A novel animal model of tegafur-induced hand-foot syndrome.

Hand-foot syndrome (HFS) is a common side effect of fluoropyrimidine anticancer drugs and often becomes a dose-limiting manifestation of toxicity once it occurs. The precise mechanism of HFS remains unclear, and effective measures to prevent or relieve it are currently limited. To investigate the pathogenesis of HFS and effective measures for treating or preventing it, establishment of animal models is crucial. Here, we gave male SD rats 170 mg/kg of tegafur (prodrug of 5-FU) daily for 35 days and evaluated their clinical and histopathological characteristics and pain-related behavioral tests. TUNEL-positive apoptotic cells and 5-FU concentrations in the plantar skin were also evaluated to investigate the mode of toxicity. Tegafur treatment induced hypersensitivity to mechanical pressure on the plantar surface beginning in Week 3, with decreased locomotor activity. Focal desquamation of the plantar skin was observed almost concomitantly and gradually worsened to palmar and plantar skin thickening with severe desquamation, cracks, or both. Histopathological lesions in the plantar skin at treatment end included desquamation and thickening, with epidermal cell swelling and spongiosis and focal inflammation in the dermis. The time-course of development and the characteristics of the tegafur-induced skin lesions were highly similar to those in human fluoropyrimidine-induced HFS, indicating that a HFS rat model was successfully established. Localized high concentrations of 5-FU in the palmar and plantar skin, with increased apoptosis, are likely involved in the mode of toxicity. Our model should clarify the pathogenesis of HFS, providing new insights into the best supportive care and prevention.

Intraorbital Dural Arteriovenous Fistula Treated by Transarterial Embolization Using Onyx: A Case Report.

Objective: Intraorbital dural arteriovenous fistula (IO-dAVF) is a rare condition, and treatment options vary from case to case. We report a case of transarterial embolization (TAE) for IO-dAVF. Case Presentation: A 62-year-old male complained of gradually worsening pain, hyperemia, and visual impairment in the right eye. He did not exhibit diplopia or exophthalmos. Cerebral angiography revealed an arteriovenous fistula in the right orbit. The feeding arteries were the ophthalmic artery (OphA) and the artery of the superior orbital fissure (ASOF), with the superior ophthalmic vein (SOV) as the main draining vein. The venous pathway from the SOV was not clearly visible, and considering the risk of blindness with TAE from the OphA, TAE from the ASOF was performed. Onyx 18 was selected as the liquid embolic material and injected through a microcatheter placed in the internal maxillary artery. Occlusion up to the SOV was achieved, and the shunt flow completely disappeared. Normal blood flow in the OphA was maintained, hyperemia improved, and no complications were observed. Conclusion: In cases of IO-dAVF, when transvenous embolization is difficult to perform, TAE using Onyx from the vessel of the external carotid artery system may be preferred over OphA.

Novel use of a closed-tip stent retriever to prevent distal embolism in the posterior circulation: illustrative case.

BACKGROUND: In mechanical thrombectomy for tandem occlusions in vertebrobasilar stroke, distal emboli from the vertebral artery lesion should be prevented. However, no suitable embolic protection devices are currently available in the posterior circulation. Here, the authors describe the case of a vertebral artery lesion effectively treated with a closed-tip stent retriever as an embolic protection device in the posterior circulation. OBSERVATIONS: A 65-year-old male underwent mechanical thrombectomy for basilar artery occlusion, with tandem occlusion of the proximal vertebral artery. After basilar artery recanalization via the nonoccluded vertebral artery, a subsequent mechanical thrombectomy was performed for the occluded proximal vertebral artery. To prevent distal embolization of the basilar artery, an EmboTrap III stent retriever was deployed as an embolic protection device within the basilar artery to successfully capture the thrombus. LESSONS: A stent retriever with a closed-tip structure can effectively capture thrombi, making it a suitable distal embolic protection device in the posterior circulation.

Clinical evaluation of mechanical thrombectomy for patients with posterior circulation occlusion: A retrospective study.

