Promethazine inhibits efflux, enhances antifungal susceptibility and disrupts biofilm structure and functioning in Trichosporon.

Trichosporon spp. are emerging opportunistic fungi associated with invasive infections, especially in patients with haematological malignancies. The present study investigated the in vitro inhibition of efflux pumps by promethazine (PMZ) as a strategy to control T. asahii and T. inkin. Planktonic cells were evaluated for antifungal susceptibility to PMZ, as well as inhibition of efflux. The effect of PMZ was also studied in Trichosporon biofilms. PMZ inhibited T. asahii and T. inkin planktonic cells at concentrations ranging from 32 to 256 µg ml-1. Subinhibitory concentrations of PMZ inhibited efflux activity in Trichosporon. Biofilms were completely eradicated by PMZ. PMZ potentiated the action of antifungals, affected the morphology, changed the amount of carbohydrates and proteins and reduced the amount of persister cells inside biofilms. The results showed indirect evidences of the occurrence of efflux pumps in Trichosporon and opens a perspective for the use of this target in the control of trichosporonosis.

Promethazine Downregulates Wnt/ß-Catenin Signaling and Increases the Biomechanical Forces of the Injured Achilles Tendon in the Early Stage of Healing.

BACKGROUND: Wnt/ß-catenin signaling suppresses the differentiation of cultured tenocytes, but its roles in tendon repair remain mostly elusive. No chemical compounds are currently available to treat tendon injury. HYPOTHESIS: We hypothesized that the inhibition of Wnt/ß-catenin signaling would accelerate tendon healing. STUDY DESIGN: Controlled laboratory study. METHODS: Tendon-derived cells (TDCs) were isolated from rat Achilles tendons. The right Achilles tendon was injured via a dermal punch, while the left tendon was sham operated. A Wnt/ß-catenin inhibitor, IWR-1, and an antihistamine agent, promethazine (PH), were locally and intramuscularly injected, respectively, for 2 weeks after surgery. The healing tendons were histologically and biomechanically evaluated. RESULTS: The amount of ß-catenin protein was increased in the injured tendons from postoperative weeks 0.5 to 2. Inhibition of Wnt/ß-catenin signaling by IWR-1 in healing tendons improved the histological abnormalities and decreased ß-catenin, but it compromised the biomechanical properties. As we previously reported that antihistamine agents suppressed Wnt/ß-catenin signaling in human chondrosarcoma cells, we examined the effects of antihistamines on TDCs. We found that a first-generation antihistamine agent, PH, increased the expression of the tendon marker genes Mkx and Tnmd in TDCs. Intramuscular injection of PH did not improve histological abnormalities, but it decreased ß-catenin in healing tendons and increased the peak force and stiffness of the healing tendons on postoperative week 2. On postoperative week 8, however, the biomechanical properties of vehicle-treated tendons became similar to those of PH-treated tendons. CONCLUSION: IWR-1 and PH suppressed Wnt/ß-catenin signaling and improved the histological abnormalities of healing tendons. IWR-1, however, compromised the biomechanical properties of healing tendons, whereas PH improved them. CLINICAL RELEVANCE: PH is a candidate repositioned drug that potentially accelerates tendon repair.

Promethazine inhibits proliferation and promotes apoptosis in colorectal cancer cells by suppressing the PI3K/AKT pathway.

AIM: To elucidate the potential effect of promethazine on colorectal cancer (CRC) cells and the underlying mechanism. MATERIALS AND METHODS: Targets of the drug promethazine (PMTZ) were identified by DrugBank and comparative toxicogenomic databases (CTD), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was performed with STRING software. The effects of PMTZ were predicted to be associated with the PI3K/AKT pathway. Cell Counting Kit 8 (CCK-8) assays were used to evaluate the effects of different concentrations of PMTZ on the proliferation of various types of CRC cells. Flow cytometry and Western blotting analyses were used to detect the degree of CRC cell apoptosis and the expression of the apoptosis-related proteins Bcl-2, Bax and caspase-3 after PMTZ treatment. The expression levels of PI3K/AKT pathway-related proteins [PI3K, AKT, phosphorylated (P)-PI3K and p-AKT] in CRC cells treated with PMTZ were analyzed by Western blotting. RESULTS: PMTZ inhibited the proliferation and promoted the apoptosis of CRC cells and suppressed the activation of the PI3K/AKT signaling pathway in a dose-dependent manner. DISCUSSION AND CONCLUSIONS: PMTZ may suppress the proliferation and induce the apoptosis of CRC cells by inhibiting the PI3K/ AKT signaling pathway. This study reported, for the first time, the function of PMTZ in CRC cells and the underlying mechanism and further confirmed the potential antitumor effects of phenothiazine. The combination of bioinformatics analyses and experiments provides informative evidence for the reuse of drugs and the development of new drugs.

