Huperzine A lowers intraocular pressure via the M3 mAChR and provides retinal neuroprotection via the M1 mAChR: a promising agent for the treatment of glaucoma.

BACKGROUND: Glaucoma is a neurodegenerative disease that shares similar pathological mechanisms with Alzheimer's disease (AD). Drug treatments for glaucoma increasingly rely upon both lowering of intraocular pressure (IOP) and optic nerve protection, as lowering of IOP alone has been unsatisfactory. Huperzine A (HupA) is an acetylcholinesterase inhibitor (AChEI) used for AD. This study investigated the potential of HupA as a treatment for glaucoma. METHODS: The ability of HupA to lower IOP via causing pupil constriction was assessed using New Zealand rabbits. The retinal neuroprotective effects of HupA were assessed in vivo using rat retinas subjected to ischemia-reperfusion (I/R) and in vitro using primary retinal neurons (PRNs) suffering from oxygen-glucose deprivation (OGD). RESULTS: HupA caused pupil constriction in a dose-time dependent manner which was reversed by the nonselective muscarinic acetylcholine receptor (mAChR) antagonist atropine and the selective M3 mAChR antagonist 4-DAMP. However, HupA had no effect on isolated iris muscle tension and calcium flow indicating an indirect M3 mAChR mediated effect. HupA exerted a neuroprotective effect against I/R and OGD to attenuate the retinal pathological lesion, improve retinal neuronal cell viability, reverse oxidative stress injury by increasing GSH levels and SOD activity, and decreasing MDA content and reduce the retinal neuronal apoptosis by decreasing Bax/Bcl-2 ratio and caspase-3 expression with no effect on the calcium flow tests. The effects were abolished by atropine and the selective M1 mAChR antagonist pirenzepine in OGD-induced PRNs suggesting an indirect M1 mAChR-mediated effect via inhibiting AChE activity to increase endogenous ACh level. Furthermore, HupA increased phosphorylated AKT level and decreased the levels of phosphorylated JNK, P38 MAPK and ERK via M1 mAChR antagonists indicating an involvement of activating the M1 mAChR and the downstream AKT/MAPK signaling pathway in the protective effects of HupA. CONCLUSIONS: HupA could significantly decrease IOP via activating M3 mAChR indirectly and produce retinal neuroprotective effect through M1 mAChR/AKT/MAPK by increasing endogenous ACh level. These investigations demonstrated that HupA was an effective drug in glaucoma treatment and the clinical application of HupA and other AChEIs for glaucoma patients should be further investigated.

A lysosome-targetable two-photon excited near-infrared fluorescent probe for visualizing hypochlorous acid-involved arthritis and its treatment.

Lysosome of phagocyte is the main site of hypochlorous acid (HClO) production, and HClO can be employed as the biomarker for the diagnosis and treatment evaluation of arthritis. In recent years, developing fluorescent probes for lysosomal HClO has attracted considerable attention, but most of them still have some defects, such as autofluorescence, phototoxicity and photobleaching because of their excitation and emission located in short-wavelength region. Due to the advantages of two-photon fluorescent probes with near-infrared emissions, a lysosome-targetable two-photon fluorescent probe (Lyso-TP-HClO) with a near-infrared emission was reported in this paper. Lyso-TP-HClO has a high selectivity and a high sensitivity to HClO in the linear range (10.0 × 10-8 to 5.0 × 10-6 M), with a detection limit of 3.0 × 10-8 M. Due to the two-photon excited near-infrared emission, Lyso-TP-HClO has excellent imaging performances, such as small autofluorescence, excellent photostability, and large imaging depth. Furthermore, Lyso-TP-HClO was successfully employed for visualizing lysosomal HClO in bacteria-infected cells. At last, we have successfully used Lyso-TP-HClO to image the arthritis and evaluate the treatment of arthritis in mice. All the results confirm that Lyso-TP-HClO is a useful chemical tool for imaging of lysosomal HClO, the diagnosis of arthritis, and treatment evaluation of arthritis.

A two-photon excited near-infrared fluorescent probe for imaging peroxynitrite during drug-induced hepatotoxicity and its remediation.

Drug-induced liver injury (DILI) has been a hot issue of public health, owing to its unpredictability and serious harm to public health. Peroxynitrite (ONOO-) is an important biomarker for the assessment and diagnosis of DILI. In this article, based on a kind of rhodamine analogue with a near-infrared (NIR) emission (610 nm-800 nm) and a two-photon absorption cross section (54 GM), a two-photon excited NIR fluorescence probe (NIR-ONOO) for ONOO- was developed. With a high selectivity and a high sensitivity to ONOO-, NIR-ONOO has a linear range for detection of ONOO- from 5.0 × 10-8 to 1.0 × 10-5 M, a good detection limit (15 nM) and a large fluorescence enhancement (340-fold). In addition, NIR-ONOO has been used to monitor ONOO- in cells with satisfactory results. Because of its two-photon excied NIR emission, NIR-ONOO also showed excellent performances for imaging ONOO- including low autofluorescence, stable and persistent fluorescence, and a deep penetration (204 µm). Finally, NIR-ONOO was successfully employed to image ONOO- in inflammatory mouse, drug-induced hepatotoxicity in cells and its remediation. All the results indicated that NIR-ONOO is a powerful chemical tool to image ONOO- and assay drug-induced hepatotoxicity.