OBJECTIVE: Although consensus has been reached regarding the use of mechanical thrombectomy for acute large anterior circulation occlusion, its effectiveness in patients with posterior circulation occlusion remains unclear. This study aimed to establish the determining factors for good clinical outcomes of mechanical thrombectomy for posterior circulation occlusion. METHODS: We extracted cases of acute large vessel occlusion (LVO) in the posterior circulation from a database comprising 536 patients who underwent mechanical thrombectomy at our hospital between April 2015 and March 2021. RESULTS: Fifty-two patients who underwent mechanical thrombectomy for LVO in the posterior circulation were identified. Five patients with simultaneous occlusion of the anterior and posterior circulation were excluded; finally, 47 patients were included in this study. The median patient age was 78 years, and 36% of the patients were women. The median National Institutes of Health Stroke Scale (NIHSS) score on admission was 31, the median posterior circulation-Alberta Stroke Program Early Computed Tomography Score (pc-ASPECTS) was 8, and the median Basilar Artery on Computed Tomography Angiography (BATMAN) score was 6. The rate of good recanalization (Thrombolysis in Cerebral Infarction scale grades 2b and 3) was 96%, and a good prognosis (modified Rankin Scale score of 0-2 at 90 days) was achieved in 19 patients (40%). The median pc-ASPECTS was significantly higher in the good prognosis group than in the poor prognosis group (10 vs. 7; p = 0.007). The median NIHSS score at presentation was significantly lower in the good prognosis group than in the poor prognosis group (17 vs. 34; p = 0.02). The median BATMAN score was significantly higher in the good prognosis group than in the poor prognosis group (8 vs. 3.5; p = 0.0002). Multivariate analysis showed that an NIHSS score ≦ 20 at presentation was the only independent factor for good prognoses. CONCLUSION: The prognosis of mechanical thrombectomy for posterior circulation LVO was better in patients with lower NIHSS scores at presentation.

Cervical dumbbell-type tumor spontaneously shrinking following an ischemic stroke.

Background: Asymptomatic cervical dumbbell-type tumors can be incidentally diagnosed. Notably, the chronological changes in the size of these tumors have not been satisfactorily described. Case Description: A 57-year-old man was clinically followed for an asymptomatic cervical dumbbell-type tumor that had the appearance of a schwannoma on magnetic resonance (MR) images obtained over a 7-year period. Notably, the tumor compressed both the spinal cord and the right vertebral artery. At the end of the 7-year period, the patient sustained a cerebral infarction due to atherosclerosis of the right vertebral artery; the angiogram revealed both atherosclerosis and the tumor compressing the right vertebral artery. After the stroke/ischemic event, the tumor progressively shrunk on MR images obtained for the following 4 years, and the spinal cord compression was similarly relieved. Conclusion: Here, we report on a 57-year-old man with cervical MR images revealing that a cervical dumbbell schwannoma was progressively compressing both the spinal cord and the right vertebral artery. However, following a cerebral infarction, the tumor underwent spontaneous shrinkage over the next 4 years, thus relieving the compression.

A case of anterior arch fracture of the atlas associated with C1 laminectomy.

Background: Spontaneous anterior arch fracture of the atlas after a C1 laminectomy (CIL) is an extremely rare complication. Case Description: A 72-year-old male presented with the sudden onset of neck pain. His prior history included; a CIL for atlantoaxial subluxation, shunt closure for a spinal dural arteriovenous fistula at C3, a cervical laminoplasty from C3 to C6 for stenosis, and a prior anterior C4/5 and C5/6 fusion 14 years ago. Once the computed tomography documented a right C1 anterior arch fracture, and occipital-cervical fusion was performed utilizing C2 laminar screws and C4 pedicle screws with halo-vest placement. Postoperatively, the neck pain resolved and he remained stable. Conclusion: Neurosurgeons should be aware of the risk of anterior arch fractures following a CIL and may alternatively consider a C1 laminoplasty in the future.