An inhibitory and beneficial effect of chlorpromazine and promethazine (C + P) on hyperglycolysis through HIF-1α regulation in ischemic stroke.

BACKGROUND: After ischemic stroke, the increased catabolism of glucose (hyperglycolysis) results in the production of reactive oxygen species (ROS) via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX). A depressive or hibernation-like effect of C + P on brain activity was reported to induce neuroprotection. The current study assesses the effect of C + P on hyperglycolysis and NOX activation. METHODS: Adult male Sprague-Dawley rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) followed by 6 or 24 h of reperfusion. At the onset of reperfusion, rats received C + P with or without temperature control, or phloretin [glucose transporter (GLUT)-1 inhibitor], or cytochalasin B (GLUT-3 inhibitor). We detected brain ROS, apoptotic cell death, and ATP levels along with HIF-1α expression. Cerebral hyperglycolysis was measured by glucose, protein expression of GLUT-1/3, and phosphofructokinase-1 (PFK-1), as well as lactate and lactate dehydrogenase (LDH) at 6 and 24 h of reperfusion. The enzymatic activity of NOX and protein expression of its subunits (gp91phox) were detected. Neural SHSY5Y cells were placed under 2 h of oxygen-glucose deprivation (OGD) followed by reoxygenation for 6 and 24 h with C + P treatment. Cell viability and protein levels of HIF-1α, GLUT-1/3, PFK-1, LDH, and gp91phox were measured. A HIF-1α overexpression vector was transfected into the cells, and then protein levels of HIF-1α, GLUT-1/3, PFK-1, and LDH were quantitated. In sham-operated rats and control cells, the protein levels of HIF-1α, GLUT-1/3, PFK-1, LDH, and gp91phox were measured at 6 and 24 h after C + P administration. RESULTS: C + P reduced the protein elevations after stroke in HIF-1α, glycolytic enzymes, as well as in ROS, cell death, glucose and lactate, but raised ATP levels in the brain. In ischemic rats exposed to GLUT-1/3 inhibitors, ROS, cell death, glucose, and lactate were all decreased, as well as GLUT-1, GLUT-3, LDH, and PFK-1 protein levels. C + P decreased ischemia-induced NOX activation by reducing the enzymatic activity and protein expression of the NOX subunit gp91phox, as was observed in the presence of GLUT-1/3 inhibitors. These markers were significantly decreased following C + P administration with the induced hypothermia, while C + P administration with temperature control at 37 °C induced lesser protection after ischemia stroke. In the OGD/reoxygenation model, C + P treatment increased cell viability and diminished protein levels of HIF-1α, GLUT-1, GLUT-3, PFK-1, LDH, and gp91phox. However, in OGD with HIF-1α overexpression, C + P was unable to effectively reduce the upregulated GLUT-1, GLUT-3, and LDH. In normal conditions, C + P reduced HIF-1α and the levels of key glycolytic enzymes depending on its pharmacological effect. CONCLUSION: C + P, partially depending on hypothermia, attenuates hyperglycolysis and NOX activation through HIF-1α regulation.

Future Oncotargets: Targeting Overexpressed Conserved Protein Targets in Androgen Independent Prostate Cancer Cell Lines.

