Environmental RNA as a Noninvasive Tool for Assessing Toxic Effects in Fish: A Proof-of-concept Study Using Japanese Medaka Exposed to Pyrene.

Although environmental RNA (eRNA) is emerging as a noninvasive tool to assess the health status of aquatic macroorganisms, the potential of eRNA in assessing chemical hazards remain largely untested. In this study, we investigated the ability of eRNA to detect changes in gene expression in Japanese medaka fish (Oryzias latipes) in response to sublethal pyrene exposure, as a model toxic chemical. We performed standardized acute toxicity tests and collected eRNA from tank water and RNA from fish tissue after 96 h of exposure. Our results showed that over 1000 genes were detected in eRNA and the sequenced read counts of these genes correlated with those in fish tissue (r = 0.50). Moreover, eRNA detected 86 differentially expressed genes in response to pyrene, some of which were shared by fish RNA, including the suppression of collagen fiber genes. These results suggest that eRNA has the potential to detect changes in gene expression in fish in response to environmental stressors without the need for sacrificing or causing pain to fish. However, we also found that the majority of sequenced reads of eRNA (>99%) were not mapped to the reference medaka genome and they originated from bacteria and fungi, resulting in low sequencing depth. In addition, eRNA, in particular nuclear genes, was highly degraded with a median transcript integrity number (TIN) of <20. These limitations highlight the need for future studies to improve the analytical methods of eRNA application.

Development of a microplate-based novel toxicity bioassay using Chlorophyta and Phaeophyceae macroalgae.

Macroalgae are one of the main producers in marine environments. However, only a few toxicity test methods have been established that use reference strains of macroalgae to evaluate the effects of chemicals on the growth and reproduction of macroalgae to monitor water quality. We selected reference strains of Chlorophyta, Ulva aragoënsis; Phaeophyceae, Ectocarpus siliculosus; and wakame, Undaria pinnatifida, as test species to establish a microplate-based method to investigate the toxicity of potassium dichromate, 3,5-dichlorophenol, and two common herbicides (diuron and simazine). We determined the growth of the three macroalgae in their early life stages and during the sporangia formation stage in E. siliculosus under laboratory conditions. We observed that the growth and sporangia formation in these algae were impaired in a dose-dependent manner. Additionally, we investigated the sensitivity of these macroalgae by comparing the toxicity values of toxicants used in this study with those obtained from a database. Compared to other microalgae and plant species, macroalgae showed a relatively high sensitivity to organic compounds, including herbicides. Growth tests using U. aragoënsis and E. siliculosus produced reliable results at 0-32 and 25-32 practical salinity units (PSU), respectively. The tests established in this study could test the toxicity of chemical substances in macroalgae and are thus expected to contribute to a better understanding of the environmental risks of chemical substances on aquatic biota. The tests could be applied to all effluent toxicity tests used for the management of seawater and brackish water quality.

Theory of coevolution of cytoplasmic male-sterility, nuclear restorer and selfing.

Gynodioecy is a sexual polymorphism in angiosperms, where hermaphroditic and female individuals coexist. This is often caused by a cytoplasmic genetic element (CGE) that destroys male functions, which is called cytoplasmic male-sterility (CMS). On the other hand, nuclear genes tend to evolve the ability to restore male function. The coevolutionary process of CMS and the restoration has been studied theoretically. Recently, a theoretical study suggested that these coevolutionary dynamics could be influenced by the rate of selfing within populations, although it assumed that the selfing rate of a population was a fixed parameter. Accordingly, we theoretically study the coevolution of three traits in this paper: CMS, nuclear restorer and selfing rate, in which we hypothesize that selfing evolution can suppress CMS evolution under some conditions. The analysis indicates three significant properties of the system; (1) CMS-restorer evolution can result in bistability under a given selfing rate, (2) the coevolution of three traits can realize intermediate levels of selfing, and (3) the evolution of high levels of selfing is conditionally associated with no CMS and/or no restoration, which may support our hypothesis.

The non-steroidal anti-inflammatory drug diclofenac sodium induces abnormal embryogenesis and delayed lethal effects in early life stage zebrafish (Danio rerio).