Deep Learning Enables Instant and Versatile Estimation of Rice Yield Using Ground-Based RGB Images.

Rice (Oryza sativa L.) is one of the most important cereals, which provides 20% of the world's food energy. However, its productivity is poorly assessed especially in the global South. Here, we provide a first study to perform a deep-learning-based approach for instantaneously estimating rice yield using red-green-blue images. During ripening stage and at harvest, over 22,000 digital images were captured vertically downward over the rice canopy from a distance of 0.8 to 0.9 m at 4,820 harvesting plots having the yield of 0.1 to 16.1 t·ha-1 across 6 countries in Africa and Japan. A convolutional neural network applied to these data at harvest predicted 68% variation in yield with a relative root mean square error of 0.22. The developed model successfully detected genotypic difference and impact of agronomic interventions on yield in the independent dataset. The model also demonstrated robustness against the images acquired at different shooting angles up to 30° from right angle, diverse light environments, and shooting date during late ripening stage. Even when the resolution of images was reduced (from 0.2 to 3.2 cm·pixel-1 of ground sampling distance), the model could predict 57% variation in yield, implying that this approach can be scaled by the use of unmanned aerial vehicles. Our work offers low-cost, hands-on, and rapid approach for high-throughput phenotyping and can lead to impact assessment of productivity-enhancing interventions, detection of fields where these are needed to sustainably increase crop production, and yield forecast at several weeks before harvesting.

An interdural spinal cyst in the cervicothoracic spine: a review and proposal for a revised classification of spinal meningeal cysts. Illustrative case.

BACKGROUND: Spinal cysts in the interdural space are extremely rare and are not included in the standard classification of spinal meningeal cysts. OBSERVATIONS: A 60-year-old female presented to our hospital with a spastic gait and numbness in both palms. Magnetic resonance imaging (MRI) revealed a spinal cyst from C4 to T4 compressing the spinal cord. Computed tomography myelography revealed a fistula at C4-5 and C5-6 that connected the cyst along the right C5 and C6 root sleeves. The cyst was located within the dura mater, and communication with the arachnoid space was achieved using a shunt tube. There was partial spastic gait amelioration after the procedure, but the patient experienced a relapse 2 months postoperation. A repeat procedure was performed without a shunt tube to allow greater communication between the cyst and the subarachnoid space. After this, marked improvement in gait function was observed, and MRI showed a significant reduction in cyst volume. LESSONS: Interdural spinal meningeal cysts are rare. When the interdural cyst cannot be removed entirely, surgery may be appropriate for providing a shunt tube or establishing communication between the cyst and arachnoid space to maintain the circulation of cerebrospinal fluid collected in the cyst cavity.

Pathological Examination of Radiologically Fused Interbody Tissue Five Years After Anterior Cervical Discectomy and Fusion Using the Titanium Cage System: A Report of Two Cases.

This case report aimed to identify potential relationships between pathological and radiological assessments of bony fusion after anterior cervical discectomy and fusion (ACDF). ACDF can resolve neurological symptoms related to cervical spondylosis, such as myelopathy and radiculopathy. Intervertebral bony fusion is a key outcome for successful ACDF, often assessed on radiography and computed tomography (CT) images. However, the pathological findings of tissues demonstrating bony fusion after ACDF have not been well studied. This report presents the cases of two female patients, aged 62 and 40 years, who underwent additional ACDFs for recurrent cervical radiculopathy. Findings from CT imaging identified intervertebral calcification in the titanium spacers placed in the first ACDF. In both cases, recurrent compression of nerve roots was observed radiologically. Cervical nerve root block identified habitual symptoms related to recurrent radiculopathy. To resolve the clinical symptoms, additional ACDFs were performed in two cases. In the second ACDF, the titanium cases from the prior ACDF were removed. Histopathological examination of the tissues from the removed cages revealed growth of cartilage tissue. This is the first report concerning the histopathological evaluation of the tissue in titanium spacers placed in ACDF. Completion of intervertebral calcification in titanium spacers placed in ACDF may not signify completion of intervertebral bony fusion after ACDF.

