Effect of diminazene on cardiac hypertrophy through mitophagy in rat models with hyperthyroidism induced by levothyroxine

Hyperthyroidism is associated with the alteration in molecular pathways involved in the regulation of mitochondrial mass and apoptosis, which contribute to the development of cardiac hypertrophy. Diminazene (DIZE) is an animal anti-infection drug that has shown promising effects on improving cardiovascular disease. The aim of the present study was to investigate the therapeutic effect of DIZE on cardiac hypertrophy and the signaling pathways involved in this process in the hyperthyroid rat model. Twenty male Wistar rats were equally divided into four groups: control, hyperthyroid, DIZE, and hyperthyroid + DIZE. After 28 days of treatment, serum thyroxine (T4) and thyroid stimulating hormone (TSH) level, cardiac hypertrophy indices, cardiac damage markers, cardiac malondialdehyde (MDA), and superoxide dismutase (SOD) level, the mRNA expression level of mitochondrial and apoptotic genes were evaluated. Hyperthyroidism significantly decreased the cardiac expression level of SIRT1/PGC1α and its downstream involved in the regulation of mitochondrial biogenesis, mitophagy, and antioxidant enzyme activities including TFAM, PINK1/MFN2, Drp1, and Nrf2, respectively, as well as stimulated mitochondrial-dependent apoptosis by reducing Bcl-2 expression and increasing Bax expression. Treatment with DIZE significantly reversed the downregulation of SIRT1, PGC1α, PINK1, MFN2, Drp1, and Nrf2 but did not significantly change the TFAM expression. Moreover, DIZE suppressed apoptosis by normalizing the cardiac expression levels of Bax and Bcl-2. DIZE is effective in attenuating hyperthyroidism-induced cardiac hypertrophy by modulating the mitophagy-related pathway, suppressing apoptosis and oxidative stress.

Nephroprotective effects of diminazene on doxorubicin-induced acute kidney injury in rats

This study aimed to investigate the potential protective effects of diminazene, an activator of angiotensin II converting enzyme (ACE2), on kidney function and structure in rats with acute kidney injury (AKI) induced by the anticancer drug doxorubicin (DOX). The impact of diminazene was compared to that of two other drugs: the ACE inhibitor lisinopril and the angiotensin II type 1 (AT1) receptor blocker valsartan. Rats were subjected to a single intraperitoneal injection of DOX (13.5 mg/kg) on the 5th day, either alone or in combination with diminazene (15 mg/kg/day), lisinopril (10 mg/kg/day), or valsartan (30 mg/kg/day) for 8 consecutive days. Various markers related to kidney function, oxidative stress, and inflammation were measured in plasma and urine. Additionally, kidney tissues were assessed histopathologically. DOX-induced nephrotoxicity was confirmed by elevated levels of plasma urea, creatinine, and neutrophil gelatinase-associated lipocalin (NGAL). DOX also led to increased urinary N-acetyl-β-D-glucosaminidase (NAG) activity and decreased creatinine clearance, albumin levels, and osmolality. Moreover, DOX caused a reduction in renal oxidative stress markers, including superoxide dismutase (SOD), glutathione reductase (GR), and catalase activities, while increasing malondialdehyde (MDA) levels. It also raised plasma inflammatory markers, tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β). Concurrently administering diminazene significantly mitigated these DOX-induced changes, including histopathological alterations like renal tubule necrosis, tubular casts, shrunken glomeruli, and increased renal fibrosis. Similar protective effects were observed with lisinopril and valsartan. These protective effects, at least in part, appear to result from the anti-inflammatory and antioxidant properties of these drugs. In summary, this study suggests that the administration of diminazene, lisinopril, or valsartan had comparable effects in ameliorating the biochemical and histopathological aspects of DOX-induced acute kidney injury in rats.

