Effects of vitamin B12 on the corneal nerve regeneration in rats.

The study was designed to investigate the effects of a new ophthalmic solution containing 0.05% vitamin B12 0.05% on corneal nerve regeneration in rats after corneal injury. Eyes of anesthetized male Wistar rats were subjected to corneal injury by removing the corneal epithelium with corneal brush (Algerbrush). After the epithelial debridement, the right eye of each animal received the instillation of one drop of the ophthalmic solution containing vitamin B12 0.05% plus taurine 0.5% and sodium hyaluronate 0.5% four time per day for 10 or 30 days. Left eyes were used as control and treated with solution containing taurine 0.5% and sodium hyaluronate 0.5% alone following the same regimen. Fluorescein staining by slit-lamp and morphological analysis was used to determine corneal wound healing. Immunohistochemistry, immunoblot and confocal microscopy were used to examine corneal re-innervation. Slit-lamp and histological analyses showed that re-epithelization of the corneas was accelerated in rats treated with vitamin B12. A clear-cut difference between the two groups of rats was seen after 10 days of treatment, whereas a near-to-complete re-epithelization was observed in both groups at 30 days. Vitamin B12 treatment had also a remarkable effect on corneal re-innervation, as shown by substantial increased in the expression of neurofilament 160 and ß-III tubulin at both 10 and 30 days. The presence of SV2A-positive nerve endings suggests the presence of synapse-like specialized structures in corneal epithelium of the eye treated with vitamin B12. Our findings suggest that vitamin B12 treatment represents a powerful strategy to accelerate not only re-epithelization but also corneal re-innervation after mechanical injury.

Oxytocin/Osteocalcin/IL-6 and NGF/BDNF mRNA Levels in Response to Cold Stress Challenge in Mice: Possible Oxytonic Brain-Bone-Muscle-Interaction.

Oxytocin (Oxt), osteocalcin (Ost), and NGF/BDNF have a role in bone homeostasis, reproduction, and cognition. Oxt/Ost is required for muscle repair. We investigated gene response of muscle and the inter-organ communication following cold stress (CS). The mRNA quantity of Ngf, Ost, Oxt, Bdnf, p75ntr, Ntrk1, Gprc6a, Oxtr, Ntrk2, UCP1, and Il-6 genes in bone, brain, soleus (SOL), and tibialis anterior (TA) muscles from adult mice following CS were investigated. The myosin heavy-chain Mhc2b, Mhc1, Mhc2x, and Mhc2a gene expression were investigated. Mice were maintained at T = 23°C or 4°C for 6 h and 5-days (5d). CS mice did not show signs of muscle degeneration. An upregulation of Ucp1 and Ngf genes by 2 and 1.5 folds, respectively, in TA after 6 h CS and Ntrk1 by 4 and 22 folds in SOL muscle after 6 h and 5d CS, respectively, was observed; while after 6 h CS p75Ntr was downregulated in either muscle. Bdnf was unaffected, while after 5d CS Ntrk2 was upregulated in TA. Ost was downregulated in SOL by 0.9-folds at 5d. Following 5d CS, Oxtr and Il-6 genes were upregulated, respectively, by 1 and 1.5 folds in SOL. A downregulation of Mhc2b, respectively, by 0.96 and 0.88-folds after 6 h and 5d CS in SOL and Mhc2a was also downregulated by 0.88-fold after 5d CS in TA. Mhc1 and Mhc2x were not affected. Changes in the expression levels of genes in TA and SOL muscles, bone, and brain following CS were regulated by IL6 and Oxt. CS potentiates the slow-twitch phenotype of SOL which is in line with the metabolic need of this muscle, and the potentiation of the slow-twitch phenotype in TA. Oxt and IL6 coordinate a phenotype-dependent tonic effect of slow-twitch muscle and Oxt regulates the inter-organ interaction between brain and SOL muscle. Muscle tropism is maintained by NGF signaling following CS.

Evidence for the involvement of cannabinoid CB1 receptors in the bimatoprost-induced contractions on the human isolated ciliary muscle.

PURPOSE: To evaluate the bimatoprost effects in the isolated human ciliary muscle and to assess how these response can be modulated by AL8810 and SR141716A. METHODS: In a myograph system (isometric force measurement), ciliary muscles were exposed cumulatively to PGF(2alpha), latanoprost, travoprost, bimatoprost, and anandamide (0.1 nM-10 microM). Experiments were also conducted in the presence of AL8810 (FP receptor antagonist; 100 nM) or SR141716A (CB(1) receptor antagonist; 10-100 nM). Contractions were expressed as the percentage of 10 microM carbachol-induced contractions. RESULTS: In quiescent tissues, concentration-response curves for bimatoprost, anandamide, PGF(2alpha,) latanoprost, and travoprost were constructed. Bimatoprost showed an important contractile effect on isolated human ciliary muscle strips (E(max) = 125% +/- 0.09%); the maximal effect was higher than that obtained with carbachol. Contractions were inhibited by SR141716A (10 and 100 nM) and AL8810 (100 nM). CONCLUSIONS: This study showed evidence of direct interaction of bimatoprost with the contractility of the human ciliary muscle through interaction with cannabinoid CB(1) receptor and prostanoid FP receptors.

