| Abstract: | After 20 to 50 days in sea water (SW), regressive changes of the kidney occur at the same rate in intact and hypophysectomized eels (Anguilla anguilla). In SW, ovine prolactin (oPRL) increases plasma electrolytes and restores a fresh water (FW) kidney structure; cell height and nuclear area increase in main segments of the nephron: first (P1) and second proximal (P2), distal (D) and initial collecting (C) tubules. A differentiation of new tubules also occurs. This effect is less intense after hypophysectomy and greater in FW. A dose of 10 μg/g body weight/day for 10 days in SW produces some harmful renal effects, barely detected at 6 μg/g/day. The kidney plays a minor role in osmotic adjustment in SW when PRL secretion is reduced (intact eels) or suppressed (hypophysectomized); PRL treatment reverses effects of SW adaptation. An inhibition of gill sodium extrusion may explain the high blood sodium level; however, kidney histological changes suggest a renal participation, perhaps through reduced water permeability as in Platichthys. |
