Secondary sex traits (SSTs) can favour males in intra-sexual competition, allowing females to reliably assess their quality. They can also be connected to other aspects of fitness, such as resistance to parasites and pathogens, as parasites have negative effects on the development of SSTs. Antlers are one of the most recognizable examples of SSTs whose development is regulated by testosterone and reflects the actual condition of the bearer. Elevated testosterone can exaggerate the size of SSTs while impairing the function of the immune system ("The Immunocompetence Handicap Hypothesis") posing a trade-off between antler development and immune function. In this study, we experimentally manipulated the parasite load in captive red deer (Cervus elaphus) males with Ivermectin during antler development for two consecutive years. Expecting an inverse proportionality between parasite load and antler size, we hypothesized the treated deer to have larger antlers than the untreated ones. Our results showed that, following the immunocompetence handicap hypothesis, parasite load was positively associated with testosterone levels. However, the application of Ivermectin suppressed the parasite load of the treated animals but did not lead to the development of larger antlers. Instead, it significantly suppressed the concentration of testosterone in the treated animals, whilst the animals that had higher testosterone also had the highest parasite load. Our findings show that Ivermectin can potentially decrease the levels of testosterone and, consequently, antler size. These findings have important implications for the management of captive populations, especially in contexts where the development of large trophies is desired.

• Klíčová slova
• Antlers, Immunocompetence handicap, Male ornaments, Parasite load, Red deer, Testosterone,
• MeSH
• ivermektin farmakologie   MeSH
• parazitární zátěž veterinární   MeSH
• parohy * MeSH
• testosteron farmakologie   MeSH
• vysoká zvěř * MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ivermektin MeSH
• testosteron MeSH

In recent years interest has grown in the occurrence and the effects of pharmaceuticals in the environment. The aim of this work is to evaluate the risk of fertilizing crops with manure from livestock treated with anthelmintics. The present study was designed to follow the fate of the commonly used anthelmintic drug, ivermectin (IVM) and its metabolites in soybeans (Glycine max (L.) Merr.), a plant that is grown and consumed world-wide for its high content of nutritional and health-beneficial substances. In vitro plantlets and soybean plants, cultivated in a greenhouse, were used for this purpose. Our results showed the uptake of IVM and its translocation to the leaves, but not in the pods and the beans. Four IVM metabolites were detected in the roots, and one in the leaves. IVM exposure decreased slightly the number and weight of the beans and induced changes in the activities of antioxidant enzymes. In addition, the presence of IVM affected the proportion of individual isoflavones and reduced the content of isoflavones aglycones, which might decrease the therapeutic value of soybeans. Fertilization of soybean fields with manure from IVM-treated animals appears to be safe for humans, due to the absence of IVM in beans, the food part of plants. On the other hand, it could negatively affect soybean plants and herbivorous invertebrates.

• Klíčová slova
• anthelmintics, antioxidant enzymes, biotransformation, drug metabolites, isoflavonoids,
• MeSH
• antioxidancia metabolismus   MeSH
• antiparazitární látky farmakologie   MeSH
• biologický transport MeSH
• Glycine max účinky léků   růst a vývoj   metabolismus   MeSH
• isoflavony metabolismus   MeSH
• ivermektin farmakologie   MeSH
• kořeny rostlin účinky léků   růst a vývoj   metabolismus   MeSH
• listy rostlin účinky léků   růst a vývoj   metabolismus   MeSH
• semena rostlinná účinky léků   růst a vývoj   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antioxidancia MeSH
• antiparazitární látky MeSH
• isoflavony MeSH
• ivermektin MeSH

