Isolation and properties of teleost prolactin

Farmer, Susan Walker; Papkoff, Harold; Bewley, Thomas A.; Hayáshida, T.; Nishioka, Richard S.; Bern, Howard A.; Li, Choh Hao

doi:10.1016/0016-6480(77)90191-5

Cited by 71 publications

(13 citation statements)

References 30 publications

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“…Identical residues in teleost and mammal PRLs are boxed with a heavy line. (24 kDa) is 4 kDa larger than the previously described tilapia PRL (7,8), and is atypically basic (pI 8.7) compared to other PRLs. Application of reversed-phase HPLC permits the isolation in a single step of both PRLs or GH from media in which pituitary regions containing PRL-or GH-secreting cells have been incubated.…”

Section: Resultscontrasting

confidence: 54%

“…GH appeared as a protein of =21 kDa. These three proteins ran as single bands (lanes 1-3), even with as much as 10 ,ug of each on a single lane (lanes [6][7][8]. It was possible to resolve the proteins by using NaDodSO4/PAGE (lane 4, Fig.…”

Section: Resultsmentioning

confidence: 99%

“…This research direction was taken following reports that mammalian PRL might be modified during release (3)(4)(5)(6) and because we thought that such modification might explain why tilapia PRL isolated previously exhibited anomalous electrophoretic behavior (7)(8)(9), even though its immunological and biological characteristics were similar to those of other vertebrate PRLs (10,11).…”

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confidence: 99%

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Isolation and partial characterization of a pair of prolactins released in vitro by the pituitary of a cichlid fish, Oreochromis mossambicus.

Specker¹,

King²,

Nishioka³

et al. 1985

Proc. Natl. Acad. Sci. U.S.A.

110

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The pituitary of the cichlid fish tilapia secretes two prolactins (PRLs) of molecular masses 20 kDa and 24 kDa. The 20-kDa PRL has an isoelectric point in the range of those of mammalian PRLs (pI 6.7), but the 24-kDa PRL is unusually basic (pI 8.7). Partial sequence information indicates that the PRLs are homologous but distinct proteins, differing by five amino acids within the first 29 NH2-terminal residues. Homology in the known region is higher with chum salmon PRL than with known mammalian PRLs. Reversed-phase HPLC permits isolation of these two PRLs and a single tilapia growth hormone from culture medium or from the pituitary in a single step. HPLC and radio-HPLC analysis of [3H]leucine pulse-chase experiments reveal that each PRL is secreted in vitro at remarkably high rates (21 pmol per gland per hr) and that the two PRLs are released in approximately equimolar amounts, suggesting the coordinate regulation of the secretion. Both PRLs exert characteristic PRL activity in that they prevent the loss of Na' from the plasma of hypophysectomized tilapia in fresh water.In teleost fishes, pituitary prolactin (PRL) production is confined to the rostral pars distalis (RPD). The RPD of the cichlid fish tilapia (Oreochromis mossambicus) consists almost entirely of PRL-secreting cells and accounts for almost one-third of the entire pituitary (1, 2). This regionalization of PRL cells differs from the scattered distribution of PRL cells in the pituitaries ofother vertebrates and has made the teleost pituitary a useful model for the study of PRL cell function.The aim of the investigations reported here was to make use of this organizational simplicity in order to isolate and characterize both stored and secreted PRL from the tilapia pituitary. This research direction was taken following reports that mammalian PRL might be modified during release (3-6) and because we thought that such modification might explain why tilapia PRL isolated previously exhibited anomalous electrophoretic behavior (7-9), even though its immunological and biological characteristics were similar to those of other vertebrate PRLs (10, 11).Our approach has been to culture the PRL-producing lobes and to isolate secreted proteins from the culture medium using reversed-phase HPLC.

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Section: Resultscontrasting

confidence: 54%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Isolation and partial characterization of a pair of prolactins released in vitro by the pituitary of a cichlid fish, Oreochromis mossambicus.

