Polyamines modulate mouse sperm motility.

Polyamines are polycationic molecules which contains two or more amino groups (-NH3+) highly charged at physiological pH, and among them we found spermine, spermidine, putrescine, and cadaverine. They interact with proteins, nucleic acids, modulate Ca2+, K+, and Na+ channels, and protect sperm from oxidative stress. In this work, we evaluate the effect of spermine, spermidine, and putrescine on the total, progressive and kinematic parameters of motility, capacitation, acrosome reaction, also in presence and absence of the dbcAMP, an analogue of the cAMP, and the IBMX, a phosphodiesterase inhibitor. In addition, we evaluated the intracellular concentrations of cAMP [cAMP]i, and performed an in silico analysis between polyamines and the sAC from mouse to predict the possible interaction among them. Our results showed that all polyamines decrease drastically the total, progressive and the kinetic parameters of sperm motility, decrease the capacitation, and only spermidine and putrescine impeded the acquisition of acrosome reaction. Moreover, the effect of polyamines was attenuated but not countered by the addition of db-cAMP and IBMX, suggesting a possible inhibition of the sAC. Also, the presence of polyamines induced a decrease of the [cAMP]i, and the in silico analysis predicted a strong interaction among polyamines and the sAC. Overall, the evidence suggests that probably the polyamines interact and inhibit the activity of the sAC.

Multiple Factors Involved in Bone Damage Caused by Chikungunya Virus Infection.

Chronic cases of chikungunya fever represent a public health problem in countries where the virus circulates. The disease is prolonged, in some cases, for years, resulting in disabling pain and bone erosion among other bone and joint problems. As time progresses, tissue damage is persistent, although the virus has not been found in blood or joints. The pathogenesis of these conditions has not been fully explained. Additionally, it has been considered that there are multiple factors that might intervene in the viral pathogenesis of the different conditions that develop. Other mechanisms involved in osteoarthritic diseases of non-viral origin could help explain how damage is produced in chronic conditions. The aim of this review is to analyze the molecular and cellular factors that could be involved in the tissue damage generated by different infectious conditions of the chikungunya virus.

Inhibition of chikungunya virus replication by N-ω-Chloroacetyl-L-Ornithine in C6/36, Vero cells and human fibroblast BJ.

BACKGROUND: Polyamines are involved in several cellular processes and inhibiting their synthesis affects chikungunya virus (CHIKV) replication and translation, and, therefore, reduces the quantity of infectious viral particles produced. In this study, we evaluated the inhibition of CHIKV replication by N-ω-chloroacetyl-L-ornithine (NCAO), a competitive inhibitor of ornithine decarboxylase, an enzyme which is key in the biosynthesis of polyamines (PAs). METHODS: The cytotoxicity of NCAO was evaluated by MTT in cell culture. The inhibitory effect of CHIKV replication by NCAO was evaluated in Vero and C6/36 cells. The intracellular polyamines were quantified by HPLC in CHIKV-infected cells. We evaluated the yield of CHIKV in titres via the addition of PAs in Vero, C6/36 cells and human fibroblast BJ treated with NCAO. RESULTS: We found that NCAO inhibits the replication of CHIKV in Vero and C6/36 cells in a dose-dependent manner, causing a decrease in the PFU/mL of at least 4 logarithms (p < 0.01) in both cell lines. Viral yields were restored by the addition of exogenous polyamines, mainly putrescine. The HPLC analyses showed that NCAO decreases the content of intracellular PAs, even though it is predominantly spermidines and spermines which are present in infected cells. Inhibition of CHIKV replication was observed in human fibroblast BJ treated with 100 µM NCAO 24 h before and 48 h after the infection at a MOI 1. CONCLUSIONS: NCAO inhibits CHIKV replication by depleting the intracellular polyamines in Vero, C6/36 cells and human fibroblast BJ, suggesting that this compound is a possible antiviral agent for CHIKV.

The opposite effect of convulsant drugs on neuronal and endothelial nitric oxide synthase - A possible explanation for the dual proconvulsive/anticonvulsive action of nitric oxide.

