Cannabis sativa (Linnaeus, 1753): The use of its extract against Rhipicephalus linnaei (Audouin, 1826) ticks

To minimize the damage caused by synthetic acaricides to non-target organisms, the use of bioactives compounds extracted from plants has been considered. In this study, semi-engorged females of Rhipicephalus linnaei ticks were exposed to Cannabis sativa flower extract (submersion for 5 minutes in different concentrations diluted in ethanol 30 %) evaluated alterations in the integument and salivary glands. The results demonstrated that lower concentrations of the extract caused damage to both the integument and salivary glands, affecting the cuticular epithelial cells responsible for synthesizing all layers of the cuticle. The concentration of 2.5 mg/mL caused more extensive damage than 5.0 mg/mL, and 40 mg/mL completely disrupted the epithelium. Exposure of the salivary glands showed that at 2.5 ug/mL dose the glandular acini was disrupted, leaving only a heterogeneous mass with some nuclei of acinar cells, leading to acinar rupture. These findings indicate that the extract from Cannabis sativa flowers irreversibly alters the morphology and consequently, interferes with the functionality of different vital organs.

Preclinical safety assessment in rats after dermal exposure to acetylcarvacrol, a potential acaricide against the brown dog tick

Carvacrol, a phenolic monoterpene found in essential oils of plants of the Lamiaceae family, emerges as an alternative acaricide of plant origin. Its acetylation was proposed to obtain a derivative compound with a better pharmacological profile and lower toxicity to non-target organisms. The present study aimed to assess the preclinical safety of acetylcarvacrol after dermal application in Wistar rats, through the examination of hematological and biochemical parameters, as well as histopathological analysis of the skin, liver and kidney. For this, twenty rats were distributed into four groups with five animals each. Three groups received treatment with different concentrations of the substance (26, 52, and 104 µL/mL) based on the lethal concentration for Rhipicephalus sanguineus ticks, and one group (Control) received only the vehicle. Acetylcarvacrol was applied daily to a trichotomized skin area for 21 days. No changes in hematological parameters were observed. Regarding biochemical analysis, a slight increase in urea and alanine transaminase levels was noted. No significant changes were observed in the kidney and liver, although the rats had developed cumulative irritant contact dermatitis at the application site, as corroborated by the histopathological analysis of the skin. In general, the results showed that the dermal application of acetylcarvacrol in the experimental conditions described here is safe. However, it can cause signs of mild systemic toxicity and skin irritation at high concentrations, suggesting that this product should be used in lower therapeutic doses and that the development of less aggressive formulations, including the combination with other acaricides, is desirable.

Evaluation of synergism in essential oils against the cattle tick Rhipicephalus microplus in Burkina Faso

The cattle tick Rhipicephalus microplus affects animal production economically by reducing weight gain and milk production and causing diseases, such as babesiosis and anaplasmosis. Using synthetic acaricides to reduce their incidence has caused the emergence of resistant tick populations. The present study aimed to assess the in vitro acaricidal activity of combinations of essential oils (EOs) from Ocimum americanum, Ocimum gratissimum, and Lippia multiflora against R. microplus larvae. In fact, numerous biological properties have been reported on EOs from these three plants, including acaricidal properties. Hence, a larval immersion test was performed using a population of R. microplus resistant to synthetic acaricides used in Burkina Faso. Results revealed that EO from O. gratissimum was the most effective on R. microplus larvae with LC50 and LC90 values at 10.36 and 15.51 mg/mL, respectively. For EO combinations, the most significant synergistic effect was obtained by combination 6 (1/3 O. americanum + 2/3 O. gratissimum +1/6 L. multiflora), with a combination index value of 0.44. All combinations presented dose reduction index >1, indicating a favorable dose reduction. According to the literature, this is the first study to determine the combination effect of EOs from the abovementioned plants in controlling R. microplus activity in vitro. Thus, the combination of these EOs is an alternative to control the resistant populations of invasive cattle ticks.

