Excessive and persistent inflammatory responses are a potential pathological condition that can lead to diseases of various systems, including nervous, respiratory, digestive, circulatory, and endocrine systems. Cannabinoid type 2 receptor(CB2R) belongs to the G protein-coupled receptor family and is widely distributed in immune cells, peripheral tissues, and the central nervous system. It plays a role in inflammatory responses under various pathological conditions. The down-regulation of CB2R activity is an important marker of inflammation and and CB2R modulators have been shown to have anti-inflammatory effects. This study explored the relationship between CB2R and inflammatory responses, delved into its regulatory mechanisms in inflammatory diseases, and summarized the research progress on CB2R modulators from plants other than cannabis, including plant extracts and monomeric compounds, in exerting anti-inflammatory effects. The aim is to provide new insights into the prevention and treatment of inflammatory diseases.
Cannabinoid Receptor Modulators/pharmacology* ; Cannabinoid Receptor Agonists/pharmacology* ; Receptors, Cannabinoid ; Cannabinoids/pharmacology* ; Anti-Inflammatory Agents/pharmacology*

The present study aimed to investigate whether cannabinoids could modulate the response mediated by ATP receptor (P2X purinoceptor). Whole-cell patch-clamp recording was performed on cultured rat trigeminal ganglionic (TG) neurons. The majority of TG neurons were sensitive to ATP (67/75, 89.33%). Extracellular pretreatment with WIN55212-2, a cannabinoid receptor 1 (CB1 receptor) agonist, reduced ATP-activated current (I(ATP)) significantly. This inhibitory effect was concentration-dependent and was blocked by AM281, a specific CB1 receptor antagonist. Pretreatment with WIN55212-2 at 1×10(-13), 1×10(-12), 1×10(-11), 1×10(-10), 1×10(-9) and 1×10(-8) mol/L reduced I(ATP) (induced by 1×10(-4) mol/L ATP) by (8.14±3.14)%, (20.11±2.72)%, (46.62±3.51)%, (72.16±5.64)%, (80.21±2.80)% and (80.59±3.55)%, respectively. The concentration-response curves for I(ATP) pretreated with and without WIN55212-2 showed that WIN55212-2 shifted the curve downward, and decreased the maximal amplitude of I(ATP) by (58.02±4.21)%. But the threshold value and EC(50) (1.15×10(-4) mol/L vs 1.27×10(-4) mol/L) remained unchanged. The inhibition of I(ATP) by WIN55212-2 was reversed by AM281, suggesting that the inhibition was mediated via the CB1 receptor. Pretreatment with forskolin [an agonist of adenylyl cyclase (AC)] or 8-Br-cAMP reversed the inhibition of I(ATP) by WIN55212-2. These results suggest that the inhibitory effect of cannabinoids on I(ATP) is mediated via the CB1 receptors, that lead to inhibition of the AC-cAMP-PKA signaling pathway.
Adenosine Triphosphate ; physiology ; Animals ; Benzoxazines ; pharmacology ; Cannabinoids ; pharmacology ; Morpholines ; pharmacology ; Naphthalenes ; pharmacology ; Neurons ; drug effects ; physiology ; Patch-Clamp Techniques ; Pyrazoles ; pharmacology ; Rats ; Receptor, Cannabinoid, CB1 ; agonists ; antagonists & inhibitors ; Signal Transduction ; Trigeminal Ganglion ; drug effects ; physiology

