The effect of natural toxins on reproduction in livestock

Ecological thresholds of toxic plants for sheep production and ecosystem multifunctionality and their trade-off in an alpine meadow

Toxic plants are a natural component of alpine meadow which co-evolved with Tibetan sheep for thousands of years. One challenge for indigenous herders is to know the ecological thresholds of toxic plants and maintain their vital functions in ways that are compatible with economic income and ecological conservation. To achieve this, field trials with Tibetan sheep grazing in alpine meadow were conducted to examine the ecological thresholds of toxic plants for sheep production and ecosystem functions and their trade-offs. Our results demonstrated that the changing point values of biomass proportion of toxic plants for dry matter intake and liveweight gain of sheep were 17% and 22%, respectively. The changing point value of biomass (richness) proportion of toxic plants for soil carbon accumulation index was 31% (59%), for soil nutrient cycling index was 38% (42%), and for ecosystem multifunctionality index was 28% (50%). The trade-off between liveweight gain of sheep and ecosystem multifunctionality first decreased and then increased along the gradient of biomass proportion of toxic plants (the value of changing point was 37%), and had a significant negative correlation with richness of toxic plants. In addition, structural equation modeling indicated that toxic plants can affect the trade-off between liveweight gain of sheep and ecosystem multifunctionality though increasing acid detergent fiber of plant and decreasing plant species richness, belowground biomass and soil total phosphorus. Consequently, opinions towards toxic plants should shift from the conventional view that they are serious threat to grassland ecosystem health to an inclusive understanding that they are beneficial to livestock and ecosystem functions under certain ecological thresholds.

Definition and Multiple Factors of Recurrent Spontaneous Abortion

Recurrent spontaneous abortion (RSA) is usually defined as three or more spontaneous abortions prior to 20-28 weeks gestation. RSA affects approximately 2-5% of all women of childbearing age, and it brings tremendous psychological and psychiatric trauma to the women and also results in economic burden. The causes could be female age, anatomical and chromosomal abnormalities, genetic, endocrinological, placental anomalies, infection, smoking and alcohol consumption, psychological factor, exposure to environmental factors such as heavy metal, environment pollution, and radiation.

Grasslands: A Source of Secondary Metabolites for Livestock Health

The need for environmentally friendly practices in animal husbandry, in conjunction with the reduction of the use of synthetic chemicals, leads us to reconsider our agricultural production systems. In that context, grassland secondary metabolites (GSMs) could offer an alternative way to support to livestock health. In fact, grasslands, especially those with high dicotyledonous plant species, present a large, pharmacologically active reservoir of secondary metabolites (e.g., phenolic compounds, alkaloids, saponins, terpenoids, carotenoids, and quinones). These molecules have activities that could improve or deteriorate health and production. This Review presents the main families of GSMs and uses examples to describe their known impact on animal health in husbandry. Techniques involved for their study are also described. A particular focus is put on anti-oxidant activities of GSMs. In fact, numerous husbandry pathologies, such as inflammation, are linked to oxidative stress and can be managed by a diet rich in anti-oxidants. The different approaches and techniques used to evaluate grassland quality for livestock health highlight the lack of efficient and reliable technics to study the activities of this complex phytococktail. Better knowledge and management of this animal health resource constitute a new multidisciplinary research field and a challenge to maintain and valorize grasslands.

Unusual alkaloids of the highland species Astragalus cryptanthus Wedd. (Fabaceae)

Two unusual caprolactam alkaloids, 3-(dimethylamino)hexahydro-2H-azepin-2-one and 3-(methylamino)-hexahydro-2H-azepin-2-one, were isolated from the aerial parts of Astragalus cryptanthus Wedd.; their structures were unambiguously determined based on data from extensive 1D and 2D NMR, GC-MS and FT-IR spectroscopic analyses. This is the first report of this alkaloid type in the genus Astragalus.