Diclofenac sodium, a non-steroidal anti-inflammatory drug widely used in both human and veterinary medicine, has been detected in aquatic environments; therefore, its ecotoxicological effects on aquatic organisms need to be clarified. Recently, toxicity testing using zebrafish (Danio rerio) embryos has been recommended from the point of view of animal welfare; therefore, we investigated the suitability of using sub-lethal endpoints observed during embryogenesis for predicting lethal effects in early life stage zebrafish exposed to diclofenac sodium. After exposure to diclofenac sodium (0.4-7.0 mg/L) from 2 hours post-fertilization to 30 days post-hatching, abnormal embryogenesis, characterized by the presence of edema and body curvature, was observed in the 7.0 mg/L exposure group but not in any other groups including controls. The body curvature was found to be the result of abnormal development of the spine. All abnormal embryos hatched without delay, but died within 1 week after hatching, suggesting that the combination of the sub-lethal endpoints of edema and abnormal development of the spine during embryogenesis may predict lethal effects in early life stage zebrafish exposed to diclofenac sodium. Further investigations to verify these findings are needed. The value of the no observed effect concentrations for the embryogenesis, survival and growth endpoints were 3.5, 1.8 and >3.5 mg/L, respectively.

Effects of triclosan on Japanese medaka (Oryzias latipes) during embryo development, early life stage and reproduction.

Triclosan has been shown to have endocrine-disrupting effects in aquatic organisms. In 2016, the US Food and Drug Administration banned the use of triclosan in consumer soaps. Before the ban, triclosan was reported at low concentrations in the aquatic environment, although the effect of triclosan on reproduction in teleost fish species is yet to be clarified. Here we investigated the effects of triclosan on embryo development and reproduction, and during the early life stage, in Japanese medaka (Oryzias latipes) by using Organisation for Economic Co-operation and Development tests 229, 212 and 210, with minor modifications. In adult medaka, exposure to 345.7 µg l-1 suppressed fecundity and increased mortality but had no effect on fertility. Exposure to 174.1 or 345.7 µg l-1 increased liver vitellogenin concentration in females but decreased liver vitellogenin concentration in males. With triclosan exposure, mortality was increased dose dependently during the embryonic and early larval stages, and a particularly steep increase in mortality was observed soon after hatching. The lowest observed effect concentrations of triclosan in Japanese medaka obtained in the present study (mortality [embryonic and larval stages, 276.3 µg l-1 ; early life stage, 134.4 µg l-1 ; adult stage, 174.1 µg l-1 ], growth [134.4 µg l-1 ], vitellogenin [174.1 µg l-1 ], fecundity [345.7 µg l-1 ] and fertility [>345.7 µg l-1 ]) were at least 55 times (compared with the USA) and up to 13 400 times (compared with Germany) greater than the detected triclosan levels in the aquatic environment. These results suggest that triclosan may not be affecting fish populations in the aquatic environment.

Evaluation of the toxicity of leaches from hydrothermal sulfide deposits by means of a delayed fluorescence-based bioassay with the marine cyanobacterium Cyanobium sp. NIES-981.

The commercial use of metals such as copper, lead, and zinc has markedly increased in recent years, resulting in increased interest in deep-sea mining of seafloor hydrothermal sulfide deposits. However, the full extent of the impact of deep-sea mining at hydrothermal field deposits on the environment remains unclear. In addition to impacting the deep sea, the leaching of heavy metals from extracted sulfide mineral may also affect the upper ocean zones as the sulfide rock is retrieved from the seafloor. Here, we used a delayed fluorescence-based bioassay using the marine cyanobacterium Cyanobium sp. NIES-981 to evaluate the toxicity of three sulfide core samples obtained from three drill holes at the Izena Hole, middle Okinawa Trough, East China Sea. Leaches from two of the cores contained high concentrations of zinc and lead, and they markedly inhibited delayed fluorescence in Cyanobium sp. NIES-981 compared with control. By examining the toxicity of artificial mixed-metal solutions with metal compositions similar to those of the leaches, we confirmed that this inhibition was a result of high zinc and lead concentrations into the leaches. In addition, we conclude that this delayed fluorescence-based bioassay is a viable method for use by deep-sea mining operations because it is quicker and requires less laboratory space and equipment than the standard assay.

Ecotoxicological Test Assay Using OECD TG 212 in Marine Java Medaka (Oryzias javanicus) and Freshwater Japanese Medaka (Oryzias latipes).