Haemonchus contortus, one of the most pathogenic of all small ruminant parasites, have developed resistance to all used anthelmintics. Detoxification enzymes, e.g. cytochromes P450 (CYPs) and efflux transporters P-glycoproteins (P-gps), which represent the main defense system against harmful xenobiotics, have been suggested to contribute to drug resistance development. The present study was designed to compare the constitutive expression of individual CYPs and P-gps in females and males of H. contortus adults and to follow up on the changes in expression of these genes in nematodes exposed to sub-lethal concentrations of ivermectin (IVM), which might occur during inaccurate treatment. The adults of inbred susceptible-Edinburgh strain (ISE, MHco3) of H. contortus were used for this purpose. The nematodes were incubated ex vivo with or without IVM (1, 10 and 100 nM) in culture medium for 4, 12 and 24 h. After incubation, total RNA was isolated and expression levels of individual CYPs and P-gps were analyzed using qPCR. Our results showed a great variability in the constitutive expression of individual CYPs and P-gps in H. contortus adults. The constitutive expression as well as the inducibility of CYPs and P-gps significantly differed in males and females. Contact of adult nematodes with sub-lethal IVM concentrations led to only minor changes in expression of CYPs, while expression of several P-gps, particularly pgp-9.2 in males and pgp-10, pgp-11 in females was increased significantly in IVM-exposed nematodes. In conclusion, inaccurate treatment of sheep with IVM might contribute to drug resistance development via increased expression of efflux transporters in H. contortus adults.

• Klíčová slova
• Anthelmintics, Drug resistance, Macrocyclic lactones, Nematode, Sex-differences,
• MeSH
• Haemonchus účinky léků   genetika   MeSH
• ivermektin farmakologie   MeSH
• léková rezistence genetika   MeSH
• P-glykoproteiny genetika   MeSH
• regulace genové exprese účinky léků   MeSH
• systém (enzymů) cytochromů P-450 genetika   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ivermektin MeSH
• P-glykoproteiny MeSH
• systém (enzymů) cytochromů P-450 MeSH

Allosteric modulators of ligand-gated receptor channels induce conformational changes of the entire protein that alter potencies and efficacies for orthosteric ligands, expressed as the half maximal effective concentration (EC50) and maximum current amplitude, respectively. Here, we studied the influence of allostery on channel pore dilation, an issue not previously addressed. Experiments were done using the rat P2X4 receptor expressed in human embryonic kidney 293T cells and gated by adenosine 5'-triphosphate (ATP) in the presence and absence of ivermectin (IVM), an established positive allosteric regulator of this channel. In the absence of IVM, this channel activates and deactivates rapidly, does not show transition from open to dilated states, desensitizes completely with a moderate rate, and recovers only fractionally during washout. IVM treatment increases the efficacy of ATP to activate the channel and slows receptor desensitization during sustained ATP application and receptor deactivation after ATP washout. The rescue of the receptor from desensitization temporally coincides with pore dilation, and the dilated channel can be reactivated after washout of ATP. Experiments with vestibular and transmembrane domain receptor mutants further established that IVM has distinct effects on opening and dilation of the channel pore, the first accounting for increased peak current amplitude and the latter correlating with changes in the EC50 and kinetics of receptor deactivation. The corresponding kinetic (Markov state) model indicates that the IVM-dependent transition from open to dilated state is coupled to receptor sensitization, which rescues the receptor from desensitization and subsequent internalization. Allosterically induced sensitization of P2X4R thus provides sustained signaling during prolonged and repetitive ATP stimulation.

• MeSH
• alosterická regulace MeSH
• gating iontového kanálu * MeSH
• HEK293 buňky MeSH
• ivermektin chemie   farmakologie   MeSH
• kinetika MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• purinergní receptory P2X4 chemie   genetika   metabolismus   MeSH
• terciární struktura proteinů MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Intramural MeSH
• Názvy látek
• ivermektin MeSH
• purinergní receptory P2X4 MeSH

