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Satoru TANAKA Tomoko UTOH Yoshiaki YAMADA Noriyuki HORIE Akihiro OKAMURA Atsushi AKAZAWA Naomi MIKAWA Hideo P OKA Hisashi KUROKURA 《Fisheries Science》2004,70(5):780-787
ABSTRACT: In order to find out the role of sodium bicarbonate (NaHCO3 ) on the initiation of sperm motility in the Japanese eel Anguilla japonica , interactions were investigated between NaHCO3 and various reagents (K+ channel blocker 4-aminopyridine [4-AP], ammonium chloride [NH4 Cl], sodium acetate and calcium chloride [CaCl2 ]) that could regulate internal factors (intracellular K+ , intracellular pH [[pH]i ] and intracellular Ca2+ ) in sperm motility. Contradictory effects of NaHCO3 were observed (i.e. an inhibitory effect when 4-AP was absent and a promoting effect when 4-AP was present). Sodium bicarbonate inhibited the initiation of sperm motility in the Japanese eel. However, NaHCO3 restored the motility of immotile sperm that 4-AP inhibited. The inhibitory effect of NaHCO3 disappeared with the addition of NH4 Cl, which raised [pH]i , but the promoting effect was not affected by [pH]i . Although NaHCO3 recovered motility in the presence of 4-AP, this recovery was also observed with the addition of CaCl2 instead of NaHCO3 . In the initiation of sperm motility in the Japanese eel, two roles for NaHCO3 are suggested: an inhibitory role relating to the regulation of [pH]i and a promoting role relating to the uptake of another initiation factor, which could be Ca2+ . 相似文献
2.
Oogenesis in the common Japanese conger Conger myriaster 总被引:1,自引:0,他引:1
TOMOKO UTOH NORIYUKI HORIE AKIHIRO OKAMURA YOSHIAKI YAMADA SATORU TANAKA NAOMI MIKAWA ATSUSHI AKAZAWA HIDEO P OKA 《Fisheries Science》2003,69(1):181-188
ABSTRACT: We investigated the process and characteristics of oogenesis in the common Japanese conger Conger myriaster . Young fish caught in November 1996 were reared for use in this experiment. Fish were sampled monthly from December 1997 to August 1998. Some were injected with human chorionic gonadotropin to stimulate ovarian maturation from May to August 1998. Oocytes from the chromatin nucleolus stage to the secondary yolk globule stage were obtained from non-hormone-treated fish; those of more advanced stages were obtained from hormone-treated ones. We divided oocyte development into eight stages from the chromatin nucleolus stage to the maturation stage. The yolk vesicle stage was not separated because yolk vesicles began to appear just after appearance of yolk globules. Oocyte, oil droplet, yolk globule and nucleus diameters all increased concomitant with oocyte development. Oil droplet and yolk globule diameters increased remarkably at the maturation stage. However, zona radiata thickness peaked at the secondary yolk globule stage, decreasing gradually thereafter. Increased gonadosomatic index was related to oocyte development as found in European and Japanese eels receiving hormone treatment to mature. The present study is the first report describing oogenesis characteristics in congrid eels. It indicates that oogenesis is almost identical to that of other anguillid eels. 相似文献
3.
Shoma MIKAWA Yasuhiro OHTA Noriyuki KAJI Md Shafiqul ISLAM Takahisa MURATA Hiroshi OZAKI Masatoshi HORI 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(11):1443-1449
Endotoxin causes gastrointestinal motility disorder. Aim of this study is to clarify
inhibitory mechanisms of lipopolysaccharide (LPS) on smooth muscle contraction in rat
ileum. Ileal tissues were isolated from control rat or from LPS-induced peritonitis model
rat. Treatment with LPS inhibited carbachol (CCh)-mediated contraction in a time-dependent
manner. Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) genes were
also upregulated, but iNOS expression was preceded by a rising of COX-2. All subtypes of
prostaglandin E2 (PGE2) receptors (EP1-EP4) were expressed in ileum,
and PGE2 and selective EP2 or EP4 agonist inhibited CCh-mediated contraction.
Selective iNOS inhibitor did not reverse LPS-induced inhibition of contraction by CCh at 1
and 2 hr, but reduced the inhibitory action at 4 hr after the LPS treatment. COX-2
inhibitor reversed the inhibitory action by LPS in all exposure time. Finally, in ileal
tissues isolated from peritonitis model rat, iNOS expression was upregulated only at 4 hr
after LPS administration, resulting in enhanced inhibitory action of LPS against
CCh-induced contraction. In conclusion, LPS induces COX-2 to produce PGE2,
which initially activates EP2 and/or EP4 on smooth muscle cells to inhibit the
contractility in early phase of LPS exposure. Moreover, in late phase of LPS treatment,
iNOS is expressed to produce NO, which in turn inhibited the contraction by CCh. The
inhibitory cascade is similar in the ileum isolated from peritonitis model rat, indicating
time-dependent changes of inhibitory action by LPS on intestinal motility in
peritonitis. 相似文献
4.