The lethal effects of chemicals is a serious concern to the protection of ecosystems, and the OECD TG 212 was established to estimate the lethal and sublethal effects on embryo and sac-fry stages of fish. It is still unclear, however, whether this test can effectively estimate the impacts of chemicals using marine fish. Therefore, this study aimed to use a recognized testing method on the marine fish Oryzias javanicus, and to assess differences in response to organotin compounds between a freshwater congener (Oryzias latipes) and O. javanicus. The lowest observed effect concentration (LOEC) of triphenyltin for lethal effect was the same in both species. The LOEC of tributyltin for lethal and sublethal effects were the same in both species. Our results provide the first evidence that O. javanicus and O. latipes are similarly affected by organotin compounds, suggesting that O. javanicus is a good model marine fish for the ecotoxicological assessment of chemicals.

Lethal and sublethal effects of aniline and chlorinated anilines on zebrafish embryos and larvae.

Environmental risk assessments show increased attention to the sublethal effects of chemicals on aquatic organisms. The Organization for Economic Cooperation and Development (OECD) established the "Fish, Short-term Toxicity Test on Embryo and Sac-fry Stages" (OECD test 212) to predict lethal effects. It is still unclear, however, whether this test can predict sublethal effects. Although their sublethal effects are still unknown, chlorinated anilines are widely used in various fields. The purpose of this study, therefore, is to investigate sublethal effects of chlorinated anilines using OECD test 212 with zebrafish, and to examine the correlation of several sublethal effects between embryo and larval stages. Embryos were exposed to aniline and nine chlorinated anilines until 8 days post-fertilization. A delayed lethal effect was observed from three of the 10 anilines tested. In the control group, the swim bladder inflated after hatching, but there was no swim-bladder inflation after exposure to the chlorinated anilines. Fertilized eggs exposed to lower concentrations of test chemicals showed effects during embryogenesis that did not affect mortality rates, such as changes in body curvature and edema. Our results show that chlorinated anilines induce not only lethal effects but also a variety of sublethal effects. Moreover, a detailed estimate of these effects requires study during both embryonic and larval stages. OECD test 212 may therefore prove useful as a method for screening chemicals for lethal and sublethal effects. Copyright © 2017 John Wiley & Sons, Ltd.

Assessment of the lethal and sublethal effects of 20 environmental chemicals in zebrafish embryos and larvae by using OECD TG 212.

Fish embryo toxicity tests are used to assess the lethal and sublethal effects of environmental chemicals in aquatic organisms. Previously, we used a short-term toxicity test published by the Organization for Economic Co-operation and Development (test no. 212: Fish, Short-term Toxicity Test on Embryo and Sac-Fry Stages [OECD TG 212]) to assess the lethal and sublethal effects of aniline and several chlorinated anilines in zebrafish embryos and larvae. To expand upon this previous study, we used OECD TG 212 in zebrafish embryos and larvae to assess the lethal and sublethal effects of 20 additional environmental chemicals that included active pharmaceutical ingredients, pesticides, metals, aromatic compounds or chlorinated anilines. Zebrafish embryos (Danio rerio) were exposed to the test chemicals until 8 days post-fertilization. A delayed lethal effect was induced by 16 of the 20 test chemicals, and a positive correlation was found between heart rate turbulence and mortality. We also found that exposure to the test chemicals at concentrations lower than the lethal concentration induced the sublethal effects of edema, body curvature and absence of swim-bladder inflation. In conclusion, the environmental chemicals assessed in the present study induced both lethal and sublethal effects in zebrafish embryos and larvae, as assessed by using OECD TG 212. Copyright © 2017 John Wiley & Sons, Ltd.

Development of an in vivo anti-androgenic activity detection assay using fenitrothion in Japanese medaka (Oryzias latipes).