BACKGROUND: Targeting evolutionarily conserved proteins in malignant cells and the adapter proteins involved in signalling that generates from such proteins may play a cardinal role in the selection of anti-cancer drugs. Drugs targeting these proteins could be of importance in developing anti-cancer drugs. OBJECTIVES: We inferred that drugs like loperamide and promethazine that act as antagonists of proteins conserved in cancer cells like voltage-gated Calcium channels (Cav), Calmodulin (CaM) and drug efflux (ABCB1) pump may have the potential to be re-purposed as an anti-cancer agent in Prostate Cancer (PCa). METHODS: Growth and cytotoxic assays were performed by selecting loperamide and promethazine to target Cav, CaM and drug efflux (ABCB1) pumps to elucidate their effects on androgen-independent PC3 and DU145 PCa cell lines. RESULT: We show that loperamide and promethazine in doses of 80-100µg/ml exert oncocidal effects when tested in DU145 and PC3 cell lines. Diphenhydramine, which shares its targets with promethazine, except the CaM, failed to exhibit oncocidal effects. CONCLUSION: Anti-cancer effects can be of significance if structural analogues of loperamide and promethazine that specifically target Cav, CaM and ABCB1 drug efflux pumps can be synthesized, or these two drugs could be re-purposed after human trials in PCa.

AMPK activation induced by promethazine increases NOXA expression and Beclin-1 phosphorylation and drives autophagy-associated apoptosis in chronic myeloid leukemia.

Relapse and drug resistance is still major challenges in the treatment of leukemia. Promethazine, an antihistaminic phenothiazine derivative, has been used to prevent chemotherapy-induced emesis, although there is no report about its antitumor potential. Thus, we evaluated the promethazine cytotoxicity against several leukemia cells and the underlying mechanisms were investigated. Promethazine exhibited potent and selective cytotoxicity against all leukemia cell types in vitro at clinically relevant concentrations. Philadelphia positive chronic myeloid leukemia (CML) K562 cells were the most sensitive cell line. The cytotoxicity of promethazine in these cells was triggered by the activation of AMPK and inhibition of PI3K/AKT/mTOR pathway. The subsequent downstream effects were NOXA increase, MCL-1 decrease, and Beclin-1 activation, resulting in autophagy-associated apoptosis. These data highlight targeting autophagy may represent an interesting strategy in CML therapy, and also the antitumor potential of promethazine by acting in AMPK and PI3K/AKT/mTOR signaling pathways. Since this drug is currently used with relative low side effects, its repurposing may represent a new therapeutic opportunity for leukemia treatment.

TCTP from Loxosceles Intermedia (Brown Spider) Venom Contributes to the Allergic and Inflammatory Response of Cutaneous Loxoscelism.

LiTCTP is a toxin from the Translationally Controlled Tumor Protein (TCTP) family identified in Loxosceles brown spider venoms. These proteins are known as histamine-releasing factors (HRF). TCTPs participate in allergic and anaphylactic reactions, which suggest their potential role as therapeutic targets. The histaminergic effect of TCTP is related to its pro-inflammatory functions. An initial characterization of LiTCTP in animal models showed that this toxin can increase the microvascular permeability of skin vessels and induce paw edema in a dose-dependent manner. We evaluated the role of LiTCTP in vitro and in vivo in the inflammatory and allergic aspects that undergo the biological responses observed in Loxoscelism, the clinical condition after an accident with Loxosceles spiders. Our results showed LiTCTP recombinant toxin (LiRecTCTP) as an essential synergistic factor for the dermonecrotic toxin actions (LiRecDT1, known as the main toxin in the pathophysiology of Loxoscelism), revealing its contribution to the exacerbated inflammatory response clinically observed in envenomated patients.

Promethazine inhibits neuronal apoptosis via PI3K/Akt signaling pathway in rats with cerebral infarction.