Pharmacovigilance database search discloses ClC-K channels as a novel target of the AT1 receptor blockers valsartan and olmesartan.

BACKGROUND AND PURPOSE: Human ClC-K chloride channels are highly attractive targets for drug discovery as they have a variety of important physiological functions and are associated with genetic disorders. These channels are crucial in the kidney as they control chloride reabsorption and water diuresis. In addition, loss-of-function mutations of CLCNKB and BSND genes cause Bartter's syndrome (BS), whereas CLCNKA and CLCNKB gain-of-function polymorphisms predispose to a rare form of salt sensitive hypertension. Both disorders lack a personalized therapy that is in most cases only symptomatic. The aim of this study was to identify novel ClC-K ligands from drugs already on the market, by exploiting the pharmacological side activity of drug molecules available from the FDA Adverse Effects Reporting System database. EXPERIMENTAL APPROACH: We searched for drugs having a Bartter-like syndrome as a reported side effect, with the assumption that BS could be causatively related to the block of ClC-K channels. The ability of the selected BS-causing drugs to bind and block ClC-K channels was then validated through an integrated experimental and computational approach based on patch clamp electrophysiology in HEK293 cells and molecular docking simulations. KEY RESULTS: Valsartan and olmesartan were able to block ClC-Ka channels and the molecular requirements for effective inhibition of these channels have been identified. CONCLUSION AND IMPLICATIONS: These results suggest additional mechanisms of action for these sartans further to their primary AT1 receptor antagonism and propose these compounds as leads for designing new potent ClC-K ligands.

Growth hormone secretagogues prevent dysregulation of skeletal muscle calcium homeostasis in a rat model of cisplatin-induced cachexia.

BACKGROUND: Cachexia is a wasting condition associated with cancer types and, at the same time, is a serious and dose-limiting side effect of cancer chemotherapy. Skeletal muscle loss is one of the main characteristics of cachexia that significantly contributes to the functional muscle impairment. Calcium-dependent signaling pathways are believed to play an important role in skeletal muscle decline observed in cachexia, but whether intracellular calcium homeostasis is affected in this situation remains uncertain. Growth hormone secretagogues (GHS), a family of synthetic agonists of ghrelin receptor (GHS-R1a), are being developed as a therapeutic option for cancer cachexia syndrome; however, the exact mechanism by which GHS interfere with skeletal muscle is not fully understood. METHODS: By a multidisciplinary approach ranging from cytofluorometry and electrophysiology to gene expression and histology, we characterized the calcium homeostasis in fast-twitch extensor digitorum longus (EDL) muscle of adult rats with cisplatin-induced cachexia and established the potential beneficial effects of two GHS (hexarelin and JMV2894) at this level. Additionally, in vivo measures of grip strength and of ultrasonography recordings allowed us to evaluate the functional impact of GHS therapeutic intervention. RESULTS: Cisplatin-treated EDL muscle fibres were characterized by a ~18% significant reduction of the muscle weight and fibre diameter together with an up-regulation of atrogin1/Murf-1 genes and a down-regulation of Pgc1-a gene, all indexes of muscle atrophy, and by a two-fold increase in resting intracellular calcium, [Ca2+ ]i , compared with control rats. Moreover, the amplitude of the calcium transient induced by caffeine or depolarizing high potassium solution as well as the store-operated calcium entry were ~50% significantly reduced in cisplatin-treated rats. Calcium homeostasis dysregulation parallels with changes of functional ex vivo (excitability and resting macroscopic conductance) and in vivo (forelimb force and muscle volume) outcomes in cachectic animals. Administration of hexarelin or JMV2894 markedly reduced the cisplatin-induced alteration of calcium homeostasis by both common as well as drug-specific mechanisms of action. This effect correlated with muscle function preservation as well as amelioration of various atrophic indexes, thus supporting the functional impact of GHS activity on calcium homeostasis. CONCLUSIONS: Our findings provide a direct evidence that a dysregulation of calcium homeostasis plays a key role in cisplatin-induced model of cachexia gaining insight into the etiopathogenesis of this form of muscle wasting. Furthermore, our demonstration that GHS administration efficaciously prevents cisplatin-induced calcium homeostasis alteration contributes to elucidate the mechanism of action through which GHS could potentially ameliorate chemotherapy-associated cachexia.