Activation of angiotensin-converting enzyme 2 produces an antidepressant-like effect via MAS receptors in mice

Angiotensin (Ang)-converting-enzyme (ACE) 2 converts Ang II into Ang (1-7), which in turn acts on MAS receptors (ACE2/Ang (1-7)/MAS receptors pathway). This pathway has neuroprotective properties, making it a potential therapeutic target for psychiatric disorders such as depression. Thus, we examined the effects of diminazene aceturate (DIZE), an ACE2 activator, on depressive-like behavior using behavioral, pharmacological, and biochemical assays. To determine whether DIZE or Ang (1-7) produce antidepressant-like effects, we measured the duration of immobility of mice in the tail suspension test following their intracerebroventricular administration. Next, we measured the levels of ACE2 activation in the cerebral cortex, prefrontal cortex, hippocampus, and amygdala after DIZE injection, and examined which cell types, including neurons, microglia, and astrocytes, express ACE2 in the hippocampus using immunofluorescence. Administration of DIZE or Ang (1-7) significantly shortened the duration of immobility time in the tail suspension test, while this effect was inhibited by the co-administration of the MAS receptor antagonist A779. DIZE activated ACE2 in the hippocampus. ACE2 was localized to neurons, astrocytes, and microglia in the hippocampus. In conclusion, these results suggest that DIZE may act on ACE2-positive cells in the hippocampus where it increases the activity of ACE2, thereby enhancing signaling of the ACE2/Ang (1-7)/MAS receptor pathway and resulting in antidepressant-like effects.

Trypanosoma Congolense Resistant to Trypanocidal Drugs Homidium and Diminazene and their Molecular Characterization in Lambwe, Kenya

PURPOSE

African animal trypanosomiasis (AAT) is a disease affecting livestock in sub-Saharan Africa. The use of trypanocidal agents is common practice to control AAT. This study aimed to identify drug-resistant Trypanosoma congolense in Lambwe, Kenya, and assess if molecular test backed with mice tests is reliable in detecting drug sensitivity.

METHODS

Blood samples were collected from cattle, in Lambwe, subjected to buffy coat extraction and Trypanosoma spp. detected under a microscope. Field and archived isolates were subjected to molecular characterization. Species-specific T. congolense and TcoAde2 genes were amplified using PCR to detect polymorphisms. Phylogenetic analysis were performed. Four T. congolense isolates were evaluated individually in 24 test mice per isolate. Test mice were then grouped (n=6) per treatement with diminazene, homidium, isometamidium, and controls. Mice were subsequently assessed for packed cell volume (PCV) and relapses using microscopy.

RESULTS

Of 454 samples, microscopy detected 11 T. congolense spp, eight had TcoAde2 gene, six showed polymorphisms in molecular assay. Phylogenetic analysis grouped isolates into five. Two archived isolates were homidium resistant, one was also diminazene resistant in mice. Two additional isolates were sensitive to all the drugs. Interestingly, one sensitive isolate lacked polymorphisms, while the second lacked TcoAde2, indicating the gene is not involved in drug sensitivity. Decline in PCV was pronounced in relapsed isolates.

CONCLUSION

T. congolense associated with homidium and diminazene resistance exist in Lambwe. The impact can be their spread and AAT increase. Polymorphisms are present in Lambwe strains. TcoAde2 is unlikely involved in drug sensitivity. Molecular combined with mice tests is reliable drug sensitivity test and can be applied to other genes. Decline in PCV in infected-treated host could suggest drug resistance.

Mechanisms of acid-sensing ion channels inhibition by nafamostat, sepimostat and diminazene

Acid-sensing ion channels (ASICs) are blocked by many cationic compounds. Mechanisms of action, which may include pore block, modulation of activation and desensitization, need systematic analysis to allow predictable design of new potent and selective drugs. In this work, we studied the action of the serine protease inhibitors nafamostat, sepimostat, gabexate and camostat, on native ASICs in rat giant striatal interneurons and recombinant ASIC1a and ASIC2a channels, and compared it to that of well-known small molecule ASIC blocker diminazene. All these compounds have positively charged amidine and/or guanidine groups in their structure. Nafamostat, sepimostat and diminazene inhibited pH 6.5-induced currents in rat striatal interneurons at -80 mV holding voltage with IC₅₀ values of 0.78 ± 0.12 μM, 2.4 ± 0.3 μM and 0.40 ± 0.09 μM, respectively, whereas camostat and gabexate were practically ineffective. The inhibition by nafamostat, sepimostat and diminazene was voltage-dependent evidencing binding in the channel pore. They were not trapped in the closed channels, suggesting "foot-in-the-door" mechanism of action. The inhibitory activity of nafamostat, sepimostat and diminazene was similar in experiments on native ASICs and recombinant ASIC1a channels, while all of them were drastically less active against ASIC2a channels. According to our molecular modeling, three active compounds bind in the channel pore between Glu 433 and Ala 444 in a similar way. In view of the relative safety of nafamostat for clinical use in humans, it can be considered as a potential candidate for the treatment of pathophysiological conditions linked to ASICs disfunction, including inflammatory pain and ischemic stroke.

