Report of the TFOS/ARVO Symposium on global treatments for dry eye disease: an unmet need.

In September 2010, a Symposium in Florence, Italy, was held to address the unmet need for global treatments for dry eye disease (DED). It was sponsored by The Tear Film & Ocular Surface Society (TFOS; www.TearFilm.org) and co-sponsored by the Association for Research in Vision & Ophthalmology (www.arvo.org). The Symposium objectives were two-fold: first, to discuss accepted and emerging clinical endpoints of DED with regulatory experts from around the world; and second, to consider how to improve clinical trials of treatments for DED. The Symposium focused on the personal and collective burden of DED, as well as the developmental and regulatory challenges associated with generating new DED therapeutics. This article provides a synopsis of many of the presentations, discussions and recommendations of this Symposium.

Characterization of phospholipase C activity at h5-HT2C compared with h5-HT2B receptors: influence of novel ligands upon membrane-bound levels of [3H]phosphatidylinositols.

Employing a novel, rapid and sensitive method for evaluation of phospholipase C (PLC) activity, the present study characterized the actions of diverse agonists and antagonists at human (h)5-HT2C receptors expressed in Chinese Hamster Ovary (CHO) cells. In addition, affinities and efficacies at these sites were compared with those obtained at h5-HT2B receptors.5-HT elicited a robust and rapid reduction in levels of the pre-labelled, membrane-bound substrate of PLC, [3H]phosphatidylinositols ([3H]PI). The time-course of [3H]PI depletion paralleled that of [3H]inositol phosphate ([3H]IP) accumulation, as determined by conventional anion exchange chromatography. Inactivation of h5-HT2C receptors with the alkylating agent, N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), revealed a large receptor reserve, with half-maximal PLC activation induced by a concentration of 5-HT occupying only 5% of sites. In analogy to 5-HT ( Emax=100%), DOI, MK212 and mCPP, as well as the novel ligands, Ro600332, Ro600175 and BW723C86, showed "full" efficacy at h5-HT2C sites. Their efficacies were similar at h5-HT2B sites, with the exception of mCPP and MK212, which acted as partial agonists. Further, lisuride and Ro600869 behaved as partial agonists and antagonists at h5-HT2C and h5-HT2B receptors, respectively. As concerns functional selectivity (potency for induction of [3H]PI depletion), only Ro600175 preferentially activated h5-HT2B sites. In contrast, Ro600332 preferentially activated h5-HT2C receptors. Amongst antagonists, RS102221 and SB242084 displayed a marked preference for h5-HT2C sites, whereas LY266097, S33526 and SB204741 behaved as selective antagonists at h5-HT2B receptors. At both h5-HT2C and h5-HT2B receptors, antagonist potency (p Kb) and binding affinity (p Ki) were highly correlated. In conclusion, this rapid and innovative method for determination of PLC activity permitted characterization of an extensive range of novel ligands at h5-HT2C receptors. Although several antagonists clearly differentiated h5-HT2C from h5-HT2B receptors under these conditions, highly selective agonists remain to be identified.

Differential actions of antiparkinson agents at multiple classes of monoaminergic receptor. III. Agonist and antagonist properties at serotonin, 5-HT(1) and 5-HT(2), receptor subtypes.

Although certain antiparkinson agents interact with serotonin (5-HT) receptors, little information is available concerning functional actions. Herein, we characterized efficacies of apomorphine, bromocriptine, cabergoline, lisuride, piribedil, pergolide, roxindole, and terguride at human (h)5-HT(1A), h5-HT(1B), and h5-HT(1D) receptors [guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding], and at h5-HT(2A), h5-HT(2B), and h5-HT(2C) receptors (depletion of membrane-bound [(3)H]phosphatydilinositol). All drugs stimulated h5-HT(1A) receptors with efficacies (compared with 5-HT, 100%) ranging from modest (apomorphine, 35%) to high (cabergoline, 93%). At h5-HT(1B) receptors, efficacies varied from mild (terguride, 37%) to marked (cabergoline, 102%) and potencies were modest (pEC(50) values of 5.8-7.6): h5-HT(1D) sites were activated with a similar range of efficacies and greater potency (7.1-8.5). Piribedil and apomorphine were inactive at h5-HT(1B) and h5-HT(1D) receptors. At h5-HT(2A) receptors, terguride, lisuride, bromocriptine, cabergoline, and pergolide displayed potent (7.6-8.8) agonist properties (49-103%), whereas apomorphine and roxindole were antagonists and piribedil was inactive. Only pergolide (113%/8.2) and cabergoline (123%/8.6) displayed pronounced agonist properties at h5-HT(2B) receptors. At 5-HT(2C) receptors, lisuride, bromocriptine, pergolide, and cabergoline were efficacious (75-96%) agonists, apomorphine and terguride were antagonists, and piribedil was inactive. MDL100,907 and SB242,084, selective antagonists at 5-HT(2A) and 5-HT(2C) receptors, respectively, abolished these actions of pergolide, cabergoline, and bromocriptine. In conclusion, antiparkinson agents display markedly different patterns of agonist and antagonist properties at multiple 5-HT receptor subtypes. Although all show modest (agonist) activity at 5-HT(1A) sites, their contrasting actions at 5-HT(2A) and 5-HT(2C) sites may be of particular significance to their functional profiles in vivo.