Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The osmoregulatory actions of ovine prolactin (oPRL), ovine growth hormone (oGH), and cortisol were tested in the euryhaline gilthead seabream Sparus aurata. Acclimated to sea water (SW, 40 ppt salinity, 1000 mOsm/kg H(2)O) or brackish water (BW, 5 ppt, salinity, 130 mOsm/kg H(2)O), injected every other day for one week (number of injections, 4) with saline (0.9% NaCl), oPRL (4 microg/g body weight), oGH (4 microg/g body weight) or cortisol (5 microg/g body weight), and transferred from SW to BW or from BW to SW 24h after the last injection. Fish were sampled before and 24h after transfer. Gill Na(+), K(+)-ATPase activity, plasma osmolality, plasma ions (sodium and chloride), plasma glucose, and muscle water moisture were examined. SW-adapted fish showed higher gill Na(+), K(+)-ATPase activity, plasma osmolality, and plasma ions levels than BW-adapted fish. Transfer from SW to BW decreased plasma osmolality and ions levels after 24h, while transfer from BW to SW increased these parameters, whereas gill Na(+),K(+)-ATPase activity was unaffected. oPRL treatment significantly decreased gill Na(+),K(+)-ATPase activity and increased plasma osmolality and ions in SW- and BW-adapted fish. This treatment minimizes loss of osmolality and ions in plasma after transfer to BW and increased these values after transfer to SW. No significant changes were observed in gill Na(+),K(+)-ATPase activity, plasma osmolality, and plasma ions in oGH-treated group with respect to saline group before or after transfer from SW to BW or from BW to SW. Treatment with cortisol induced, in SW-adapted fish, a significant increase of gill Na(+),K(+)-ATPase activity and decrease of plasma osmolality and plasma ions. In BW-adapted fish this treatment induced a significant increases in gill Na(+),K(+)-ATPase activity, plasma osmolality, and plasma ions. After transfer to SW cortisol-treated fish had higher plasma osmolality than the saline group. Our results support the osmoregulatory role of PRL in the adaptation to hypoosmotic environment in the gilthead seabream S. aurata. Further studies will be necessary to elucidate the osmoregulatory role of GH in this species. Cortisol results suggest a "dual osmoregulatory role" of this hormone in S. aurata.
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PMID:Osmoregulatory action of PRL, GH, and cortisol in the gilthead seabream (Sparus aurata L). 1244 Nov 19

The hypothesis that protein kinase C (PKC) and tyrosine kinases, as well as serine-threonine and tyrosine phosphatases, are involved in prolactin (PRL) signalling in theca cells harvested from porcine follicles was tested. Theca cells were incubated with PRL for 24 h to stimulate progesterone (P4) production. In addition, treatments included inhibitors of PKC and tyrosine kinases, as well as serine-threonine phosphatase inhibitor and tyrosine phosphatase inhibitor. Prolactin significantly stimulated P4 production by theca cells and all inhibitors suppressed the PRL-stimulated P4 production. After incubation with PRL for 2, 5, 10 or 20 min, theca cells were homogenized and cytosolic and membrane fractions were obtained. This was followed by determination of PKC activity in partially purified subcellular fractions by measuring the transfer of 32P from [gamma-32P] adenosine triphosphatase (ATP) to histone III-S. In unstimulated porcine theca cells the major proportion of PKC activity was present in the cytosol. Incubation of cells with PRL resulted in a rapid, time-dependent increase in the amount of PKC activity in the membrane fraction. Protein kinase C activity in the membrane fraction was maximal after 10 min of cells' exposure to PRL. Protein kinase C activation was assessed also by measuring the specific association of 3H-phorbol dibutyrate (3H-PDBu) with theca cells after treatment with PRL. Prolactin significantly increased 3H-PDBu-specific binding in theca cells. In contrast to PKC, total inositol phosphate accumulation was not affected by PRL in the current study. In summary, PRL stimulated P4 production by porcine theca cells derived from large follicles. The results of the study were consistent with the hypothesis that PKC is one of the intracellular mediators of PRL action in porcine theca cells. Protein kinase C activation does not appear to occur through the action of phosphatidylinositol-dependent phospholipase C. Moreover, the involvement of tyrosine kinases, as well as tyrosine and serine-threonine phosphatases, in PRL signalling in the examined cells is suggested.
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PMID:Prolactin signalling in porcine theca cells: the involvement of protein kinases and phosphatases. 1272 1