Nitric oxide (NO) participates in processes such as endothelium-dependent vasodilation and neurotransmission/neuromodulation. The role of NO in epilepsy is controversial, attributing it to anticonvulsant but also proconvulsant properties. Clarification of this dual effect of NO might lead to the development of new antiepileptic drugs. Previous results in our laboratory indicated that this contradictory role of NO in seizures could depend on the nitric oxide synthase (NOS) isoform involved, which could play opposite roles in epileptogenesis, one of them being proconvulsant but the other anticonvulsant. The effect of convulsant drugs on neuronal NO (nNO) and endothelial NO (eNO) levels was investigated. Considering the distribution of neuronal and endothelial NOS in neurons and astrocytes, resp., primary cultures of neurons and astrocytes were used as a study model. The effects of convulsant drugs pentylenetetrazole, thiosemicarbazide, 4-aminopyridine and bicuculline on NO levels were studied, using a spectrophotometric method. Their effects on NO levels in neurons and astrocytes depend on the concentration and time of treatment. These convulsant drugs caused an increase in nNO, but a decrease in eNO was proportional to the duration of treatment in both cases. Apparently, nNO possesses convulsant properties mediated by its effect on the glutamatergic and GABAergic systems, probably through GABAA receptors. Anticonvulsant properties of eNO may be the consequence of its effect on endothelial vasodilation and its capability to induce angiogenesis. Described effects last as seizures do. Considering the limitations of these kinds of studies and the unexplored influence of inducible NO, further investigations are required.

In Combo Studies for the Optimization of 5-Aminoanthranilic Acid Derivatives as Potential Multitarget Drugs for the Management of Metabolic Syndrome.

Metabolic syndrome is a set of risk factors that consist of abdominal obesity, arterial hypertension, alterations in the lipid profile, and hyperglycemia. The current therapeutic strategy includes polypharmacy, using three or more drugs to control each syndrome component. However, this approach has drawbacks that could lead to therapeutic failure. Multitarget drugs are molecules with the ability to act on different targets simultaneously and are an attractive alternative for treating complex diseases such as metabolic syndrome. Previously, we identified a triamide derivative of 5-aminoanthranilic acid that exhibited hypoglycemic, hypolipemic, and antihypertensive activities simultaneously. In the present study, we report the synthesis and in combo evaluation of new derivatives of anthranilic acid, intending to identify the primary structural factors that improve the activity over metabolic syndrome-related parameters. We found that substitution on position 5, incorporation of 3,4-dimethoxyphenyl substituents, and having a free carboxylic acid group lead to the in vitro inhibition of HMG-CoA reductase, and simultaneously the diminution of the serum levels of glucose, triglycerides, and cholesterol in a diet-induced in vivo model.

Participation of signaling proteins in sperm hyperactivation.

Sperm hyperactivation is described as a fast whip movement of the flagellum, an irregular trajectory, and an asymmetrically flagellum bend. This motility pattern is achieved during the passage of the sperm along the female genital tract. It helps the spermatozoa to cross through different viscous ambient fluids to finally reach the oocyte. Important signaling proteins are located in the sperm head and flagellum, and they all play an important role in the cascade that controls the sperm hyperactivation. The presence of HCO3- modulates the activity of the soluble adenylyl cyclase (sAC), leading to the production of cAMP. In turn, cAMP modulates the sperm-specific Na+/H+ exchanger (sNHE) and the t-complex protein 11 (TCP11) which play an essential role on the signaling pathway (cAMP/PKA and tyrosine phosphorylation) and sperm hypermotility. sNHE, cystic fibrosis transmembrane conductance regulator (CFTR), and voltage-gated proton channel (Hv) mainly contribute to the regulation of the intracellular pH (pHi) during capacitation. HCO3- entrance and the removal of H+ from the cytoplasm induces the alkalization of pHi, and this change will contribute to the activation of the cation channel of sperm (CatSper). Recently, it was described the participation on sperm motility and the regulation of calcium channels of an autophagy-related protein, the microtubule-associated protein light chain 3 (LC3). This review gathers important literature about the essential roles of sAC, sNHE, CFTR, Hv, and CatSper in the acquisition of sperm hyperactivation, and provides an integrated overview of recently described roles of TCP11 and LC3 on the sperm signaling pathway. Additionally, we provide insight into the infertility induced by the dysfunction of these critical proteins.