The effects of endocrine disruptors, including anti-androgenic chemicals, on aquatic environments have received increased attention in recent years. Currently, the method used to screen chemicals for anti-androgenic activity is called the androgenized female stickleback screen, and it was established by the Organization of Economic Cooperation and Development in 2011 using the three-spined stickleback. However, screening chemicals for anti-androgenic activity has yet to be established using Japanese medaka. Thus, the purpose of this study was to establish a screening method for anti-androgenic activity utilizing the number of papillary processes in Japanese medaka (Oryzias latipes) as an indicator of the chemical's anti-androgenic activity. Thus, at 35 days post-fertilization, medaka were exposed to fenitrothion, an anti-androgenic compound, for 28 days. In the control group, the formation of papillary processes was observed in XY medaka, but not in XX medaka. However, after fenitrothion exposure, the number of papillary processes was significantly decreased in a dose-dependent manner in XY medaka; in the 300 µg l-1 concentration group, four of 11 XY medaka showed no papillary processes even if there were no significant effects on total length and wet body weight compared with the control group. Our results indicate that the number of papillary processes in Japanese medaka can be used as an indicator of anti-androgenic activity and that this model may prove useful as a chemical screening method. Copyright © 2016 John Wiley & Sons, Ltd.

Rapid ecotoxicological bioassay using delayed fluorescence in the marine cyanobacterium Cyanobium sp. (NIES-981).

The use of delayed fluorescence intensity as an endpoint for rapid estimation of the effective concentration (ECx) has been reported as an alternative to standard growth inhibition (at 72 h after exposure) in some algal species including Pseudokirchneriella subcapitata. In marine algae, although an approach of bioassaying using delayed fluorescence measurements has not been performed yet, its development would provide many benefits for marine environmental risk assessment. In this study, we selected marine cyanobacterium Cyanobium sp. (NIES-981) as our test algal species and demonstrated that this species is valid for the standard growth inhibition test based on criteria provide by Organization for Economic Co-operation and Development guidelines. Furthermore, standard inhibition tests and shorter period test using DF were performed in NIES-981 using five chemicals (3,5-DCP, simazine, diflufenican, K2Cr2O7, and CuSO4), and their EC50 and low-toxic-effect values (EC10, EC5, and NOEC) were determined from two dose-response curves. Based on comparisons of the two dose-response curves and the EC50 values, we conclude that DF intensity is useful as an endpoint for rapid estimation of EC50 in NIES-981.

Alpha1 -adrenergic receptors mediate bladder overactivity induced by cold stress in rats with bladder outlet obstruction.

PURPOSE: To determine if alpha1 -adrenergic receptors (AR) mediate bladder overactivity induced by cold stress in rats with bladder outlet obstruction (BOO). MATERIALS AND METHODS: The urethras of 10-week-old female Sprague-Dawley rats were ligated to create BOO. After 4 weeks, cystometric investigations were performed at room temperature (RT, 27 ± 2°C) for 20 min. The rats were then given 0.3 mg/kg naftopidil (n = 6) or vehicle (n = 5) intravenously. Five minutes later, they were transferred to low temperature (LT, 4 ± 2°C), and the cystometric patterns were again recorded for 40 min. In BOO rats and in sham-operated rats (n = 8) the expression levels of alpha1A - and alpha1D -AR mRNAs and the presence of alpha1A - and alpha1D -AR immunoreactivity on calcitonin gene-related peptide (CGRP)-positive nerve cells were investigated. RESULTS: During LT exposure, the vehicle-treated BOO rats exhibited cold stress-induced bladder overactivity. In the naftopidil-treated rats, the increase of basal pressure and decreases of both voiding interval and bladder capacity induced by LT were significantly reduced compared to the vehicle-treated animals. In the bladders of BOO rats exposed to LT, the expression of alpha1D -AR mRNA was significantly higher than in sham-operated rats, and the immunoreactivity for alpha1D -ARs on the CGRP-positive nerve cells tended to be more pronounced. CONCLUSIONS: Alpha1 -ARs mediate part of the bladder overactivity induced by cold stress in rats with BOO. Cold stress increases the expression of alpha1D -AR mRNA and the immunoreactivity for alpha1D -ARs on the CGRP-positive nerve cells in BOO rats. Naftopidil partially inhibits the cold stress overactivity, suggesting that it is mediated, at least partially, through alpha1D/1A -ARs.

Reproductive morphology and DNA sequences of the brown alga Platysiphon verticillatus support the new combination Platysiphon glacialis.

