Disc-electrophoretic identification of prolactin in the cichlid teleosts Tilapia and Cichlasoma and densitometric measurement of its concentration in Tilapia pituitaries during salinity transfer experiments

Clarke, W. Craig

doi:10.1139/z73-103

Cited by 32 publications

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References 18 publications

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“…For tilapia prolactin slightly lower (Clarke, 1973;Farmer et al, 1977) or higher (Specker et cil., 1984) values have been reported after SDS electrophoresis. We consider such dif ferences typical for the SDS p ro ced u re, which involves denaturation and binding of an anionic detergent, treatments that may affect electrophoretic mobility.…”

Section: Discussionmentioning

confidence: 99%

Environmental control of prolactin synthesis in the teleost fish Oreochromis (formerly Sarotherodon) mossambicus

Bonga

Flik

Löwik

et al. 1985

General and Comparative Endocrinology

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In the cichlid fish Oreochromis mossambicus prolactin cell activity is inversely related to the osmolarity and the Ca:~ concentration of the ambient water. Prolactin cell activity was estimated, at the end of a 3-week experimental period, by determination of the rate of prolactin synthesis during incubation of the rostral parts of the pituitary gland, in the pres ence of 13HJlysine. Since the secretory activity of isolated prolactin cells is known to be inversely related to the osmolarity of the incubation medium, the possibility was investi gated that the effects of changes in ionic composition of the ambient water on prolactin secretion in vivo are mediated by changes in osmolarity of the blood plasma. No support was found for this hypothesis. In fish exposed to high water osmolarities prolactin cell activity was reduced, while plasma osmolarity increased. In contrast, at high Ca:~ con centrations of the water, when prolactin secretion was inhibited to a similar extent, plasma osmolarity was significantly reduced. Although direct effects of plasma osmolarity on pro lactin cells cannot be excluded completely, it is unlikely that plasma osmolarity is the predominant factor in the control of prolactin cell activity in situ. The physiological signif icance of the capacity of isolated prolactin cells to respond to changes in osmolarity of the ambient medium-a capacity shared with some other endocrine cell types-is therefore unclear. V 1985 Academic Press. Inc.In general there is consensus about the osmolarity of the water as an important am bient factor controlling prolactin secretion in fish (Ensor and Ball, 1972; Dubourg ct cil., 1980; W endelaar Bonga and Van der Meij, 1981). For species such as stickle backs and the cichlid O reochrom is mosscimhicus (further called tilapia), the water concentrations of Ca2+ and Mg2 + and the pH of the water are important additional factors (W endelaar Bonga, 1978;Ogasawara and Yamada, 1979; Van der Meij, 1980, 1981; Wendelaar Bonga cl ciL, 1983. However, spe cies-specific differences have been reported for the responses of prolactin cells to changes in external Ca:+ levels (Dubourg ct a i, 1983).With respect to the internal control of larity. There is ample evidence for the pres ence of hypothalamic control (Wigham ct ul., 1975; Peter and M cKeown, 1975;Ball, 1981). The osm olarity of blood plasm a could be a factor in mediating the effects of the osmolarity of the water on prolactin se cretion (Sage, 1968; N ag ah am a ct cil., 1975), since prolactin cells in vitro respond to osm olarity of the incubation m edium (Sage, 1968; N agaham a ct cil., 1975; Wigham ct cil., 1977; Grau ct cil., 1981).However it should be stressed that the ev idence supporting this hypothesis is indi rect and based on the study of prolactin cells that were deprived of their hypotha lamic connections. The question remains to be answered whether prolactin cells in situ can respond autonomously to plasma os molarity if the hypothalamic control mechprolactin secretion, two mechanisms have anisms a...

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Section: Discussionmentioning

confidence: 99%

Environmental control of prolactin synthesis in the teleost fish Oreochromis (formerly Sarotherodon) mossambicus

Bonga

Flik

Löwik

et al. 1985

General and Comparative Endocrinology

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“…Gillichthys suffers a much greater decline in plasma sodium concentrations than the coho and is unable to survive indefinitely in fresh water (Nagahama et al 1973(Nagahama et al , 1975. However, Tilapia regulates its plasma sodium levels very well, with partial recovery after only 1 day in fresh water and complete recovery at 1 week (Clarke 1973). The relative performance of the three species can be explained by a comparison of the relative size of the RPD.…”

Section: Discussionmentioning

confidence: 99%

Influence of salinity on ultrastructure of the secretory cells of the adenohypophyseal pars distalis in yearling coho salmon (Oncorhynchus kisutch)

Nagahama¹,

Wc²,

Ws³

1977

Can. J. Zool.

