The Effects of Chronic Lead Exposure on Testicular Development of Japanese Quail (Coturnix japonica): Histopathological Damages, Oxidative Stress, Steroidogenesis Disturbance, and Hypothalamus-Pituitary-Testis Axis Disruption

Mechanisms underlying reproductive responses of Japanese quails to heat stress conditions

Exposure to heat stress can cause a significant increase in the death rate and disease susceptibility of poultry birds, ultimately impacting the profitability of the poultry industry. Despite being a more economical choice, Japanese quails (Coturnix japonica) are not immune to the harmful effects of heat stress. Quails may experience negative effects on their reproductive performance due to excessive reactive molecules caused by heat stress. However, they have developed various mechanisms to maintain their reproductive abilities in such conditions. The neuroendocrine system in birds plays a vital role in regulating their reproductive responses to thermal stress, and it is also connected to other environmental factors such as photoperiod that can impact their reproductive performance. Hormones are crucial in the complex interactions necessary for sexual maturation and reproductive responses to heat stress in Japanese quails living in stressful thermal conditions.

Lead induced cerebellar toxicology of developmental Japanese quail (Coturnix japonica) via oxidative stress-based Nrf2/Keap1 pathway inhibition and glutathione-mediated apoptosis signaling activation

Lead (Pb) is a heavy metal that has been recognized as a neurotoxin, meaning it can cause harmful effects on the nervous system. However, the neurotoxicology of Pb to birds still needs further study. In this study, we examined the neurotoxic effects of Pb exposure on avian cerebellum by using an animal model-Japanese quail (Coturnix japonica). The one-week old male chicks were exposed to 50, 200 and 500 mg/kg Pb of environmental relevance in the feed for five weeks. The results showed Pb caused cerebellar microstructural damages charactered by deformation of neuroglia cells, granule cells and Purkinje cells with Nissl body changes. Moreover, cerebellar neurotransmission was disturbed by Pb with increasing acetylcholine (ACh) and decreasing acetylcholinesterase (AChE), dopamine (DA), γ-Aminobutyric Acid (GABA) and Na+/K+ ATPase. Meanwhile, cerebellar oxidative stress was caused by Pb exposure represented by increasing reactive oxygen species (ROS) and malondialdehyde (MDA) as well as decreasing catalase (CAT), glutathione peroxidase (GPX), glutathione (GSH) and superoxide dismutase (SOD). Moreover, RNA-Seq analysis showed that molecular signaling pathways in the cerebellum were disrupted by Pb exposure. In particular, the disruption of nuclear factor erythroid-2-related factor 2 (Nfr2)/kelch-like ECH-associated protein 1 (Keap1) pathway and glutathione metabolism pathway indicated increasing cell apoptosis and functional disorder in the cerebellum. The present study revealed that Pb induced cerebellar toxicology through structural injury, oxidative stress, neurotransmission interference and abnormal apoptosis.

A critical review on the ecotoxicity of heavy metal on multispecies in global context: A bibliometric analysis

Heavy metals (HMs) have become a significant concern in the current era, with deleterious effects on diverse living organisms when exposed beyond threshold concentrations. Both nature and human beings have been constantly casting out HMs into environmental matrices through various activities. Innumerable cases of threatened diseases such as cancer, respiratory ailments, reproductive defects, skin diseases, and several others have been a cause of significant concern for humans as the number of instances has been increasing with each decade. HMs migrates via several pathways to infiltrate biological organisms and amass within them. Even though numerous treatment approaches are available for remediating HM pollution, however, they are expensive, along with other setbacks. Due to such constraints, combating HM contamination requires environmentally conscious strategies like bioremediation, which employs an array of biological systems to remove HMs from the environment. Nonetheless, to address the current global HM pollution situation, it is critical to comprehend not only how these hazardous HMs cause toxicity in various living organisms but also the knowledge gaps that currently exist concerning the subject of HM ecotoxicity. In the present investigation, data was extracted from Google Scholar using software program called Harzing's Publish or Perish. The collected information has been subsequently displayed as a network file using the VOSViewer software tool. Thus, the current review presents a significant insight with the inclusion of a readily accessible bibliometric analysis to comprehend the present status of HMs research, global research trends, existing knowledge discrepancies, and research challenges. Further, it also provides an in-depth review of HMs ecotoxicity, with a focus on arsenic (As), cadmium (Cd), and lead (Pb). Thus, as indicated by the bibliometric study, the present review will assist future investigators studying HMs ecotoxicity by providing baseline data concerning a wide range of living organisms and by addressing research gaps.

