Regional differences in the ultrastructure of mucosal macrophages in the rat large intestine.

We previously clarified the histological characteristics of macrophages in the rat small intestine using serial block-face scanning electron microscopy (SBF-SEM). However, the regional differences in the characteristics of macrophages throughout the large intestine remain unknown. Here, we performed a pilot study to explore the regional differences in the ultrastructure of mucosal macrophages in the large intestine by using SBF-SEM analysis.

Quantification of the tissue distribution and accumulation of the neonicotinoid pesticide clothianidin and its metabolites in maternal and fetal mice.

Neonicotinoids (NNs) are commonly used pesticides that have a selective agonistic action on insect nicotinic acetylcholine receptors. Recent evidence has shown that NNs have adverse effects in the next generation of mammals, but it remains unclear how NNs transferred from dams to fetuses are distributed and accumulated in fetal tissues. Here, we aimed to clarify the tissue distribution and accumulation properties of the NN clothianidin (CLO) and its 6 metabolites in 7 tissues and blood in both dams and fetuses of mice administered CLO for a single day or for 9 consecutive days.

Effect of clothianidin exposure at the no-observed-adverse-effect level (NOAEL) in a mouse model of atopic dermatitis.

The effects of exposure to clothianidin (CLO), a neonicotinoid pesticide (NN), on the thymus and intestinal microbiota were recently revealed. Immune cells express nicotinic acetylcholine receptors (nAChRs), an NN target, suggesting CLO may disrupt the immune system. However, the relationship between CLO and atopic dermatitis (AD) is unknown.

No-observed-adverse-effect-level (NOAEL) clothianidin, a neonicotinoid pesticide, impairs hippocampal memory and motor learning associated with alteration of gene expression in cerebellum.

Neonicotinoid pesticides (NNs) have been associated with numerous neurobehavioral effects in rodents, raising concerns about their impact on cognitive function. Clothianidin (CLO), a type of NN, was orally administered to male mice (10 weeks old, C57BL/6N) at the no-observed-adverse-effect level (NOAEL) of 50 mg/kg/day as indicated in the pesticide risk assessment report. Behavioral tests (novel location recognition and rotarod tests) evaluated hippocampal memory and cerebellar motor learning.

Establishment of an organ culture system to maintain the structure of mouse Müllerian ducts during development.

We previously showed that the anti-Müllerian hormone (AMH), infiltrating from the testis to the mesonephros reaches the cranial and middle regions of the Müllerian duct (MD) and induces their regression using an organ culture in mice. However, it is difficult to maintain structural integrity, such as the length and diameter and normal direction of elongation of the caudal region of the MD, in conventional organ culture systems. Therefore, the pathway of AMH to the caudal MD region remains uncharted.

Effects of exposure to the neonicotinoid pesticide clothianidin on α-defensin secretion and gut microbiota in mice.

The mechanism by which the neonicotinoid pesticide clothianidin (CLO) disrupts the intestinal microbiota of experimental animals is unknown. We focused on α-defensins, which are regulators of the intestinal microbiota. Subchronic exposure to CLO induced dysbiosis and reduced short-chain fatty acid-producing bacteria in the intestinal microbiota of mice.

Effects of exposure to the neonicotinoid pesticide clothianidin on mouse intestinal microbiota under unpredictable environmental stress.

Recent research has demonstrated the toxicity of neonicotinoid pesticides (NNs) in mammals through their interaction with nicotinic acetylcholine receptors (nAChRs). These effects are reported to extend to the intestinal microbiota as well. In addition, environmental stress affects the expression of nAChRs, which may alter sensitivity to NNs.

Direct diffusion of anti-Müllerian hormone from both the cranial and caudal regions of the testis during early gonadal development in mice.

Background: The Müllerian duct (MD), the primordium of the female reproductive tract, is also formed in males during the early stage of development, then regresses due to the anti-Müllerian hormone (AMH) secreted from the testes. However, the detailed diffusion pathway of AMH remains unclear. We herein investigated the mechanism by which AMH reaches the middle region of the MD using an organ culture system.

Histological study on the reginal difference in the localization of mucosal enteric glial cells and their sheath structure in the rat intestine.

The present study aimed to histologically clarify the regional specificity of the mucosal enteric glial cells (mEGCs) in the rat intestine with serial block-face scanning electron microscopy (SBF-SEM). SBF-SEM analysis with the ileum, the cecum and the descending colon revealed that mEGC nuclei were more abundant in the data stacks from the apical portion of the villus and the lateral portion of the crypt of the ileum. mEGCs exhibited a high rate of coverage over the nerve bundle around the lateral portion of the ileal crypt, but showed an extremely low level of coverage in the luminal portion of the cecum.

