Saša M. Trailović

Ivermectin effects on motor coordination and contractions of isolated rat diaphragm.

Ivermectin, the antiparasitic drug from the macrocyclic lactones class raises attention due to its high efficiency against nematodes and arthropods and very specific toxic and side effects that it may produce in host. Dominant clinical symptoms of adverse effects and toxicity of ivermectin in animals are tremor, ataxia, CNS depression and coma which often results in mortality. In our study increasing intravenous doses of ivermectin, (6 or more times higher than therapeutic dose: 1.25, 2.5, 3.75, 5.0, 6.25 and 7.5 mg/kg), caused dose-dependent disturbance of motor coordination in treated rats. The median effective dose (ED50) that was able to impair the rota-rod performance in rats treated 3 min before testing was 2.52 mg/kg. This effect weakens over time, while in the rats treated 60 min before the rota-rod test, ED50 of ivermectin was 4.21 mg/kg. Whereas, all tested doses of ivermectin did not cause any other clinical symptoms of toxicity. Ivermectin has no effect on the contractions of isolated diaphragm caused by the EFS, which effectively blocked mecamylamine (100 μM) and pancuronium (1 and 2 μM). Effect on motor coordination is the first detectable clinical symptom of ivermectin toxicity and apparently is a result of its central effects.

Blood serum protein status in broilers fed with increasing concentrations of ochratoxin A

The 42-day long study was performed on a total number of 48 Hybro broilers divided into four groups. After the pre-experimental period of 14 days, 3 experimental groups of broilers (n=12) were formed and fed diets that contained 0.5, 1.0 and 1.5 mg/kg ochratoxin A (OTA) during the next seven consecutive days. In the same period, the control group of broilers was fed a diet with no toxin added. After the period of toxin addition, blood samples were taken from 6 animals in each group. The remaining animals (n=6) from the control and experimental groups were fed diets without OTA until the 42nd day of the study, when the blood samples were taken again. The total level of blood serum proteins was affected by treatment with different doses of OTA, but a significant and dose dependent increase of albumins together with a decrease of γ-globulin fraction was established. A/G ratio (Albumine/Globuline) suggested that the globulins were the dominant protein fraction in the blood serum samples obtained from all the broilers included in this study. The concentrations of α- and β- globulin in the serum were within physiological limits, but the concentration of γ-globulins significantly decreased. It can be concluded that the increasing dietary OTA levels (0.5, 1.0 and 1.5 mg/kg) had dose-dependent cumulative effect on blood serum proteins status in broilers, and the effect lasts even after the withdrawal of OTA from the feed.

L-ARGININE-NO SYSTEM PARTICIPATES IN THE ANALGESIC EFFECT OF FLUNIXIN MEGLUMINE IN THE RAT

Abstract This study investigated whether the L-arginine-NO system participates in the analgesic effect of flunixin meglumine in the rat. Hyperalgesia was induced by intraplantar (i.pl.) administration of carrageenan (500 μg) into the rat’s hind paw. Electronic von Frey apparatus was used to determine paw withdrawal threshold induced by pressure as the painful stimulus, measured in grams (g). Flunixin meglumine (FM; 0.09-0.1 mg/kg; s.c.) and NG-nitro-L-arginine methyl ester (L-NAME; 10 mg/kg; i.p.), given separately as a pre-treatment, i.e. 15 min before i.pl. injection of carrageenan, produced a significant antinociception. When FM (0.09 mg/kg) and a sub-effective dose of L-NAME (5 mg/kg) were co-administered, the antinociceptive effect was significantly increased in comparison with the effect of FM alone. L-arginine (L-ARG;10 mg/kg; i.p.) itself did not produce significant effect on carrageenan-induced hyperalgesia, but significantly reduced the antinociceptive effects of both FM and FM + L-NAME combination. The inhibition of the production of NO might be involved in the mechanism of the analgesic effect of FM.

Carvacrol importance in veterinary and human medicine as ecologic insecticide and acaricide

Carvacrol is an active ingredient of essential oils from different plants, mainly from oregano and thyme species. It poseses biocidal activity agains many artropodes of the importance for veterinary and human medicine. Carvacrol acts as repelent, larvicide, insecticide and acaricide. It acts against pest artropodes such as those that serve as mechanical or biological vectors for many causal agents of viral, bacterial and parasitic diseases for animals and humans. Therefore, it may be used not only in pest arthropodes control but in vector borne diseases control, too. In the paper carvacrol bioactivity against mosquitoes, house flies, cockroaches, ticks and mites are described. Potencial modes of carvacrol action on artropodes are given, too. Carvacrol reachs its biotoxicity against arthropodes alone or in combination with other active ingredients from the same plant of its origin, such as tymol, cymen or others. The paper explains reasons for frequently investigations on essential oils and other natural products of plant origin to their biotoxicity against food stored pest or pest of medicinal importance, as well as, needs for their use in agriculture, veterinary and human medicine.