Discovery of diminazene as a dual inhibitor of SARS-CoV-2 human host proteases TMPRSS2 and furin using cell-based assays

The proteases TMPRSS2 (transmembrane protease serine 2) and furin are known to play important roles in viral infectivity including systematic COVID-19 infection through priming of the spike protein of SARS-CoV-2 and related viruses. To discover small-molecules capable of inhibiting these host proteases, we established convenient and cost-effective cell-based assays employing Vero cells overexpressing TMPRSS2 and furin. A cell-based proteolytic assay for broad-spectrum protease inhibitors was also established using human prostate cancer cell line LNCaP. Evaluation of camostat, nafamostat, and gabexate in these cell-based assays confirmed their known TMPRSS2 inhibitory activities. Diminazene, a veterinary medicinal agent and a known furin inhibitor was found to inhibit both TMPRSS2 and furin with IC₅₀s of 1.35 and 13.2 μM, respectively. Establishment and the use of cell-based assays for evaluation TMPRSS2 and furin inhibitory activity and implications of dual activity of diminazene vs TMPRSS2 and furin are presented.

Drug-resistant trypanosome isolates populations in dogs in Enugu North Senatorial Zone, Southeastern Nigeria

African animal trypanosomosis is an important wasting and endemic protozoan disease causing morbidities and mortalities in animals in the sub-Saharan Africa. Currently, chemotherapy is the widely used method of African animal trypanosomosis control, especially in dogs in the sub-Saharan Africa. However, their efficacy is threatened by the emergence of drug-resistant trypanosomes owing to their extensive use and misuse over several decades amongst other factors. Thus, this study focused on the trypanocidal sensitivity and characterization of Trypanosoma species isolated from dogs in Enugu North Senatorial Zone (ENSZ), Southeastern Nigeria. Trypanosoma brucei (n = 44) and T. congolense (n = 4) isolated from naturally infected dogs in ENSZ, Southeastern Nigeria, between January and August 2016 were subjected to single dose test to assess their sensitivity to diminazene aceturate (DA) and isometamidium chloride (ISM). Subsequently, DA and multidrug-resistant isolates were further subjected to DA multi-dose test and CD₅₀ was determined and was used to characterize the drug-resistant trypanosomes. Clones were derived from a randomly selected multidrug-resistant isolate and their sensitivity also assessed. 100% and 83.3% of T. congolense and T. brucei respectively were resistant to the trypanocides. Amongst the drug-resistant isolates, 50%, 16.7%, and 33.3% were resistant to DA, ISM, and both trypanocides respectively with CD₅₀ ranging between 11 and 32.34 mg/kg. Drug-resistant trypanosomes were characterized into highly resistant (CD₅₀ = 11-24.99 mg/kg) and very highly resistant (CD₅₀ =  > 25 mg/kg) trypanosome isolates. Clones also expressed high levels of resistance to both DA and ISM with CD₅₀ values between 35.58 and 38.85 mg/kg. Trypanocidal resistance was, thus, confirmed and appears to be widespread in dogs in ENSZ, Southeastern Nigeria. The adoption of an integrated trypanosomosis control strategy in ENSZ is most desirous.