Swainsonine exposure induces impairment of host immune response in pregnant BALB/c mice

BACKGROUND

Swainsonine can cause serious disorders in reproduction of livestock, affecting both corpora lutea and reproductive hormone. The purpose of this study was to investigate the mechanisms of swainsonine about the immunotoxic effects on pregnant mice in vivo.

RESULTS

The peripheral Th1/Th2 was detected by Ionomycin and phorbol myristate acetate (PMA)-stimulating peripheral blood mononuclear cells (PBMC) of phase pregnant mice. Relevant cytokines in serum was evaluated after exposed to different dose of swainsonine. Gene expression of IL-1β, IFN-γ, TNF-α, IL-4 and IL-10 in PBMC was assessed by real-time PCR. Swainsonine caused vacuolization phenomenon of lutein cells and a dose-effect relationship. The IL-1β, IFN-γ and TNF-α were promoted, but IL-4 and IL-10 were suppressed in serum. Swainsonine significantly increased IL-1β, IFN-γ and TNF-α nuclear translocation and decreased IL-4 and IL-10. Swainsonine resulted in a significant shift of peripheral Th1/Th2 paradigm to Th1.

CONCLUSIONS

Our data demonstrate that the immunomodulatory of swainsonine disturbed the regular immunologic state of the pregnant mice. This may increase the risk of abortion and probably resulted in serious disorders in reproduction of livestock.

Hematological and histopathological effects of swainsonine in mouse

BACKGROUND

Livestock that consume locoweed exhibit multiple neurological symptoms, including dispirited behavior, staggered gait, trembling, ataxia, impaired reproductive function and cellular vacuolar degeneration of multiple tissues due to toxicity from plant-derived alkaloids such as swainsonine.

RESULTS

Swainsonine was administered to F(0) and F(1) mice by intraperitoneal injection before, during and after pregnancy at the following doses: 0.525 mg/kg BW(I), 0.2625 mg/kg BW(II), 0.175 mg/kg BW(III) and 0 mg/kg BW(IV). Hemosiderin deposits were observed the lamina propria of endometrium in uterus and the red pulp of spleen. Ovary corpus lutea counts in F(0) mice were higher in swainsonine-treated mice compared to control mice. Indirect bilirubin content and reticulocyte numbers were increased in swainsonine-treated F(0) and F(1) generation mice compared to control group (P < 0.05). Lactate dehydrogenase, alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase content in F(0)-I and F(0)-II mice were significantly increased compared with F(0)-IV group mice (P < 0.05). Red blood cells, hemoglobin and mean corpuscular hemoglobin levels were significantly decreased in F(0) and F(1) mice compared with the control group (P < 0.05).

CONCLUSIONS

Swainsonine exerts effects on estrus period and reproductive ability, and offspring of dams dosed with swainsonine were affected in-utero or from nursing. Damage to liver, uterus and spleen, as well as hematological changes, are observable before neurological symptoms present.

Sesquiterpene lactones: adverse health effects and toxicity mechanisms

Sesquiterpene lactones (STLs) present a wide range of biological activities, mostly based on their alkylating capabilities, which underlie their therapeutic potential. These compounds are the active constituents of a variety of plants, frequently used as herbal remedies. STLs such as artemisinin and its derivatives are in use as first-line antimalarials while others, such as parthenolide, have recently reached cancer clinical trials. However, the toxicological profile of these compounds must be thoroughly characterized, since the same properties that make STL useful medicines can also cause severe toxicity. STL-containing plants have long been known to induce a contact dermatitis in exposed farm workers, and also to cause several toxic syndromes in farm animals. More recently, concerns are been raised regarding the genotoxic potential of these compounds and the embryotoxicity of artemisinins. A growing number of STLs are being reported to be mutagenic in different in vitro and in vivo assays. As yet no systematic studies have been published, but the genotoxicity of STLs seems to depend not so much on direct DNA alkylation as on oxidative DNA damage and other partially elucidated mechanisms. As the medicinal use of these compounds increases, further studies of their toxic potential are needed, especially those focusing on the structural determinants of genotoxicity and embryotoxicity.

