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MISC - 坂本　竜哉

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Prolactin, somatolactin and growth hormone gene expression during parr-smolt transformation of Atlantic salmon

Agustsson, T, K. Sundell, T. Sakamoto, M. Ando, B. Th, Bj嗷nsson

Aquaculture 2003年

Fishy tales of prolactin-releasing peptide

Sakamoto, T, M. Fujimoto, M. Ando

Int. Rev. Cytol 225: 91-130 2003年

Isolation and characterization of a homologue of mammalian prolactin-releasing peptide from the tilapia brain and its effect on prolactin release from the tilapia pituitary

AP Seale, T Itoh, S Moriyama, A Takahashi, H Kawauchi, T Sakamoto, M Fujimoto, LG Riley, T Hirano, EG Grau

GENERAL AND COMPARATIVE ENDOCRINOLOGY 125 ( 3 ) 328 - 339 2002年2月

記述言語：英語出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE

In the tilapia (Oreochromis mossambicus), as in many teleosts, prolactin (PRL) plays a major role in osmoregulation in freshwater. Recently, PRL-releasing peptides (PrRPs) have been characterized in mammals. Independently, a novel C-terminal RF (arginine-phenylalanine) amide peptide (Carrasius RF amide: C-RFa), which is structurally related to mammalian PrRPs, has been isolated from the brain of the Japanese crucian carp. The putative PrRP was purified from an acid extract of tilapia brain by affinity chromatography with antibody against synthetic C-RFa and HPLC on a reverse-phase ODS-120 column. The tilapia PrRP cDNA was subsequently cloned by polymerase chain reaction. The cDNA consists of 619 bp encoding a preprohormone of 117 amino acids. Sequence comparison of the isolated peptide and the preprohormone revealed that tilapia PrRP contains 20 amino acids and is identical to C-RFa. Incubation of the tilapia pituitary with synthetic C-RFa (100 nM) significantly stimulated the release of two forms of tilapia PRL (PRI188 and PRI177). However, the effect of C-RFa was less pronounced than the marked increase in PRL release in response to hyposmotic medium. The ability of C-RFa to stimulate PRL release appears to be specific, since C-RFa failed to stimulate growth hormone release from the pituitary in organ culture. In contrast, rat and human PrRPs had no effect on PRL release. C-RFa was equipotent with chicken GnRH in stimulating PRL release in the pituitary preincubated with estradiol 17beta. Circulating levels of PRL were significantly increased 1 h after intraperitoneal injection of 0.1 mug/g of C-RFa in female tilapia in freshwater but not in males. These results suggest that C-RFa is physiologically involved in the control of PRL secretion in tilapia. (C) 2002 Elsevier Science (USA).

DOI： 10.1006/gcen.2001.7727

Web of Science

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Calcium ion triggeres the rapid morphological oscillation of chloride cells in the mudskipper

Sakamoto, T, M. Ando

J. Comp. Physiol. B 2002年

Ureogenic function and periodic urea excretion in a gobiid fish, Mugilogobius abei.

Iwata, K, M. Kajimura, T. Sakamoto

Fish. Sci 2002年

Growth hormone and prolactin in expression during environmental adaptation of gobies

Sakamoto, T, K. Iwata, M. Ando

Fish. Sci. 2002年

Differential display of skin mRNAs regulated during adaptation of mudskipper to different environments

Sakamoto, T, H. Yasunaga, S. Yokota, M. Ando

J. Comp. Physiol. B 2002年

Medaka, Oryzias latipes, as a model for hypoosmoregulation of euryhaline fishes

Sakamoto, T, T. Kozaka, A. Takahashi, H. Kawauchi, M. Ando

Aquaculture 2001年

Regulation of the ion-transporting mitochondrion-rich cell during adaptation of teleost fishes to different salinities

Sakamoto, T, K. Uchida, S. Yokota

Zool. Sci. 2001年

Regulation of the ion-transporting mitochondrion-rich cell during adaptation of teleost fishes to different salinities

Sakamoto, T, K. Uchida, S. Yokota

Zool. Sci., 18: 1163-1174 2001年

Growth hormone endocrinology of Atlantic salmon (Salmo salar): pituitary gene expression, hormone storage, secretion and plasma levels during parr--smolt transformation

Agustsson, T, K. Sundell, T. Sakamoto, M. Ando, B. Th, Bj嗷nsson

J. Endocrinol. 2001年

Rapid morphological oscillation of mitochondrion-rich cell in estuarine mudskipper following salinity changes

Sakamoto, T, S. Yokota, M. Ando

J. Exp. Zool. 2000年

Functional ureogenesis in the gobiid fish, Mugilogobius abei

Iwata, K, M. Kajimura, T. Sakamoto

J. Exp. Biol. 2000年

Induction of mRNAs in response to acclimation of trout cells to different osmolalities

Sakamoto, T, N. Ojima, M. Yamashita

Fish. Physiol. Biochem. 2000年

Functional ureogenesis in the gobiid fish, DBMugilogobius abei(/)-DB.(共著)

J. Exp. Biol. 203 3703 - 3715 2000年

Is the primitive regulation of pituitary prolactin (tPRL(177) and tPRL(188)) secretion and gene expression in the euryhaline tilapia (Oreochromis mossambicus) hypothalamic or environmental?

