Role of TRPV1 channels on glycogen synthase kinase-3β and oxidative stress in ouabain-induced bipolar disease

Affinin, Isolated from Heliopsis longipes, Induces an Antihypertensive Effect That Involves CB1 Cannabinoid Receptors and TRPA1 and TRPV1 Channel Activation

In previous studies, we demonstrated that the ethanolic extract of Heliopsis longipes roots and its main alkamide, affinin, elicit a vasorelaxant effect through a mechanism involving activation of the gasotransmitter pathways and stimulation of cannabinoid type 1 receptors and transient receptor potential ankyrin 1 and transient receptor potential vanilloid 1 channels. However, it has not yet been demonstrated whether the EEH and affinin are capable of lowering high blood pressure. Therefore, the aim of the present study was to determine the effect of the oral administration of the EEH and affinin on the systolic blood pressure of NG-nitro-L-arginine methyl ester-induced hypertensive rats and to explore the participation of cannabinoid receptors and transient receptor potential channels in the mechanism of action of this alkamide. Our results showed that the ethanolic extract of H. longipes and affinin significantly lowered systolic blood pressure and induced an improvement in endothelial function, which is associated with increased serum nitric oxide levels. Inhibition of cannabinoid type 1 receptors by rimonabant (3 mg/kg), transient receptor potential ankyrin 1 channels by HC-030031 (8 mg/kg), and transient receptor potential vanilloid 1 channels by capsazepine (5 mg/kg) significantly decreased the antihypertensive effect induced by affinin, suggesting that the blood pressure-lowering effect of this alkamide involves activation of cannabinoid type 1 receptors and transient receptor potential ankyrin 1 and transient receptor potential vanilloid 1 channels.

GLP-1 agonist liraglutide improves ouabain-induced mania and depressive state via GSK-3β pathway

Bipolar disorder (BD) is a severe mental illness characterized by aberrant mood changes between hypomania and mania or mixed states and depression. Metabolic changes also accompany disease progression and cause significant morbidity. Symptomatic treatment options are available, but asymptomatic patients and poor drug responders are significant problems. Based on the most common pharmacological agent that is used in the treatment, lithium and its main mechanisms of action, oxidative stress, and glycogen synthase kinase-3β (GSK-3β) signaling are extensively investigated. However, knowledge about the effects of compounds that positively affect oxidative stress and GSK-3β signaling, such as glucagon-like peptide-1 (GLP-1) mimetics, liraglutide, is still missing. Therefore, in this study, we aimed to investigate the effects of liraglutide on the ouabain-induced bipolar disease model in rats. After intracerebroventricular single dose ouabain administration, animals were treated with 100, 200, and 400 µg/kg liraglutide (s.c.) and valproic acid (200 mg/kg, i.p.) for 10 d. The locomotion and depressive states of animals were assessed by an open field, forced swimming test, and sucrose preference tests. Serum total antioxidant (TAS) and oxidant states (TOS) and glutathione, malonyl dialdehyde (MDA) levels in the brain tissue were determined. GSK-3β phosphorylation was evaluated by western blotting. Our results demonstrated that liraglutide attenuated ouabain-induced hyperlocomotion and depressive state. Additionally, liraglutide prevented oxidative stress after ouabain administration. Decreased GSK-3β phosphorylation due to the ouabain insult was alleviated by liraglutide treatment. These findings indicate that the manic and depressive-like behaviors are ameliorated by liraglutide, which exerted antioxidant action, possibly improving GSK-3β phosphorylation.