Disruption of postnatal neurogenesis and adult-stage suppression of synaptic plasticity in the hippocampal dentate gyrus after developmental exposure to sterigmatocystin in rats.

Exposure to sterigmatocystin (STC) raises concerns on developmental neurological disorders. The present study investigated the effects of maternal oral STC exposure on postnatal hippocampal neurogenesis of offspring in rats. Dams were exposed to STC (1.7, 5.0, and 15.0 ppm in diet) from gestational day 6 until day 21 post-delivery (weaning), and offspring were maintained without STC exposure until adulthood on postnatal day (PND) 77, in accordance with OECD chemical testing guideline Test No. 426. On PND 21, 15.0-ppm STC decreased type-3 neural progenitor cell numbers in the subgranular zone (SGZ) due to suppressed proliferation. Increased γ-H2AX-immunoreactive (+) cell numbers in the SGZ and Ercc1 upregulation and Brip1 downregulation in the dentate gyrus suggested induction of DNA double-strand breaks in SGZ cells. Upregulation of Apex1 and Ogg1 and downregulation of antioxidant genes downstream of NRF2-Keap1 signaling suggested induction of oxidative DNA damage. Increased p21WAF1/CIP1+ SGZ cell numbers and suppressed cholinergic signaling through CHRNB2-containing receptors in GABAergic interneurons suggested potential neurogenesis suppression mechanisms. Multiple mechanisms involving N-methyl-d-aspartate (NMDA) receptor-mediated glutamatergic signaling and various GABAergic interneuron subpopulations, including CHRNA7-expressing somatostatin+ interneurons activated by BDNF-TrkB signaling, may be involved in ameliorating the neurogenesis. Upregulation of Arc, Ptgs2, and genes encoding NMDA receptors and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors suggested synaptic plasticity facilitation. On PND 77, ARC+ granule cells decreased, and Nos2 was upregulated following 15.0 ppm STC exposure, suggesting oxidative stress-mediated synaptic plasticity suppression. Inverse pattern in gene expression changes in vesicular glutamate transporter isoforms, Slc17a7 and Slc17a6, from weaning might also be responsible for the synaptic plasticity suppression. The no-observed-adverse-effect level of maternal oral STC exposure for offspring neurogenesis was determined to be 5.0 ppm, translating to 0.34-0.85 mg/kg body weight/day.

Successful shrinkage of anterior communicating artery aneurysm after ACA-ACA bypass with interposed occipital artery graft in pediatric moyamoya disease: illustrative case.

BACKGROUND: Selecting therapeutic options for moyamoya disease (MMD)-associated anterior communicating artery (ACoA) aneurysm, a rare pathology in children, is challenging because its natural course remains unclear. OBSERVATIONS: A 4-year-old boy exhibiting transient ischemic attacks was diagnosed with unilateral MMD accompanied by an unruptured ACoA aneurysm. Although superficial temporal artery to middle cerebral artery anastomosis eliminated his symptoms, the aneurysm continued to grow after surgery. Since a previous craniotomy and narrow endovascular access at the ACoA precluded both aneurysmal clipping and coil embolization, the patient underwent a surgical anastomosis incorporating an occipital artery graft between the bilateral cortical anterior cerebral arteries (ACAs). This was intended to augment blood flow in the ipsilateral ACA territory and to reduce the hemodynamic burden on the ACoA complex. The postoperative course was uneventful, and radiological images obtained 12 months after surgery revealed good patency of the bypass and marked shrinkage of the aneurysm in spite of the intact contralateral internal carotid artery. LESSONS: Various clinical scenarios should be assessed carefully with regard to this pathology. Bypass surgery aimed at reducing flow to the aneurysm might be an alternative therapeutic option when neither coiling nor clipping is feasible.