The cyclooxygenase (COX) pathway converts arachidonic acid (ArA) into prostaglandins (PGs), which interact with the stress response in mammals and possibly in fish as well. Acetylsalicylic acid (ASA) is a COX inhibitor and was used to characterize the effects of PGs on the release of several hormones and the stress response of tilapia (Oreochromis mossambicus). Plasma PGE2 was significantly reduced at 100 mg ASA/kg body wt, and both basal PGE2 and cortisol levels correlated negatively with plasma salicylate. Basal plasma 3,5,3'-triiodothyronine (T3) was reduced by ASA treatment, whereas prolactin (PRL)188 increased at 100 mg ASA/kg body wt. ASA depressed the cortisol response to the mild stress of 5 min of net confinement. As expected, glucose and lactate were elevated in the stressed control fish, but the responses were blunted by ASA treatment. Gill Na+-K+-ATPase activity was not affected by ASA. Plasma osmolarity increased after confinement in all treatments, whereas sodium only increased at the high ASA dose. This is the first time ASA has been administered to fish in vivo, and the altered hormone release and the inhibition of the acute stress response indicated the involvement of PGs in these processes.
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PMID:Effects of acetylsalicylic acid treatment on thyroid hormones, prolactins, and the stress response of tilapia (Oreochromis mossambicus). 1284 67

The electrophysiological and ion-transporting properties of cultured gill epithelia from freshwater (FW) rainbow trout were examined in the presence of cortisol and prolactin as media supplements. Epithelia were of the double-seeded insert (DSI) type containing both pavement cells (PVCs) and mitochondria-rich cells (MRCs) and were grown in Leibovitz's L15 media on filters allowing exposure to different apical media conditions. Experiments were carried out in two series after 7-9 days symmetrical (L15 apical-L15 basolateral) culture. In both series, 100% L15 was maintained as the basolateral medium throughout and supplemented with physiologically relevant doses of either prolactin (50 ng/ml), cortisol (500 ng/ml), or cortisol + prolactin (500 + 50 ng/ml, respectively). In series 1, epithelia were exposed to progressively diluted apical media (100, 75, 50, 25, 12.5% L15, and FW) at 24-h intervals. The preparations retained integrity [high transepithelial resistance (TER); low ion efflux rates] during this prolonged dilution protocol. Cortisol, or cortisol + prolactin, resulted in a greater TER and reduced ion efflux rates during dilution, likely an effect on junctional permeability of PVCs, but did not promote active Na+ and Cl- uptake from apical FW. In series 2, epithelia were directly exposed to apical FW and ion fluxes measured over the first 6 h. Under these conditions, cortisol or cortisol + prolactin promoted active uptake of both Na+ and Cl- simultaneously from apical FW, probably attributable to actions on the MRCs. However, Na+-K+-ATPase activities were not significantly altered by any of the treatments in either series. Overall, prolactin alone did not appear to promote FW adaptation but exhibited synergism with cortisol. These results provide further support for the cultured DSI epithelium as an in vitro model for ion transport in FW fish.
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PMID:Effects of cortisol and prolactin on Na+ and Cl- transport in cultured branchial epithelia from FW rainbow trout. 1289 56

Ouabain, a cardiac glycoside and inhibitor of Na(+), K(+)-ATPase, is now believed to be a steroid hormone in mammals, involved in blood pressure and volume regulation and possibly acting as a natriuretic hormone. We have identified ouabain-like immunoreactivity in the plasma and tissues of a euryhaline teleost, the tilapia (Oreochromis mossambicus), by means of solid-phase extraction followed by a specific radioimmunoassay. Plasma concentrations of immunoreactive ouabain were 5-20pg/ml. Ouabain immunoreactivity was detected in all the tissues examined, with highest concentrations in the head kidney followed by intestine and body kidney. When the fish in fresh water were transferred to seawater, plasma osmolality increased significantly after 2, 4, 8, and 24h. Significant increases were observed in plasma ouabain immunoreactivity after 4 and 24h, and a significant correlation was seen between ouabain immunoreactivity and plasma osmolality. There was also a significant correlation between the plasma osmolality and cortisol concentrations. Upon transfer from seawater to fresh water, significant increases were seen in plasma cortisol after 4 and 8h and in immunoreactive ouabain after 4h. When the correlation was analyzed using all the data obtained during the two transfer experiments, plasma ouabain immunoreactivity and cortisol were significantly correlated with plasma osmolality, whereas there was a significant negative correlation between plasma prolactin and osmolality. A significant positive correlation was also seen between plasma cortisol and ouabain immunoreactivity. These results suggest that immunoreactive ouabain may be involved, together with cortisol, in the maintenance of hydromineral balance in the tilapia.
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PMID:Changes in plasma concentrations of immunoreactive ouabain in the tilapia in response to changing salinity: is ouabain a hormone in fish? 1464 48