Swainsonine differentially affects steroidogenesis and viability in caprine luteal cells in vitro

Plants containing swainsonine (SW) have been reported to impair reproductive function and fertility after long-term ingestion by livestock. However, direct effects of SW on luteal cell steroidogenesis remain unclear. In this study, primary and transfected luteal cells were used to investigate the effects of SW on progesterone secretion and cell viability and the mechanisms involved in these processes. After treatment with various concentrations of SW for 24 or 48 hours, progesterone production and the number of living cells were assessed using radioimmunoassay and trypan blue dye exclusion assay, respectively. Lower concentrations of SW enhanced basal, 22R-hydroxycholesterol- or pregnenolone-stimulated progesterone secretion (P < 0.05), whereas higher concentrations of SW inhibited progesterone secretion (P < 0.05). Lower concentrations of SW promoted expression of P450 side-chain cleavage enzyme and 3β-hydroxysteroid dehydrogenase, two key enzymes involved in luteal cell steroidogenesis, at mRNA and protein levels (P < 0.05), but did not affect expression of steroidogenic acute regulatory protein and cell proliferation. In contrast, higher concentrations of SW inhibited luteal cell proliferation by inducing growth phase 1/quiescent state cell cycle arrest and apoptosis (P < 0.05). Taken together, these results demonstrated that lower concentrations of SW induced progesterone production through upregulation of P450 side-chain cleavage enzyme and 3β-hydroxysteroid dehydrogenase without affecting cell viability, whereas higher concentrations of SW induced cell cycle arrest and apoptosis and impaired steroidogenesis. These findings provided new insights into understanding the effect of SW on luteal cell steroidogenesis.

Pathological findings in fetuses of goats and cattle poisoned by Sida carpinifolia (Malvaceae)

In Brazil, the consumption of Sida carpinifolia by livestock has been associated with neurological diseases linked to lysosomal storage disorders. This paper describes the pathological findings in two caprine fetuses from dams that were experimentally poisoned with S. carpinifolia. The goats were orally dosed with 10 and 13g/kg of a paste of green chopped S. carpinifolia for 30 days and were observed for an additional 15 days period after the last dosage with the plant; thereafter they were euthanized and necropsied. The dams showed only slight clinical signs. The study also includes the findings in one bovine fetus from a naturally S. carpinifolia poisoned cow which showed mild incoordination, generalized tremors, staggering, and frequent falls. The cow was euthanized and necropsied. While there were no significant histopathological changes in the goats, in the cow vacuolation of Purkinje neurons of the cerebellum, pancreatic acinar cells, and thyroid follicular cells were observed. The main microscopic changes observed in the caprine and bovine fetuses were vacuolation in the epithelium of renal tubules, thyroid follicular cells, and Purkinje neurons of the cerebellum. Transmission electron microscopy of sections from CNS of the cow and its fetus revealed vacuoles containing fine granular material surrounded by membrane. Lectin-histochemistry of CNS sections from goat fetuses marked lightly to sWGA lectins, WGA, and Con-A.

The antioxidant epigallocatechin gallate (EGCG) moderates the deleterious effects of maternal hyperthermia on follicle-enclosed oocytes in mice

