Response of “prolactin-secreting” cells of Tilapia mossambica to environmental salinity

Dharmamba, Muthusamy; Nishioka, Richard S.

doi:10.1016/0016-6480(68)90051-8

Cited by 98 publications

(29 citation statements)

References 26 publications

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“…However, in Gasterosteus aculeatus the secretory granules were evenly distributed (Benjamin, 1974). The round secretory granules with varying electron-dense content and a narrow clear halo were similar to those described in a number of teleosts (Schreibman et al, 1973;Benjamin, 1974;Holmes and Ball, 1974;Betchaku and Douglas, 1980;Quesada et al, 1988), although a wide separation of the secretory granule core from its limiting membrane has been described in some species (Dharmamba and Nishioka, 1968;Abraham, 1971;Cook and van Overbeeke, 1972;Benjamin, 1974;Leatherland et al, 1974;Batten et al, 1975). However, the semicore osmiophilic inclusion seen in some granules of the M. yellowtail ACTH cells has not been described in the teleosts so far studied.…”

Section: Discussionsupporting

confidence: 74%

Immunocytochemical and ultrastructural characterization of melanotropin and adrenocorticotropin cells from the mediterranean yellowtail (Seriola dumerilii, Risso 1810)

et al. 1997

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Section: Discussionsupporting

confidence: 74%

Immunocytochemical and ultrastructural characterization of melanotropin and adrenocorticotropin cells from the mediterranean yellowtail (Seriola dumerilii, Risso 1810)

et al. 1997

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“…While the discovery of two distinct Prl molecules in tilapia suggested the evolution of distinct actions, no clear differences in osmoregulatory action have been demonstrated (Specker et al 1985). This issue has been recently revisited by Fiol et al (2009) Early studies have shown greater RPD and Prl cell size (Dharmamba & Nishioka 1968), greater Prl cell activity (Nagahama et al 1975), and greater hypophyseal Prl content (Nicoll et al 1981) in tilapia maintained in FW compared to tilapia maintained in SW. Later, Yoshikawa-Ebesu et al (1995) reported that hyposmotically induced Prl 177 and Prl 188 synthesis is more robust in RPDs of fish acclimated to FW than in RPDs of fish acclimated to SW. Likewise, mRNA levels for both prl genes were higher in pituitaries of tilapia acclimated to FW than in pituitaries of fish acclimated to 1 ⁄ 4 SW or SW (Shepherd et al 1999).…”

Section: Discussionmentioning

confidence: 99%

Prolactin177, prolactin188 and prolactin receptor 2 in the pituitary of the euryhaline tilapia, Oreochromis mossambicus, are differentially osmosensitive

