Orexins/Hypocretins Acting at Gi Protein-Coupled OX2 Receptors Inhibit Cyclic AMP Synthesis in the Primary Neuronal Cultures

Orexins A and B are newly discovered neuropeptides with pleiotropic activity. They signal through two G protein-coupled receptors: OX1 and OX2. In this study, we examined the expression of orexin receptors and effects of the receptors’ activation on cyclic AMP formation in the primary neuronal cell cultures from rat cerebral cortex. Both types of orexin receptors were expressed in rat cortical neurons; the level of OX2R was markedly higher compared to OX1R. Orexin A (an agonist of OX1R and OX2R) and [Ala11-D-Leu15]orexin B (a selective agonist of OX2R) did not affect basal cyclic AMP formation in the primary neuronal cell cultures. Both peptides (0.001–1 μM) inhibited, in a concentration-dependent manner and IC50 values in low nanomolar range, the increase in the nucleotide production evoked by forskolin (1 μM; a direct activator of adenylyl cyclase), pituitary adenylate cyclase-activating polypeptide (PACAP27; 0.1 μM), and vasoactive intestinal peptide (VIP; 3 μM). Effects of orexin A on forskolin-, PACAP27-, and VIP-stimulated cyclic AMP synthesis were blocked by TCS OX2 29 (a selective antagonist of OX2R), and unaffected by SB 408124 (a selective antagonist of OX1R). Pretreatment of neuronal cell cultures with pertussis toxin (PTX) abolished the inhibitory action of orexin A on forskolin- and PACAP-stimulated cyclic AMP accumulation. It is suggested that in cultured rat cortical neurons orexins, acting at OX2 receptors coupled to PTX-sensitive Gi protein, inhibit cyclic AMP synthesis

Regional differences in physicians’ behavior and factors influencing the intensity of PCSK9 inhibitor therapy with alirocumab: a subanalysis of the ODYSSEY APPRISE study

BackgroundDespite better accessibility of the effective lipid-lowering therapies, only about 20% of patients at very high cardiovascular risk achieve the low-density lipoprotein cholesterol (LDL-C) goals. There is a large disparity between European countries with worse results observed for the Central and Eastern Europe (CEE) patients. One of the main reasons for this ineffectiveness is therapeutic inertia related to the limited access to appropriate therapy and suitable dosage intensity. Thus, we aimed to compare the differences in physicians’ therapeutic decisions on alirocumab dose selection, and factors affecting these in CEE countries vs. other countries included in the ODYSSEY APPRISE study.MethodsODYSSEY APPRISE was a prospective, single-arm, phase 3b open-label (≥12 weeks to ≤30 months) study with alirocumab. Patients received 75 or 150 mg of alirocumab every 2 weeks, with dose adjustment during the study based on physician's judgment. The CEE group in the study included Czechia, Greece, Hungary, Poland, Romania, Slovakia, and Slovenia, which we compared with the other nine European countries (Austria, Belgium, Denmark, Finland, France, Germany, Italy, Spain, and Switzerland) plus Canada.ResultsA total of 921 patients on alirocumab were involved [modified intention-to-treat (mITT) analysis], including 114 (12.4%) subjects from CEE countries. Therapy in CEE vs. other countries was numerically more frequently started with lower alirocumab dose (75 mg) at the first visit (74.6 vs. 68%, p = 0.16). Since week 36, the higher dose was predominantly used in CEE patients (150 mg dose in 51.6% patients), which was maintained by the end of the study. Altogether, alirocumab dose was significantly more often increased by CEE physicians (54.1 vs. 39.9%, p = 0.013). Therefore, more patients achieved LDL-C goal at the end of the study (<55 mg/dl/1.4 mmol/L and 50% reduction of LDL-C: 32.5% vs. 28.8%). The only factor significantly influencing the decision on dose of alirocumab was LDL-C level for both countries’ groups (CEE: 199.2 vs. 175.3 mg/dl; p = 0.019; other: 205.9 vs. 171.6 mg/dl; p < 0.001, for 150 and 75 mg of alirocumab, respectively) which was also confirmed in multivariable analysis (OR = 1.10; 95% CI: 1.07–1.13).ConclusionsDespite larger unmet needs and regional disparities in LDL-C targets achievement in CEE countries, more physicians in this region tend to use the higher dose of alirocumab, they are more prone to increase the dose, which is associated with a higher proportion of patients reaching LDL-C goals. The only factor that significantly influences decision whether to increase or decrease the dose of alirocumab is LDL-C level