Exposure to Sublethal Concentrations of Lead (Pb) Affects Ecologically Relevant Behaviors in House Sparrows (Passer domesticus)

Global contamination of environments with lead (Pb) poses threats to many ecosystems and populations. While exposure to Pb is toxic at high concentrations, recent literature has shown that lower concentrations can also cause sublethal, deleterious effects. However, there remains relatively little causal investigation of how exposure to lower concentrations of environmental Pb affects ecologically important behaviors. Behaviors often represent first-line responses of an organism and its internal physiological, molecular, and genetic responses to a changing environment. Hence, better understanding how behaviors are influenced by pollutants such as Pb generates crucial information on how species are coping with the effects of pollution more broadly. To better understand the effects of sublethal Pb on behavior, we chronically exposed adult wild-caught, captive house sparrows (Passer domesticus) to Pb-exposed drinking water and quantified a suite of behavioral outcomes: takeoff flight performance, activity in a novel environment, and in-hand struggling and breathing rate while being handled by an experimenter. Compared to controls (un-exposed drinking water), sparrows exposed to environmentally relevant concentrations of Pb exhibited decreases in takeoff flight performance and reduced movements in a novel environment following 9-10 weeks of exposure. We interpret this suite of results to be consistent with Pb influencing fundamental neuro-muscular abilities, making it more difficult for exposed birds to mount faster movements and activities. It is likely that suppression of takeoff flight and reduced movements would increase the predation risk of similar birds in the wild; hence, we also conclude that the effects we observed could influence fitness outcomes for individuals and populations altering ecological interactions within more naturalistic settings.

Aflatoxin B1-Induced Testosterone Biosynthesis Disorder via the ROS/AMPK Signaling Pathway in Male Mice

The worldwide prevalence of Aflatoxin B1 (AFB1), which contaminates feedstock and food, is on the rise. AFB1 inhibits testosterone (T) biosynthesis, but the mechanism is not yet clear. By establishing in vivo and in vitro models, this study found the number of Leydig cells (LCs), T content, and the expression of T biosynthesis key enzymes were suppressed after AFB1 treatment. AFB1 exposure also increased reactive oxygen species (ROS) and promoted mitochondrial injury and mitochondrial pathway apoptosis. Moreover, the AMPK signaling pathway was activated, and using an AMPK inhibitor relieved apoptosis and the suppressed T biosynthesis key enzymes of LCs caused by AFB1 through regulating downstream p53 and Nur77. Additionally, adding ROS intervention could inhibit AMPK activation and alleviate the decreased T content caused by AFB1. In summary, AFB1 promotes the apoptosis of LCs and inhibits T biosynthesis key enzyme expression via activating the ROS/AMPK signaling pathway, which eventually leads to T synthesis disorder.

Role of Eruca sativa L. seeds in boosting the reproductive performance of male Japanese quails (Coturnix c. japonica)