Specker¹,

King²,

Nishioka³

et al. 1985

Proc. Natl. Acad. Sci. U.S.A.

110

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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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“…The development of fetal and neonatal sodium excretion ability (1,2) and its relationship with hormones involved in volume regulation such as the renin-angiotensin-aldosterone system (3,4) vasopressin (5,6), and, more recently, atrial natriuretic factor (6) have been investigated and are still controversial. PRL is a hormone with apparently little effect in the control of fluid volume in mature animals (7,8); however, its role has been recently questioned in fluid and electrolyte homeostasis throughout vertebrate phylogeny (9) and its elevated levels (10) during gestation and the neonatal period.…”

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Effects of Prolactin on Na+K+-ATPase Activity in the Nephron during Maturation in the Rat

et al. 1992

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ABSTRACT. The effect of prolactin (PRL) on renal Na+K+-ATPase was investigated in 7-d-old neonatal rats. Animals were treated by bromocriptine (Br; a blocker of endogenous PRL secretion), and the enzyme activity was compared with that of untreated controls. Na+K+-ATPase was determined in renal sections in the medullary thick ascending limb of Henle's loop and in the distal tubule by cytochemistry. In the distal tubule, Na+K+-ATPase activity was significantly lower in Br-treated animals than in controls ( Mechanisms by which fluid and salt balances are preserved in the fetal and neonatal periods are not completely understood. The development of fetal and neonatal sodium excretion ability (1, 2) and its relationship with hormones involved in volume regulation such as the renin-angiotensin-aldosterone system (3, 4) vasopressin (5, 6), and, more recently, atrial natriuretic factor (6) have been investigated and are still controversial. PRL is a hormone with apparently little effect in the control of fluid volume in mature animals (7, 8); however, its role has been recently questioned in fluid and electrolyte homeostasis throughout vertebrate phylogeny (9) and its elevated levels (10) during gestation and the neonatal period.Renal Na+Kt-ATPase, the driving force of tubular reabsorption, plays a key role in fluid and electrolyte homeostasis; in a previous study (1 1), we reported in mature animals a parallelism in enzyme activity and PRL levels in vivo and PRL stimulation of the sodium pump in vitro in a range of concentrations similar to those observed during maturation, suggesting that the hormone may control the enzyme activity at this period. In the 20 present study, we first investigated the effect of in vivo changes in PRL secretion on renal Na+K+-ATPase in 7-d-old rats. Groups of neonatal rats were treated with Br, a drug that blocks PRL secretion, for 5 d and renal Na+K+-ATPase activity in these treated animals was compared with that of untreated animals. The hormone effects were investigated in vitro by determining the enzyme activity in kidney sections from Br-treated and control animals after incubation with increasing concentrations of ovine PRL. MATERIALS AND METHODSAnimals. Pregnant Sprague-Dawley rats (Charles River Breeding Laboratories, Wilmington, MA) were obtained and allowed to deliver naturally at our research facilities. They were observed at least twice daily to determine the exact parturition time; day birth counted as d 1. Pups were kept with their dam. All animals had free access to the standard laboratory diet (Soufirat, UAR, Epinay sur Seine, France) and tap water. Litters (n = 3) were reduced to five pups, and treatment for a given litter was determined randomly. No animals died. Ten male adult rats (300 g) were used as a reference group (adult control).Br Treatment. On d 7, three pups from each litter (Br) were treated with Br (2-Br-ergocriptine mesylate; Sandoz Pharmaceuticals, Hanover, NJ). Because in preliminary experiments intraperitoneal and S.C. injections induced necrosis, the drug...

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Isolation and properties of teleost prolactin

Cited by 71 publications

References 30 publications

Isolation and partial characterization of a pair of prolactins released in vitro by the pituitary of a cichlid fish, Oreochromis mossambicus.

Isolation and partial characterization of a pair of prolactins released in vitro by the pituitary of a cichlid fish, Oreochromis mossambicus.

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

Effects of Prolactin on Na+K+-ATPase Activity in the Nephron during Maturation in the Rat

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