Determination of the discriminant doses to identify resistance to fipronil, flumethrin and coumaphos, in Rhipicephalus sanguineus s.l. (Acari: Ixodidae) from Mexico

Rhipicephalus sanguineus s.l. is an intra- and peridomiciliary tick of medical and veterinary importance, whose control is carried out through the application of various ixodicides, to which it can develop resistance. The objective of this work was to determine the discriminant doses (d.d.) to identify resistance against three ixodicides - fipronil, flumethrin and coumaphos - in R. sanguineus s.l. larvae originating from Mexico. Engorged ticks were collected from naturally infested dogs residing in rural communities in five Mexican states; the dogs had no history of recent treatment with ixodicides. All ticks were identified as R. sanguineus s.l. They were incubated for 25 days and their progeny was used in the larval package test (LPT) to be exposed to d.d. as determined in Rhipicephalus microplus, and those that were susceptible were analyzed using the LPT with six concentrations, for fipronil from 0.1 to 0.003125%, for flumethrin from 0.02 to 0.000625% and for coumaphos from 0.4 to 0.0125%. Mortality was analyzed with Probit methodology, to calculate the 50 and 99% lethal concentrations (LC50 and LC99). The d.d. was determined as a consensus value by multiplying the LC99 value × 2. Nine double susceptible samples (fipronil + flumethrin) and one triple susceptible sample (fipronil + flumethrin + coumaphos) were found; the d.d. determined were fipronil 0.05%, flumethrin 0.01% and coumaphos 0.43%. These doses can be used to rapidly and inexpensively identify resistant populations in samples collected in the field.

Liver and spleen of hosts of Rhipicephalus linnaei exposed to synthetic (afoxolaner) and natural acaricides (esters from castor oil). A comparative clinical-morphological study

In dogs, Rhipicephalus linnaei transmits pathogens such as Ehrlichia canis, Babesia vogeli, and Hepatozoon canis. The veterinary market has synthetic acaricides to ticks control. Esters derived from castor oil are efficient. However, there is little information about their effects on non-target organisms. This work consisted of a clinical (AST, ALT, and ALP) and histological and histochemical analysis (liver and spleen) of female rabbits exposed to these esters and afoxolaner. The rabbits were divided into three groups: control group (CG) received Bandeirante® rabbit feed; the afoxolaner treatment (TG1) received rabbit feed and two doses of afoxolaner; castor oil esters treatment (TG2) received rabbit feed enriched with esters (1.75 g esters/kg). No alterations were observed in the AST, ALT, and ALP enzymes in exposure to esters TG2. Rabbits from TG1 showed changes in AST. The liver of rabbits exposed to afoxolaner underwent histological and histochemical changes, such as steatosis and vacuolation, as well as poor protein labeling. Polysaccharides were intensely observed in the group exposed to esters. The spleen showed no changes in any of the exposure. Esters from castor oil caused fewer liver changes when incorporated into the feed and fed to rabbits than exposure to afoxolaner.

Efficacy of essential oils of Egletes viscosa and Lippia schaueriana on the reproductive biology of Rhipicephalus sanguineus sensu lato engorged females

The study analyzed the chemical composition and the acaricide effect of Egletes viscosa Less (macela-da-terra) and Lippia schaueriana Mart. (lipia-da-serra) essential oils (EOs) on Rhipicephalus sanguineus s. l. (Acari: Ixodidae) engorged females. The chemical analysis (GC-MS and GC-FID) identified 27 components in E. viscosa EO and 18 in L. schaueriana EO, which comprise more than 98% of its constituents. The effects of the oils on the reproductive biology of R. sanguineus ticks were assessed by adult immersion test. Both EOs significantly reduced (p < 0.05) the egg production index when the females were exposed to 25 and 50 mg/mL, also affecting the egg viability. During the laying process, the eggs produced by the females exposed to the EO showed several morphological alterations such as dehydrated, darkened, and disaggregated, and these alterations were more severe as the concentrations increased. The mortality percentages were 58.9%, 70.8% and 92.7% when the ticks were exposed to 12.5, 25 and 50 mg/mL of E. viscosa oil, respectively. In the same concentrations, the efficacy of L. schaueriana was 39.3%, 53.4%, and 84.6%. Therefore, it can be concluded that the essential oils of E. viscosa and L. schaueriana have acaricidal effect in females of R. sanguineus s.l ticks.

Oxidative stress, apoptosis and histopathological alterations in brain stem and diencephalon induced by subacute exposure to fipronil in albino rats

