Continuous infusion of physostigmine in patients with perioperative septic shock: A pharmacokinetic/pharmacodynamic study with population pharmacokinetic modeling

Nicotinic acetylcholine receptor-mediated effects of varenicline on LPS-elevated prostaglandin and cyclooxygenase levels in RAW 264.7 macrophages

Introduction: The purpose of this study is to delineate anti-inflammatory and antioxidant potential of varenicline, a cigarette smoking cessation aid, on decreasing lipopolysaccharide (LPS)-elevated proinflammatory cytokines in RAW 264.7 murine macrophage cultures which we showed earlier to occur via cholinergic anti-inflammatory pathway (CAP) activation. To this end, we investigated the possible suppressive capacity of varenicline on LPS-regulated cyclooxygenase (COX-1 and COX-2) via α7 nicotinic acetylcholine receptor (α7nAChR) activation using the same in vitro model. Materials and Methods: In order to test anti-inflammatory effectiveness of varenicline, the levels of COX isoforms and products (PGE2, 6-keto PGF1α, a stable analog of PGI2, and TXA2) altered after LPS administration were determined by Enzyme Linked Immunosorbent Assay (ELISA). The antioxidant effects of varenicline were assessed by measuring reductions in reactive oxygen species (ROS) using a fluorometric intracellular ROS assay kit. We further investigated the contribution of nAChR subtypes by using non-selective and/or selective α7nAChR antagonists. The results were compared with that of conventional anti-inflammatory medications, such as ibuprofen, celecoxib and dexamethasone. Results: Varenicline significantly reduced LPS-induced COX-1, COX-2 and prostaglandin levels and ROS to an extent similar to that observed with anti-inflammatory agents used. Discussion: Significant downregulation in LPS-induced COX isoforms and associated decreases in PGE2, 6-keto PGF1α, and TXA2 levels along with reduction in ROS may be partly mediated via varenicline-activated α7nAChRs.

Varenicline Prevents LPS-Induced Inflammatory Response via Nicotinic Acetylcholine Receptors in RAW 264.7 Macrophages

The cholinergic anti-inflammatory pathway plays an important role in controlling inflammation. This study investigated the effects of varenicline, an α7 nicotinic acetylcholine receptor (α7nAChR) agonist, on inflammatory cytokine levels, cell proliferation, and migration rates in a lipopolysaccharide (LPS)-induced inflammation model in RAW 264.7 murine macrophage cell lines. The cells were treated with increasing concentrations of varenicline, followed by LPS incubation for 24 h. Prior to receptor-mediated events, anti-inflammatory effects of varenicline on different cytokines and chemokines were investigated using a cytokine array. Nicotinic AChR-mediated effects of varenicline were investigated by using a non-selective nAChR antagonist mecamylamine hydrochloride and a selective α7nAChR antagonist methyllycaconitine citrate. TNFα, IL-1β, and IL-6 levels were determined by the ELISA test in cell media 24 h after LPS administration and compared with those of dexamethasone. The rates of cellular proliferation and migration were monitored for 24 h after drug treatment using a real-time cell analysis system. Varenicline decreased LPS-induced cytokines and chemokines including TNFα, IL-6, and IL-1β via α7nAChRs to a similar level that observed with dexamethasone. Varenicline treatment decreased LPS-induced cell proliferation, without any nAChR involvement. On the other hand, the LPS-induced cell migration rate decreased with varenicline via α7nAChR. Our data suggest that varenicline inhibits LPS-induced inflammatory response by activating α7nAChRs within the cholinergic anti-inflammatory pathway, reducing the cytokine levels and cell migration.

Pharmacological Influencing of The Cholinergic Anti-inflammatory Pathway in Infectious Diseases and Inflammatory Pathologies

The cholinergic anti-inflammatory pathway is a part of the parasympathetic nervous system and it can also be entitled as an anti-inflammatory reflex. It consists of terminations of the vagal nerve into blood, acetylcholine released from the terminations, macrophages and other cells having α7 nicotinic acetylcholine receptor (α7 nAChR), calcium ions crossing through the receptor and interacting with nuclear factors, and erythrocytes with acetylcholinesterase (AChE) terminating the neurotransmission. Stopping of inflammatory cytokines production is the major task for the cholinergic antiinflammatory pathway. The cholinergic anti-inflammatory pathway can be stimulated or suppressed by agonizing or antagonizing α7 nAChR or by inhibition of AChE. This review is focused on cholinergic anti-inflammatory pathway regulation by drugs. Compounds that inhibit cholinesterases (for instance, huperzine, rivastigmine, galantamine), and their impact on the cholinergic anti-inflammatory pathway are discussed here and a survey of actual literature is provided.