Seale

Moorman²,

Stagg³

et al. 2012

Journal of Endocrinology

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Two forms of prolactin (Prl), prolactin 177 (Prl 177 ) and prolactin 188 (Prl 188 ), are produced in the rostral pars distalis (RPD) of the pituitary gland of euryhaline Mozambique tilapia, Oreochromis mossambicus. Consistent with their roles in fresh water (FW) osmoregulation, release of both Prls is rapidly stimulated by hyposmotic stimuli, both in vivo and in vitro. We examined the concurrent dynamics of Prl 177 and Prl 188 hormone release and mRNA expression from Prl cells in response to changes in environmental salinity in vivo and to changes in extracellular osmolality in vitro. In addition, mRNA levels of Prl receptors 1 and 2 (prlr1 and prlr2) and osmotic stress transcription factor 1 (ostf1) were measured. Following transfer from seawater (SW) to FW, plasma osmolality decreased, while plasma levels of Prl 177 and Prl 188 and RPD mRNA levels of prl 177 and prl 188 increased. The opposite pattern was observed when fish were transferred from FW to SW. Moreover, hyposmotically induced release of Prl 188 was greater in Prl cells isolated from FW-acclimated fish after 6 h of incubation, while the hyposmotically induced increase in prl 188 mRNA levels was only observed in SW-acclimated fish. In addition, prlr2 and ostf1 mRNA levels in Prl cells from both FW-and SW-acclimated fish increased in direct proportion to increases in extracellular osmolality both in vivo and in vitro. Taken together, these results indicate that the osmosensitivity of the tilapia RPD is modulated by environmental salinity with respect to hormone release and gene expression. Journal of Endocrinology (2012) 213, 89-98Introduction A necessary component of the systems that direct osmoregulatory processes are osmoreceptors that detect deviations from salt and water balance and initiate adaptive responses to restore equilibrium. The prolactin (Prl)-secreting cells of the euryhaline Mozambique tilapia (Oreochromis mossambicus) comprise a nearly homogeneous portion of the rostral pars distalis (RPD) of the pituitary (conservatively O95%) and are directly stimulated by physiologically relevant decreases in extracellular osmolality in vitro , Seale et al. 2006b. Consistent with its role as an essential hormone for fresh water (FW) acclimation (reviewed by Hirano (1986), Manzon (2002) and Sakamoto & McCormick (2006)) plasma Prl levels increase in vivo when tilapia are transferred from seawater (SW) to FW (Yada et al. 1994, Seale et al. 2002. The operation of tilapia Prl cells as true osmoreceptors and the anatomical organization of these cells in tilapia RPD provide an accessible model to integrate osmosensing mechanisms with gene transcription, hormone synthesis and hormone secretion (Seale et al. 2005).Hyposmotically induced Prl release from tilapia lactotrophs is dependent on the entry of extracellular Ca 2C through stretch-activated ion channels upon cell swelling (Seale et al. 2003). There is evidence that the influx of extracellular Ca 2C may have distinct intracellular effects depending on the acclimation salinity of the animal fro...

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“…Pioneering studies in various teleosts including tilapia identified an inverse relation between environmental salinity and prolactin cell activity in vivo (Dharmamba & Nishioka 1968, Olivereau 1969, Ball 1969a and between medium osmolality and PRL release in vitro (Sage 1965, 1968, Ingleton et al 1973, Nagahama et al 1974, Zambrano et al 1974. These findings would seem to indicate that the PRL cell activity of these teleosts reflects changes in extracellular osmolality during adaptation to different salinities.…”

Section: Introductionmentioning

confidence: 99%

“…The structure of the tilapia pituitary is advantageous for studying the regulation of PRL release and synthesis because the PRL cells are segregated into a nearly homogenous mass located in the rostral pars distalis and comprise greater than 95% of the cells in this region of the pituitary (see Dharmamba & Nishioka 1968. This region of the pituitary can be easily dissected to obtain a nearly homogenous population of PRL-secreting cells, devoid of growth hormone (GH)-secreting cells (Dharmamba & Nishioka 1968.…”

Section: Introductionmentioning

confidence: 99%

Is the primitive regulation of pituitary prolactin (tPRL177 and tPRL188) secretion and gene expression in the euryhaline tilapia (Oreochromis mossambicus) hypothalamic or environmental?

Shepherd¹,

Sakamoto

Hyodo³

et al. 1999

Journal of Endocrinology

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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 ¼ seawater, tilapia were transferred to fresh water (FW), ¼ 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 the 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.

show abstract

Response of “prolactin-secreting” cells of Tilapia mossambica to environmental salinity

Cited by 98 publications

References 26 publications

Immunocytochemical and ultrastructural characterization of melanotropin and adrenocorticotropin cells from the mediterranean yellowtail (Seriola dumerilii, Risso 1810)

Immunocytochemical and ultrastructural characterization of melanotropin and adrenocorticotropin cells from the mediterranean yellowtail (Seriola dumerilii, Risso 1810)

Prolactin177, prolactin188 and prolactin receptor 2 in the pituitary of the euryhaline tilapia, Oreochromis mossambicus, are differentially osmosensitive

Is the primitive regulation of pituitary prolactin (tPRL177 and tPRL188) secretion and gene expression in the euryhaline tilapia (Oreochromis mossambicus) hypothalamic or environmental?

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