This study aims to clarify the role of the polyunsaturated fatty acid arachidonic acid (ArA, 20:4n-6) in the stress response of Mozambique tilapia (Oreochromis mossambicus). ArA is converted into eicosanoids, including prostaglandins, which can influence the response to stressors. Tilapia, a species able to form ArA from its precursor, was supplemented with ArA for 18 days, after which they were confined for 5 min. Acetylsalicylic acid (ASA, COX-inhibitor) was subsequently administered to distinguish ArA-mediated effects from enhanced prostaglandin E(2) (PGE(2)) synthesis. ArA supplemented fish had higher ArA levels in gills and kidneys, and these levels were further enhanced after ASA treatment. Levels of total monounsaturated and polyunsaturated fatty acids as well as docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and ArA, were altered 24h after confinement, particularly in the kidneys. ArA supplementation had no effect on basal cortisol levels, while ArA + ASA reduced basal cortisol levels. ArA + ASA augmented the cortisol response to confinement. The combination of ArA + ASA also elevated plasma basal prolactin (tPRL)(177) and 3,5,3'-triiodothyronine (T(3)) levels. Neither ArA nor ASA affected the stress-associated increases in plasma glucose and lactate. Na(+), K(+)-ATPase activity in the gills was reduced after ArA supplementation and was even further suppressed by subsequent ASA treatment. In an additional feeding trial, ArA supplementation enhanced the renal Na(+), K(+)-ATPase activity. In vitro, ArA was a potent inhibitor of the Na(+), K(+)-ATPase activity of gill and kidney homogenates. In contrast, PGE(2) had no effect on branchial ATPase, whereas the effect on renal ATPase activity was concentration dependent. Modifying the dietary intake of ArA alters the response of tilapia to an acute stressor and influences osmoregulatory processes and it is unlikely that these effects are due to an enhanced production of prostaglandins.
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PMID:Dietary supplementation with arachidonic acid in tilapia (Oreochromis mossambicus) reveals physiological effects not mediated by prostaglandins. 1556 Aug 68

The effects of ovine prolactin (oPRL) and striped bass prolactin (sbPRL; Morone saxatilis) on plasma osmolality, electrolyte balance, and gill Na(+),K(+)-ATPase activity were investigated in hypophysectomized (Hx), freshwater (FW)-acclimated, hybrid striped bass (M. saxatilisxMorone chrysops). They were kept in dilute (isoosmotic) seawater for about 10 days after surgery. Seven days after transfer to FW, Hx fish had lower plasma osmolality and lower levels of Na(+), Cl(-), and Ca(2+) than sham-operated and intact fish. Fish were injected four times with oPRL (1, 5, or 20 microg/g body mass), sbPRL (10 or 100 ng/g), or hormone vehicle (0.9% NaCl) at 48-h intervals (days 0, 2, 4, and 6) in FW and then sampled for blood plasma 24 h after the fourth injection (day 7). In Hx fish, oPRL (5 and 20 microg/g) and sbPRL (10 and 100 ng/g) were effective in maintaining plasma osmolality and levels of Na(+), Cl(-), and Ca(2+) above values seen in saline-injected controls. Hypophysectomy did not affect branchial Na(+),K(+)-ATPase activity, but enzyme activity was significantly reduced in Hx fish receiving oPRL (20 mug/g) or sbPRL (10 or 100 ng/g). These results indicate that PRL acts to maintain plasma osmotic and ionic balance in FW-adapted hybrid striped bass, and that this may involve downregulation of branchial Na(+),K(+)-ATPase activity.
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PMID:Osmoregulatory effects of hypophysectomy and homologous prolactin replacement in hybrid striped bass. 1564 68