Indole-3-Carbinol, a Phytochemical Aryl Hydrocarbon Receptor-Ligand, Induces the mRNA Overexpression of UBE2L3 and Cell Proliferation Arrest.

Cervical cancer (CC) is one of the most common cancers in women, and is linked to human papillomavirus (HPV) infection. The virus oncoprotein E6 binds to p53, resulting in its degradation and allowing uncontrolled cell proliferation. Meanwhile, the HPV E7 protein maintains host cell differentiation by targeting retinoblastoma tumor suppressor. The host cell can ubiquitinate E6 and E7 through UBE2L3, whose expression depends on the interaction between the aryl hydrocarbon receptor (AhR) with Xenobiotic Responsive Elements (XREs) located in the UBE2L3 gene promoter. In this study, we used cell culture to determine the effect of indole-3-carbinol (I3C) over cellular viability, apoptosis, cell proliferation, and mRNA levels of UBE2L3 and CYP1A1. In addition, patients' samples were used to determine the mRNA levels of UBE2L3 and CYP1A1 genes. We found that I3C promotes the activation of AhR and decreases cell proliferation, possibly through UBE2L3 mRNA induction, which would result in the ubiquitination of HPV E7. Since there is a strong requirement for selective and cost-effective cancer treatments, natural AhR ligands such as I3C could represent a novel strategy for cancer treatment.

Proteomic analysis of Plasmodium berghei in the ring phase during in vivo antiparasitic treatment with kramecyne.

Malaria is a parasitic disease of global importance due to its high annual death toll. The treatment for this infection is difficult for the increase in the populations of parasites resistant to the existing medicines, the development of new antimalarials is urgent needed. Several products developed for the control of malaria from herbalist have had a profound impact, for example, quinine obtained from the bark of the cinchona tree and recently those derived from artemisinin, whose discovery was the reason for the awarding of the 2015 Nobel Prize. The aim of the present study was to evaluate a compound named kramecyne extracted of "chayotillo" (Krameria cystisoides) plant used by the antiparasitic effect against some blood and intestinal protozoa (Giardia duodenalis y Trypanosoma cruzi). In addition is using for the treatment of inflammatory diseases. Measuring parasitaemia at different times, it was observed that in mice treated with kramecyne, it reached only 14% of parasitaemia at 7 days with a dose of 15 mg/kg, using chloroquine as a control drug, because it has not been demonstrated that parasites that infect rodents have developed resistance against this drug. Our results showed that kramecyne decreases the expression of parasite proteins that participate in biological processes, such as invasion, cytoadherence, pathogenicity and energy metabolism. With these results, it is proposed that this compound has repercussions on the metabolism of the parasite and could be useful for use as an antimalarial.

High Fructose and High Fat Diet Impair Different Types of Memory through Oxidative Stress in a Sex- and Hormone-Dependent Manner.

Metabolic syndrome (MetS) contributes to the spread of cardiovascular diseases, diabetes mellitus type 2, and neurodegenerative diseases. Evaluation of sex- and hormone-dependent changes in body weight, blood pressure, blood lipids, oxidative stress markers, and alterations in different types of memory in Sprague-Dawley rats fed with a high fat and high fructose (HFHF) diet were evaluated. After 12 weeks of feeding the male and female rats with HFHF, body weight gain, increase in blood pressure, and generation of dyslipidemia compared to the animals fed with chow diet were observed. Regarding memory, it was noted that gonadectomy reverted the effects of HFHF in the 24 h novel object recognition task and in spatial learning/memory analyzed through Morris water maze, males being more affected than females. Nevertheless, gonadectomy did not revert long-term memory impairment in the passive avoidance task induced by HFHF nor in male or female rats. On the other hand, sex-hormone-diet interaction was observed in the plasma concentration of malondialdehyde and nitric oxide. These results suggest that the changes observed in the memory and learning of MetS animals are sex- and hormone-dependent and correlate to an increase in oxidative stress.