Hyperthermia-induced oxidative stress is one of the mechanisms suggested to underlie loss of developmental competence in mouse embryos. In this study, we examined whether pretreatment with the antioxidant epigallocatechin gallate (EGCG) can alleviate the negative effects of hyperthermia on developmental competence of the ovarian pool of oocytes and improve embryonic development. Female mice (CB6F1) were synchronized (eCG+hCG) and injected with 0.4 ml EGCG (100 mg/kg body weight) or with saline. Both EGCG- and saline-treated mice were exposed to heat stress (HS; 40 degrees C, 65% RH) or kept under normothermal conditions (Control; 22 degrees C, 45% RH). In vivo-derived zygotes were recovered 20 h after hCG administration and cultured in vitro. Maternal hyperthermia attenuated embryonic cleavage rate in association with further disruption in embryonic early cleavage and subsequently, with embryonic development. While pretreatment with EGCG did not affect the proportion of zygotes that cleaved to the two-cell stage, it appeared to moderate the effect of hyperthermia on both cleavage timing and developmental rate, as reflected by an increased rate of early cleaved embryos and blastocyst formation. Blastocyst developmental competence was also improved, as indicated by the increased total cell number and percentage of embryos that underwent hatching, in association with reduced apoptotic status, as reflected by the percentage of TUNEL-positive cells and intensity of caspase activity for the HS-EGCG embryos vs. HS-saline ones. In summary, while hyperthermia disrupts the competence of the follicle-enclosed oocyte, in vivo administration of the antioxidant EGCG improves developmental competence and the quality of the embryos that develop from these oocytes.

Maternal hyperthermia disrupts developmental competence of follicle-enclosed oocytes: in vivo and ex vivo studies in mice

Mammalian oocytes are susceptible to thermal stress at various stages of follicular development. We examined whether the ovarian pool of oocytes is susceptible to maternal hyperthermia and if so, whether hyperthermia at the germinal vesicle (GV) stage further affects the developmental competence of preimplantation embryos and offspring quality. Synchronized female mice were exposed to thermal stress (40 degrees C, 65% RH) for 1.5-2h or maintained under normothermal conditions (25 degrees C, 45% RH). Thereafter, mice were paired with stud males. In the first experiment, mated mice were sacrificed 20h post hCG administration, and in vivo-derived zygotes were recovered and cultured in vitro. Maternal hyperthermia decreased the percentage of putative zygotes of apparent normal morphology in the heat-stressed group (81+/-1.3%) as compared to the control group (86+/-1.2%). Developmental competence was also compromised as expressed by the disruption in cleavage timing pattern, resulting in a reduced developmental rate to the blastocyst stage (57+/-2.6% versus 84+/-1.9%). In the second experiment, both groups were left with stud males until litter delivery. Litter size in the first delivery cycle was lower for the heat-stressed group (7.7+/-1.1 pups), followed by a slight increase throughout consecutive cycles as compared to the control group (11.3+/-1.0 pups). Behavioral examinations of 8-week-old pups revealed similar locomotor activity and learning potential between the groups. In summary, the findings indicate that a subpopulation of the ovarian pool of follicles is highly sensitive to thermal stress and that maternal hyperthermia disrupts developmental competence of GV-stage oocytes. Pups that developed from oocytes that survived thermal stress exhibited a developmental potential similar to that of the of control pups.

Angiogenesis in the Caprine Caruncles in Non-Pregnant and Pregnant Normal and Swainsonine-Treated Does

Microvascular corrosion casts of caruncles from non-pregnant and pregnant doe goats at 4, 7, 10, 13, 16, and 18 weeks were examined with scanning electron microscopy. The internal convex surface of the caruncles of non-pregnant does was covered with capillary meshes of regular diameter and form, without crypts. As pregnancy advanced the complexity of the vasculature increased: at 4 weeks the surface showed a pattern of ridges separated by troughs. At later stages, branches of radial arteries penetrated the periphery forming an extensive mesh of capillaries on the concave surface. Capillary diameters increased significantly during pregnancy, especially after 4 weeks, when large flattened sinusoids formed. These sinusoids had a great deal of surface area for potential contact with the fetal component. The caprine placenta is usually considered to have increased interhemal distance compared with endotheliochorial and hemochorial types: our results suggest that the very extensive development of sinusoids and crypts may compensate for any negative consequences of the placental architecture. Placental angiogenesis, which is physiologically normal, may serve as a general model of this process in other circumstances, such as tumor. The effect of swainsonine (active compound of locoweed and a potential anticancer drug) on vascular development showed no differences in sinusoidal diameters at 7 weeks, but a decrease in capillary density was noted. Swainsonine caused a great distortion to the vasculature at 18 weeks. The effects of this compound on the vascular development lend credibility to its potential as an anticancer agent.