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NAGAHAMA, Y., W. C. CLARKE, and W. S. HOAR. 1977. Influence of salinity on ultrastructure of the secretory cells of the adenohypophyseal pars distalis in yearling coho salmon (Oncorhynchus kisutch). Can. J. Zool. 55: 183-198. Six different types of secretory cells were identified by light and electron microscopy in the adenohypophyseal pars distalis of yearling coho salmon acclimated to fresh or salt water. Prolactin cells are markedly more active in the freshwater than the seawater fish; these cells exhibit definite functional activity 3 days after transfer from salt to fresh water, indicating an osmoregulatory role of prolactin in the freshwater environment. Plasma sodium showed a significant decline 6h after transfer from sea water to fresh water and, even after I week, remained lower than in the fully acclimated freshwater fish. Corticotropic (ACTH) cells did not appear cytologically different in freshwater and seawater fish. GH cells, the most prominent cells in the proximal pars distalis, appear more numerous and more granulated in the seawater fish, suggesting an osmoregulatory involvement in young coho salmon. Putative thyrotropic (TSH) and putative gonadotropic cells (GTH) can be distinguished by differences in granulation; only one type of GTH cell is evident with ultrastructural features that differ from those of sexually mature salmon. Stellate, non-granulated ceUs occur in all regions of the adenohypophysis but more frequently in the prolactin follicles; they are much more prominent in the seawater than freshwater fish. NAGAHAMA, Y., W. C. CLARKE et W. S. HOAR. 1977. Influence of salinity on ultrastructure of the secretory cells of the adenohypophyseal pars distalis in yearling coho salmon (Oncorhynchus kisutch). Can. J. Zool. 55: 183-198. L'examen aux microscopes photonique et electronique de la pars distalis adenohypophysaire de saumons argent& d'un an acclimatts a I'eau douce ou B I'eau salee revele I'existance de six types distincts de cellules secretrices. Les cellules a prolactine sont beaucoup plus actives chez les saumons acclimates a I'eau douce; ces cellules manifestent une activite fonctionnelle bien definie 3 jours apres le transfer des poissons d'eau salee en eau douce, mettant ainsi en lumiire le r61e osmoregulateur de la prolactine en eau douce. Six heures aprks le passage d'eau salee en eau douce, on enregistre une diminution marquee du sodium plasmatique; m2me apres une semaine, ce taux reste plus bas que chez les poissons complttement acclimates al'eau douce. Les cellules a ACTH ne se distinguent pas cytologiquement chez les deux groupes de poissons. Les cellules BGH, les plus grosses de laportion proximale de la pars distalis, semblent plus nombreuses et plus granuleuses chez les poissons d'eau salee, ce qui peut indiquer qu'elles ont un r6le osmorkgulateur chez le ieune saumon amente. Les cellules a TSH et les cellules B GTH se distinguent par leurs granulations; un seil type de cellules B GTH comporte des ultrastructures distinctes de celles au'on trouve chez les saumons B maturi...

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In vitro effects of prolactin and cortisol on water permeability of the urinary bladder of the teleost Gillichthys mirabilis

Doneen

Bern

1974

J. Exp. Zool.

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Urinary bladders of the euryhaline teleost Gillichthys mirabilis were maintained in organ culture under defined conditions for four days. Examination of bladders cultured in medium containing cortisol or prolactin or both hormones indicates that cortisol increases bladder water permeability and that prolactin antagonizes the cortisol effect, causing a reduction in water permeability.Bladders co-cul tured with teleost pituitaries or with teleost rostra1 pars distalis show a pronounced reduction in osmotic permeability. The effects of prolactin and cortisol in vivo appear to be reproducible in vitro.Prolactin has several osmoregulatory actions in teleost fish: on the gills, intestine and kidney.bladder of some euryhaline teleosts adapted to fresh water (cf. Johnson, '73), In general, prolactin is considered to be the major hormone involved in adjustment of teleosts to fresh water. in the adaptation of euryhaline teleosts to sea water (Utida et al., '72), has been shown by Johnson ('73) to antagonize the decrease in bladder permeability induced by prolactin in 133% seawater-acclimated Platichthys stellatus. lactin reduces and cortisol increases bladder osmotic permeability in seawater Gillichthys mirabilis (Hirano et al., '73; Doneen and Nagahama, '73). Because prolactin and cortisol act in opposite fashion, interpretation of experiments in which prolactin is given to intact seawater animals may be complicated by the effects of endogenous cortisol.It also reduces net water movement across the urinary Cortisol, considered to be the major factor Pro-173This report presents the r e s u l t s of our i n i t i a l studies on whole wlichthys bladders maintained i n organ culture under conditions which permit complete definition of the hormonal environment. Thus, i t i s possible t o analyze the separate e f f e c t s of prolactin and cortisol on bladder function. In addition, the t e l e o s t bladder i s shown t o be especially s e n s i t i v e t o t e l e o s t pro1 actins.MATERIALS AND METHODS The sac1 i ke bladders were removed from seawater Gillichthys mirabilis and placed f o r 30 minutes in t e l e o s t Ringer solution containing p e n i c i l l i n (2000 U/ml), streptomycin (2000 mcg/ml) and mycostatin (1000 U/ml). Bladders were then transferred t o small p l a s t i c t i s s u e culture dishes containing 2 ml of culture medium (199 in Hank's Balanced S a l t Solution) w i t h o r without added hormones. mones used were prolactin (ovine, NIH PS-lo), cortisol acetate, insulin and ACTH.Bladders were cultured f o r four days a t 15O. HorFor co-culture experiments, p i t u i t a r i e s were removed from freshwater Tilapia mossambica and 5% seawater-adapted G. mirabilis. the rostra1 par d i s t a l i s ( R P D ) was separated from the proximal pars d i s t a l i s t pars intermedia (PPD t PI): the e n t i r e Gillichthys p i t u i t a r y was used. In the Tilapia materialFollowing the 4-day incubation, bladders were removed from culture and the osmotic permeability coefficient (Pas) was measured as previou...

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Disc-electrophoretic identification of prolactin in the cichlid teleosts Tilapia and Cichlasoma and densitometric measurement of its concentration in Tilapia pituitaries during salinity transfer experiments

Cited by 32 publications

References 18 publications

Environmental control of prolactin synthesis in the teleost fish Oreochromis (formerly Sarotherodon) mossambicus

Environmental control of prolactin synthesis in the teleost fish Oreochromis (formerly Sarotherodon) mossambicus

Influence of salinity on ultrastructure of the secretory cells of the adenohypophyseal pars distalis in yearling coho salmon (Oncorhynchus kisutch)

In vitro effects of prolactin and cortisol on water permeability of the urinary bladder of the teleost Gillichthys mirabilis

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