Transgenerational effects of developmental neurotoxicity induced by exposure to a no-observed-adverse-effect level (NOAEL) of neonicotinoid pesticide clothianidin.

Neonicotinoid pesticides (NNs) transfer rapidly from mother to offspring, which exhibit neurobehavioral effects. However, no studies have investigated NNs' transgenerational effects. We exposed F0 generation mice (mothers) to a no-observed-adverse-effect level (NOAEL) of clothianidin (CLO) during gestation and lactation, and examined the adult neurobehavioral effects of three generations of offspring (F1, F2, F3).

Diurnal changes in bacterial settlement on the Peyer's patch and surrounding mucosa in the rat ileum and its effect against the intestinal immune system.

Our previous study revealed the diurnal change in the indigenous bacteria settling on the terminal region of the rat ileum. In the present study, we investigated the diurnal change in indigenous bacteria on the most distal ileal Peyer's patch (PP) and surrounding ileal mucosa and explored how stimulation from indigenous bacteria for a day affects the intestinal immune system at the beginning of the light phase. Histological measurement revealed that bacteria adjacent to the follicle-associated epithelium of PP and to the villous epithelium of the surrounding ileal mucosa are more abundant at zeitgeber time (ZT)0 and ZT18 than at ZT12.

Developmental stage-specific exposure and neurotoxicity evaluation of low-dose clothianidin during neuronal circuit formation.

Neonicotinoid pesticides (NN) were recently reported to exhibit adverse effects in higher vertebrates. Moreover, NNs are routinely transferred from mother to offspring, raising concerns about their effects on future generations. The fetal and neonatal periods are the most critical to the formation of neural circuits in the brain through neurogenesis and differentiation, neuronal migration, axon guidance, and synaptogenesis.

Substrain differences in Sry expression at the stage of sex determination in C57BL/6 mouse strains.

The expression of sex determining region of the Y chromosome (Sry) in the fetal gonads is important for male development. In a mouse model of disorders of sex development (C57BL/6 (B6)-XY), the gonadal phenotype and the timing of Sry expression differ due to differences among B6 substrains as the genetic background. Since differences in Sry expression among B6 substrains have been speculated, the present study examined Sry expression in B6J, B6JJmsSlc, and B6NCrl mice.

Neurotoxicity and behavioral disorders induced in mice by acute exposure to the diamide insecticide chlorantraniliprole.

Diamide insecticides activate ryanodine receptors expressed in lepidopteran skeletal muscle and promote Ca release in the sarcoplasmic reticulum, causing abnormal contractions and paralysis, leading to death of the pest. Although they had been thought not to act on nontarget organisms, including mammals, adverse effects on vertebrates were recently reported, raising concerns about their safety in humans. We investigated the neurotoxicity of the acute no-observed-adverse-effect level of chlorantraniliprole (CAP), a diamide insecticide, in mice using clothianidin (CLO), a neonicotinoid insecticide, as a positive control.

Next-generation effects of fetal and lactational exposure to the neonicotinoid pesticide clothianidin on the immune system and gut microbiota.

Recently, the effects of exposure to clothianidin (CLO) on the thymus and gut microbiota have become clear, but no report has examined its next-generation impacts. Pregnant C57BL/6N mice were administered a no-observed-adverse-effect-level dose of CLO until weaning. We examined CLO's effects on the gut microbiota and immune organs of dams and their 3- and 10-week-old male offspring.

Histological study on regional specificity of the mucosal nerve network in the rat large intestine.

Our previous studies and others have revealed detailed characteristics of the mucosal nerve network in the small intestine, but much remains unknown about the corresponding network in the large intestine. We herein investigated regional differences in the expression of neurochemical markers, the nerve network structure, and the cells in contact with nerve fibers by histological analysis using both immunohistochemistry and serial block-face scanning electron microscopy (SBF-SEM). Immunohistochemistry revealed that immunopositive structures for protein gene product 9.

Quantitative elucidation of the transfer of the neonicotinoid pesticide clothianidin to the breast milk in mice.

Neonicotinoid pesticides (NNs) have been reported to have neurobehavioral effects on offspring after fetal and lactational exposure. In this study, clothianidin (CLO), an NN, was administered orally as a single dose (6.5 mg/kg: 1/10 of the no-observed-adverse-effect level in the current Pesticide Evaluation Report) to 10-day post-partum ICR mice, and CLO and its metabolites desmethyl-CLO (dm-CLO) were quantified using liquid chromatography-electrospray ionization/tandem mass spectrometry (LC-ESI/MS/MS) after collecting maternal breast milk and blood samples over time (1, 3, 6, 9, 12, and 24 h after administration).