Monodisperse Liposomes with Femtoliter Volume Enable Quantitative Digital Bioassays of Membrane Transporters and Cell-Free Gene Expression.

Digital bioassays have emerged as a new category of bioanalysis. However, digital bioassays for membrane transporter proteins have not been well established yet despite high demands in molecular physiology and molecular pharmacology due to the lack of biologically functional monodisperse liposomes with femtoliter volumes. Here, we established a simple and robust method to produce femtoliter-sized liposomes (femto-liposomes). We prepared 106 monodispersed water-in-oil droplets stabilized by a lipid monolayer using a polyethylene glycol-coated femtoliter reactor array device. Droplets were subjected to the optimized emulsion transfer process for femto-liposome production. Liposomes were monodispersed (coefficient of variation = 5-15%) and had suitable diameter (0.6-5.3 µm) and uniform volumes of subfemtoliter or a few femtoliters; thus, they were termed uniform femto-liposomes. The unilamellarity of uniform femto-liposomes allowed quantitative single-molecule analysis of passive and active transporter proteins: α-hemolysin and FoF1-ATPase. Digital gene expression in uniform femto-liposomes (cell-free transcription and translation from single DNA molecules) was also demonstrated, showing the versatility of digital assays for membrane transporter proteins and cell-free synthetic biology.

Downregulation of low-density lipoprotein receptor class A domain-containing protein 4 (Ldlrad4) in the liver of rats treated with nongenotoxic hepatocarcinogen to induce transforming growth factor ß signaling promoting cell proliferation and suppressing apoptosis in early hepatocarcinogenesis.

We previously found downregulation of low-density lipoprotein receptor class A domain-containing protein 4 (LDLRAD4), a negative regulator of transforming growth factor (TGF)-ß signaling, in glutathione S-transferase placental form (GST-P) expressing (+ ) pre-neoplastic lesions produced by treatment with nongenotoxic hepatocarcinogens for up to 90 days in rats. Here, we investigated the relationship between LDLRAD4 downregulation and TGFß signaling in nongenotoxic hepatocarcinogenesis. The transcripts of Tgfb and Hb-egf increased after ≥28 days of treatment. After 84 or 90 days, Snai1 increased transcripts and the subpopulation of GST-P+ foci downregulating LDLRAD4 co-expressed TGFß1, phosphorylated EGFR, or phosphorylated AKT2, and downregulated PTEN, showing higher incidences than those in GST-P+ foci expressing LDLRAD4. The subpopulation of GST-P+ foci downregulating LDLRAD4 also co-expressed caveolin-1 or TACE/ADAM17, suggesting that disruptive activation of TGFß signaling through a loss of LDLRAD4 enhances EGFR and PTEN/AKT-dependent pathways via caveolin-1-dependent activation of TACE/ADAM17 during nongenotoxic hepatocarcinogenesis. The numbers of c-MYC+ cells and PCNA+ cells were higher in LDLRAD4-downregulated GST-P+ foci than in LDLRAD4-expressing GST-P+ foci, suggesting a preferential proliferation of pre-neoplastic cells by LDLRAD4 downregulation. Nongenotoxic hepatocarcinogens markedly downregulated Nox4 after 28 days and later decreased cleaved caspase 3+ cells in LDLRAD4-downregulated GST-P+ foci, suggesting an attenuation of apoptosis by LDLRAD4 downregulation through activation of the EGFR pathway. At the late hepatocarcinogenesis stage in a two-stage model, LDLRAD4 downregulation was higher in adenoma and carcinoma than in pre-neoplastic cell foci, suggesting a role of LDLRAD4 downregulation in tumor development. Our results suggest that nongenotoxic hepatocarcinogens cause disruptive activation of TGFß signaling through downregulating LDLRAD4 toward carcinogenesis in the rat liver.

Developmental exposure to diacetoxyscirpenol reversibly disrupts hippocampal neurogenesis by inducing oxidative cellular injury and suppressed differentiation of granule cell lineages in mice.