Signaling cross-talk between cannabinoid and muscarinic systems actives Rho-kinase and increases the contractile responses of the bovine ciliary muscle.

The aim of the present study was to evaluate the role of a possible interaction between cannabinoid and muscarinic systems, both widely expressed in the ocular structure and involved in the control of bovine ciliary muscle contractility and intraocular pressure modulation. The ciliary muscle strips isolated by bovine eyes were exposed cumulatively to anandamide in the presence and in the absence of carbachol (5 nM), in a miograph system for isometric recording. The experiments were also conducted in the presence of AM251 (100 nM), 4-DAMP (100 nM), Pertussis toxin (500 ng/ml), U73122 (0.1 and 1 µM), chelerythrine (1 and 10 µM) and Y27632 (1 and 10 µM). Contractile responses were expressed as the percentage of 10 µM carbachol-induced contraction. The anandamide-induced contraction on bovine ciliary muscle strips was enhanced by the previous stimulation of Gq-protein-coupled muscarinic M3 receptors with carbachol. The contractile response to anandamide plus carbachol was affected by different inhibitors such as Pertussis toxin, phospholipase C, protein kinase C and Rho-kinase. The key results of the present study show that sequential activation of muscarinic M3 receptors and cannabinoid CB1 receptors produce synergistic contractile effects of the bovine ciliary muscle by involving the activation of Rho-kinase and protein kinase C.

Synthesis and biological evaluation of direct thrombin inhibitors bearing 4-(piperidin-1-yl)pyridine at the P1 position with potent anticoagulant activity.

The design and synthesis of a new class of nonpeptide direct thrombin inhibitors, built on the structure of 1-(pyridin-4-yl)piperidine-4-carboxamide, are described. Starting from a strongly basic 1-amidinopiperidine derivative (6) showing poor thrombin (fIIa) and factor Xa (fXa) inhibition activities, anti-fIIa activity and artificial membrane permeability were considerably improved by optimizing the basic P1 and the X-substituted phenyl P4 binding moieties. Structure-activity relationship studies, usefully complemented with molecular modeling results, led us to identify compound 13b, which showed excellent fIIa inhibition (Ki = 6 nM), weak anti-Xa activity (Ki = 5.64 µM), and remarkable selectivity over other serine proteases (e.g., trypsin). Compound 13b showed in vitro anticoagulant activity in the low micromolar range and significant membrane permeability. In mice (ex vivo), 13b demonstrated anticoagulant effects at 2 h after oral dosing (100 mg·kg(-1)), with a significant 43% prolongation of the activated partial thromboplastin time (aPTT), over controls (P < 0.05).

Involvement of the peroxisome proliferator-activated receptor (PPAR) alpha in vascular response of endocannabinoids in the bovine ophthalmic artery.

Endocannabinoids regulate vascular tone in a variety of vascular tissues. This study aimed to investigate the role of peroxisome proliferators-activated receptors (PPARs) in anandamide- and palmitoylethanolamide-induced relaxant responses on the bovine ophthalmic artery and to evaluate the mechanisms involved. The effects of anandamide and palmitoylethanolamide were examined under myographic conditions on arterial rings pharmacologically pre-contracted with 5-HT. Anandamide and palmitoylethanolamide relaxed the ophthalmic artery rings in time- and concentration-dependent manner stimulating the PPAR alpha (PPARα). The vasorelaxation to endocannabinoids was inhibited by PPARα antagonist GW6471 (1µM), but not the PPAR gamma (PPARγ) antagonist GW9662 (1 µM). Anandamide-induced relaxation was attenuate during the first 60 min by AM251, a selective antagonist of cannabinoid CB(1) receptors, and Pertussis toxin, an inhibitor of G(i/o) protein; by the contrast, the palmitoylethanolamide-induced vasorelaxation was unaffected by cannabinoid antagonists and Pertussis toxin. Endothelium removal decreases slightly the potency and efficacy to endocannabinoids. The relaxant effect to anandamide and palmitoylethanolamide was inhibited by L-NMMA (300 µM), an inhibitor of nitric oxide synthase, and iberiotoxin (200 nM), a selective blocker of large conductance Ca²âº-activated K⁺ (BK(Ca)). These data support the view that anandamide and palmitoylethanolamide relax the ophthalmic artery in a time-dependent manner via the transcription factors PPARα suggesting a function for them in the physiological mechanisms of vascular regulation.

Effects of bevacizumab on neuronal viability of retinal ganglion cells in rats.

