133) selective agonists to improve these manifestations during a 3-week time period. The levels of the endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) were measured in plasma and brain areas involved in the control of these manifestations. Patients with knee osteoarthritis and healthy controls were recruited to evaluate pain, affective, and cognitive symptoms, as well as plasma endocannabinoid levels and cannabinoid receptor gene expression in peripheral blood lymphocytes. The affective manifestations of osteoarthritis were enhanced in CB1R knockout mice and absent in CB2R knockouts. Interestingly, both ACEA and JWH133 ameliorated the nociceptive and affective alterations, whereas ACEA also improved the associated memory impairment. An increase of 2-AG levels in prefrontal cortex and plasma was observed in this mouse model of osteoarthritis. In agreement, an increase of 2-AG plasmatic levels and an upregulation of CB1R and CB2R gene expression in peripheral blood lymphocytes were observed in patients with osteoarthritis compared with healthy subjects. Changes found in these biomarkers of the ECS correlated with pain, affective, and cognitive symptoms in these patients. The ECS plays a crucial role in osteoarthritis and represents an interesting pharmacological target and biomarker of this disease.

Recent evidence suggests that cannabidiol (CBD) may be useful for the treatment of different neuropsychiatric disorders. However, some controversy regarding its profile as a drug of abuse hampers the further development of basic and clinical studies. In this study, the behavioral profile of CBD as a potential drug of abuse was evaluated in C57BL/6J mice. Reinforcing properties of CBD (15, 30, and 60 mg/kg; i.p.) were assessed using the conditioned place preference (CPP) paradigm. Spontaneous withdrawal symptoms and motor activity in the open field were examined 12 h after the last CBD administration (30 mg/kg/12 h, i.p., 6 days). CBD plasma concentrations were measured at 2, 4, 8, 12, and 24 h after the administration of CBD (30 mg/kg, i.p.). Furthermore, an oral CBD self-administration paradigm (50 mg/kg; CBD water-soluble 1.2 mg/mL) was performed to evaluate whether this drug produced any effects on motivation compared with a non-reinforcing substance (water). We found that CBD failed to induce CPP, withdrawal symptoms, or altered motor behavior 12 h after its administration. At that time, only traces of CBD were detected, ensuring that the lack of alterations in somatic signs and locomotor activity was not due to residual drug in plasma. Interestingly, mice displayed similar motivation and consumption of CBD and water. Taken together, these results show that CBD lacks activity as a drug of abuse and should stimulate the development of the basic and clinical studies needed to elucidate its potential therapeutic use for the treatment of neuropsychiatric and drug use disorders.