Crystallization of the zebrafish P2X4 receptor in both open and closed states revealed conformational differences in the ectodomain structures, including the dorsal fin and left flipper domains. Here, we focused on the role of these domains in receptor activation, responsiveness to orthosteric ATP analogue agonists, and desensitization. Alanine scanning mutagenesis of the R203-L214 (dorsal fin) and the D280-N293 (left flipper) sequences of the rat P2X4 receptor showed that ATP potency/efficacy was reduced in 15 out of 26 alanine mutants. The R203A, N204A, and N293A mutants were essentially non-functional, but receptor function was restored by ivermectin, an allosteric modulator. The I205A, T210A, L214A, P290A, G291A, and Y292A mutants exhibited significant changes in the responsiveness to orthosteric analog agonists 2-(methylthio)adenosine 5'-triphosphate, adenosine 5'-(γ-thio)triphosphate, 2'(3'-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate, and α,β-methyleneadenosine 5'-triphosphate. In contrast, the responsiveness of L206A, N208A, D280A, T281A, R282A, and H286A mutants to analog agonists was comparable to that of the wild type receptor. Among these mutants, D280A, T281A, R282A, H286A, G291A, and Y292A also exhibited increased time-constant of the desensitizing current response. These experiments, together with homology modeling, indicate that residues located in the upper part of the dorsal fin and left flipper domains, relative to distance from the channel pore, contribute to the organization of the ATP binding pocket and to the initiation of signal transmission towards residues in the lower part of both domains. The R203 and N204 residues, deeply buried in the protein, may integrate the output signal from these two domains towards the gate. In addition, the left flipper residues predominantly account for the control of transition of channels from an open to a desensitized state.

• MeSH
• adenosintrifosfát metabolismus   MeSH
• alanin genetika   metabolismus   MeSH
• gating iontového kanálu účinky léků   MeSH
• HEK293 buňky MeSH
• ivermektin farmakologie   MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• metoda terčíkového zámku MeSH
• molekulární sekvence - údaje MeSH
• mutageneze MeSH
• purinergní receptory P2X - agonisté farmakologie   MeSH
• purinergní receptory P2X4 chemie   genetika   metabolismus   MeSH
• sekvence aminokyselin MeSH
• sekvenční seřazení MeSH
• simulace molekulární dynamiky MeSH
• terciární struktura proteinů MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adenosintrifosfát MeSH
• alanin MeSH
• ivermektin MeSH
• purinergní receptory P2X - agonisté MeSH
• purinergní receptory P2X4 MeSH

The binding of ATP to trimeric P2X receptors (P2XR) causes an enlargement of the receptor extracellular vestibule, leading to opening of the cation-selective transmembrane pore, but specific roles of vestibule amino acid residues in receptor activation have not been evaluated systematically. In this study, alanine or cysteine scanning mutagenesis of V47-V61 and F324-N338 sequences of rat P2X4R revealed that V49, Y54, Q55, F324, and G325 mutants were poorly responsive to ATP and trafficking was only affected by the V49 mutation. The Y54F and Y54W mutations, but not the Y54L mutation, rescued receptor function, suggesting that an aromatic residue is important at this position. Furthermore, the Y54A and Y54C receptor function was partially rescued by ivermectin, a positive allosteric modulator of P2X4R, suggesting a rightward shift in the potency of ATP to activate P2X4R. The Q55T, Q55N, Q55E, and Q55K mutations resulted in non-responsive receptors and only the Q55E mutant was ivermectin-sensitive. The F324L, F324Y, and F324W mutations also rescued receptor function partially or completely, ivermectin action on channel gating was preserved in all mutants, and changes in ATP responsiveness correlated with the hydrophobicity and side chain volume of the substituent. The G325P mutant had a normal response to ATP, suggesting that G325 is a flexible hinge. A topological analysis revealed that the G325 and F324 residues disrupt a β-sheet upon ATP binding. These results indicate multiple roles of the extracellular vestibule amino acid residues in the P2X4R function: the V49 residue is important for receptor trafficking to plasma membrane, the Y54 and Q55 residues play a critical role in channel gating and the F324 and G325 residues are critical for vestibule widening.

• MeSH
• adenosintrifosfát chemie   metabolismus   MeSH
• alosterická regulace MeSH
• aminokyseliny chemie   genetika   metabolismus   MeSH
• bodová mutace MeSH
• gating iontového kanálu účinky léků   fyziologie   MeSH
• HEK293 buňky MeSH
• hydrofobní a hydrofilní interakce MeSH
• ivermektin chemie   farmakologie   MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• metoda terčíkového zámku MeSH
• molekulární modely MeSH
• mutageneze cílená MeSH
• purinergní receptory P2X4 chemie   genetika   metabolismus   MeSH
• sekundární struktura proteinů MeSH
• transfekce MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Intramural MeSH
• Názvy látek
• adenosintrifosfát MeSH
• aminokyseliny MeSH
• ivermektin MeSH
• purinergní receptory P2X4 MeSH

