estradiol affects prolactin producing cells and calcium levels in a teleost, heteropneustesfossilis, kept in different calcium concentrations

Background: this study investigated the effects of estradiol on plasma calcium and prolactin cells of heteropneustes fossilis kept in calcium-deficient and normal freshwater. methods: fish were deprived of food and divided into groups a-d. 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 estradiol. plasma calcium levels and prolactin cells were studied after 1, 3, 5, 10 and 15 days. results: normal-calcium freshwater: in group a calcium levels remained unaffected. in group b, estradiol provoked hypercalcemia from day 3 to 10 although calcium decreased after day 15. prolactin cells in group b became degranulated after 10 day. nuclear volume increased from day 10 onwards. calcium-deficient freshwater: calcium levels in group c decreased from day 1 to 3 thereafter increased from day 5 to 15. plasma calcium of group d increased from day 3 to 15. in group c prolactin cells exhibited hyperactivity on day 3 and degranulation on day 5. nuclear volume increased from day 5 onwards. on day 10 and 15 certain cells became degenerated. in group d degranulation of prolactin cells began on day 3 which proceeded to complete degranulation on day 10. nuclear volume increased from day 5 onwards. conclusions: estradiol enhanced prolactin production and increased blood calcium in fooddeprived fishes kept in calcium-deficient medium suggesting that calcium needed for elevation of blood calcium was derived from internal sources.