To investigate the developmental exposure effect of diacetoxyscirpenol (DAS) on postnatal hippocampal neurogenesis, pregnant ICR mice were provided a diet containing DAS at 0, 0.6, 2.0, or 6.0 ppm from gestational day 6 to day 21 on weaning after delivery. Offspring were maintained through postnatal day (PND) 77 without DAS exposure. On PND 21, neural stem cells (NSCs) and all subpopulations of proliferating progenitor cells were suggested to decrease in number in the subgranular zone (SGZ) at ≥ 2.0 ppm. At 6.0 ppm, increases of SGZ cells showing TUNEL+, metallothionein-I/II+, γ-H2AX+ or malondialdehyde+, and transcript downregulation of Ogg1, Parp1 and Kit without changing the level of double-stranded DNA break-related genes were observed in the dentate gyrus. This suggested induction of oxidative DNA damage of NSCs and early-stage progenitor cells, which led to their apoptosis. Cdkn2a, Rb1 and Trp53 downregulated transcripts, which suggested an increased vulnerability to DNA damage. Hilar PVALB+ GABAergic interneurons decreased and Grin2a and Chrna7 were downregulated, which suggested suppression of type-2-progenitor cell differentiation. On PND 77, hilar RELN+ interneurons increased at ≥ 2.0 ppm; at 6.0 ppm, RELN-related Itsn1 transcripts were upregulated and ARC+ granule cells decreased. Increased RELN signals may ameliorate the response to the decreases of NSCs and ARC-mediated synaptic plasticity. These results suggest that DAS reversibly disrupts hippocampal neurogenesis by inducing oxidative cellular injury and suppressed differentiation of granule cell lineages. The no-observed-adverse-effect level of DAS for offspring neurogenesis was determined to be 0.6 ppm (0.09-0.29 mg/kg body weight/day).

Differential responses on energy metabolic pathway reprogramming between genotoxic and non-genotoxic hepatocarcinogens in rat liver cells.

To clarify difference in the responses on the reprogramming of metabolism toward carcinogenesis between genotoxic and non-genotoxic hepatocarcinogens in the liver, rats were repeatedly administered genotoxic hepatocarcinogens (N-nitrosodiethylamine, aflatoxin B1, N-nitrosopyrrolidine, or carbadox) or non-genotoxic hepatocarcinogens (carbon tetrachloride, thioacetamide, or methapyrilene hydrochloride) for 28, 84, or 90 days. Non-genotoxic hepatocarcinogens revealed transcript expression changes suggestive of suppressed mitochondrial oxidative phosphorylation (OXPHOS) after 28 days and increased glutathione S-transferase placental form-positive (GST-P+) foci downregulating adenosine triphosphate (ATP) synthase subunit beta, mitochondrial precursor (ATPB), compared with genotoxic hepatocarcinogens after 84 or 90 days, suggesting that non-genotoxic hepatocarcinogens are prone to suppress OXPHOS from the early stage of treatment, which is in contrast to genotoxic hepatocarcinogens. Both genotoxic and non-genotoxic hepatocarcinogens upregulated glycolytic enzyme genes and increased cellular membrane solute carrier family 2, facilitated glucose transporter member 1 (GLUT1) expression in GST-P+ foci for up to 90 days, suggesting induction of a metabolic shift from OXPHOS to glycolysis at early hepatocarcinogenesis by hepatocarcinogens unrelated to genotoxic potential. Non-genotoxic hepatocarcinogens increased c-MYC+ cells after 28 days and downregulated Tp53 after 84 or 90 days, suggesting a commitment to enhanced metabolic shift and cell proliferation. Genotoxic hepatocarcinogens also enhanced c-MYC activation-related metabolic shift until 84 or 90 days. In addition, both genotoxic and non-genotoxic hepatocarcinogens upregulated glutaminolysis-related Slc1a5 or Gls, or both, after 28 days and induced liver cell foci immunoreactive for neutral amino acid transporter B(0) (SLC1A5) in the subpopulation of GST-P+ foci after 84 or 90 days, suggesting glutaminolysis-mediated facilitation of cell proliferation toward hepatocarcinogenesis. These results suggest differential responses between genotoxic and non-genotoxic hepatocarcinogens on reprogramming of energy metabolic pathways toward carcinogenesis in liver cells from the early stage of hepatocarcinogen treatment.