The effect of four avermectins on the population growth of pest mite Lepidoglyphus destructor was tested in laboratory experiments. The avermectins (abamectin, doramectin, emamectin-benzoate and ivermectin) of analytical purity were incorporated into an experimental diet at the same molar concentrations, ranging from 0.16 to 8 nmol/3 g of diet. Using an initial population of 50 mites, the population growth was recorded after 21 days at 85 % relative humidity and 25 °C; 12 repeats were performed per avermectin concentration and control. The diets containing the avermectins successfully suppressed the population growth of L. destructor. The EC(50) recalculated to ng of substance per g of diet showed different suppressive effects of the avermectins: doramectin (181 ng/g diet), abamectin (299 ng/g diet), emamectin-benzoate (812 ng/g diet) and ivermectin (992 ng/g diet). Of the tested avermectins, abamectin is registered for the control of phytophagous mites and ivermectin against parasitic mites, i.e., Psoroptes ovis. Although emamectin-benzoate and ivermectin were less effective on L. destructor, all of the tested avermectins are highly suitable compounds for the control of synanthropic mites.

• MeSH
• akaricidy aplikace a dávkování   farmakologie   MeSH
• ivermektin analogy a deriváty   farmakologie   MeSH
• rozmnožování účinky léků   MeSH
• roztoči účinky léků   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• akaricidy MeSH
• avermectin MeSH Prohlížeč
• ivermektin MeSH

Purinergic P2X receptors represent a novel structural type of ligand-gated ion channels activated by extracellular ATP. So far, seven P2X receptor subunits have been found in excitable as well as non-excitable tissues. Little is known about their structure, mechanism of channel opening, localization, and role in the central nervous system. The aim of this work is to summarize recent investigations and describe our contribution to elucidating the structure of the ATP binding site and transmembrane domains of the P2X receptor, we also discuss the expression and physiological roles played by the ATP and P2X receptors in the anterior pituitary and hypothalamus.

• MeSH
• adenosintrifosfát metabolismus   MeSH
• gonadotropní buňky metabolismus   MeSH
• hypofýza metabolismus   MeSH
• hypothalamus metabolismus   MeSH
• ivermektin chemie   farmakologie   MeSH
• kvarterní struktura proteinů MeSH
• lidé MeSH
• molekulární modely MeSH
• neuroglie metabolismus   MeSH
• neurony metabolismus   MeSH
• purinergní receptory P2 chemie   účinky léků   metabolismus   MeSH
• sekundární struktura proteinů MeSH
• terciární struktura proteinů MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• adenosintrifosfát MeSH
• ivermektin MeSH
• purinergní receptory P2 MeSH

Ivermectin (IVM) applied extracellularly increases the sensitivity of P2X4 receptor (P2X4R) to ATP, enhances the maximum current amplitudes, and greatly prolongs the deactivation kinetics. In this manuscript, we focused on identification of receptor-specific residues responsible for IVM effects on channel gating using the wild-type rat homomeric P2X4R, several chimeric P2X2/P2X4 receptors, and single-point P2X4R-specific mutants in the ectodomain and two transmembrane domains. Experiments with chimeric receptors revealed that the Val49-Val61 but not the Val64-Tyr315 ectodomain sequence is important for the effects of IVM on channel deactivation. Receptor-specific mutations placed in the Gly29-Val61 and Asp338-Leu358 regions showed the importance of Trp50, Val60, and Val357 residues in IVM regulation of the rate of channel deactivation, but not on the maximum current amplitude. These results suggest that the transmembrane domains and the nearby ectodomain region contribute to the effects of IVM on channel deactivation.

