scholarly journals The in vitro metabolism of cortisol by ovarian follicles of rainbow trout (Oncorhynchus mykiss): comparison with ovulated oocytes and pre-hatch embryos

Reproduction ◽  
2012 ◽  
Vol 144 (6) ◽  
pp. 713-722 ◽  
Author(s):  
Mao Li ◽  
Heather L Christie ◽  
John F Leatherland
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Ovarian Follicles ◽  
Tissue Samples ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Early Embryos ◽  
Vitellogenic Stage ◽  
Gst Activity

Mid-vitellogenic stage rainbow trout (Oncorhynchus mykiss) ovarian follicles (both intact and yolk free (YF)), ovulated oocytes and embryos were co-incubated with [2,4,6,7-3H]cortisol for 18 h to determine the degree and nature of the metabolism and biotransformation of the glucocorticoid. There was evidence of the conversion of cortisol to the less biologically potent glucocorticoid, cortisone, and the formation of glucocorticoid sulphates (both cortisol and cortisone) for all cell and tissue samples, suggesting the presence of 11β-hydroxysteroid dehydrogenase (11β-HSD) and glucocorticoid sulphotransferase (GST) activity at all stages; however, GST activity was particularly marked in both intact and YF ovarian follicles, suggesting an important role of follicles in limiting the exposure of oocyte to maternal cortisol. As there was no evidence of 11β-HSD or GST activity in ovarian fluid, the findings affirm that ovarian follicles (probably the thecal and granulosa cells) provide a barrier against the transfer of cortisol to the oocytes by forming sulphated steroids, whereas ovulated oocytes and early embryos have a more limited capacity to either metabolize or conjugate cortisol and are therefore more vulnerable at the post-ovulatory and early embryonic stages to increases in exposure to the glucocorticoid.

Estrogenic activity of multicyclic aromatic hydrocarbons in rainbow trout (Oncorhynchus mykiss) in vitro assays

2019 ◽  
Vol 207 ◽  
pp. 43-51 ◽  
Author(s):  
Richard C. Kolanczyk ◽  
Jeffrey S. Denny ◽  
Barbara R. Sheedy ◽  
Patricia K. Schmieder ◽  
Mark A. Tapper
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Aromatic Hydrocarbons ◽  
Estrogenic Activity ◽  
In Vitro Assays ◽  
Rainbow Trout Oncorhynchus Mykiss

scholarly journals The role of nitrosative and oxidative stress in rainbow trout (Oncorhynchus mykiss) liver tissue applied mercury chloride (HgCl2)

2021 ◽  
Vol 38 (3) ◽  
pp. 269-273
Author(s):  
Mehmet Reşit Taysı ◽  
Muammer Kırıcı ◽  
Mahinur Kırıcı ◽  
Hasan Ulusal ◽  
Bünyamin Söğüt ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Liver Tissue ◽  
Stress Index ◽  
Mercury Chloride ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Total Antioxidant ◽  
Ld50 Value

The aim of this study was to determine oxidative stress caused by mercury chloride (HgCl2) in rainbow trout (Oncorhynchus mykiss) liver tissue. For this purpose, the LD50 value of HgCl2 on rainbow trout was determined as 551 μg/L. In the study, 40 fish in four groups were exposed to 25% and 50% (138 and 276 µg/L) of the two subletal doses of HgCl2 for 2 and 7 days, with 10 fish (n=10) in each group. To determine oxidative stress; peroxynitrite (ONOO−), total oxidant level (TOS), total antioxidant level (TAS), oxidative stress index (OSI) and malondialdehyde (MDA) were analyzed. In the study, it was observed that the differences between the groups in terms of ONOO−, TOS, TAS and OSI levels in the liver tissues was significant (P<0.05), however, this difference was not significant (P>0.05) in terms of MDA values. As a result, it can be concluded that HgCl2 increases ONOO−, TOS, TAS, OSI and MDA levels in liver tissue and even small doses of mercury are toxic to fish.

Regulation of glucose production in rainbow trout: role of epinephrine in vivo and in isolated hepatocytes

2000 ◽  
Vol 278 (4) ◽  
pp. R956-R963 ◽  
Author(s):  
Jean-Michel Weber ◽  
Deena S. Shanghavi
Keyword(s):  
Rainbow Trout ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Isolated Hepatocytes ◽  
Relative Increase ◽  
Dependent Manner ◽  
Rainbow Trout Oncorhynchus Mykiss

The rate of hepatic glucose production (Ra glucose) of rainbow trout ( Oncorhynchus mykiss) was measured in vivo by continuous infusion of [6-3H]glucose and in vitro on isolated hepatocytes to examine the role of epinephrine (Epi) in its regulation. By elevating Epi concentration and/or blocking β-adrenoreceptors with propranolol (Prop), our goals were to investigate the mechanism for Epi-induced hyperglycemia to determine the possible role played by basal Epi concentration in maintaining resting Ra glucose and to assess indirect effects of Epi in the intact animal. In vivo infusion of Epi caused hyperglycemia (3.75 ± 0.16 to 8.75 ± 0.54 mM) and a twofold increase in Ra glucose (6.57 ± 0.79 to 13.30 ± 1.78 μmol ⋅ kg− 1 ⋅ min− 1, n = 7), whereas Prop infusion decreased Ra from 7.65 ± 0.92 to 4.10 ± 0.56 μmol ⋅ kg− 1 ⋅ min− 1( n = 10). Isolated hepatocytes increased glucose production when treated with Epi, and this response was abolished in the presence of Prop. We conclude that Epi-induced trout hyperglycemia is entirely caused by an increase in Ra glucose, because the decrease in the rate of glucose disappearance normally seen in mammals does not occur in trout. Basal circulating levels of Epi are involved in maintaining resting Ra glucose. Epi stimulates in vitro glucose production in a dose-dependent manner, and its effects are mainly mediated by β-adrenoreceptors. Isolated trout hepatocytes produce glucose at one-half the basal rate measured in vivo, even when diet, temperature, and body size are standardized, and basal circulating Epi is responsible for part of this discrepancy. The relative increase in Ra glucose after Epi stimulation is similar in vivo and in vitro, suggesting that indirect in vivo effects of Epi, such as changes in hepatic blood flow or in other circulating hormones, do not play an important role in the regulation of glucose production in trout.

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