Ameliorating effect of postweaning exposure to antioxidant on disruption of hippocampal neurogenesis induced by developmental hypothyroidism in rats.

Developmental hypothyroidism as a model of autism spectrum disorders disrupts hippocampal neurogenesis through the adult stage. The present study investigated the ameliorating effect of postweaning exposure to antioxidant on the hypothyroidism-induced disruptive neurogenesis. Mated female Sprague-Dawley rats were treated with 0 or 10 ppm 6-propyl-2-thiouracil (PTU) as an anti-thyroid agent in drinking water from gestational day 6 to postnatal day (PND) 21 on weaning. PTU-exposed male offspring were fed either basal diet, diet containing α-glycosyl isoquercitrin (AGIQ) at 5,000 ppm or α-lipoic acid (ALA) at 1,000 ppm as an antioxidant from PND 21 to PND 77. PTU-exposure decreased DCX+ and NeuN+ granule cell lineage subpopulations, synaptic plasticity-related FOS+ granule cells, and hilar PVALB+ and GAD67+ GABAergic interneurons, increased hilar SST+ and CALB2+ interneurons, and upregulated Gria3, Otx2, and antioxidant enzyme genes in the dentate gyrus on PND 77. These results suggest disruption of neurogenesis remained in relation with increase of oxidative stress and compensatory responses to the disruption at the adult stage. AGIQ recovered expression of some antioxidant enzyme genes and was effective for restoration of NeuN+ postmitotic granule cells and PVALB+ and SST+ interneurons. In contrast, ALA was effective for restoration of all interneuron subpopulations, as well as postmitotic granule cells, and upregulated Grin2a that may play a role for the restoration. Both antioxidants recovered expression of Otx2 and AGIQ-alone recovered Gria3, suggesting a reversal of disruptive neurogenesis by compensatory responses. Thus, postweaning antioxidant exposure may be effective for ameliorating developmental hypothyroidism-induced disruptive neurogenesis by restoring the function of regulatory system.

Twenty-eight-day repeated oral doses of sodium valproic acid increases neural stem cells and suppresses differentiation of granule cell lineages in adult hippocampal neurogenesis of postpubertal rats.

Developmental exposure to valproic acid (VPA), a model compound for experimental autism, has shown to primarily target GABAergic interneuron subpopulations in hippocampal neurogenesis of rat offspring. The VPA-exposed animals had revealed late effects on granule cell lineages, involving progenitor cell proliferation and synaptic plasticity. To investigate the possibility whether hippocampal neurogenesis in postpubertal rats in a protocol of 28-day repeated exposure is affected in relation with the property of a developmental neurotoxicant by developmental exposure, VPA was orally administered to 5-week-old male rats at 0, 200, 800 and 900 mg/kg body weight/day for 28 days. At 900 mg/kg, GFAP+ cells increased in number, but DCX+ cells decreased in number in the granule cell lineages. Moreover, CHRNB2+ cells and NeuN+ postmitotic neurons decreased in number in the hilus of the dentate gyrus. Transcript level examined at 900 mg/kg in the dentate gyrus was increased with Kit, but decreased with Dpsyl3, Btg2, Pvalb and Chrnb2. These results suggest that VPA increased type-1 stem cells in relation to the activation of SCF-KIT signaling and suppression of BTG2-mediated antiproliferative effect on stem cells. VPA also decreased type-3 progenitor cells and immature granule cells probably in relation with PVALB+ interneuron hypofunction and reduced CHRNB2+ interneuron subpopulation in the hilus, as well as with suppression of BTG2-mediated terminal differentiation of progenitor cells. Thus, the disruption pattern of VPA by postpubertal exposure was different from developmental exposure. However, disruption itself can be detected, suggesting availability of hippocampal neurogenesis in detecting developmental neurotoxicants in a 28-day toxicity study.