Polyamines Influence Mouse Sperm Channels Activity.

Polyamines are ubiquitous polycationic compounds that are highly charged at physiological pH. While passing through the epididymis, sperm lose their capacity to synthesize the polyamines and, upon ejaculation, again come into contact with the polyamines contained in the seminal fluid, unleashing physiological events that improve sperm motility and capacitation. In the present work, we hypothesize about the influence of polyamines, namely, spermine, spermidine, and putrescine, on the activity of sperm channels, evaluating the intracellular concentrations of chloride [Cl-]i, calcium [Ca2+]i, sodium [Na+]i, potassium [K+]i, the membrane Vm, and pHi. The aim of this is to identify the possible regulatory mechanisms mediated by the polyamines on sperm-specific channels under capacitation and non-capacitation conditions. The results showed that the presence of polyamines did not directly influence the activity of calcium and chloride channels. However, the results suggested an interaction of polyamines with sodium and potassium channels, which may contribute to the membrane Vm during capacitation. In addition, alkalization of the pHi revealed the possible activation of sperm-specific Na+/H+ exchangers (NHEs) by the increased levels of cyclic AMP (cAMP), which were produced by soluble adenylate cyclase (sAC) and interact with the polyamines, evidence that is supported by in silico analysis.

Influence of Echeveria gibbiflora DC aqueous crude extract on mouse sperm energy metabolism and calcium-dependent channels.

ETHNOPHARMACOLOGY RELEVANCE: In traditional Mexican medicine, Echeveria gibbiflora DC has been used as a vaginal post-coital rinse to prevent pregnancy. The aqueous crude extract (OBACE) induces sperm immobilization/agglutination and a hypotonic-like effect, likely attributed to the high concentration of calcium bis-(hydrogen-1-malate) hexahydrate [Ca2+ (C4H5O5)2•6H2O]. Likewise, OBACE impedes the increase of [Ca2+]i during capacitation. AIM OF THE STUDY: Evaluate the effect of OBACE on sperm energy metabolism and the underlying mechanism of action on sperm-specific channel. MATERIAL AND METHODS: In vitro, we quantified the mouse sperm immobilization effect and the antifertility potential of OBACE. The energetic metabolism status was also evaluated by assessing the ATP levels, general mitochondrial activity, mitochondrial membrane potential, and enzymatic activity of three key enzymes of energy metabolism. Furthermore, the effect of the ion efflux of Cl- and K+, as well as the pHi, were investigated in order to elucidate which channel is suitable to perform an in silico study. RESULTS: Total and progressive motility notably decreased, as did fertility rates. ATP levels, mitochondrial activity and membrane potential were reduced. Furthermore, the activities of the three enzymes decreased. Neither Cl- or K+ channels activities were affected at low concentrations of OBACE; nevertheless, pHi did not alkalinize. Finally, an in silico analysis was performed between the Catsper channel and calcium bis-(hydrogen-1-malate) hexahydrate, which showed a possible blockade of this sperm cation channel. CONCLUSION: The results were useful to elucidate the effect of OBACE and to propose it as a future male contraceptive.

Structure-Based Virtual Screening and In Vitro Evaluation of New Trypanosoma cruzi Cruzain Inhibitors.

Chagas disease (CD), or American trypanosomiasis, causes more than 10,000 deaths per year in the Americas. Current medical therapy for CD has low efficacy in the chronic phase of the disease and serious adverse effects; therefore, it is necessary to search for new pharmacological treatments. In this work, the ZINC15 database was filtered using the N-acylhydrazone moiety and a subsequent structure-based virtual screening was performed using the cruzain enzyme of Trypanosoma cruzi to predict new potential cruzain inhibitors. After a rational selection process, four compounds, Z2 (ZINC9873043), Z3 (ZINC9870651), Z5 (ZINC9715287), and Z6 (ZINC9861447), were chosen to evaluate their in vitro trypanocidal activity and enzyme inhibition. Compound Z5 showed the best trypanocidal activity against epimatigote (IC50 = 36.26 ± 9.9 µM) and trypomastigote (IC50 = 166.21 ± 14.5 µM and 185.1 ± 8.5 µM on NINOA and INC-5 strains, respectively) forms of Trypanosoma cruzi. In addition, Z5 showed a better inhibitory effect on Trypanosoma cruzi proteases than S1 (STK552090, 8-chloro-N-(3-morpholinopropyl)-5H-pyrimido[5,4-b]-indol-4-amine), a known cruzain inhibitor. This study encourages the use of computational tools for the rational search for trypanocidal drugs.