We investigated gradual dilution of the apical medium (Leibovitz's L15 to fresh water [FW], analogous to gradual reduction in environmental salinity) and basolateral hormone support on the electrophysiological and ion-transporting properties of "developing" FW trout gill epithelia cultured on filter inserts. Epithelia were of the double-seeded type, containing both pavement cells and mitochondria-rich cells. In these experiments we were able to circumvent "symmetrical development" (typically L15 apical/L15 basolateral for 6-9 days) by commencing dilution of apical media (unchanged L15 basolateral, i.e., asymmetrical conditions) at culture-day 3, the time when transepithelial resistance (TER) and potential (TEP) would normally be increasing rapidly under symmetrical conditions. In Series 1 (without basolateral hormone support), epithelia were exposed to progressively diluted apical media (100%, 75%, 50% L15) at 24-hr intervals, thereafter cultured in 50% L15 apical media for 4 days, and then in apical FW. In Series 2, epithelia were exposed to progressively diluted apical media (100%, 75%, 50%, 25%, 12.5% L15, and FW) at 24-hr intervals with physiologically relevant doses of cortisol (500 ng ml(-1)), prolactin (50 ng ml(-1)), or cortisol + prolactin (500 ng ml(-1) + 50 ng ml(-1), respectively) added to basolateral media (100% L15). In Series 1, TER reached a plateau phase over 25 kohms cm2 under 50% L15/L15 culture conditions (after 4 days of culture) but fell to approximately 6 kohms cm2 after 24 hr in FW/L15 conditions. In Series 2, TER stabilized at 4-11 kohms cm2 depending on treatment. In general, apical media dilution during epithelial development was well tolerated. Preparations exhibited continued integrity right down to apical FW, indicated by only modest increases in net ion losses (i.e., basolateral to apical movement of ions), relatively stable TER values, and the expected changeover from positive to negative TEP in FW. Cortisol was clearly beneficial to FW adaptation, promoting greater TER, reduced unidirectional and net Na+ and Cl- flux rates, and elevated Na+, K+ -ATPase activity. Prolactin also offered some support, where its actions on TER were less than but additive to those of cortisol. There was no direct evidence that prolactin limited ion movements during gradual dilution. These in vitro studies demonstrate that "developing epithelia" were able to tolerate gradual dilution of apical media, the remarkable barrier properties of gill epithelia, and the importance of cortisol and prolactin in promoting integrity of this barrier during FW adaptation.
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PMID:Response of developing cultured freshwater gill epithelia to gradual apical media dilution and hormone supplementation. 1567 8

The full length genes encoding the catalytic alpha and glycosylated beta subunits of the sodium pump (Na+-K+-ATPase) were cloned and characterized from silver sea bream gill. Using in vitro preparations of gill tissue it was found that growth hormone (10 and 100 ng/ml) caused an increase in subunit transcription, translation, and Na+-K+-ATPase enzyme activity. Similarly, insulin-like growth factor 1 (10 and 100 ng/ml) also caused an increase in Na+-K+-ATPase subunit amounts and enzyme activity. Cortisol (10 and 100 ng/ml) increased alpha subunit transcript and protein but did not modulate beta subunit expression or enzyme activity. Ovine prolactin did not cause any changes in Na+-K+-ATPase subunit transcription, translation or enzyme activity. This study is the first to describe how both Na+-K+-ATPase alpha and beta subunits are modulated at transcriptional and translational levels in fish osmoregulatory tissue upon exposure to hormones.
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PMID:Cloning and characterization of sea bream Na+-K+-ATPase alpha and beta subunit genes: in vitro effects of hormones on transcriptional and translational expression. 1588 7

Ouabain, a cardiac glycoside and inhibitor of Na(+), K(+)-ATPase, is now believed to be a steroid hormone in mammals. We have recently identified ouabain immunoreactivity in the plasma of the tilapia, a euryhaline teleost. Changes in plasma concentrations of immunoreactive ouabain (20-40 pM) in response to salinity change were well correlated with the changes in plasma osmolality and cortisol. Our previous studies have shown that cortisol rapidly inhibits prolactin (PRL) release from the tilapia pituitary by suppressing intracellular Ca(2+) ([Ca(2+)]i) and cAMP. In the present study, low doses of ouabain (10-1000 pM) inhibited PRL release dose-dependently during 2-24 h of incubation. There was no effect on growth hormone (GH) release, except for a significant increase at 1000 pM during 8-24 h of incubation. Significant dose-related increases in PRL release were observed at higher doses of ouabain (100-1000 nM), whereas significant inhibition was seen in GH release at 1000 nM during 2-24h of incubation. Ouabain at 1-100 pM had no effect on Na(+), K(+)-ATPase activity of the pituitary homogenate. The enzyme activity was inhibited by higher concentrations of ouabain, 10% at 1 nM, 15% at 10 nM, 28% at 100 nM, and 45% at 1000 nM. Ouabain also attenuated stimulation of PRL release by the Ca(2+) ionophore, A23187, and by a combination of dibutyryl cAMP and a phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthin. Intracellular Ca(2+) concentrations were monitored in the dispersed PRL cells with the Ca(2+)-sensitive dye, fura-2. Ouabain at 1 nM reversibly reduced [Ca(2+)]i within seconds, whereas 1 microM ouabain increased [Ca(2+)]i. A rapid reduction in [Ca(2+)]i was also observed when PRL cells were exposed to 1 microM cortisol, whereas there was no consistent effect at 1 nM. These results suggest that ouabain at physiological concentrations rapidly inhibits PRL release from the tilapia pituitary by suppressing intracellular Ca(2+) and cAMP metabolism. The stimulation of PRL release by high concentrations of ouabain (100-1000 nM) may result from an increase in [Ca(2+)]i, and subsequent depolarization due to the inhibition of Na(+), K(+)-ATPase activity.
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PMID:Physiological concentrations of ouabain rapidly inhibit prolactin release from the tilapia pituitary. 1592 43


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