• MeSH
• adenosintrifosfát chemie   MeSH
• antiparazitární látky farmakologie   MeSH
• ivermektin chemie   farmakologie   MeSH
• krysa rodu Rattus MeSH
• lidé MeSH
• molekulární sekvence - údaje MeSH
• purinergní receptory P2 chemie   MeSH
• purinergní receptory P2X4 MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• tryptofan chemie   MeSH
• valin chemie   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Intramural MeSH
• Názvy látek
• adenosintrifosfát MeSH
• antiparazitární látky MeSH
• ivermektin MeSH
• P2RX4 protein, human MeSH Prohlížeč
• P2rx4 protein, rat MeSH Prohlížeč
• purinergní receptory P2 MeSH
• purinergní receptory P2X4 MeSH
• tryptofan MeSH
• valin MeSH

Ivermectin is an antiparasitic drug widely used in veterinary and human medicine. We have found earlier that repeated treatments of rats with high doses of this drug led to significant increase of cytochrome P450-dependent 7-methoxyresorufin O-demethylase (MROD) and 7-ethoxyresorufin O-deethylase (EROD) activities in hepatic microsomes. In the present study, the effects of ivermectin on cytochrome P450 (CYP) activities were investigated in mouflon (Ovis musimon) and fallow deer (Dama dama). This study was conducted also to point out general lack of information on both basal levels of CYP enzymes and their inducibilities by veterinary drugs in wild ruminants. Liver microsomes were prepared from control animals, mouflons, after single or repeated (six doses in six consecutive days) treatments with therapeutic doses of ivermectin (0.5 mg kg(-1) of body weight), and fallow deer exposed to repeated doses of ivermectin under the same conditions. Alkyloxyresorufins, testosterone and chlorzoxazone were used as the specific substrate probes of activities of the CYP isoenzymes. A single therapeutic dose of ivermectin significantly induced (300-400% of the control group) the activities of all alkyloxyresorufin dealkylases tested in mouflon liver microsomes. Repeated doses of ivermectin also caused an increase of these activities, but due to fair inter-individual differences, this increase was not significant. The administration of ivermectin led to an induction (170-210% of the control) of the testosterone 6beta- and 16alpha-hydroxylase activities in mouflon liver but no significant modulation of chlorzoxazone hydroxylase (CZXOH) activity was found in mouflon liver. CYP-dependent activities in hepatic microsomes were generally higher in fallow deer than in mouflons. However, with the exception of slight increase in the 7-benzyloxyresorufin O-dealkylase (BROD) activities, no significant modulation of the other activities was observed. The induction of CYP3A-like isoenzyme was confirmed by immunoblotting only in the microsomes from mouflons administered with repeated doses of ivermectin; however, no significant increase of CYP1A isoenzymes was observed due to a weak cross-reactivity of anti-rat CYP1A1/2 polyclonal antibodies used in the study. The results indicate that ivermectin should be considered as an inducer of several cytochrome P450 isoenzymes, including CYP1A, 2B and 3A subfamilies, in mouflons. The comparison of induction effect of ivermectin in rat, mouflon and fallow deer also demonstrates the inter-species differences in inducibility of CYP enzymes.

• MeSH
• anthelmintika aplikace a dávkování   farmakologie   MeSH
• aromatické hydroxylasy * MeSH
• cytochrom P450 CYP2C8 MeSH
• cytochrom P450 CYP2C9 MeSH
• enzymová indukce MeSH
• frakcionace buněk MeSH
• imunoblotting MeSH
• ivermektin aplikace a dávkování   farmakologie   MeSH
• izoenzymy metabolismus   MeSH
• jaterní mikrozomy účinky léků   enzymologie   MeSH
• lidé MeSH
• molekulární struktura MeSH
• přežvýkavci metabolismus   MeSH
• rodina 2 cytochromů P450 MeSH
• steroid-16-alfa-hydroxylasa MeSH
• steroidhydroxylasy metabolismus   MeSH
• systém (enzymů) cytochromů P-450 metabolismus   MeSH
• vysoká zvěř metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• anthelmintika MeSH
• aromatické hydroxylasy * MeSH
• CYP2C11 protein, rat MeSH Prohlížeč
• CYP2C8 protein, human MeSH Prohlížeč
• CYP2C9 protein, human MeSH Prohlížeč
• cytochrom P450 CYP2C8 MeSH
• cytochrom P450 CYP2C9 MeSH
• ivermektin MeSH
• izoenzymy MeSH
• rodina 2 cytochromů P450 MeSH
• steroid-16-alfa-hydroxylasa MeSH
• steroidhydroxylasy MeSH
• systém (enzymů) cytochromů P-450 MeSH
• testosterone 7-alpha-hydroxylase, hamster MeSH Prohlížeč