OBJECTIVE: To study the effect of promethazine on neuronal apoptosis in rats with cerebral infarction (CI) through the phosphatidylinositol 3-hydroxy kinase/protein kinase B (PI3K/Akt) signaling pathway. MATERIALS AND METHODS: A total of 36 Sprague-Dawley rats were randomly divided into the sham group (n=12), model group (n=12), and promethazine group (n=12). The external carotid artery was only exposed in the model group, and the ischemia-reperfusion model after CI was established using the suture method in the other two groups. After modeling, the normal saline was intraperitoneally injected in the sham group and model group, while promethazine was intraperitoneally injected in the promethazine group. The rats were sampled after 1 week of intervention. The neurological deficits of rats were evaluated using the Zea-Longa score, and the cognitive function, the spatial learning, and memory of rats were detected via the water maze test. Moreover, the expressions of B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X protein (Bax) in brain tissues were detected via immunohistochemistry, and the relative protein expressions of PI3K p85, PI3K p110, and p-Akt were detected via Western blotting. The mRNA expressions of Bax and Bcl-2 were detected via quantitative Polymerase Chain Reaction (qPCR), and the apoptosis was detected via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. RESULTS: The Zea-Longa score was significantly increased in the model group and promethazine group compared with that in the sham group (p<0.05), while it significantly declined in the promethazine group compared with that in the model group (p<0.05). The escape latency was significantly prolonged and the times of crossing platform were significantly reduced in the model group and promethazine group compared with those in the sham group (p<0.05), while the escape latency was significantly shortened and the times of crossing platform were significantly increased in the promethazine group compared with those in the model group (p<0.05). Compared with those in the sham group, the positive expression of Bax was significantly increased, while the positive expression of Bcl-2 was remarkably decreased in the model group and promethazine group (p<0.05). Compared with those in the model group, the positive expression of Bax was significantly decreased, while the positive expression of Bcl-2 was remarkably increased in the promethazine group (p<0.05). Besides, the model group and promethazine group had evidently higher relative protein expressions of PI3K p85, PI3K p110, and p-Akt than the sham group (p<0.05), while the promethazine group also had evidently higher relative protein expressions of PI3K p85, PI3K p110, and p-Akt than the model group (p<0.05). Compared with the sham group, model group, and promethazine group had remarkably increased relative mRNA expression of Bax, and remarkably decreased relative mRNA expression of Bcl-2 (p<0.05). Compared with those in the model group, the relative mRNA expression of Bax was remarkably decreased, while the relative mRNA expression of Bcl-2 was remarkably increased in the promethazine group (p<0.05). Finally, the apoptosis rate was significantly higher in the model group and promethazine group than that in the sham group (p<0.05), while it was significantly lower in the promethazine group than that in the model group (p<0.05). CONCLUSIONS: Promethazine inhibits neuronal apoptosis in CI rats by upregulating the PI3K/Akt signaling pathway, thereby exerting a protective effect.

Neuroleptic Drug Targets a Brain-Eating Amoeba: Effects of Promethazine on Neurotropic Acanthamoeba castellanii.

Acanthamoeba spp. has recently been reported to express diverse group of ion channels and receptors that are expressed by human cells which bind drugs that are used in noninfectious diseases. Bioinformatics computational tools, growth assays, and 3D structural modeling have enabled the discovery of primitive muscarinic receptors, voltage-gated calcium channels, and ion transport pumps such as Na-K ATPase in this protist pathogen. The significance of the reported receptors and ion channels in the biology of Acanthamoeba is yet to be determined. We selected promethazine, which is a known antagonist of proteins like dopaminergic, histaminergic, muscarinic receptors, and calmodulin, to determine its effects on the growth and proliferation of trophozoites and cysts of Acanthamoeba spp. In order to elucidate the receptors involved in the effects produced by promethazine, we also performed individual experiments on Acanthamoeba trophozoites and cysts in the presence of the agonist of the above-mentioned receptors. Our results show that promethazine in the range of 60-100 µg/mL proved to be amoebicidal for Acanthamoeba trophozoites and at slightly higher doses ranging around 125-250 µg/mL also showed partial cysticidal effects. We also show the evidence of homology between the human targets of promethazine and similar targets in Acanthamoeba by the use of bioinformatic computational tools and 3D modeling. Promethazine and its structural analogs, because of being FDA-approved, have a wider margin of safety that can be tested as potential anti- Acanthamoeba agents in diseases like keratitis and encephalitis caused by this protist pathogen.

Luteinizing hormone signaling is involved in synchronization of Leydig cell's clock and is crucial for rhythm robustness of testosterone production†.