Effects of endocrine disrupters on the oocytes and embryos of farm animals

Currently, approximately 60 chemicals have been identified as endocrine disruptors (EDs): exogenous agents that interfere with the synthesis, secretion, transport, metabolism, binding, action, or elimination of natural blood-borne hormones. Farm animals ingest these substances with food and drinking water. Their stability and lipid solubility has led to increased concern that these substances may compromise the reproductive health of both humans and animals. Oocytes are a permanent cell population established before birth which is exposed to environmental stimuli for a period that, in farm animals, can be as long as several years. Oocyte competence is acquired within the ovary during the developmental stages that precede ovulation and its role is critical during the interval between fertilization and the so-called maternal to embryonic transition, when the transcriptional activity of the embryonic genome becomes fully functional. Any perturbation of these delicate process is likely to reduce oocyte developmental competence and, therefore, to cause an arrest of embryonic development at any given stage. A critical analysis of the doses and time of exposure is presented together with a description of the effects of different EDs on farm animal oocytes and early embryonic development. Finally some of the mechanisms mediating EDs effects on the oocytes will be described. In particular the role of arylhydrocarbon receptor, maternal mRNA stability and cytoplasmic remodelling during oocyte maturation will be discussed in some details.

Experimental intoxication of pregnant goats with Tetrapterys multiglandulosa A. Juss. (Malpighiaceae)

Green leaves of Tetrapterys multiglandulosa A. Juss were fed to pregnant goats from day 35 of pregnancy. Five goats received 10g/kgBW (group I), five received 20g/kgBW (group II) and five were used as control (group III), and received only hay, fresh grass and commercial ration. All animals were clinically examined daily and submitted to ultrasonography every three days. Fetal death and vulvar catarrhal discharge with subsequent abortion were observed at the end of the second month of pregnancy in group II and at the third month of pregnancy in group I. Animals from groups I and II were slaughtered after abortion and necropsied. Goats from the control group were necropsied at the same time. The main lesions in the aborted goats were focal placentitis with early involution (apoptosis) and placentary coagulation necrosis, acute focal endometritis and vulvo-vaginal petechiae. All aborted fetuses were underdeveloped when compared to control fetuses, probably due to fetal malnutrition, since no congenital malformations could be noted. The majority of aborted fetuses showed some degree of autolysis, as fetal death occurred five and three days before abortion, in groups I and II, respectively. The most remarkable fetal lesions were focal or diffuse hemorrhages in the skin, meninges and visceral serosae.

Feed and forage toxicants affecting embryo survival and fetal development

Early embryonic and fetal development in mammals is sensitive to deficiencies and excesses of specific nutrients and toxicants. Operating directly and/or indirectly, these deficiencies and excesses can result in embryonic death or, in less severe circumstances, disruption of normal embryo and fetal growth. This paper explores the threats posed by feed and forage toxicants to the developing embryo and their impact on early programming of fetal development. Using significant examples, we consider the relevance of temporal sensitivities during early development in utero, and their implications for the morphology and functional competence of specific organs and tissues.

Effect of natural toxins on reproduction

Poisonous plants grow in most plant communities found on rangelands and pastures. They are one of the principal causes of economic loss to the livestock industry. One major costly effect is on reproduction, which includes birth defects, abortions, lengthened calving intervals, and interference with oogenesis, spermatogenesis, libido, and estrus. Those plants that cause wasting, temporary illness, and other such effects can adversely effect reproduction livestock.