Platysiphon verticillatus, a brown alga endemic to the Arctic, was described based on vegetative specimens collected at Inglefield Bay, West Greenland. The species is distinctive in having a lanceolate blade-like thallus terminated by a terete portion, both covered with hair-like assimilatory filaments. Punctaria glacialis was described from Eastern Greenland, and the species differs from other Punctaria species in lacking hairs and plurilocular zoidangia. Unilocular zoidangia were reported, but instead of zoids being released they formed cell walls in situ developing the appearance of plurilocular zoidangia. However, the fate of the zoids, as well as the walled cells was not traced, and the life history of the alga has remained unclear. By comparing DNA sequences (cox1, cox3, and rDNA ITS2) of specimens morphologically referable to Platysiphon verticillatus and Punctaria glacialis collected at Baffin Island, as well as re-examining morphology and studying crude cultures, we concluded that they are the same taxonomic entity. Furthermore, their cox3 sequence and vegetative morphology agreed with those of the type specimen of Punctaria glacialis. Consequently, we propose Platysiphon glacialis comb. nov. The life cycle could not be completed in culture, but we hypothesize that in situ germination of the unizoids produces reduced gametophytes housed in peripheral tissue of erect sporophytic thalli.

[UNDIFFERENTIATED CARCINOMA OF THE URETER WITH FETAL CLINICAL COURSE: A CASE REPORT].

Undifferentiated carcinoma of ureter is rare neoplastic lesion, and the natural history of undifferentiated carcinoma of ureter has not been known well yet. We hereby presented an autopsy case of undifferentiated carcinoma of the ureter with rapid progression from the initial stage. A 62-year-old male visited the local urologist complaining of asymptomatic gross hematuria. Cystoscopy revealed the outflow of hematuria from the right ureteral orifice. Abdominal CT showed the right hydronephrosis with atrophic change of the renal parenchyma and the stenosis of upper ureter. He was referred to our hospital on suspicion of a right ureteral tumor. Magnetic resonance imaging and retrograde ureterography did not reveal a tumor in the right ureter. He complained of low back pain 4 months after the initial hematuria, and CT revealed the diffuse enlargement of the right kidney, swelling of the abdominal lymph nodes, and lung nodules. Renal biopsy was done, and only undifferentiated cells were revealed histopathologically without any specific findings to diagnose the primary organ. The tumor increased progressively, and he died about 6 months after the initial gross hematuria. Autopsy was performed, and urothelial carcinoma was found in the right ureter as the primary lesion. The ureteral tumor infiltrated to the right kidney, right adrenal gland, liver, duodenum, and pancreas with undifferentiation. Undifferentiated tumor cells were also found in distant metastatic lesion including the abdominal lymph nodes, left adrenal gland, liver, lung, pleura, and peritoneum.

Comparative transcriptome analysis of Discosporangium mesarthrocarpum (Phaeophyceae), Schizocladia ischiensis (Schizocladiophyceae), and Phaeothamnion confervicola (Phaeothamniophyceae), with special reference to cell wall-related genes.

Within the stramenopile lineage, only brown algae (Phaeophyceae) have evolved complex multicellularity, although some other members of the lineage (e.g., Schizocladia in Schizocladiophyceae; Phaeothamnion in Phaeothamniophyceae) also develop simple multicellular thalli. The development of an adherent extracellular matrix (ECM) is considered to be one of the key steps in the evolution of multicellularity, because ECM is involved in adhesion of cells to each other and in cell-cell communication essential for developmental, reproductive, and sophisticated defense systems. Because there are no unicellular organisms within brown algae, we considered that comparison of other stramenopile taxa closely related to brown algae and having multicellular thalli could yield clues to elucidate the evolution of multicellularity in brown algae. In this study, we investigated transcriptomes involved in cell wall polysaccharide metabolism of three stramenopile species, Discosporangium mesarthrocarpum, which is suggested to be one of the most basal taxa within Phaeophyceae, S. ischiensis, and P. confervicola. We employed 454-FLX high-throughput pyrosequencing to generate expressed sequence tag (EST) databases for these species, and performed comparative analyses between these databases and the genome sequence of the brown alga Ectocarpus siliculosus. Results indicate that cell wall polysaccharide metabolism pathways of D. mesarthrocarpum are similar to E. siliculosus, whereas those of S. ischiensis and P. confervicola are significantly different from E. siliculosus, suggesting that the components of the cell wall in S. ischiensis and P. confervicola are likely to be different from those of E. siliculosus.

Muscarinic receptors mediate cold stress-induced detrusor overactivity in type 2 diabetes mellitus rats.