In mammals, circadian clock regulates concentration of many reproductive hormones including testosterone. Previously, we characterized pattern of circadian transcription of core clock genes in testosterone-producing Leydig cells. Here, the potential role of luteinizing hormone receptor (LHR)-cAMP signaling in synchronization of Leydig cell's circadian clock and rhythmic testosterone production were examined. Results showed that activation of LHR-cAMP signaling in primary rat Leydig cell culture increased Star/STAR and changed expression of many clock genes (upregulated Per1/PER1, Dec1/2, and Rorb, and downregulated Bmal1 and Rev-erba/b). Inhibition of protein kinase A prevented LHR-triggered increase in transcription of Per1 and Dec1. Effect of stimulated LHR-cAMP signaling on Leydig cell's clock transcription was also confirmed in vivo, using rats treated with single hCG injection. To analyze in vivo effect of low LH-cAMP activity on rhythmical Leydig cell function, rats with experimental hypogonadotropic hypogonadism were used. Characteristics of hypogonadal rats were decreased LH and testosterone secretion without circadian fluctuation; in Leydig cells decreased arrhythmic cAMP and transcription of steroidogenic genes (Cyp11a1 and Cyp17a1) were observed, while decreased Star/STAR expression retains circadian pattern. However, expression of clock genes, despite changes in transcription levels (increased Bmal1, Per2, Cry1, Cry2, Rora, Rorb, Rev-erba/b/REV-ERBB, Dec1, Csnk1e, and decreased Npas2 and PER1) kept circadian patterns observed in control groups. Altogether, the results strengthened the hypothesis about role of LH-cAMP signaling as synchronizer of Leydig cell's clock. However, clock in Leydig cells is not sufficient to sustain rhythmicity of testosterone production in absence of rhythmic activity of LH-cAMP signaling.

Deciphering the enhanced inhibitory, disaggregating and cytoprotective potential of promethazine towards amyloid fibrillation.

Increasing evidence proposed that amyloid deposition by proteins play a crucial role in an array of neurotoxic and degenerative disorders like Parkinson's disease, systemic amyloidosis etc, that could be controlled by anti-aggregation methodologies which either inhibit or disaggregate such toxic aggregates. The present work targets the amyloid inhibiting and disaggregating potential of promethazine (PRM) against human insulin (HI) and human lysozyme (HL) fibrillogenesis. Biophysical techniques like Rayleigh scattering measurements (RLS), Thioflavin T (ThT) and 8-Anilinonaphthalene-1-sulfonic acid (ANS) fluorescence measurement, circular dichroism (CD) and dynamic light scattering (DLS) measurements illustrated the inhibitory action of PRM. The half maximal inhibitory concentration (IC50) of PRM for HI and HL was estimated to be 114.81±1.21µM and 186.20±1.03µM, respectively. Microscopic techniques revealed the absence of fibrillar structures when HI and HL was co-incubated with PRM. Cytoprotective behavior of PRM was investigated by cell based cytotoxicity assay performed on SH-SY5Y neuronal cell lines. The half maximal disaggregation concentration (DC50) was calculated as 21.37±0.89µM and 45.70±0.76µM, signifying that PRM is much potent to disaggregate pre formed fibrils rather than to inhibit fibrillation. Thus, PRM could be beneficial as therapeutic agent that can aid in the cure of amyloid related diseases.

Promethazine Hydrochloride Inhibits Ectopic Fat Cell Formation in Skeletal Muscle.

Fatty degeneration of skeletal muscle leads to muscle weakness and loss of function. Preventing fatty degeneration in skeletal muscle is important, but no drug has been used clinically. In this study, we performed drug repositioning using human platelet-derived growth factor receptor α (PDGFRα)-positive mesenchymal progenitors that have been proved to be an origin of ectopic adipocytes in skeletal muscle. We found that promethazine hydrochloride (PH) inhibits adipogenesis in a dose-dependent manner without cell toxicity. PH inhibited expression of adipogenic markers and also suppressed phosphorylation of cAMP response-element binding protein, which was reported to be a primary regulator of adipogenesis. We established a mouse model of tendon rupture with intramuscular fat deposition and confirmed that emerged ectopic adipocytes are derived from PDGFRα+ cells using lineage tracing mice. When these injured mice were treated with PH, formation of ectopic adipocytes was suppressed significantly. Our results show that PH inhibits PDGFRα+ mesenchymal progenitor-dependent ectopic adipogenesis in skeletal muscle and suggest that treatment with PH can be a promising approach to prevent fatty degeneration of skeletal muscle.