In vitro fermentation of oligosaccharides obtained from enzymatic hydrolysis of Opuntia streptacantha mucilage.

BACKGROUND: Among Cactaceae, the genus Opuntia is widely known for the use of its biomass as cattle fodder and in human nutrition (e.g. species such as Opuntia ficus indica and Opuntia streptacantha). In particular, O. streptacantha (OS) produces abundant mucilage and, hence, the characterization of its properties and nutritional value is important. Accordingly, determination of the dietary fiber content of the OS mucilage and the fermentability of its hydrolysis products (oligosaccharides, OLI) is important for developing new uses of the crop as a functional food. RESULTS: The values for insoluble dietary fiber and soluble dietary fiber in the mucilage were 204.6 and 371.6 g kg-1 , respectively. After hydrolysis of OS mucilage with α-amylase, three purified fractions of OLI were evaluated (OLI-A, OLI-B and OLI-C). OLI (1% w/v) stimulated the growth of the commercial probiotic strains (Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium animalis subsp. lactis) in vitro, showing behaviors similar to those of commercial inulin. The production of short chain fatty acids (SCFAs) in the fermentation broth was also determined. The final pH of the fermentation broth as well as the identification and concentrations of SCFA depended on the type of OLI and probiotic used. CONCLUSION: The OS mucilage is an unconventional fiber source and can be used to produce non-digestible OLI as functional compounds. This knowledge will be useful for proposing new sustainable ways of processing cacti crops for food and industrial purposes. © 2018 Society of Chemical Industry.

TMEM16A inhibition impedes capacitation and acquisition of hyperactivated motility in guinea pig sperm.

Ca2+ -activated Cl- channels (CaCCs) are anionic channels that regulate many important physiological functions associated with chloride and calcium flux in some somatic cells. The molecular identity of CaCCs was revealed to be TMEM16A and TMEM16B (also known as Anoctamin or ANO1 and ANO2, respectively) in all eukaryotes. A recent study suggests the presence of TMEM16A in human sperm and a relationship with the rhZP-induced acrosome reaction. However, to the best of our knowledge, little is known about the role of TMEM16A in other spermatic processes such as capacitation or motility. In this study, we evaluated the effects of two TMEM16A antagonists on capacitation, acrosome reaction, and motility in guinea pig sperm; these antagonists were T16Ainh-A01, belonging to a second generation of potent antagonists of TMEM16A, and niflumic acid (NFA), a well-known antagonist of TMEM16A (CaCCs). First of all, we confirmed that the absence of Cl- in the capacitation medium changes motility parameters, capacitation, and the progesterone-induced acrosome reaction. Using a specific antibody, TMEM16A was found as a protein band of ∼120 kDa, which localization was in the apical crest of the acrosome and the middle piece of the flagellum. Inhibition of TMEM16A by T16Ainh-A01 affected sperm physiology by reducing capacitation, blocking the progesterone-induced acrosome reaction under optimal capacitation conditions, inhibiting progressive motility, and the acquisition of hyperactivated motility, diminishing [Ca2+ ]i, and increasing [Cl- ]i. These changes in sperm kinematic parameters provide new evidence of the important role played by TMEM16A in the production of sperm capable of fertilizing oocytes.

Effects of aqueous crude extract of Echeveria gibbiflora on mouse sperm function.