Herein we attempt to shed light on the potential improving effect of Eruca sativa seeds (ESS) on the reproductive aspects of male Japanese quails. To accomplish this objective, two groups of quails were supplemented with ESS powder at doses of 5 and 10 g/kg feed from 7 days to 140 days of age, in addition to the control group, which did not receive treatment. Forty males were reared singly in cages to evaluate sperm characters and 32 males were raised with 64 females to evaluate fertility and sperm penetrability. Sixty-six phytochemical compounds were found according to gas chromatography-mass spectrometry analysis of ESS. The most plentiful ones are 13-docosenoic acid methyl ester, 9-octadecenoic acid methyl ester, and linoleic acid methyl ester. Both 5 g/kg and 10 g/kg doses of ESS showed similar effectiveness in enhancing various reproductive parameters, including gonadal index, sperm characteristics, fertility, libido, and cloacal gland attributes. However, some aspects like sperm concentration and testosterone levels exhibited a dose-dependent response. There is no significant change in mortality rate of supplemented groups compared to the control one. ESS also caused a reduction in feed intake and an enhancement in feed conversion ratio without affecting final body weight and body weight gain. This suggests potential nutritional benefits beyond reproductive health. The low-dose-fed group showed a significant reduction in total cholesterol and malondialdehyde compared to the high-dose-fed and unfed groups. The higher dose notably increased total antioxidant capacity compared to the lower dose and control group. Despite the positive effects on male reproductive parameters, there wasn't a significant impact on hatchability percentage, indicating that while male fertility improved, it might not have directly affected the viability of the eggs. Overall, the study suggests that ESS could be a safe and promising addition to the diet of male Japanese quails to enhance their reproductive capabilities without adverse effects. The findings could have implications for poultry farming by potentially improving breeding efficiency and health outcomes in quails.

Sodium acetate abates lead-induced sexual dysfunction by upregulating testosterone-dependent eNOS/NO/cGMP signaling and activating Nrf2/HO-1 in male Wistar rat

Oxidative stress has been linked with lead toxicity, including lead-induced sexual dysfunction. On the contrary, sodium acetate has been proven to exert antioxidant activity. However, the effect of sodium acetate on lead-induced sexual dysfunction has not been fully explored. This study investigated the effect of sodium acetate on lead-induced sexual dysfunction, exploring the involvement of testosterone, eNOS/NO/cGMP, and Nrf2/HO-1 signaling. Twenty male Wistar rats with similar weights were randomly assigned into four groups (n = 5 rats/group) after two weeks of acclimatization. Animals were vehicle-treated (0.5 ml/day of distilled water, per os), acetate-treated (200 mg/kg/day, per os), lead-treated (20 mg/kg/day, per os), or lead + acetate-treated. The results revealed that sodium acetate treatment attenuated lead-induced rise in penile lead, malondialdehyde and oxidized glutathione concentrations, and acetylcholinesterase activity. In addition, lead exposure prolonged mount, intromission, and ejaculation latency and reduced mount, intromission, and ejaculation frequency, as well as the motivation to mate and penile reflex, which were improved by acetate treatment. More so, acetate treatment ameliorated lead-induced reductions in absolute and relative penile weight, eNOS, NO, cGMP, luteinizing hormone, follicle-stimulating hormone, testosterone, dopamine, Nrf2, HO-1, and reduced glutathione concentrations, as well as glutathione reductase, glutathione peroxidase, glutathione-S-transferase, superoxide dismutase, and catalase activities. In conclusion, this study demonstrates that sodium acetate attenuated lead-induced sexual dysfunction by upregulating testosterone-dependent eNOS/NO/cGMP and Nrf2/HO-1 signaling. Despite the compelling data presented in this study, other possible associated mechanisms in the protective role of acetate should be explored.

Microplastics induced inflammation in the spleen of developmental Japanese quail (Coturnix japonica) via ROS-mediated p38 MAPK and TNF signaling pathway activation1