Phenothiazines Enhance Mild Hypothermia-induced Neuroprotection via PI3K/Akt Regulation in Experimental Stroke.

Physical hypothermia has long been considered a promising neuroprotective treatment of ischemic stroke, but the treatment's various complications along with the impractical duration and depth of therapy significantly narrow its clinical scope. In the present study, the model of reversible right middle cerebral artery occlusion (MCAO) for 2 h was used. We combined hypothermia (33-35 °C for 1 h) with phenothiazine neuroleptics (chlorpromazine & promethazine) as additive neuroprotectants, with the aim of augmenting its efficacy while only using mild temperatures. We also investigated its therapeutic effects on the Phosphatidylinositol 3 kinase/Protein kinase B (PI3K/Akt) apoptotic pathway. The combination treatment achieved reduction in ischemic rat temperatures in the rectum, cortex and striatum significantly (P < 0.01) faster than hypothermia alone, accompanied by more obvious (P < 0.01) reduction of brain infarct volume and neurological deficits. The combination treatment remarkably (P < 0.05) increased expression of p-Akt and anti-apoptotic proteins (Bcl-2 and Bcl-xL), while reduced expression of pro-apoptotic proteins (AIF and Bax). Finally, the treatment's neuroprotective effects were blocked by a p-Akt inhibitor. By combining hypothermia with phenothiazines, we significantly enhanced the neuroprotective effects of mild hypothermia. This study also sheds light on the possible molecular mechanism for these effects which involves the PI3K/Akt signaling and apoptotic pathway.

Ultraviolet A photosensitivity profile of dexchlorpheniramine maleate and promethazine-based creams: Anti-inflammatory, antihistaminic, and skin barrier protection properties.

BACKGROUND: Unwanted side effects such as dryness, hypersensitivity, and cutaneous photosensitivity are challenge for adherence and therapeutical success for patients using treatments for inflammatory and allergic skin response. AIMS: In this study, we compared the effects of two dermatological formulations, which are used in inflammatory and/or allergic skin conditions: dexchlorpheniramine maleate (DCP; 10 mg/g) and promethazine (PTZ; 20 mg/g). METHODS: We evaluated both formulations for phototoxicity potential, skin irritation, anti-inflammatory and antihistaminic abilities, and skin barrier repair in vitro and ex vivo using the standard OECD test guideline n° 432, the ECVAM protocol n° 78, and cultured skin explants from a healthy patient. Ultraviolet A was chosen as exogenous agent to induce allergic and inflammatory response. RESULTS: Both PTZ and DCP promoted increases in interleukin-1 (IL-1) synthesis in response to ultraviolet A (UVA) radiation compared to control. However, the increase observed with PTZ was significantly greater than the DCP, indicating that the latter has a lower irritant potential. DCP also demonstrated a protective effect on UVA-induced leukotriene B4 and nuclear factor kappa B (NF-κB) synthesis. Conversely, PTZ demonstrates more robust UVA antihistaminic activity. Likewise, PTZ promoted a significantly greater increase in the production of involucrin and keratin 14, both associated with protective skin barrier property. CONCLUSION: In conclusion, these data suggest possible diverging UVA response mechanisms of DCP and PTZ, which gives greater insight into the contrasting photosensitizing potential between DCP and PTZ observed in the patients.

Meniere's disease.

Meniere's disease (MD) is a disorder of the inner ear that causes vertigo attacks, fluctuating hearing loss, tinnitus and aural fullness. The aetiology of MD is multifactorial. A characteristic sign of MD is endolymphatic hydrops (EH), a disorder in which excessive endolymph accumulates in the inner ear and causes damage to the ganglion cells. In most patients, the clinical symptoms of MD present after considerable accumulation of endolymph has occurred. However, some patients develop symptoms in the early stages of EH. The reason for the variability in the symptomatology is unknown and the relationship between EH and the clinical symptoms of MD requires further study. The diagnosis of MD is based on clinical symptoms but can be complemented with functional inner ear tests, including audiometry, vestibular-evoked myogenic potential testing, caloric testing, electrocochleography or head impulse tests. MRI has been optimized to directly visualize EH in the cochlea, vestibule and semicircular canals, and its use is shifting from the research setting to the clinic. The management of MD is mainly aimed at the relief of acute attacks of vertigo and the prevention of recurrent attacks. Therapeutic options are based on empirical evidence and include the management of risk factors and a conservative approach as the first line of treatment. When medical treatment is unable to suppress vertigo attacks, intratympanic gentamicin therapy or endolymphatic sac decompression surgery is usually considered. This Primer covers the pathophysiology, symptomatology, diagnosis, management, quality of life and prevention of MD.

