Prolactin-releasing peptide is essential to maintain the prolactin level and osmotic balance in freshwater teleost fish

Peptides ◽  
2006 ◽  
Vol 27 (5) ◽  
pp. 1104-1109 ◽  
Author(s):  
Masaaki Fujimoto ◽  
Tatsuya Sakamoto ◽  
Tomokazu Kanetoh ◽  
Michiyo Osaka ◽  
Shunsuke Moriyama
Keyword(s):  
Teleost Fish ◽  
Prolactin Level ◽  
Freshwater Teleost ◽  
Osmotic Balance ◽  
Prolactin Releasing Peptide

Diel patterns of baseline glucocorticoids and stress responsiveness in a teleost fish (bluegill, Lepomis macrochirus)

2014 ◽  
Vol 92 (5) ◽  
pp. 417-421 ◽  
Author(s):  
A. Cousineau ◽  
J.D. Midwood ◽  
K. Stamplecoskie ◽  
G. King ◽  
C.D. Suski ◽  
...  
Keyword(s):  
Teleost Fish ◽  
Lepomis Macrochirus ◽  
Freshwater Teleost ◽  
Diel Patterns ◽  
Baseline Cortisol ◽  
Maximum Value ◽  
Stress Responsiveness ◽  
In The Wild ◽  
Time Periods ◽  
Glucose Responsiveness

Little is known about whether glucocorticoids (GC) and GC responsiveness vary on a diel basis in the wild, especially for fish. Using bluegill (Lepomis macrochirus Rafinesque, 1819) as a model freshwater teleost fish, we tested whether baseline concentration and stress responsiveness of GCs (i.e., plasma glucose and cortisol) varied over a 24 h period. Blood samples from lake-dwelling wild bluegill were obtained across six periods representing a complete circadian cycle to determine GC levels in newly captured fish (i.e., within 3 min of capture; baseline), the maximum value (maximum) 45 min following exposure to a standardized aerial exposure stressor, and determining responsiveness (by subtracting minimum from maximum). Our results revealed that baseline glucose concentration did not vary on a diel basis, whereas baseline cortisol concentration did. Maximum and stress-induced glucose responsiveness varied significantly among several time periods with lowest values recorded at midnight and higher values at mid-day. Maximum and stress-induced cortisol responsiveness were consistent across time periods. Collectively, these data suggest that baseline concentrations and stress-induced values of GCs in a freshwater temperate teleost fish tend to be consistent across diel periods such that there is apparently an absence of strong GC diel patterns.

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