Fipronil (FIP) is a highly effective insecticide that has been used in agriculture and veterinary medicine. Its neurotoxic effect to insects and to non-target organisms, after nonintentional exposure, was reported. Many studies were conducted to evaluate FIP effects on mammals. However, slight is known about its effect on the brain stem and diencephalon. The current study was designed to investigate the ability of FIP to induce oxidative stress as a molecular mechanism of FIP neurotoxicity that resulted in apoptosis and neural tissue reactivity in these regions. Ten adult male rats received 10 mg/kg of FIP technical grade by oral gavage, daily for 45 days. Brain stem and diencephalon were processed to examine oxidative stress-induced macromolecular alteration (MDA, PCC and DNA fragmentation). Also, the histopathological assessment and immunoreactivity for caspase-3 (active form), iNOS and GFAP were performed on the thalamus, hypothalamus and medulla oblongata. Our results revealed that FIP significantly raised MDA, PCC and DNA fragmentation (p ≤ 0.05). In addition, significantly increased immunoreactivity to GFAP, iNOS and caspase-3 (active form) in the FIP-treated group was noticed (p ≤ 0.05). Moreover, alterations in the histoarchitecture of the neural tissue of these regions were observed. We conclude that FIP can induce oxidative stress, leading to apoptosis and tissue reaction in brain stem and diencephalon.

Fipronil induced oxidative stress in neural tissue of albino rat with subsequent apoptosis and tissue reactivity

Fipronil (FIP) insecticide is extensively used in agriculture, public health and veterinary medicine. Although it is considered as a neurotoxin to insects (target organisms) and exhibits neurological signs upon vertebrates (non-target organisms) exposure, slight is known about its potential neurotoxic effects and its molecular mechanisms on vertebrates. The current study is designed to assess oxidative stress as a molecular mechanism of FIP neurotoxicity subordinated with apoptosis and neural tissue reactivity. Ten adult male albino rats received 10 mg/kg body weight fipronil technical grade by oral gavage daily for 45 days (subacute exposure). Brain neural tissue regions (hippocampus, cerebellum and caudate putamen) were processed to examine oxidative stress induced cellular macromolecular alterations as MDA, PCC and DNA fragmentation. Besides, TNF-α and Bcl-2 gene expression and immunoreactivity for caspase-3 (active form), iNOS and GFAP were evaluated. Also, histopathological assessment was conducted. We found that FIP significantly raised MDA, PCC and DNA fragmentation (p ≤ 0.05). Also, it significantly upregulated TNF-α and non-significantly down-regulated Bcl-2 gene expression (p ≤ 0.05). Further, significant increased immunoreactivity to GFAP, iNOS and caspase-3 (active form) in these brain neural tissue regions in FIP treated group was noticed (p ≤ 0.05). Histopathological findings, including alterations in the histological architecture and neuronal degeneration, were also observed in these brain regions of FIP treated group. In conclusion, we suggest the ability of FIP to induce oxidative stress mediated macromolecular alterations, leading to apoptosis and tissue reaction in these brain regions which showed variable susceptibility to FIP toxic effects.

Protective Effect of Red Okra (Abelmoschus esculentus (L.) Moench) Pods against Sodium Nitrite-Induced Liver Injury in Mice

Vegetables, drinking water, and preserved meats may contain sodium nitrite (NaNO2), which causes liver disease by inducing oxidative stress. Phytochemicals are highly recommended as an alternative to synthetic drugs and affordable medicines to treat liver disease because they have fewer or no side effects. Therefore, this study aims to determine the antioxidant and hepatoprotective potential of red okra fruit ethanol extract against NaNO2-induced liver damage. Thirty-six male mice were separated into six groups. The normal control group (WA) was given distilled water only, and the NaNO2 (SN) group was given only 50 mg/kg BW NaNO2. The other four groups (P1, P2, P3, and P4) were given NaNO2 and red okra ethanol extract at doses of 25, 50, 75, and 100 mg/kg BW, respectively. Gavage was administered orally for 21 consecutive days. Commercial kits define all biochemical parameters according to the manufacturer's instructions. Liver tissue staining followed standard protocols using hematoxylin and eosin. The study revealed that NaNO2 induction causes oxidative stress and damages the liver. The activity of antioxidant enzymes (superoxide dismutase and catalase) significantly increased in the groups treated (P2-P4) with ethanol extract of red okra (p < 0.05). Besides, the oxidants (malondialdehyde, F2-isoprostanes, and nitric oxide) in the liver homogenate significantly decreased in the P4 group, which were given red okra ethanol extract (p < 0.05). Likewise, red okra pods decreased significantly for the serum biochemical parameters of liver damage (aspartate aminotransferase, alkaline phosphatase, and alanine aminotransferase) in the P3 and P4 groups (p < 0.05). Then, it led to a restoration of the histological structure compared to exposed mice (SN), as the pathological scores decreased significantly in the P3 and P4 groups (p < 0.05), as well as the number of the necrotic and swollen liver cells was reduced. Hepatocytes returned to normal. The results showed that the ethanol extract of red okra fruit could be helpful as an affordable medicine. It is an antioxidant and hepatoprotective agent to protect the liver from damage caused by NaNO2.

