scholarly journals Elevation of plasma somatolactin concentrations during acidosis in rainbow trout (Oncorhynchus mykiss)

1996 ◽  
Vol 199 (5) ◽  
pp. 1043-1051 ◽  
Author(s):  
S Kakizawa ◽  
T Kaneko ◽  
T Hirano
Keyword(s):  
Rainbow Trout ◽  
Plasma Cortisol ◽  
Initial Level ◽  
Plasma Concentrations ◽  
Water Acidification ◽  
Acid Base ◽  
Exposed Fish ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Blood Ph ◽  
Cortisol Levels

Somatolactin (SL) is a putative pituitary hormone of the growth hormone (GH)/prolactin (PRL) family in fish; its physiological function has yet to be determined. Acidosis was induced in rainbow trout (Oncorhynchus mykiss) by exposure to acidic water (pH 4.5) or by exhaustive exercise, and plasma concentrations of SL, PRL and GH as well as other plasma parameters were examined. A decrease in blood pH was observed in fish from 1 day after water acidification until the end of the experiment at day 7. Plasma SL levels in the acid-exposed fish increased, reached a peak on day 1 and then returned to the initial level by day 4. No change was seen in plasma concentrations of PRL throughout the experiment. Plasma levels of GH, in contrast, decreased in the acid-exposed fish on days 2 and 4. Plasma cortisol levels in the acid-exposed fish were higher than the control level on days 4 and 7, although plasma cortisol levels did not increase above the initial level in response to water acidification. There was no significant change in the expression of SL-, PRL- and GH-mRNA in the pituitary gland. Levels of plasma Na+ and lactate were reduced 12 h after water acidification and remained low throughout the experiment. Exhaustive exercise in shallow water at neutral pH (7.5) resulted in a transient but pronounced acidosis, associated with increases in plasma SL, cortisol, Ca2+, phosphate and lactate levels. Plasma SL levels returned to the initial level along with the recovery of blood acid-base status. In contrast, plasma cortisol levels stayed elevated even 24 h after exercise. There was no correlation between plasma PRL and GH levels and blood pH. Elevation of plasma SL levels during acidosis suggests the possible involvement of SL in acid-base regulation in rainbow trout.

Elevated dietary intake of L-tryptophan counteracts the stress-induced elevation of plasma cortisol in rainbow trout (Oncorhynchus mykiss)

2002 ◽  
Vol 205 (23) ◽  
pp. 3679-3687 ◽  
Author(s):  
Olivier Lepage ◽  
Olof Tottmar ◽  
Svante Winberg
Keyword(s):  
Rainbow Trout ◽  
Plasma Cortisol ◽  
Elevated Plasma ◽  
Monoamine Neurotransmitter ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Serotonergic Activity ◽  
Commercial Feed ◽  
Pelleted Feed ◽  
Cortisol Levels ◽  
Neuroendocrine Axis

SUMMARYJuvenile rainbow trout were isolated in individual compartments and allowed to acclimate for 1 week, during which they were fed commercial trout pellets. The feed was then replaced by pelleted feed supplemented with L-tryptophan(TRP) at two, four or eight times the concentration in the commercial feed. Fish were fed these supplemented feeds daily to satiety for 1 week, after which half of the fish were stressed, by lowering the water level for 2 h,while the remaining fish were left undisturbed. In undisturbed fish,supplementary dietary TRP resulted in slightly elevated plasma cortisol levels. In response to the stress, fish that had been fed control feed showed elevated plasma cortisol levels, but fish fed the TRP-supplemented feed displayed a significant reduction in this stress-induced elevation of plasma cortisol levels. Plasma and brain TRP levels were elevated in fish fed TRP-supplemented feed. TRP is the precursor of the monoamine neurotransmitter serotonin. Brain serotonergic activity was elevated by stress and also tended to be increased by elevated dietary TRP intake. The central serotonergic system is involved in the control of the hypothalamic—pituitary—interrenal axis, the action of serotonin being to stimulate or inhibit this neuroendocrine axis through different projections.

Renal expression and localization of SLC9A3 sodium/hydrogen exchanger and its possible role in acid-base regulation in freshwater rainbow trout (Oncorhynchus mykiss)

2008 ◽  
Vol 295 (3) ◽  
pp. R971-R978 ◽  
Author(s):  
Goran Ivanis ◽  
Marvin Braun ◽  
Steve F. Perry
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Transcriptional Activation ◽  
Plasma Cortisol ◽  
Renal Tubules ◽  
Acid Base ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Sodium Hydrogen Exchanger ◽  
Renal Expression