Isothermal microcalorimetry - A quantitative method to monitor Trypanosoma congolense growth and growth inhibition by trypanocidal drugs in real time

Trypanosoma congolense is a protozoan parasite that is transmitted by tsetse flies, causing African Animal Trypanosomiasis, also known as Nagana, in sub-Saharan Africa. Nagana is a fatal disease of livestock that causes severe economic losses. Two drugs are available, diminazene and isometamidium, yet successful treatment is jeopardized by drug resistant T. congolense. Isothermal microcalorimetry is a highly sensitive tool that can be used to study growth of the extracellular T. congolense parasites or to study parasite growth inhibition after the addition of antitrypanosomal drugs. Time of drug action and time to kill can be quantified in a simple way by real time heat flow measurements. We established a robust protocol for the microcalorimetric studies of T. congolense and developed mathematical computations in R to calculate different parameters related to growth and the kinetics of drug action. We demonstrate the feasibility and benefit of the method exemplary with the two standard drugs, diminazene aceturate and isometamidium chloride. The method and the mathematical approach can be translated to study other pathogenic or non-pathogenic cells if they are metabolically active and grow under axenic conditions.

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Isothermal microcalorimetry enables heat flow measurement of T. congolense in real-time.

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Heat flow measurements correlate with number of viable cells.

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Growth and drug-induced growth inhibition can be deducted from heat flow curves.

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Pharmacodynamic drug action parameters can be computed from heat flow curves.

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This method is a valuable tool in the drug discovery process against T. congolense.

Aberrant use and poor quality of trypanocides: a risk for drug resistance in south western Ethiopia

BACKGROUND

Trypanocidal drugs have been used to control African animal trypanosomosis for several decades. In Ethiopia, these drugs are available from both authorized (legal) and unauthorized (illegal) sources but documentation on utilization practices and quality of circulating products is scanty. This study looked at the practices of trypanocidal drug utilization by farmers and the integrity of active ingredient in trypanocides sold in Gurage zone, south western Ethiopia. The surveys were based on a structured questionnaire and drug quality determination of commonly used brands originating from European and Asian companies and sold at both authorized and unauthorized markets. One hundred farmers were interviewed and 50 drug samples were collected in 2013 (Diminazene aceturate = 33 and Isometamidium chloride = 17; 25 from authorized and 25 from unauthorized sources). Samples were tested at the OIE-certified Veterinary Drug Control Laboratory (LACOMEV) in Dakar, Senegal, by using galenic standards and high performance liquid chromatography.

RESULTS

Trypanosomosis was found to be a major threat according to all interviewed livestock keepers in the study area. Diminazene aceturate and isometamidium chloride were preferred by 79% and 21% of the respondents respectively, and 85% of them indicated that an animal receives more than six treatments per year. About 60% of these treatments were reported to be administered by untrained farmers. Trypanocidal drug sources included both unauthorized outlets (56%) and authorized government and private sources (44%). A wide availability and usage of substandard quality drugs was revealed. Twenty eight percent of trypanocidal drugs tested failed to comply with quality requirements. There was no significant difference in the frequency of non-compliance between diminazene-based and isometamidium chloride products (P = 0.87) irrespective of the marketing channel (official and unofficial). However, higher rates of non-compliant trypanocides were detected for drugs originating from Asia than from Europe (P = 0.029).

CONCLUSION

The findings revealed the presence of risk factors for the development of drug resistance, i.e. wide distribution of poor quality drugs as well as substandard administration practices. Therefore, it is strongly recommended to enforce regulatory measures for quality control of veterinary drugs, to expand and strengthen veterinary services and to undertake trypanocidal drug efficacy studies of wider coverage.

Trypanocidal Effects of Cisplatin alone and in Combination with Nigella sativa Oil on Experimentally Infected Mice with Trypanosoma evansi

BACKGROUND

Due to the limited number of the available drugs for the treatment of trypanosomiasis, this study was designed to evaluate the trypanocidal effects of cisplatin or/and Nigella sativa oil (NSO) in experimentally infected mice with T. evansi.

METHODS

During 2015 at the Parasitology Department, Menoufia University, Menoufia, Egypt, sixty Swiss albino mice were divided into six groups: normal control (I), infected control (II); cisplatin-treated (III); NSO-treated (IV); combined cisplatin + NSO-treated (V) and diminazene-treated (VI). The tested drugs were evaluated by the assessment of parasitaemia, measurement of aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, creatinine, serum IgM and a histopathological study.