Mast cells and histamine play an important role in edema and leukocyte recruitment induced by Potamotrygon motoro stingray venom in mice.

This work aimed to investigate mechanisms underlying the inflammatory response caused by Potamotrygon motoro stingray venom (PmV) in mouse paws. Pre-treatment of animals with a mast cell degranulation inhibitor (cromolyn) diminished edema (62% of inhibition) and leukocyte influx into the site of PmV injection. Promethazine (histamine type 1 receptor antagonist) or thioperamide (histamine type 3 and 4 receptor antagonist) also decreased edema (up to 30%) and leukocyte numbers, mainly neutrophils (40-50 %). Cimetidine (histamine type 2 receptor antagonist) had no effect on PmV-induced inflammation. In the RBL-2H3 lineage of mast cells, PmV caused proper cell activation, in a dose-dependent manner, with release of PGD2 and PGE2. In addition, the role of COXs products on PmV inflammatory response was evaluated. Indomethacin (COX-1/COX-2 inhibitor) or etoricoxib (COX-2 inhibitor) partially diminished edema (around 20%) in PmV-injected mice. Indomethacin, but not etoricoxib, modulated neutrophil influx into the site of venom injection. In conclusion, mast cell degranulation and histamine, besides COXs products, play an important role in PmV-induced reaction. Since PmV mechanism of action remains unknown, hindering accurate treatment, clinical studies can be performed to validate the prescription of antihistaminic drugs, besides NSAIDs, to patients injured by freshwater stingrays.

Pharmacophore modeling for hERG channel facilitation.

Human ether-a-go-go-related gene (hERG) channels play a critical role in cardiac action potential repolarization. The unintended block of hERG channels by compounds can prolong the cardiac action potential duration and induce arrhythmia. Several compounds not only block hERG channels but also enhance channel activation after the application of a depolarizing voltage step. This is referred to as facilitation. In this study, we tried to extract the property of compounds that induce hERG channel facilitation. We first examined the facilitation effects of structurally diverse hERG channel blockers in Xenopus oocytes. Ten of 13 assayed compounds allowed facilitation, suggesting that it is an effect common to most hERG channel blockers. We constructed a pharmacophore model for hERG channel facilitation. The model consisted of one positively ionizable feature and three hydrophobic features. Verification experiments suggest that the model well describes the structure-activity relationship for facilitation. Comparison of the pharmacophore for facilitation with that for hERG channel block showed that the spatial arrangement of features is clearly different. It is therefore conceivable that two different interactions of a compound with hERG channels exert two pharmacological effects, block and facilitation.

Direct modification of bioactive phenothiazines by exposure to laser radiation.

Whereas exposure of combinations of a phenothiazine and bacterium to incoherent UV increases the activity of the phenothiazine, exposure of the phenothiazine alone does not yield an increase of its activity. Because the laser beam energy is greater than that produced by the incoherent UV sources, exposure of phenothiazines to specific lasers may yield molecules with altered activities over that of the unexposed parent. Chlorpromazine, thioridazine and promethazine active against bacteria were exposed to two distinct lasers for varying periods of time. Absorption and fluorescence spectra were conducted prior to and post-exposure and the products of laser exposure evaluated for activity against a Staphylococcus aureus ATCC strain via a disk susceptibility assay. Exposure to lasers alters the absorption/fluorescence spectra of the phenothiazines; reduces the activity of thioridazine against the test bacterium; produces a highly active chlorpromazine compound against the test organism. Exposure of phenothiazines to lasers alters their structure that results in altered activity against a bacterium. This is the first report that lasers can alter the physico-chemico characteristics to the extent that altered bioactivity results. Exposure to lasers is expected to yield compounds that are difficult to make via chemical manipulation methods. A survey of selected patents of interest, even co-lateral for the subject of this article is shortly made.