UNLABELLED: The present study evaluates the possible antifertility effect of aqueous crude extract (OBACE) of Echeveria gibbiflora, a plant that belongs to the crassulaceae family, used in traditional Mexican medicine as a vaginal post coital rinse to prevent pregnancy and shown to have an immobilization/agglutination effect on sperm of different mammal species. We evaluated the effect of OBACE on functional parameters of mouse sperm, such as viability, capacitation, and acrosome reaction. In addition, due to the high concentrations of calcium bis-(hydrogen-1-malate) hexahydrate [Ca (C4H5O5)2•6H2O] present in this plant extract, we evaluated its effect on Ca(2+) influx in mouse sperm under capacitating conditions. Moreover, we determined the acute toxicity of OBACE and its in vivo effect in mouse sperm motility administering a single daily dose of 50 and 100 mg/kg during seven days, intraperitoneally. The sperm viability was not affected by the presence of different concentrations of OBACE, however, the capacitation and acrosome reaction suffered a significant decrease in a concentration-dependent manner, coinciding with the reduction of Ca(2+) influx. Furthermore, OBACE displayed an LD50 of 3,784.42 mg/kg and can be classified as a low toxic substance. Also, in vivo OBACE showed an inhibition of total and progressive motility on mouse sperm alongside a significant decrease of motility kinematic parameters and IVF rates. The results confirm the antifertility effect of this plant used in Mexican folk medicine. Further study on OBACE as a possible contraceptive treatment is warranted because of its activity and low in vivo toxicity. ABBREVIATIONS: ALH: lateral amplitude; AP: acid phosphatase; BCF: beat frequency; BSA: bovine serum albumine; CTC: chlortetracycline; FDA: fluorescein diacetate; Fura-2 AM: fura-2-acetoxymethyl ester; HIV: human immunodeficiency virus; IVF: in vitro fertilization; OBACE: aqueous crude extract of Echeveria gibbiflora; PI: propidum iodide; SN: supernatant; VAP: average path velocity; VCL: track speed; VSL: straight line velocity.

N-ω-chloroacetyl-L-ornithine has in-vitro activity against cancer cell lines and in-vivo activity against ascitic and solid tumors.

N-ω-chloroacetyl-L-ornithine (NCAO) is an ornithine decarboxylase (ODC) inhibitor that is known to exert cytotoxic and antiproliferative effects on three neoplastic human cancer cell lines (HeLa, MCF-7, and HepG2). Here, we show that NCAO has antiproliferative activity in 13 cancer cell lines, of diverse tissue origin from human and mice, and in a mouse cancer model in vivo. All cell lines were sensitive to NCAO after 72 h of treatment (the EC50 ranged from 1 to 50.6 µmol/l). The Ca Ski cell line was the most sensitive (EC50=1.18±0.07 µmol/l) and MDA-MB-231 was the least sensitive (EC50=50.6±0.3 µmol/l). This ODC inhibitor showed selectivity for cancer cells, exerting almost no cytotoxic effect on the normal Vero cell line (EC50>1000 µmol/l). NCAO induced apoptosis and inhibited tumor cell migration in vitro. Furthermore, in vivo, this compound (at 50 and 100 mg/kg, daily intraperitoneal injection for 7 days) exerted potent antitumor activity against both solid and ascitic tumors in a mouse model using the myeloma (Ag8) cell line. At these same two doses, the toxicological evaluation showed that NCAO has no obvious systemic toxicity. The current results suggest that the antitumor activity is exerted by apoptosis related not only to a local but also a systemic cytotoxic effect exerted by NCAO on tumor cells. The applications for NCAO as an antitumor agent may be extensive; however, further studies are needed to ascertain the antitumor activity on other types of tumor in vivo and to determine the precise molecular mechanism of its activity.

N-ω-chloroacetyl-l-ornithine, a new competitive inhibitor of ornithine decarboxylase, induces selective growth inhibition and cytotoxicity on human cancer cells versus normal cells.

Many cancer cells have high expression of ornithine decarboxylase (ODC) and there is a concerted effort to seek new inhibitors of this enzyme. The aim of the study was to initially characterize the inhibition properties, then to evaluate the cytotoxicity/antiproliferative cell based activity of N-ω-chloroacetyl-l-ornithine (NCAO) on three human cancer cell lines. Results showed NCAO to be a reversible competitive ODC inhibitor (Ki = 59 µM) with cytotoxic and antiproliferative effects, which were concentration- and time-dependent. The EC50,72h of NCAO was 15.8, 17.5 and 10.1 µM for HeLa, MCF-7 and HepG2 cells, respectively. NCAO at 500 µM completely inhibited growth of all cancer cells at 48 h treatment, with almost no effect on normal cells. Putrescine reversed NCAO effects on MCF-7 and HeLa cells, indicating that this antiproliferative activity is due to ODC inhibition.

