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Sexual maturity modifies the responsiveness of the pituitary-interrenal axis to stress in male rainbow trout.

Abstract：

:A significant reduction in stress-induced plasma cortisol levels is apparent in mature male rainbow trout compared to immature fish of both sexes and of the same age and strain. Mean plasma cortisol levels in groups of immature fish subjected to a standard 1-hr confinement stress were consistently higher (range 93.9 +/- 4.9-114.8 +/- 4.1 ng ml-1) than mean levels in mature males exposed to the same procedure (range 47.0 +/- 4.3-71.7 +/- 5.7 ng ml-1), throughout the 4-month period around spawning (P < 0.001). Body weight was not found to be a significant determinant of poststress cortisol level. The dissimilarity in plasma cortisol levels between mature and immature fish following confinement does not stem from differences in the dynamics of the response; during a 24-hr period of confinement the rate of elevation of plasma cortisol levels was similar for both mature male and immature fish, but mature male fish attained a significantly lower peak cortisol level (51.6 +/- 5.2 ng ml-1) than immature fish (89.5 +/- 7.7 ng ml-1), a disparity which was maintained throughout the period of stress (P < 0.05-P < 0.001). The reduced responsiveness of the interrenal tissue of mature male fish during stress appears to be modulated by the hypothalamus/pituitary. Plasma ACTH levels in mature male trout (44 +/- 9 pg ml-1) are significantly lower than those in immature fish (71 +/- 9 pg ml-1, P < 0.01) within 30 min of the onset of confinement and remain so during a 3-hr period of confinement. These data suggest that the cortisol/ACTH feedback equilibrium has been modified in mature fish to a lower "set point." Furthermore, although stress caused a significant decline of plasma alpha-MSH levels in both immature fish and mature males, N-acetyl-beta-endorphin levels were reduced only in mature male fish during confinement stress.

journal_name

Gen Comp Endocrinol

journal_title

General and comparative endocrinology

authors

Pottinger TG,Balm PH,Pickering AD

doi

10.1006/gcen.1995.1073

subject

Has Abstract

pub_date

1995-06-01 00:00:00

pages

311-20

issue

eissn

0016-6480

issn

1095-6840

pii

S0016-6480(85)71073-8

journal_volume

pub_type

杂志文章

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Sexual maturity modifies the responsiveness of the pituitary-interrenal axis to stress in male rainbow trout.