RESULTS

NSO showed a trypanocidal effect, however; it was not as effective as cisplatin or diminazene. There were significant increases of AST, ALT, urea, and creatinine in group II and III, which were significantly reduced in cisplatin + NSO-treated group (V). Moreover, there were significant reductions in serum IgM and the pathological changes of the examined organs of group V when they were compared with other treated groups.

CONCLUSION

Cisplatin combined with NSO showed a trypanocidal effect against T. evansi with preservation of vital organs functions and architecture.

A modulatory role of ASICs on GABAergic synapses in rat hippocampal cell cultures

Rapid acidification occurring during synaptic vesicle release can activate acid-sensing ion channels (ASICs) both on pre- and postsynaptic neurons. In the latter case, a fraction of postsynaptic current would be mediated by cation-selective acid-sensing ion channels. Additionally, in both cases, activation of acid-sensing ion channels could modulate synaptic strength by affecting transmitter release and/or sensitivity of postsynaptic receptors. To address potential involvement of acid-sensing ion channels in mediation/modulation of synaptic transmission at hippocampal GABAergic synapses, we studied effects of three structurally different blockers of acid-sensing ion channels on evoked postsynaptic currents using the patch-clamp technique. We found that GABAergic postsynaptic currents, recorded below their reversal potential as inward currents, are suppressed by all the employed blockers of acid-sensing ion channels. These currents were suppressed by ~ 20 % in the presence of a novel blocker 5b (1 μM) and by ~30 % in the presence of either amiloride (25 μM) or diminazene (20 μM). In the same cells the suppression of postsynaptic currents, recorded above their reversal potential as outward currents was statistically insignificant. These results imply that the effects of blockers in our experiments are at least partially postsynaptic. On the other hand, in the case of mediation of a fraction of postsynaptic current by acid-sensing ion channels, an increase of outward currents would be expected under our experimental conditions. Our analysis of a bicuculline-resistant fraction of postsynaptic currents also suggests that effects of the blockers are predominantly modulatory. In this work we present evidence for the first time that acid-sensing ion channels play a functional role at hippocampal GABAergic synapses. The suppressing effect of the blockers of acid-sensing ion channels on GABAergic transmission is due, at least partially, to a postsynaptic but (predominantly) modulatory mechanism. We hypothesize that the modulatory effect is due to functional crosstalk between ASICs and GABA_A-receptors recently reported in isolated neurons, however, verification of this hypothesis is necessary.

Drug quality analysis through high performance liquid chromatography of isometamidium chloride hydrochloride and diminazene diaceturate purchased from official and unofficial sources in Northern Togo

Trypanocidal drugs remain the most accessible and thus commonly used means of controlling tsetse transmitted animal African trypanosomosis. In Togo, trypanocides are sold on official as well as unofficial markets, but the quality of these trypanocides is undocumented so a drug quality assessment study was conducted from May 2013 to June 2014. Trypanocides supplied by European, Indian and Chinese pharmaceutical companies and sold on official and unofficial markets in Togo were purchased. In total fifty-two trypanocides were obtained, 24 of these samples from official markets and 28 from unofficial markets made up of a total of 36 diminazene diaceturate and 16 isometamidium chloride hydrochloride samples. The samples were analysed in the reference laboratory of the OIE (World Organisation for Animal Health), Laboratory for the Control of Veterinary Medicines (LACOMEV) in Dakar which uses galenic testing and high performance liquid chromatography (HPLC) testing as standard reference analysis methods. The results revealed a high proportion of trypanocides of sub-standard quality on the Togolese market: 40% were non-compliant to these quality reference standards. All of the HPLC non-compliant samples contained lower amounts of active ingredient compared to the concentration specified on the packaging. Non-compliance was higher in samples from the unofficial (53.57%) than from the official markets (25%; p=0.04).The main drug manufacturers, mostly of French origin in the study area, supply quality drugs through the official legal distribution circuit. Products of other origins mostly found on illegal markets present a significantly lower quality.