Sub-chronic copper pretreatment reduces oxidative damage in an experimental Huntington's disease model.

Quinolinic acid (QUIN) striatal injection in rat reproduces the main neurochemical features of Huntington's disease (HD), including oxidative damage. In this study, we evaluated the effect of a copper (Cu) supplement in drinking water (90 ppm Cu, 28 days) on the QUIN-induced HD model in the rat. Copper exposure caused no signs of liver toxicity; however, it produced significant Cu accumulation in striatum. It is noteworthy that QUIN also caused increased striatal Cu content; when the supplement was administered to animals with QUIN-injury, an even higher metal striatal accumulation was observed. Cu pre-treatment preserved striatal gamma-aminobutyric acid (GABA) content, which was reduced by QUIN intrastriatal injection. Similarly, apomorphine-induced circling behavior was reduced in Cu-pretreated QUIN-damaged rats. Metal supplement in drinking water prevented both lipid peroxidation and reactive oxygen species (ROS) formation caused by QUIN in striatum. In Cu-treated groups, superoxide dismutase-1 (SOD1) activity showed a significant increase, while SOD2 activity was slightly enhanced. Although the pathophysiological role for higher Cu levels in patients with HD and in experimental models of the disease is not fully understood, results in the present study suggest that Cu oral intake stimulates anti-oxidant defenses, an effect that may be a potential factor for reducing the progression of HD.

Effect of oxamic analogues on functional mice sperm parameters.

The present study evaluates the effect of oxamate derivatives (N-ethyl, N-propyl, N-butyl oxamates) on functional murine sperm parameters, towards a new male non-hormonal contraceptive. These derivatives are selective inhibitors of lactate dehydrogenase-C4 (LDH-C4). LDH-C4 is a sperm-specific enzyme that plays an important role in ATP production for maintaining progressive motility as well as to induce capacitation and hyperactivation. The results demonstrate that all oxamate derivatives selectively inhibited LDH-C4 in mouse sperm extracts. The IC(50) values for hexokinase and glyceraldehyde-3-phosphate dehydrogenase were at least an order of magnitude greater than LDH-C4 IC(50) values. Prodrugs of oxamate derivatives assayed on sperm cells diminished normal sperm motility parameters, acrosome reaction, and cell viability in a concentration dependent manner. Also, we performed in vivo studies to determine the potential toxicity and possible contraceptive ability of these inhibitors. Mouse sperm were more sensitive to the N-butyl oxamate ethyl ester (NBOXet). Furthermore, results showed that NBOXet was of a low toxicity substance that diminished the total and progressive motility as well as the kinematic parameters of sperm cells. Data from in vitro and in vivo studies showed that N-butyl oxamate and its prodrug, are selective inhibitors of sperm LDH-C4, has low toxicity, and inhibits sperm progressive motility, offering some of the desirable characteristics of a male contraceptive: effect, low toxicity, and selectivity.

Oxamic acid analogues as LDH-C4-specific competitive inhibitors.

We performed kinetic studies to determine whether oxamate analogues are selective inhibitors of LDH-C4, owing to their potential usefulness in fertility control and treatment of some cancers. These substances were shown to be competitive inhibitors of LDH isozymes and are able to discriminate among subtle differences that differentiate the active sites of LDH-A4, LDH-B4 and LDH-C4. N-Ethyl oxamate was the most potent inhibitor showing the highest affinity for LDH-C4. However, N-propyl oxamate was the most selective inhibitor showing a high degree of selectivity towards LDH-C4. Non-polar four carbon atoms chains, linear or branched, dramatically diminished the affinity and selectivity towards LDH-C4. N-Propyl oxamate significantly reduced ATP levels, capacitation and mouse sperm motility, in line with results shown by others, suggesting that LDH-C4 plays an essential role in mouse fertility.