OBJECTIVES: This study determined if muscarinic receptors could mediate the cold stress-induced detrusor overactivity induced in type 2 diabetes mellitus rats. METHODS: Ten-week-old female Goto-Kakizaki diabetic rats (n = 12) and Wister Kyoto non-diabetic rats (n = 12) were maintained on a high-fat diet for 4 weeks. Cystometric investigations of the unanesthetized rats were carried out at room temperature (27 ± 2°C) for 20 min. They were intravenously administered imidafenacin (0.3 mg/kg, n = 6) or vehicle (n = 6). After 5 min, the rats were transferred to a low temperature (4 ± 2°C) for 40 min where the cystometry was continued. The rats were then returned to room temperature for the final cystometric measurements. Afterwards, expressions of bladder muscarinic receptor M3 and M2 messenger ribonucleic acids and proteins were assessed by reverse transcription polymerase chain reaction and immunohistochemistry. RESULTS: In non-diabetic Wister Kyoto rats, imidafenacin did not reduce cold stress-induced detrusor overactivity. In diabetic Goto-Kakizaki rats, just after transfer to a low temperature, the cold stress-induced detrusor overactivity in imidafenacin-treated rats was reduced compared with vehicle-treated rats. Within the urinary bladders, the ratio of M3 to M2 receptor messenger ribonucleic acid in the diabetic Goto-Kakizaki rats was significantly higher than that of the non-diabetic Wister Kyoto rats. The proportion of muscarinic M3 receptor-positive area within the detrusor in diabetic Goto-Kakizaki rats was also significantly higher than that in non-diabetic Wister Kyoto rats. CONCLUSIONS: Imidafenacin partially inhibits cold stress-induced detrusor overactivity in diabetic Goto-Kakizaki rats. In this animal model, muscarinic M3 receptors partially mediate cold stress-induced detrusor overactivity.

[A case of advanced prostate fibrosarcoma that reacted well to chemotherapy].

Prostate fibrosarcoma is an extremely rare tumor for which complete excision has been the mainstay of treatment. Although chemotherapy has been attempted in cases with positive surgical margins and/or advanced stage disease, the effectiveness of this therapy has not been established. Herein, we report a case of advanced prostate fibrosarcoma that reacted well to chemotherapy. A 40-year-old man was referred for treatment of a large prostatic tumor with multiple lung, liver, and bone metastases. Needle biopsy of the prostate revealed that the tumor was a high-grade undifferentiated sarcoma. Chemotherapy with doxorubicin and ifosfamide was administered. After five courses of chemotherapy, the primary prostate tumor decreased markedly, and the lung and liver metastases almost disappeared. Radical cystoprostatectomy and ileal conduit formation were performed. Pathological diagnosis was fibrosarcoma. Another three courses of doxorubicin and ifosfamide therapy were performed, and doxorubicin was replaced by etoposide because the maximum dose of doxorubicin was reached. However, the effectiveness of the second-line therapy was poor, and the tumor progressed again. The patient died of lung metastasis 15 months later.

The relationship between α1-adrenergic receptors and TRPM8 channels in detrusor overactivity induced by cold stress in ovariectomized rats.

PURPOSE: We studied whether cold stress induced detrusor overactivity in ovariectomized rats is associated with increased thermosensitive TRPM8 channel expression in the skin and whether the response could be inhibited by α1-adrenergic receptor blockade. MATERIALS AND METHODS: A total of 24 Sprague-Dawley® rats at postnatal week 30 were randomly selected for ovariectomy (16) or sham ovariectomy (8). Five weeks later cystometric measurements of conscious, freely moving rats were made at room temperature (mean ± SEM 28C ± 2C) for 20 minutes. Eight ovariectomized rats were intravenously administered 1.0 mg/kg naftopidil. The other 8 ovariectomized and 8 sham operated rats were given naftopidil-free vehicle. Five minutes later they were transferred to a low temperature environment (mean 4C ± 2C) and micturition patterns were again recorded. TRPM8 channel expression in lumbar skin was estimated by real-time reverse-transcriptase polymerase chain reaction and immunohistochemistry. RESULTS: TRPM8 channel mRNA and protein in the skin of ovariectomized rats were significantly higher than in sham operated rats. At room temperature micturition parameters were similar in sham operated and ovariectomized rats. At low temperature sham operated and ovariectomized rats showed cold stress induced detrusor overactivity but increased micturition frequency and decreased bladder capacity were significantly greater in ovariectomized rats. Treatment of ovariectomized rats with naftopidil inhibited cold stress induced detrusor overactivity. CONCLUSIONS: Cold stress induced detrusor overactivity in rats with decreased estrogen is associated with TRPM8 channel up-regulation in the skin and mediated by nerve pathways using α1-adrenergic receptors.