Sex-specific behavioral effects of acute exposure to the neonicotinoid clothianidin in mice.

Although neonicotinoids are among the major classes of pesticides that affect mammalian nervous systems, little is known about sex differences in their effects. This study aimed to examine whether the neurobehavioral effects of a neonicotinoid, clothianidin (CLO), differed between sexes. Male and female C57BL/6N mice were orally administered CLO (5 or 50 mg/kg) at or below the chronic no-observed-adverse-effect-level (NOAEL) and subjected to behavioral tests of emotional and learning functions.

Region specificity of fibroblast-like cells in the mucosa of the rat large intestine.

Our previous studies using immunohistochemistry and serial block-face scanning electron microscopy (SBF-SEM) clarified that fibroblast-like cells (FBLCs) in the rat ileal mucosa are classifiable into several subtypes, but their characteristics throughout the large intestine remain unknown. In this study, we investigated the region-specific characteristics of FBLCs in the rat large intestine using histological analysis including SBF-SEM. Immunohistochemistry revealed that CD34CD31 FBLCs were localized in the lamina propria beneath the crypt bases throughout the large intestine and were more abundant in the descending colon than in the other regions.

Histological study of diurnal changes in bacterial settlement in the rat alimentary tract.

The composition of fecal bacteria is reported to change throughout the day, whereas the circadian rhythmicity of indigenous bacteria that settle on the epithelium is mostly unknown. The present study aimed to clarify the diurnal changes in the settlement of indigenous bacteria in the rat alimentary tract using histological analysis. The settlement of indigenous bacteria on the mucosal epithelium throughout the day and the diurnal changes in settlement levels were observed in the esophagus, the nonglandular area of the stomach, and the ileum.

Elucidation of the neurological effects of clothianidin exposure at the no-observed-adverse-effect level (NOAEL) using two-photon microscopy in vivo imaging.

Neonicotinoid pesticides (NNs) cause behavioral abnormalities in mammals, raising concerns about their effects on neural circuit activity. We herein examined the neurological effects of the NN clothianidin (CLO) by in vivo Ca imaging using two-photon microscopy. Mice were fed the no-observed-adverse-effect-level (NOAEL) dose of CLO for 2 weeks and their neuronal activity in the primary somatosensory cortex (S1) was observed weekly for 2 weeks.

Ultrastructural and phenotypical diversity of macrophages in the rat ileal mucosa.

Several types of macrophages have been reported in the intestinal mucosa, but their histological localization remains ambiguous. Here, we obtained detailed information about ultrastructural and phenotypical diversity of macrophage-like cells (MLCs) in the rat ileal mucosa using immunofluorescent analysis and serial block-face scanning electron microscopy (SBF-SEM). The results revealed that the cells immunopositive for CD68, the pan-macrophage marker, included CD163CD4, CD163CD4, and CD163CD4 cells in the lamina propria (LP) of the intestinal villus and around the crypt.

Aging-related changes in the sensitivity of behavioral effects of the neonicotinoid pesticide clothianidin in male mice.

Neonicotinoids, which act as agonists of the nicotinic acetylcholine receptors of insects, are widely used pesticides worldwide. Although epidemiological studies revealed that the detection amounts of neonicotinoids in urine are higher in the elderly population than other age-groups, there is no available information regarding the risks of neonicotinoids to older mammals. This study was aimed to investigate aging-related differences in the behavioral effects of the neonicotinoid pesticide clothianidin (CLO).

Effects of in utero and lactational exposure to the no-observed-adverse-effect level (NOAEL) dose of the neonicotinoid clothianidin on the reproductive organs of female mice.

Recently, developmental exposure to clothianidin (CLO) has been shown to cause reproductive toxicity in male mice, but the effects in female mice remain to be clarified. Pregnant C57BL/6N mice were given a no-observed-adverse-effect-level (NOAEL) dose of CLO until weaning. We then examined ovaries of 3- or 10-week-old female offspring.

Fetal and lactational exposure to the no-observed-adverse-effect level (NOAEL) dose of the neonicotinoid pesticide clothianidin inhibits neurogenesis and induces different behavioral abnormalities at the developmental stages in male mice.

Recently, it has been reported that neonicotinoid pesticides (NNs) are transferred from mother to child and are assumed to affect the next generation, but the behavioral effects of NN exposure at different developmental stages have not been investigated. We exposed mice to no-observed-adverse-effect level (NOAEL) doses of clothianidin (CLO) during the fetal and lactational period, and then evaluated the neurobehavioral effects in juvenile and adult mice. Significant increases in anxiety-like behavior and locomotor activity were observed in juveniles and adults, respectively, and neuronal activity and neurogenesis in the hippocampal dentate gyrus were affected in both stages.