Prolactin Induced Alterations in Plasma Minerals (Calcium and Phosphate) and Ultimobranchial Gland of Stinging Catfish, Heteropneustes fossilis Maintained in Different Calcium Media

Abstract

Effects of prolactin administration were investigated on plasma calcium, and ultimobranchial gland (UBG) of a freshwater catfish, Heteropneustes fossilis. Fish were divided into groups AD. Group A and B were kept in artificial freshwater with normal electrolytes. Group C and D were maintained in calcium-deficient freshwater. Vehicle was administered to groups A and C. Groups B and D were injected with prolactin. Plasma calcium, inorganic phosphate levels and UBG were studied after 1, 3, 5, 10 and 15 days. Prolactin treatment caused hypercalcemia from day 3 to day 10; however, the values become narmocalcemic at day 10 and day 15. Similarily, from day 5 onwards a progressive increase in the plasma phosphate level has been noticed. UBG cells of prolactin-treated fish (kept in artificial freshwater) exhibit increased nuclear volume and poor staining response (from day 5 to 10). On day 15 few degenerating cells and a decline in nuclear volume have been noticed. In vehicle-injected fish (group C) the plasma calcium level decreases from day 1 to day 3 (as compared to level of the fish kept in artificial freshwater). Thereafter, the level records an increase from day 5 resulting in hypercalcemia at day 10 and day 15. In prolactin treated fish (group D) the plasma calcium level shows no change up to day 3 as compared to the vehicle-injected group (group C). From day 5 to day 15, the value indicates progressive increase in plasma calcium level. The plasma phosphate level of vehicle-injected fish (group C) remains unaltered on day 1. A progressive hypophosphatemia has been observed between day 3 and day 5. Thereafter, the values indicate a tendency to increase. Up to day 3 the plasma phosphate level of prolactin-injected fish (group D) is almost same as compared to that of vehicle-injected specimens (group C). Thereafter, the level indicates a tendency to increase thus resulting in hyperphosphatemia 5 day onwards.