Two opposite dose-dependent effects of diazinon on the motor activity of the rat ileum

Acute poisoning with OPs may lead to a range of neurological effects, which cannot be explained by AChE inhibition alone. Several OPs interact directly with cholinergic receptors in mammals, but such data does not exist for invertebrates. The aim of current study was to investigate the direct and indirect effects of diazinon on the contractions of rat ileum and to compare those effects on the nervemuscle preparation of the Ascaris suum. In the presence of increasing concentrations of diazinon (3, 10 and 30nM), EFS-induced ileal contractions were increased significantly. In the same preparation, diazinon 3nM, significantly increased contractions induced by EFS, but did not affect the contractions caused by 5MFI. Contrarily, 1μM of diazinon significantly and reversibly inhibited the EFS-induced ileal contractions. Diazinon exhibited competitive and non-competitive inhibitions of 5MFI induced contractions. The control EC50 of 5MFI was 2.48μM with Rmax=1.88g. In the presence of diazinon, EC50 was 12.45μM, while Rmax was reduced to 0.43g. After washing, the EC50 and Rmax values were again closer to the control level (3.80μM and 1.04g). Diazinon 1μM did not inhibit Ascaris suum contractions caused by ACh, but it increased the Rmax. Diazinon in our study exhibits two opposite effects on the motor activity of the ileum. In low nanomolar concentrations the dominat is its effect on AChE and the stimulation of contractions. Furthermore, in concentrations that approach micromolar values diazinon has a direct inhibitory effect on muscarinic receptors. The direct inhibitory effect of diazinon on A. suum contractions was not found.

Monepantel is a non-competitive antagonist of nicotinic acetylcholine receptors from Ascaris suum and Oesophagostomum dentatum

Zolvix® is a recently introduced anthelmintic drench containing monepantel as the active ingredient. Monepantel is a positive allosteric modulator of DEG-3/DES-2 type nicotinic acetylcholine receptors (nAChRs) in several nematode species. The drug has been reported to produce hypercontraction of Caenorhabditis elegans and Haemonchus contortus somatic muscle. We investigated the effects of monepantel on nAChRs from Ascaris suum and Oesophagostomum dentatum heterologously expressed in Xenopus laevis oocytes. Using two-electrode voltage-clamp electrophysiology, we studied the effects of monepantel on a nicotine preferring homomeric nAChR subtype from A. suum comprising of ACR-16; a pyrantel/tribendimidine preferring heteromeric subtype from O. dentatum comprising UNC-29, UNC-38 and UNC-63 subunits; and a levamisole preferring subtype (O. dentatum) comprising UNC-29, UNC-38, UNC-63 and ACR-8 subunits. For each subtype tested, monepantel applied in isolation produced no measurable currents thereby ruling out an agonist action. When monepantel was continuously applied, it reduced the amplitude of acetylcholine induced currents in a concentration-dependent manner. In all three subtypes, monepantel acted as a non-competitive antagonist on the expressed receptors. ACR-16 from A. suum was particularly sensitive to monepantel inhibition (IC50 values: 1.6 ± 3.1 nM and 0.2 ± 2.3 μM). We also investigated the effects of monepantel on muscle flaps isolated from adult A. suum. The drug did not significantly increase baseline tension when applied on its own. As with acetylcholine induced currents in the heterologously expressed receptors, contractions induced by acetylcholine were antagonized by monepantel. Further investigation revealed that the inhibition was a mixture of competitive and non-competitive antagonism. Our findings suggest that monepantel is active on multiple nAChR subtypes.

DIAGNOSIS AND THERAPY OF LIVER FLUKE (FASCIOLOIDES MAGNA) INFECTION IN FALLOW DEER (DAMA DAMA) IN SERBIA.

Abstract Giant liver fluke (Fascioloides magna) infection is an important health problem of cervids in southeastern Europe. We measured the prevalence and intensity of infection with F. magna in a fenced area near the Danube River in the South Bačka District of Serbia. Parasitologic, pathomorphologic, and histopathologic examinations were conducted from November 2007 to February 2008, beginning with a population of 127 adult fallow deer (Dama dama). After a positive diagnosis, therapy with triclabendazole-medicated corn was applied. Deer were treated at four baiting stations, using medicated feed providing triclabendazole at an estimated dose of 10–14 mg/kg of body weight per deer. Treatment lasted for 7 d in early February 2008 and an additional 7 d 2 wk later. For the complete success of pharmacotherapy it was necessary to prevent any contact of deer with the snail intermediate host (Galba truncatula). Intervention in the habitat, removing grass and low vegetation, and draining ponds reduces the possibility of contact. Six months after the treatment, livers of hunted deer were reddish, with fibrous tracks; pigmentation and cysts in the parenchyma were surrounded by a fibrous capsule and their fecal samples contained no eggs of F. magna. Over the following years, livers of hunted deer were negative, and the last control cull in March 2015 confirmed complete absence of infection. We reconfirmed the presence of giant liver flukes in fallow deer in Serbia, apparently the result of natural spread across the Danube from Hungary and Croatia. We also report that the treatment of deer with triclabendazole-medicated corn is an effective method for administration of therapeutic doses of drug in semicaptive deer. Interventions in the environment are necessary to prevent recontact of deer with habitats used by the snail intermediate host, and enable the success of the therapy.