Shoma MIKAWA Yuichi MIYAGAWA Noriko TODA Yoshinori TOMINAGA Naoyuki TAKEMURA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(1):7-13
Pulmonary hypertension (PH) often occurs due to a left heart disease, such as
myxomatous mitral valve disease (MMVD), in dogs and is diagnosed using Doppler
echocardiography and estimated pulmonary arterial pressure. Diagnosis of PH in dogs
requires expertise in echocardiography: however, the examination for PH is difficult to
perform in a clinical setting. Thus, simple and reliable methods are required for the
diagnosis of PH in dogs. The purpose of this study was to develop models using multiple
logistic regression analysis to detect PH due to left heart disease in dogs with MMVD
without echocardiography. The medical records of dogs with MMVD were retrospectively
reviewed, and 81 dogs were included in this study and classified into PH and non-PH
groups. Bivariate analysis was performed to compare all parameters between the groups, and
variables with P values of <0.25 in bivariate analysis were included
in multiple logistic regression analysis to develop models for the detection of PH. In
multiple logistic regression analysis, the model included a vertebral heart scale short
axis of >5.2 v, and a length of sternal contact of >3.3 v was considered suitable
for the detection of PH. The predictive accuracy of this model (85.9%) was judged
statistically adequate, and therefore, this model may be useful to screen for PH due to
left heart disease in dogs with MMVD without echocardiography. 相似文献
5.
Shoma MIKAWA Shohei YAMAMOTO Md Shafiqul ISLAM Noriyuki KAJI Takahisa MURATA Risuke MIZUNO Hiroshi OZAKI Masatoshi HORI 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2015,77(10):1195-1199
Maropitant is a neurokinin 1 receptor (NK1R) antagonist that is clinically used as a new
anti-emetic drug for dogs. Substance P (SP) and its receptor NK1R are considered to
modulate gastrointestinal peristalsis. In addition, SP works as an inflammatory mediator
in gastrointestinal diseases. Aim of this study is to clarify the effects of maropitant on
intestinal motility and inflammation in mice. Ex vivo examination of
luminal pressure-induced intestinal motility of whole intestine revealed that maropitant
(0.1–10 µM) increased frequency of contraction, decreased amplitude of
contraction and totally inhibited motility index in a concentration-dependent manner. We
measured intestinal transit in vivo by measuring transportation of orally
administered luminal content labeled with phenol red. Our results demonstrated that
maropitant (10 mg/kg, SC) delayed intestinal transit. Geometric center value was
significantly decreased in maropitant-treated mice. Anti-inflammatory effects of
maropitant against leukocytes infiltration into the intestinal smooth muscle layer in
post-operative ileus (POI) model mice were measured by immunohistochemistry. In POI model
mice, a great number of CD68-positive macrophages or MPO-stained neutrophils infiltrated
into the inflamed muscle region of the intestine. However, in the maropitant treated mice,
the infiltration of leukocytes was not inhibited. The results indicated that maropitant
has ability to induce disorder of intestinal motility in mice, but has no
anti-inflammatory action in the mouse of a POI model. In conclusion, in mice, maropitant
induces disorder of intestinal motility in vivo. 相似文献
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Naomi MIKAWA Tomoko UTOH Noriyuki HORIE Akihiro OKAMURA Yoshiaki YAMADA Atsushi AKAZAWA Satoru TANAKA Katsumi TSUKAMOTO Ikuo HIRONO Takashi AOKI 《Fisheries Science》2004,70(6):960-970
ABSTRACT: Estrogen receptor (ER) cDNA was cloned from the liver of common Japanese conger Conger myriaster . Common Japanese conger ER cDNA contains 2543 nucleotides including an open reading frame that encodes 596 amino acids, with a molecular weight of 66.1 kDa. The deduced amino-acid sequence of the common Japanese conger ER shares 85% identity with that of eel Anguilla japonica ER-β, and 39–46% and 53–59% identity with the deduced sequences of ER-α and ER-β of other species, respectively. In a phylogenetic analysis, the common Japanese conger ER was found to cluster with the ER-β of other species. The common Japanese conger ER-β also has six domains (A–F), which are conserved in the nuclear receptor superfamily. The amino-acid sequences in the C and E domains were highly conserved between common Japanese conger ER-β and other ER. However, the other domains showed low homology. In the female common Japanese conger, ER-β mRNA was highly expressed in the liver and pituitary gland. The expression levels of the ER-β gene increased from the oil droplet stage to the primary yolk globule stage and were maintained until the migratory nucleus stage. 相似文献
7.
NORIYUKI HORIE TOMOKO UTOH YOSHIAKI YAMADA AKIHIRO OKAMURA HUAN ZHANG NAOMI MIKAWA ATSUSHI AKAZAWA SATORU TANAKA HIDEO P OKA 《Fisheries Science》2002,68(5):972-983
Development of embryos and larvae in the common Japanese conger Conger myriaster was observed after artificial fertilization. Eggs were obtained from females matured artificially by hormone injections and milt was obtained from males matured naturally. Fertilized eggs were kept in seawater at 12–14°C. The first cleavage occurred at 4 h, epiboly began at 24 h, the embryonic body was formed at 38 h and hatching occurred at 84 h after insemination. Newly hatched larvae were approximately 2.5 mm (total length) and similar to those of Anguilla japonica in terms of external features. The mouth and anus opened on the 7th day after hatching. Pigments began to appear at the tip of the tail on the 10th day. The total length of the larvae reached approximately 8 mm on the 11th day. Eye pigmentation began on the 14th day. One larva lived for 19 days without food. 相似文献
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