Functional roles of transient receptor potential melastatin 8 (TRPM8) channels in the cold stress-induced detrusor overactivity pathways in conscious rats.

AIMS: We determined if transient receptor potential melastatin 8 (TRPM8) channels are involved in the detrusor overactivity induced by menthol, or exposure to low temperature (LT). METHODS: Two days prior to cystometric investigation, the bladders of 10-week-old Sprague-Dawley rats were cannulated to measure bladder pressure. After a 20 min baseline cystometry period, the TRPM8 channel antagonist, N-(4-tert-butylphenyl)-4-(3-chloropyridin-2-yl)piperazine-1-carboxamide (BCTC), or vehicle, was administered through a jugular vein catheter (n = 6). A 90% menthol solution was sprayed onto bare leg skin once every 5 min for 20 min, and then cystometric measurements were repeated. After a 30-min recovery period, the rats were intravenously administered 0.1 µmol/kg BCTC. Five minutes later, they were again sprayed and cystometry recorded. In separate experiments, cannulated rats were intravenously administered 0.001, 0.01, or 0.1 µmol/kg BCTC (n = 6 each dose). Five minutes later, they were exposed to LT (4 ± 2°C) for 20 min of cystometry. RESULTS: Menthol spray decreased voiding interval, micturition volume, and bladder capacity in the BCTC-free rats. However after BCTC administration, these effects were prevented. Exposure to LT elicited detrusor overactivity that caused decreased voiding interval, micturition volume, and bladder capacity. However, at 0.01 and 0.1 µmol/kg, BCTC inhibited this cold stress-induced detrusor overactivity. CONCLUSIONS: Since the TRPM8 channel agonist, BCTC, inhibited detrusor overactivity in rats sprayed with the TRPM8 channel agonist, menthol, and the drug also inhibited cold stress-induced detrusor overactivity, we conclude that TRPM8 channels mediate, at least partially, detrusor overactivity elicited by exposure to LT.

A galenical produced from Ba-Wei-Die-Huang-Wan (THC-002) provides resistance to the cold stress-induced detrusor overactivity in conscious rats.

AIMS: We determined if THC-002, a galenical produced from Ba-Wei-Die-Huang-Wan, could increase skin temperature and inhibit detrusor overactivity induced by sudden whole body cooling. Further, we determined if THC-002 could decrease expression of transient receptor potential melastatin 8 (TRPM8) channels associated with the cold responses. METHODS: Hind leg skin temperature of female 10-week-old Sprague-Dawley rats was measured by thermal imaging. Experimental rats (n = 12) were given oral 100 mg/kg THC-002 daily for one week, and controls (n = 12) were similarly treated with THC-002-free solution. Afterwards, thermal imaging and cystometric investigations of the freely moving conscious rats were performed at room temperature (RT, 27 ± 2°C) for 20 min. The rats were then transferred to a low temperature (LT, 4 ± 2°C) environment during which thermal imaging and cystometric measurements were taken at 5, 10, 20, 30, and 40 min. Afterward, the skin tissues were harvested to estimate expression levels of TRPM8 channels by immunohistochemistry and real-time reverse-transcription polymerase chain reaction. RESULTS: The RT skin temperature of THC-002-treated rats was significantly higher than controls. During the first 20 min under LT, the control rats exhibited cold stress-induced detrusor overactivity such as decreased voiding interval and bladder capacity. THC-002 partially inhibited the detrusor overactivity patterns. During the second 20 min, skin temperature was relatively stable, and the detrusor overactivity of both groups slowly disappeared. THC-002 significantly reduced expression of TRPM8 channel protein and mRNA. CONCLUSIONS: THC-002 inhibited cold stress-induced detrusor overactivity resulting from decreasing skin temperature. Therefore, THC-002 might provide resistance to cold stress-exacerbated lower urinary tract symptoms.