Experiments were performed to assess the possible involvement of the Na+/H+ exchanger isoform 3 (NHE3; SLC9A3) in renal acid-base regulation in adult rainbow trout ( Oncorhynchus mykiss). NHE3 mRNA was expressed at high levels in the kidney relative to its paralog, NHE2. The results of in situ hybridization demonstrated an abundance of NHE3 mRNA in renal tubules. The combination of immunocytochemistry and histological staining revealed that NHE3 was confined to the apical membrane of proximal tubules, where it was colocalized with the vacuolar-type H+-ATPase. Levels of NHE3 protein (assessed by Western blotting) were increased during hypercapnia, likely as a result of increased transcription, as indicated by increasing levels of NHE3 mRNA (as determined by real-time PCR). Plasma cortisol concentration was increased during hypercapnia, and administration of exogenous cortisol caused a marked increase in NHE3 mRNA and protein. Thus we speculate that the elevation of plasma cortisol during hypercapnia contributes to transcriptional activation of NHE3 that ultimately promotes acid-base regulation by stimulating H+ secretion and HCO3− reabsorption.

scholarly journals Improving glucocorticoid replacement therapy using a novel modified-release hydrocortisone tablet: a pharmacokinetic study

2009 ◽  
Vol 161 (1) ◽  
pp. 119-130 ◽  
Author(s):  
Gudmundur Johannsson ◽  
Ragnhildur Bergthorsdottir ◽  
Anna G Nilsson ◽  
Hans Lennernas ◽  
Thomas Hedner ◽  
...  
Keyword(s):  
Single Dose ◽  
Replacement Therapy ◽  
Plasma Cortisol ◽  
Plasma Concentrations ◽  
Pharmacokinetic Studies ◽  
Double Blind ◽  
Once Daily ◽  
Physiological Serum ◽  
Cortisol Levels ◽  
Dual Release

BackgroundEndogenous plasma cortisol levels have a well-defined circadian rhythm. The aim of this project is to develop a once daily oral dual-release formulation for cortisol replacement therapy that mimics the diurnal variation in the plasma cortisol profile.ObjectiveTo determine single-dose plasma pharmacokinetics and dose-proportionality of oral 5 and 20 mg dual-release hydrocortisone tablets in healthy volunteers. In addition, the effect of food intake was investigated for the 20 mg dose.DesignA randomised, controlled, two-way cross-over, double-blind, phase I study of oral hydrocortisone (modified (dual) release; 5 and 20 mg) with an open food-interaction arm.MethodsThe single dose pharmacokinetic studies were performed with betamethasone suppression. The two first study days were blinded and randomised between morning administration of 5 and 20 mg tablet in a fasting state. The third day was open with a 20 mg tablet taken 30 min after a high-calorie, high-fat meal. The plasma samples were assayed using both a validated LC–MS/MS and an immunoassay. The plasma pharmacokinetic variables were calculated using non-compartmental data analysis.ResultsThe time to reach a clinically significant plasma concentration of cortisol (>200 nmol/l) was within 20 min and a mean peak of 431 (s.d. 126) nmol/l was obtained within 50 min after administration of the 20 mg tablet. Plasma cortisol levels remained above 200 nmol/l for around 6 h thereafter and all plasma concentrations 18–24 h after intake were below 50 nmol/l. In the fed state the time to reach 200 nmol/l was delayed by 28 and 9 min based on LC–MS/MS and immunoassay, respectively. The 5 and 20 mg tablets produced an increase in plasma exposure of cortisol that was not fully dose proportional.ConclusionThe dual release hydrocortisone tablet with once-daily administration produced a diurnal plasma cortisol profile mimicking the physiological serum cortisol profile.

Acid-Base Regulation Following Exhaustive Exercise: A Comparison Between Freshwaterand Sea Water-Adapted Rainbow Trout (Salmo Gairdneri)

1989 ◽  
Vol 141 (1) ◽  
pp. 407-418 ◽  
Author(s):  
Y. TANG ◽  
D. G. McDONALD ◽  
R. G. BOUTILIER
Keyword(s):  
Rainbow Trout ◽  
Sea Water ◽  
Environmental Water ◽  
Exhaustive Exercise ◽  
Salmo Gairdneri ◽  
Acid Base ◽  
Genetic Stock ◽  
Arterial Blood ◽  
Blood Ph ◽  
Counter Ions

Blood acid-base regulation following exhaustive exercise was investigated in freshwater- (FW) and seawater- (SW) adapted rainbow trout (Salmo gairdneri) of the same genetic stock. Following exhaustive exercise at 10°C, both FW and SW trout displayed a mixed respiratory and metabolic blood acidosis. However, in FW trout the acidosis was about double that of SW trout and arterial blood pH took twice as long to correct. These SW/FW differences were related to the relative amounts of net H+ equivalent excretion to the environmental water, SW trout excreting five times as much as FW trout. The greater H+ equivalent excretion in SW trout may be secondary to changes in the gills that accompany the adaptation from FW to SW. It may also be related to the higher concentrations of HCO3− as well as other exchangeable counter-ions (Na+ and Cl−) in the external medium in SW compared to FW.

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