Male dominance, plasma hormone concentrations, and availability of milt in male rainbow trout (Oncorhynchus mykiss)

The relationships among social status, endocrine profile, and amounts of milt available by stripping were examined in pairs of male rainbow trout (Oncorhynchus mykiss) competing for access to sexually active females in laboratory spawning channels. Gonadotropic hormone (GtH II), the gonadal steroids 11-ketotestosterone, testosterone, and 17α,20β-dihydroxy-4-pregnen-3-one, and milt volumes increased in dominant males in response to stimuli provided by a nesting female. Subordinate males in the same location did not show endocrine or milt responses. Following the removal of the dominant male of each pair, plasma hormone and milt levels increased in the previously subordinate males. This result indicates that endocrine and spermiation responses depend upon close-range sensory and behavioural interaction with the sexually active female. Treatment with testosterone did not cause a change in behaviour or social status of smaller males predicted to be subordinate.

Download Full-text

The Influence of Social Status on Hepatic Glucose Metabolism in Rainbow Trout Oncorhynchus mykiss

Physiological and Biochemical Zoology ◽

10.1086/666497 ◽

2012 ◽

Vol 85 (4) ◽

pp. 309-320 ◽

Cited By ~ 16

Author(s):

Kathleen M. Gilmour ◽

Sheryn Kirkpatrick ◽

Andrey Massarsky ◽

Brenda Pearce ◽

Sarah Saliba ◽

...

Keyword(s):

Rainbow Trout ◽

Glucose Metabolism ◽

Oncorhynchus Mykiss ◽

Social Status ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Hepatic Glucose Metabolism ◽

Hepatic Glucose

Download Full-text

Diminished social status affects ionoregulation at the gills and kidney in rainbow trout (Oncorhynchus mykiss)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f04-032 ◽

2004 ◽

Vol 61 (4) ◽

pp. 618-626 ◽

Cited By ~ 22

Author(s):

Katherine A Sloman ◽

Graham R Scott ◽

D Gordon McDonald ◽

Chris M Wood

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Social Status ◽

Metabolic Cost ◽

Whole Body ◽

Sodium Reabsorption ◽

Plasma Sodium ◽

Sodium Efflux ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Uptake Rates

Competition for social status can result in physiological differences between individuals, including differences in ionoregulatory ability. Subordinate rainbow trout (Oncorhynchus mykiss) had two-fold higher uptake rates of sodium across the gill and two-fold higher whole-body sodium efflux rates than the dominant fish with which they were paired. Sodium efflux was then divided into branchial and renal components, both of which were higher in subordinates. Branchial sodium efflux accounted for 95%98% of sodium loss. Plasma sodium concentrations were more variable, although not significantly different, in subordinate fish, suggesting that the increased loss of sodium in these trout is compensated for by an increase in uptake rates. Urine flow rates and plasma cortisol concentrations were higher in subordinate fish, but there was no difference in glomerular filtration rate between dominants and subordinates. Renal sodium reabsorption was significantly reduced in subordinates. In summary, the ionoregulation of subordinate individuals was altered, most likely occurring as a result of stress-induced changes in gill permeability, resulting in a higher throughput of water and increased branchial sodium efflux. These changes in ionoregulatory ability have many physiological implications, including the increased susceptibility of subordinates to ionoregulatory challenges and an increased metabolic cost of ionoregulation.

Download Full-text

Low social status impairs hypoxia tolerance in rainbow trout (Oncorhynchus mykiss)

Journal of Comparative Physiology B ◽

10.1007/s00360-012-0648-9 ◽

2012 ◽

Vol 182 (5) ◽

pp. 651-662 ◽

Cited By ~ 6

Author(s):

J. B. Thomas ◽

K. M. Gilmour

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Social Status ◽

Hypoxia Tolerance ◽

Rainbow Trout Oncorhynchus Mykiss

Download Full-text

The impact of social status on the erythrocyte β-adrenergic response in rainbow trout, Oncorhynchus mykiss

Comparative Biochemistry and Physiology Part A Molecular & Integrative Physiology ◽

10.1016/j.cbpa.2005.11.008 ◽

2006 ◽

Vol 143 (2) ◽

pp. 162-172 ◽

Cited By ~ 15

Author(s):

J.B. Thomas ◽

K.M. Gilmour

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Social Status ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Adrenergic Response ◽

The Impact

Download Full-text

Social status affects lipid metabolism in rainbow trout, Oncorhynchus mykiss

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00402.2017 ◽

2018 ◽

Vol 315 (2) ◽

pp. R241-R255 ◽

Cited By ~ 6

Author(s):

Daniel J. Kostyniuk ◽

Brett M. Culbert ◽

Jan A. Mennigen ◽

Kathleen M. Gilmour

Keyword(s):

Rainbow Trout ◽

Lipid Metabolism ◽

Oncorhynchus Mykiss ◽

Social Status ◽

De Novo Lipogenesis ◽

Strong Increase ◽

Hepatic Lipid Metabolism ◽

Hepatic Lipid ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Altered Glucose

Juvenile rainbow trout ( Oncorhynchus mykiss) confined in pairs form social hierarchies in which socially subordinate fish display characteristic traits, including reduced growth rates and altered glucose metabolism. These effects are, in part, mediated by chronically elevated cortisol levels and/or reduced feeding. To determine the effects of social status on lipid metabolism, trout were held in pairs for 4 days, following which organismal and liver-specific indexes of lipid metabolism were measured. At the organismal level, circulating triglycerides were elevated in dominant trout, whereas subordinate trout exhibited elevated concentrations of circulating free fatty acids (FFAs) and lowered plasma total cholesterol levels. At the molecular level, increased expression of lipogenic genes in dominant trout and cpt1a in subordinate trout was identified, suggesting a contribution of increased de novo lipogenesis to circulating triglycerides in dominant trout and reliance on circulating FFAs for β-oxidation in the liver of subordinates. Given the emerging importance of microRNAs (miRNA) in the regulation of hepatic lipid metabolism, candidate miRNAs were profiled, revealing increased expression of the lipogenic miRNA-33 in dominant fish. Because the Akt-TOR-S6-signaling pathway is an important upstream regulator of hepatic lipid metabolism, its signaling activity was quantified. However, the only difference detected among groups was a strong increase in S6 phosphorylation in subordinate trout. In general, the changes observed in lipid metabolism of subordinates were not mimicked by either cortisol treatment or fasting alone, indicating the existence of specific, emergent effects of subordinate social status itself on this fuel.

Download Full-text