Objective: JWH133, a cannabinoid type 2 receptor agonist, was tested for its ability to protect mice from bleomycin-induced pulmonary fibrosis. Methods: By using a random number generator, 24 C57BL/6J male mice were randomly divided into the control group, model group, JWH133 intervention group, and JWH133+a cannabinoid type-2 receptor antagonist (AM630) inhibitor group, with 6 mice in each group. A mouse pulmonary fibrosis model was established by tracheal instillation of bleomycin (5 mg/kg). Starting from the first day after modeling, the control group mice were intraperitoneally injected with 0.1 ml of 0.9% sodium chloride solution, and the model group mice were intraperitoneally injected with 0.1 ml of 0.9% sodium chloride solution. The JWH133 intervention group mice were intraperitoneally injected with 0.1 ml of JWH133 (2.5 mg/kg, dissolved in physiological saline), and the JWH133+AM630 antagonistic group mice were intraperitoneally injected with 0.1 ml of JWH133 (2.5 mg/kg) and AM630 (2.5 mg/kg). After 28 days, all mice were killed; the lung tissue was obtained, pathological changes were observed, and alveolar inflammation scores and Ashcroft scores were calculated. The content of type Ⅰ collagen in the lung tissue of the four groups of mice was measured using immunohistochemistry. The levels of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) in the serum of the four groups of mice were measured using enzyme-linked immunosorbent assay (ELISA), and the content of hydroxyproline (HYP) in the lung tissue of the four groups of mice was measured. Western blotting was used to measure the protein expression levels of type Ⅲ collagen, α-smooth muscle actin (α-SMA), extracellular signal regulated kinase (ERK1/2), phosphorylated P-ERK1/2 (P-ERK1/2), and phosphorylated ribosome S6 kinase type 1 (P-p90RSK) in the lung tissue of mice in the four groups. Real-time quantitative polymerase chain reaction was used to measure the expression levels of collagen Ⅰ, collagen Ⅲ, and α-SMA mRNA in the lung tissue of the four groups of mice. Results: Compared with the control group, the pathological changes in the lung tissue of the model group mice worsened, with an increase in alveolar inflammation score (3.833±0.408 vs. 0.833±0.408, P<0.05), an increase in Ashcroft score (7.333±0.516 vs. 2.000±0.633, P<0.05), an increase in type Ⅰ collagen absorbance value (0.065±0.008 vs. 0.018±0.006, P<0.05), an increase in inflammatory cell infiltration, and an increase in hydroxyproline levels [(1.551±0.051) μg/mg vs. (0.974±0.060) μg/mg, P<0.05]. Compared with the model group, the JWH133 intervention group showed reduced pathological changes in lung tissue, decreased alveolar inflammation score (1.833±0.408, P<0.05), decreased Ashcroft score (4.167±0.753, P<0.05), decreased type Ⅰ collagen absorbance value (0.032±0.004, P<0.05), reduced inflammatory cell infiltration, and decreased hydroxyproline levels [(1.148±0.055) μg/mg, P<0.05]. Compared with the JWH133 intervention group, the JWH133+AM630 antagonistic group showed more severe pathological changes in the lung tissue of mice, increased alveolar inflammation score and Ashcroft score, increased type Ⅰ collagen absorbance value, increased inflammatory cell infiltration, and increased hydroxyproline levels. Compared with the control group, the expression of α-SMA, type Ⅲ collagen, P-ERK1/2, and P-p90RSK proteins in the lung tissue of the model group mice increased, while the expression of type Ⅰ collagen, type Ⅲ collagen, and α-SMA mRNA increased. Compared with the model group, the protein expression of α-SMA (relative expression 0.60±0.17 vs. 1.34±0.19, P<0.05), type Ⅲ collagen (relative expression 0.52±0.09 vs. 1.35±0.14, P<0.05), P-ERK1/2 (relative expression 0.32±0.11 vs. 1.14±0.14, P<0.05), and P-p90RSK (relative expression 0.43±0.14 vs. 1.15±0.07, P<0.05) decreased in the JWH133 intervention group. The type Ⅰ collagen mRNA (2.190±0.362 vs. 5.078±0.792, P<0.05), type Ⅲ collagen mRNA (1.750±0.290 vs. 4.935±0.456, P<0.05), and α-SMA mRNA (1.588±0.060 vs. 5.192±0.506, P<0.05) decreased. Compared with the JWH133 intervention group, the JWH133+AM630 antagonistic group increased the expression of α-SMA, type Ⅲ collagen, P-ERK1/2, and P-p90RSK protein in the lung tissue of mice, and increased the expression of type Ⅲ collagen and α-SMA mRNA. Conclusion: In mice with bleomycin-induced pulmonary fibrosis, the cannabinoid type-2 receptor agonist JWH133 inhibited inflammation and improved extracellular matrix deposition, which alleviated lung fibrosis. The underlying mechanism of action may be related to the activation of the ERK1/2-RSK1 signaling pathway.
Mice ; Male ; Animals ; Pulmonary Fibrosis/pathology* ; Cannabinoid Receptor Agonists/metabolism* ; Collagen Type I/pharmacology* ; Collagen Type III/pharmacology* ; Hydroxyproline/pharmacology* ; Sodium Chloride/metabolism* ; Mice, Inbred C57BL ; Lung/pathology* ; Cannabinoids/adverse effects* ; Bleomycin/metabolism* ; Collagen/metabolism* ; Inflammation/pathology* ; RNA, Messenger/metabolism*

It is now well established that several G protein- coupled receptors can signal without agonist stimulation (constitutive receptors). Inverse agonists have been shown to inhibit the activity of such constitutive G protein-coupled receptor signaling. Agonist activation of the Gi/o-coupled peripheral cannabinoid receptor CB2 normally inhibits adenylyl cyclase type V and stimulates adenylyl cyclase type II. Using transfected COS cells, we show here that application of SR144528, an inverse agonist of CB2, leads to a reverse action (stimulation of adenylyl cyclase V and inhibition of adenylyl cyclase II). This inverse agonism of SR144528 is dependent on the temperature, as well as on the concentration of the cDNA of CB2 transfected. Pertussis toxin blocked the regulation of adenylyl cyclase activity by SR 144528.
Adenylate Cyclase/antagonists&inhibitors/genetics/metabolism ; Animals ; Binding, Competitive ; Bornanes/metabolism/*pharmacology ; COS Cells ; Cannabinoids/metabolism ; Cercopithecus aethiops ; Isoenzymes/antagonists&inhibitors/genetics/metabolism ; Pyrazoles/metabolism/*pharmacology ; Rats ; *Receptor, Cannabinoid, CB2 ; Receptors, Cannabinoid ; Receptors, Drug/agonists/*antagonists&inhibitors/genetics/metabolism ; Signal Transduction/drug effects/physiology ; Transfection