Transcriptomic modifications of the thyroid gland upon exposure to phytosanitary-grade fipronil: Evidence for the activation of compensatory pathways

Fipronil is a phenylpyrazole insecticide used for the control of a variety of pest for domestic, veterinary and agricultural uses. Fipronil exposure is associated to thyroid disruption in the rat. It increases thyroid hormone (TH) hepatic clearance. The effect on thyroxine (T4) clearance is about four fold higher than the effect on T4 plasma concentrations suggesting that the thyroid gland might develop compensatory mechanisms. The aim of this study was to document the potential effects of fipronil treatment on the thyroid transcriptome together with its effects on TSH and TH blood levels under well characterized internal exposure to fipronil and its main metabolite fipronil sulfone. Fipronil (3 mg/kg/d by gavage for 14 days) clearance increased while its half-life decreased (about 10 fold) throughout treatment. Fipronil treatment in adult female rats significantly decreased total T4 and free triiodothyronine (T3) concentrations. Key genes related to thyroid hormone synthesis and/or cellular dynamic were modulated by fipronil exposure. RT-PCR confirmed that thyroglobulin gene expression was upregulated. A trend toward higher Na/I symporter expression was also noted, while sulfotransferase 1a1 gene expression was down-regulated. The expression of genes potentially involved in thyroid cell dynamic were upregulated (e.g. prostaglandin synthase 1, amphiregulin and Rhoa). Our results indicate that both pathways of TH synthesis and thyroid cell dynamics are transcriptional targets of fipronil and/or its main sulfone metabolite. The underlying mechanisms remain to be elucidated.

Impacts of resveratrol versus platelet-rich plasma for treatment of experimentally lithium-induced thyroid follicular cell toxicity in rats. A histological and immunohistochemical study

Lithium (Li) is used for the treatment and prophylaxis of mental disorders, associated with many serious hazards. Resveratrol (RSV) has various beneficial therapeutic effects. Platelet-rich plasma (PRP) is a new promising curative tool. This study aimed to assess the impacts of RSV versus PRP on lithium-induced thyroid follicular cell toxicity in adult male rats. Forty-nine adult male rats were divided into four groups: group I: control rats; group II: lithium-treated rats; group III: lithium- and resveratrol-treated rats; group IV: lithium and PRP-treated rats. Thyroid specimens were taken and processed for histological and immunohistochemical methods. Morphometrical studies and statistical analysis were done. Group II showed distorted thyroid follicles, significantly increased collagen fibers, and highly positive P53 immunostaining (P < 0.01). Ultrastructural examination showed dilated rough endoplasmic reticulum and damaged mitochondria. Groups III and IV exhibited significant amelioration of the histological and electron microscopic changes mentioned previously. PRP remedy was more effective than RSV for treatment of Li-induced thyroid follicular cell toxicity.

Entomopathogenic nematodes in pharmaceutical formulations for Rhipicephalus microplus (Acari: Ixodidae) control: In vitro evaluation of compatibility, thermotolerance, and efficiency

This work aimed to investigate candidate biological control agents against the cattle tick Rhipicephalus microplus by studying three entomopathogenic nematodes (EPN) isolates from two species, Heterorhabditis bacteriophora (isolates LPP30 and HP88) and Heterorhabditis baujardi (isolate LPP7). The study comprised the pharmacotechnical development of four test formulations, and their biological evaluation, in three stages: 1) selection of the fittest EPN isolate at 16 ± 1 °C after 120 h of incorporation in the formulations; 2) determination of the effects of temperature and incubation time on the survival of the selected isolate in formulations; 3) evaluation of the in vitro efficacy (infectivity) of the selected EPN formulations and their components against R. microplus females after 72 h exposure. H. baujardi LPP7 presented the highest survival rates in 0.1% carboxymethyl cellulose sodium (CMC) formulations (100% at 25 °C, up to 10 days after incorporation). At the highest tested temperature (34.2 °C), 54% of LPP7 survived for up to 72 h in CMC formulations. The infectivity of LPP7-containing formulation against R. microplus was 99%, reducing oviposition, egg production index and larval hatching. Considering the pressing need for safer acaricide products, incorporation of EPNs in pharmaceutical formulations is presented as a promising approach for the biological control of cattle tick infestations, potentially reducing environmental impact and resistance development associated with chemical acaricides.