IMPAIRED CORTISOL SECRETION IN YELLOW PERCH (PERCA-FLAVESCENS) FROM LAKES CONTAMINATED BY HEAVY-METALS - IN-VIVO AND IN-VITRO ASSESSMENT

The characteristic elevation of plasma cortisol levels in response to an acute stress of capture was impaired in both male and female yellow perch (Perca flavescens) from lakes contaminated by heavy metals. The impairment of the cortisol stress response was observed in fish 4+ ye ars and older whereas the capacity to elevate plasma cortisol levels o f fish younger than 4+ was not significantly different at contaminated and reference sites. The responsiveness to ACTH of the interrenal tis sue of 4+ yellow perch was evalutated in vitro to determine whether th e impairment of the cortisol stress response is caused by a dysfunctio n of the interrenal tissue or if the dysfunction is located elsewhere in the hypothalamo-pituitary-interrenal axis controlling the secretion of cortisol. The amount of cortisol secreted by the interrenal tissue of yellow perch from a contaminated site in response to a 10-min stim ulation with 10(-7) M ACTH was significantly lower compared with fish from the reference site. These results indicate that the impairment of the cortisol stress response observed in fish from polluted sites is caused, at least in part, by a dysfunction of the interrenal tissue.