Diminazene enhances stability of atherosclerotic plaques in ApoE-deficient mice

Angiotensin (Ang) II contributes to the development of atherosclerosis, while Ang-(1-7) has atheroprotective actions. Accordingly, angiotensin-converting enzyme 2 (ACE2), which breaks-down Ang II and forms Ang-(1-7), has been suggested as a target against atherosclerosis. Here we investigated the actions of diminazene, a recently developed ACE2 activator compound, in a model of vulnerable atherosclerotic plaque. Atherosclerotic plaque formation was induced in the carotid artery of ApoE-deficient mice by a shear stress (SS) modifier device. The animals were treated with diminazene (15mg/kg/day) or vehicle. ACE2 was strongly expressed in the aortic root and low SS-induced carotid plaques, but poorly expressed in the oscillatory SS-induced carotid plaques. Diminazene treatment did not change the lesion size, but ameliorated the composition of aortic root and low SS-induced carotid plaques by increasing collagen content and decreasing both MMP-9 expression and macrophage infiltration. Interestingly, these beneficial effects were not observed in the oscillatory SS-induced plaque. Additionally, diminazene treatment decreased intraplaque ICAM-1 and VCAM-1 expression, circulating cytokine and chemokine levels and serum triglycerides. In summary, ACE2 was distinctively expressed in atherosclerotic plaques, which depends on the local pattern of shear stress. Moreover, diminazene treatment enhances the stability of atherosclerotic plaques.

PCR and microsatellite analysis of diminazene aceturate resistance of bovine trypanosomes correlated to knowledge, attitude and practice of livestock keepers in South-Western Ethiopia

African Animal Trypanosomosis is threatening the agricultural production and cattle breeding more severely than any other livestock disease in the continent, even more since the advent of drug resistance. A longitudinal study was conducted from November 2012 to May 2013 in the Ghibe valley to evaluate diminazene aceturate (DA) resistance and assess livestock owner's perception of trypanocidal drug use. Four Peasant Associations (PAs) were purposively selected and the cattle randomly sampled in each PAs. At the beginning of the study (t0), 106 bovines positive for trypanosomes by the haematocrit centrifugation technique (HCT) and 119 negative control animals were recruited for six months follow-up using HCT, 18S-PCR-RFLP, DpnII-PCR-RFLP and microsatellite analysis. Prevalence of trypanosomosis was 18.1% based on the HCT technique and the mean PCV value was 23.6±5.1% for the 587 sampled cattle. Out of the 106 HCT positive, 64 (60.4%) were positive for the presence of trypanosomes using the 18S-PCR-RFLP. Species detection showed 38 (59.4%) Trypanosoma congolense savannah, 18 (28.1%) Trypanosoma vivax, 5 (7.8%) Trypanosoma theileri and 3 (4.7%) T. congolense Kilifi. Among the T. congolense savannah samples, 31 (81.6%) showed a DA resistant RFLP profile, 2 (5.3%) a mixed profile and 5 did not amplify using the DpnII-PCR-RFLP. A positive HCT had a significant effect on PCV (p<0.001) with the mean PCV value equal to 24.4±0.2% in the absence of trypanosomes and to 20.9±0.3% in the presence of trypanosomes. PCV increased significantly (p<0.001) with 4.4±0.5% one month after treatment. All T. congolense savannah type were analyzed using microsatellite markers TCM1, TCM3 and TCM4. The main events were new infections (40.0%) and relapses (37.5%) with cures lagging at 22.5%. In 10 purposively selected PAs a semi-structured questionnaire was used. The average herd size was the highest in Abelti PA (6.7±1.8 TLU) and the mean herd size was statistically different (p=0.01) in the 10 PAs. Trypanosomosis was designated as the main disease affecting cattle by 97% of the respondents. DA was used by 95.5% of the farmers though more than half of them (51.9%) were not familiar with isometamidium (ISM). There was a trend to overdose young small animals and to underdose large ones. Oxen were treated very frequently (nearly 20 times/year) and calves almost never. To improve the situation in the Ghibe valley, extension messages should be delivered to promote a rational drug use, improved livestock management and the application of strategic vector control methods.