Aberrant epigenetic gene regulation in hippocampal neurogenesis of mouse offspring following maternal exposure to 3,3'-iminodipropionitrile.

Maternal exposure to 3,3'-iminodipropionitrile (IDPN) affects hippocampal neurogenesis in mouse offspring, with biphasic disruption, which facilitates neurogenesis during exposure and reduces the broad range of the granule cell lineage population at the adult stage. The present study investigated the epigenetically hypermethylated and downregulated genes related to the IDPN-induced disrupted neurogenesis. Mated female mice were treated with IDPN at 0 or 1200 ppm in drinking water from gestational day 6 to postnatal day (PND) 21 on weaning. The hippocampal dentate gyrus of male offspring on PND 21 was subjected to methyl-capture sequencing and real-time reverse transcription-PCR analyses, followed by validation analyses on DNA methylation. Three genes, Edc4, Kiss1 and Mrpl38, were identified as those showing promoter-region hypermethylation and transcript downregulation, with Mrpl38 sustaining the changes through PND 77. Immunohistochemically, MRPL38, a mitochondrial ribosomal protein, revealed an irreversible decrease in the number of immunoreactive interneurons in the dentate gyrus hilar region, suggesting a causal relationship with the long-lasting effect on neurogenesis by the impaired migration due to mitochondrial dysfunction of interneurons, which regulate the differentiation and survival of granule cell lineages. Downregulation of Edc4 may also be responsible for decreased neurogenesis on PND 77 owing to a mechanism involving interleukin-6 downregulation via processing body dysfunction. Downregulation of Kiss1 may be responsible for the facilitation of neurogenesis during IDPN-exposure due to decreased glutamatergic neurotransmission and also for suppressed neurogenesis on PND 77 due to decreased expression of immediate-early genes, which play a crucial role in the maintenance of cell differentiation or plasticity.

Expression Characteristics of Genes Hypermethylated and Downregulated in Rat Liver Specific to Nongenotoxic Hepatocarcinogens.

This study examined hypermethylated and downregulated genes specific to carbon tetrachloride (CCl4) by Methyl-Seq analysis combined with expression microarray analysis in the liver of rats treated with CCl4 or N-nitrosodiethylamine (DEN) for 28 days, by excluding those with DEN. Among 52 genes, Ldlrad4, Proc, Cdh17, and Nfia were confirmed to show promoter-region hypermethylation by methylation-specific quantitative PCR analysis on day 28. The transcript levels of these 4 genes decreased by real-time reverse transcription-PCR analysis in the livers of rats treated with nongenotoxic hepatocarcinogens for up to 90 days compared with untreated controls and genotoxic hepatocarcinogens. Immunohistochemically, LDLRAD4 and PROC showed decreased immunoreactivity, forming negative foci, in glutathione S-transferase placental form (GST-P)+ foci, and incidences of LDLRAD4- and PROC- foci in GST-P+ foci induced by treatment with nongenotoxic hepatocarcinogens for 84 or 90 days were increased compared with those with genotoxic hepatocarcinogens. In contrast, CDH17 and NFIA responded to hepatocarcinogens without any relation to the genotoxic potential of carcinogens. All 4 genes did not respond to renal carcinogens after treatment for 28 days. Considering that Ldlrad4 is a negative regulator of transforming growth factor-ß signaling, Proc participating in p21WAF1/CIP1 upregulation by activation, Cdh17 inducing cell cycle arrest by gene knockdown, and Nfia playing a role in a tumor-suppressor, all these genes may be potential in vivo epigenetic markers of nongenotoxic hepatocarcinogens from the early stages of treatment in terms of gene expression changes. LDLRAD4 and PROC may have a role in the development of preneoplastic lesions produced by nongenotoxic hepatocarcinogens.