Microplastics (MPs) have been found in virtually every environment on earth and become a source of pollution around the world. The toxicology of microplastics on immunity is an emerging area of research, and more studies are needed to fully understand the effects of microplastics exposure on animal health. Therefore, we tried to determine the immunotoxic effects of microplastics on avian spleen by using an animal model- Japanese quail (Coturnix japonica). One-week chicks were exposed to environmentally relevant concentrations of 0.02 mg/kg, 0.4 mg/kg and 8 mg/kg polystyrene microplastics in the feed for 5 weeks. The results demonstrated that microplastics induced microstructural injuries featured by cell disarrangement and vacuolation indicating splenic inflammation. Ultrastructural damages including membrane lysis and mitochondrial vacuolation also suggested inflammatory responses in the spleen by microplastics exposure. Meanwhile, increasing reactive oxygen species (ROS) and Malondialdehyde (MDA) while the inactivation of superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) indicated oxidative stress in the spleen. Moreover, the increasing level of proinflammatory cytokines including Tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin-1β (IL-1β), interleukin-6 (IL-6) and decreasing level of anti-inflammatory cytokine interleukin-10 (IL-10) implied splenic inflammation. Furthermore, transcriptomic analysis showed that microplastics induced inflammatory responses in the spleen through p38 mitogen-activated protein kinases (p38 MAPK) pathway activation and tumor necrosis factor (TNF) signaling stimulation. The signaling stimulation also aggravated cell apoptosis in the spleen. The present study may benefit to understand potential mechanisms of developmental immunotoxicology of microplastics.

Lead exposure disrupted ileal barrier of developmental Japanese quails(Coturnix japonica): Histopathological damages, microbiota dysbiosis and immune disorder

The gut barrier plays an essential role in maintaining homeostasis and is usually composed of a mechanical barrier, a chemical barrier, an immune barrier, and a biological barrier. However, the impacts of lead (Pb) exposure on avian gut barrier are still unclear. Therefore, the present study tried to determine the toxic effects of Pb on ileal barrier of a biological model-Japanese quail (Coturnix japonica). One-week old quails were exposed to 0, 50, 500 and 1000 ppm Pb in drinking water for 5 weeks. The results showed mechanic barrier in the ileum was disrupted with microstructural deformation featured by epithelial cell abscission, villi contractions and goblet cells reduction as well as ultrastructural changes characterized by swollen mitochondria, blurry tight junctions and microvilli subtraction. Meanwhile, the expression of genes associated with intestinal tight junctions was downregulated in Pb-treated groups indicating tight junction malfunction. Moreover, less mucus and downregulation of expression of mucin2 (Muc2) and Krüppel-like factor 4 (Klf4) indicated chemical barrier disturbance by Pb. In addition, the alteration of microbial diversity and emergence of pathogen bacteria suggested ileal biological barrier disruption by Pb. Furthermore, Pb caused immune dysfunction in the ileum through promoting the expression of pro-inflammatory factors including interleukin 1 beta (IL-1β), interleukin 6 (IL-6), Interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α) and nuclear factor kappa B (NF-κB) and inhibiting the expression of anti-inflammatory factor interleukin 10 (IL-10). The present study demonstrated that Pb may pose health risks to birds through gut barrier damages.

Heavy metal toxicity in poultry: a comprehensive review

Arsenic (As), lead (Pb), cadmium (Cd), and mercury (Hg) have been recognized as most toxic heavy metals that are continuously released into the environment, both from natural sources and from anthropogenic production of fertilizers, industrial activities, and waste disposal. Therefore, As, Cd, Hg, and Pb are found in increasing concentrations in bodies of water, fodder, feed, and in the tissues of livestock, including poultry, in the surroundings of industrial areas, leading to metabolic, structural, and functional abnormalities in various organs in all animals. In poultry, bioaccumulation of As, Pb, Cd, and Hg occurs in many organs (mainly in the kidneys, liver, reproductive organs, and lungs) as a result of continuous exposure to heavy metals. Consumption of Cd lowers the efficiency of feed conversion, egg production, and growth in poultry. Chronic exposure to As, Pb, Cd, and Hg at low doses can change the microscopic structure of tissues (mainly in the brain, liver, kidneys, and reproductive organs) as a result of the increased content of these heavy metals in these tissues. Histopathological changes occurring in the kidneys, liver, and reproductive organs are reflected in their negative impact on enzyme activity and serum biochemical parameters. Metal toxicity is determined by route of exposure, length of exposure, and absorbed dosage, whether chronic and acute. This review presents a discussion of bioaccumulation of As, Cd, Pb, and Hg in poultry and the associated histopathological changes and toxic concentrations in different tissues.