BS Shepherd, T Sakamoto, S Hyodo, RS Nishioka, C Ball, HA Bern, EG Grau

JOURNAL OF ENDOCRINOLOGY 161 ( 1 ) 121 - 129 1999年4月

記述言語：英語出版者・発行元：SOC ENDOCRINOLOGY

We examined the effects of environmental salinity on circulating levels of the two prolactins (tPRL(177) and tPRL(188)) and levels of pituitary tPRL(177) and tPRL(188) mRNA in the euryhaline tilapia, Oreochromis mossambicus. Fish were sham-operated or hypophysectomized and the rostral pars distalis (RPD) autotransplanted onto the optic nerve. Following post-operative recovery in 1/4 seawater, tilapia were transferred to fresh water (FW), 1/4 seawater (SW) or SW. Serum tPRL(177) and tPRL(188) levels in sham-operated and RPD-autotransplanted fish were highest in FW and decreased as salinity was increased. tPRL(177) and tPRL(188) mRNA levels in RPD implants as well as in pituitaries from the sham-operated fish were also highest in FW and decreased with increasing salinity. Serum osmolality increased with salinity, with the highest levels occurring in die seawater groups. We conclude that some plasma factor (probably plasma osmolality), in the absence of hypothalamic innervation, exerts a direct regulatory action on prolactin release and gene expression in the pituitary of O. mossambicus. This regulation is in accord with the actions of the two prolactins in the freshwater osmoregulation of the tilapia.

Web of Science

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Development of the myotomal neuromuscular system in embryonic and larval angelfish, Pterophyllum scalare

Sakamoto, H, M. Yoshida, T. Sakamoto, K. Uematsu

Zool. Sci. 1999年

Novel [³H]clnidine binding sites in the intestine of the eal acclimated to sea water(共著)

Zool. Sci 15 ( 2 ) 205 - 212 1998年

Novel [3H]clonidine binding sites in the intestine of the eel acclimated to sea water

Hung Tae Kim, Tatsuya Sakamoto, Masaaki Ando

Zoological Science 15 ( 2 ) 205 - 212 1998年

記述言語：英語出版者・発行元：Zoological Society of Japan

Novel clonidine binding sites were characterized in the intestinal membrane isolated from seawater eels. The specific clonidine binding sites consisted of at least two classes, high affinity (Kd = 1.4 ± 0.3 nM, n = 5) and low affinity (Kd = 175 ± 34 nM, n = 5) sites. The specific binding of 2 nM [3H]clonidine was most enhanced at 20°C and at pH 7.5, and reversed by unlabelled clonidine. Such binding was hardly inhibited by adrenaline, yohimbine or rauwolscine, indicating that most binding sites are distinct from α2-adrenoceptor. The specific clonidine binding was inhibited by various imidazoline/guanidinium drugs, indicating existence of imidazoline/guanidinium receptive sites (IGRS) or imidazoline receptors in the eel intestine. Competition experiments revealed that rank order to displace 2 nM [3H]clonidine from their binding sites was as follows: guanabenz &gt
cirazoline = naphazoline = UK14304 = ST587 ≥ clonidine ≥ idazoxan = RX821002 = tolazoline &gt
ST93 = oxymetazoline = amiloride = ST91 &gt
yohimbine = efaroxan = rauwolscine ≥ adrenaline = ST567 = histamine = agmatine. The rank order was different from those in I1 or I2 sites of IGRS reported in various mammalian tissues, suggesting existence of new IGRS, non I1 and non I2 sites, in the eel intestine. In addition, structure-affinity relationships are discussed from the results of competition experiments. Although physiological role of IGRS is not clear yet even in mammalian cells/tissues, eel intestine may be a good model to elucidate how the IGRS act in the cell and to decide what is the endogenous ligand for the IGRS, since eel intestine contains great amount of IGRS and it responds to guanabenz, an exogenous clonidine derivative.

DOI： 10.2108/zsj.15.205

Scopus

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Novel [3H]clonidine binding sites in the intestine of the eel acclimated to sea water

Kim, H. T, T. Sakamoto, M. Ando

Zool. Sci 1998年

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