The aim of this study was to investigate the effects of single and repeated intravitreal injections of bevacizumab on various retinal layers focusing more on retinal ganglion cells (RGCs) in healthy rats. Male Wistar rats were treated with intravitreal injection of bevacizimab (4 µL) within right eye. Left eyes were injected with the same volume of balanced salt solution (BSS) and used as control. Ten rats received a single intravitreal injection and ten rats had three injections, with seven days time interval. Histological and immunohistochemical evaluations and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay were performed in order to find out if some degree of apoptosis could occur on RGCs. Histological and immunohistochemical analyses showed that bevacizumab induces neuronal loss compared to control eyes, after multiple injections. RGCs apoptosis after multiple treatments was demonstrated to occur by TUNEL, Annexin V and Bax assays. The loss of ganglion cells following repeated injections was confirmed and quantified by the decrease in RGC specific protein Brn3a measured by western blotting in ten additional rats. The present results need to be considered when multiple intravitreal injection of bevacizumab are performed to treat retinal diseases.

ß-D-glucosyl conjugates of highly potent inhibitors of blood coagulation factor Xa bearing 2-chorothiophene as a P1 motif.

We synthesized a novel O-glucoside of the recently reported potent factor Xa (fXa) inhibitor 1, which bears a 5-chlorothien-2-yl moiety and 1-isopropylpiperidine as fragments that bind the S1 and S4 enzyme pockets, respectively. A ß-D-glucosyl unit was conjugated through an ether-linked C3-alkyl spacer to the central phenyl ring of 1. The synthesized ß-D-glucose-based compound 16 achieved picomolar inhibitory potency against human fXa (K(i)=60 pM) and high selectivity over thrombin and other serine proteases. In addition to the chlorothienyl S1 binder, a large gain in ΔG resulted from the addition of protonated 1-isopropylpiperidine (ΔΔG=29.7-30.5 kJ mol(-1)), which should bind to the aromatic S4 pocket through efficient cation-π and C-H···π interactions. Instead, the C3-alkyl-linked glucose fragment, which is likely directed toward the solvent outside the enzyme binding site, improves ΔG by an average of 2.9-3.8 kJ mol(-1) . Compound 16 showed sub-micromolar in vitro anticoagulant activity, as assessed by prothrombin time (PT) and activated thromboplastin time (aPTT) clotting assays in pooled human plasma (PT(2) and aPTT(2) equal to 0.135 and 0.389 µM, respectively). Although compound 16 was 1.4-fold less active than parent compound 1 in the ex vivo anticoagulant assay in mice, it showed a significant (1.6-fold) prolongation of PT relative to controls (P<0.05) 60 min after oral dosing (75 mg kg(-1)).

Epigallocatechin-3-gallate relaxes the isolated bovine ophthalmic artery: involvement of phosphoinositide 3-kinase-Akt-nitric oxide/cGMP signalling pathway.

The present study investigates the direct action and the underlying mechanism(s) of epigallocatechin-3-gallate (EGCG) vasomotor effects on the bovine isolated ophthalmic artery. Adjacent rings were cut from each artery and mounted in a wire miograph system for isometric recording. Concentration-response curves for EGCG were constructed by adding cumulative concentrations of the drug to arterial rings pre-contracted with 5-HT (1 microM). Effects of mechanical endothelial cell removal and of selective blockers of the nitric oxide (NO)/cGMP pathways were investigated on the EGCG relaxant responses. EGCG relaxed ophthalmic arteries and maximum relaxation was 78.4+/-2.64%. Mechanical removal of endothelium, blockade of soluble guanylyl cyclase by 1H-1,2,4-oxadiazolo [4,3-a]quinoxalin-1-one (ODQ, 1 and 5 microM) or inhibition of nitric oxide (NO) synthase by N(G)-nitro-L-arginine (L-NAME, 50 and 100 microM) reduced significantly the relaxant response to catechin; moreover, the NO donor S-nitroso-N-acetylpenicillamine (SNAP, 100 microM) significantly increased the vasorelaxant responses to EGCG. Relaxation to EGCG was inhibited by iberiotoxin (200 nM), a blocker of big-conductance Ca(2+)-activated K(+) (BK(Ca)) channel, whereas the blockade of K(ATP) channel by glibenclamide (5 microM) and of small-conductance Ca(2+)-activated K(+) (SK(Ca)) channel by apamin (100 nM) elicited no effect. Interestingly, also inhibition of phosphoinositide-3-kinase (PI3K) by wortmannin (100 nM) and of Akt by SH6 (1 microM) markedly decreased the EGCG-evoked vasorelaxation. These data suggest that EGCG induced vasorelaxation in ophthalmic arteries with endothelium-intact via the activation of the NO/cGMP signalling pathway and defined an intriguing role for PI3K and Akt as upstream mediators for activation of NO-mediated relaxant responses.