Dichrostachys cinerea (L.) Wight et Arn (Mimosaceae) hydro-alcoholic extract action on the contractility of tracheal smooth muscle isolated from guinea-pig.

BACKGROUND: Dichrostachys cinerea (L.) Wight et Arn. (Mimosaceae) is largely used in ethno-medically across Africa, and mainly employed for the treatment of asthma in Ivory Coast and Gabon. The paper analyses the relaxation induced by the methanolic extract of D. cinerea (Edici) in the guinea-pig trachea preparations (GPTPs). PURPOSE: This study aimed to bring out the scientific basis to the use of this plant leading to the validation of this phytomedicine. METHOD: The aorta obtained from guinea-pigs was immediately placed in a Mac Ewen solution. Experiments were performed in preparations suspended between two L-shaped stainless steel hooks in a 10 ml organ bath containing Mac Ewen solution. The isometric contractile force of the aorta strips of guinea-pig were recorded by using a strain gauge. The different drugs were directly administered into the organ bath and the magnitude of GPTPs was evaluated. RESULTS: Phytochemical analysis of the methanolic extract of Dichrostachys cinerea (Edici) using chemical methods revealed the presence of flavenoids, tannins, sterols, triterpenes and polyphenols. Pharmacological studies performed in GPTPs show that of Dichrostachys cinerea (0.1 mg/ml - 2 mg/ml) evoked a broncho-constriction in GPTPs. Whereas, at concentration up to 2 mg/ml, Edici induced a significant dose-dependent relaxation in the GPTPs. KCl-, ACh- or histamine-evoked contractions of isolated trachea was significantly inhibited by increasing concentrations of Edici (3.5-10 mg/ml). Edici (10 mg/ml) as well as promethazine (0.25 mg/ml) significantly inhibited contractions induced by increasing concentrations of histamine (1×10-7-1×10-4mg/ml). In the presence of atropine at a concentration of 10-6mg/ml, contractile response curve (CRC) evoked by ACh (1×10-5-1×10-2 mg/ml) was significantly abolished in concentration-dependent manner. Edici did not significantly reduced ACh evoked contraction (10-5-10-2mg/ml). CONCLUSION: These observations suggest that Edici could act through two mechanisms: firstly by activation of ß-adrenergic or histaminergic receptors; and secondly muscarinic receptors may not be greatly involved, that justifying the use of the extract in traditional Medicine in Africa.

Effect of MDR modulators verapamil and promethazine on gene expression levels of MDR1 and MRP1 in doxorubicin-resistant MCF-7 cells.

PURPOSE: One of the major problems of cancer chemotherapy is the development of multidrug resistance (MDR) phenotype. Among the numerous mechanisms of MDR, a prominent one is the increased expression of membrane transporter proteins, the action of which leads to decreased intracellular drug concentration and cytotoxicity of drugs. Among them, P-gp and MRP1, encoded by MDR1 and MRP1 genes, respectively, have been associated with MDR phenotype. Chemical modulators can be used to reverse MDR. These chemicals can either modulate MDR due to their substrate analogy (such as calcium channel blocker verapamil) or interact with phospholipid membranes (such as antihistaminic drug promethazine). This study focuses on the effect of verapamil and promethazine on the expression levels of MDR1 and MRP1 genes and the drug transport activity in doxorubicin-resistant MCF-7 breast carcinoma cell line. METHODS: Doxorubicin-resistant MCF-7 (MCF-7/Dox) cells were incubated with either verapamil or promethazine, and total RNA was isolated. Real-time PCR (qPCR) was carried out by using specific primers for MDR1, MRP1, and ß-actin genes. Intracellular doxorubicin accumulation was also examined by confocal laser scanning microscopy in treated cells. RESULTS: Results demonstrated a significant decrease in both MDR1 and MRP1 expression levels after promethazine applications. It has also been shown that treatment of the cells with verapamil results in significant decrease in MDR1 mRNA levels. Confocal laser scanning microscopy images demonstrated that the intracellular accumulation of doxorubicin was increased after verapamil treatment in MCF-7/Dox cells. CONCLUSIONS: The present study gives an idea about the efficiency of verapamil and promethazine on MDR reversal both in gene expression and in transport activity levels.