The present study includes the responses of plasma calcium and prolactin cells of a freshwater teleost, Heteropneustes fossilis injected with prolactin and maintained in artificial freshwater or calcium-deficient freshwater. Fish were divided into groups A-D. Groups A and B were kept in artificial freshwater. Groups 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 levels and prolactin cells were studied after 1, 3, 5, 10 and 15 days.In group B, prolactin treatment provoked hypercalcemia from day 3 to day 5; however, the values became normocalcemic at day 10 and day 15.A significant decrease in the nuclear volume of prolactin cells has been noticed in 5 day prolactin treated fish (group B). This response progresses till day 15. Moreover, on day 10 and day 15, depletion in the cytoplasmic granulation has been observed.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 prolactin cells of vehicle-injected fish (group C) exhibit hyperactivity on day 3 which is evident by the degranulation, hyperchromaticity of the nuclei and increased nuclear volume. Few cells are seen to degranulate completely after day 5. From day 5 to day 15, the nuclear volume is further increased. Certain cells are seen degenerating on day 10 and day 15.The prolactin cells of prolactin treated fish (group D) have not shown any change till day 5. Between day 10 and day 15 there is a progressive decrease in the nuclear volume. Moreover, vacuolization and degeneration have also been noticed.
Adult fish Heteropneustes fossilis were divided into 4 groups –(i) Group A: kept in artificial freshwater and daily injected intraperitoneally with vehicle; (ii) Group B: kept in artificial freshwater and were daily injected intraperitoneally with 0.1 mg/100 g body wt of oProlactin; (iii) Group C: maintained in calcium-deficient freshwater and daily injected intraperitoneally with vehicle; (iv) Group D: kept in calcium-deficient freshwater and daily injected intraperitoneally with 0.1 mg/100 g body wt of oProlactin. Blood samples were taken 2 h after the last injection on 1, 3, 5, 10 and 15 days of the treatment. Plasma calcium levels were analyzed. The corpuscles of Stannius (CS) were fixed for histological studies. Artificial freshwater: The plasma calcium levels of vehicle-injected specimens (group A) remained unaltered throughout the experiment. Following prolactin treatment (group B) the plasma calcium levels progressively increased from day 3 to day 5. The values became normocalcemic at day 10 and day 15. After day 5 following prolactin administration (group B), the nuclear volume of AF-positive cells increased and the cells were seen degranulated. After day 10, there was an increased dilatation of sinusoids and the nuclear volume of AF-positive cells showed further increase. On day 15, these changes were exaggerated. The AFnegative cells of the corpuscles of Stannius of prolactin-treated fish (group B) showed no change in their histological structure and nuclear volume. Calcium-deficient freshwater: The plasma calcium level decreased in vehicle-injected fish (group C) from day 1 to day 3 (as compared to level of the fish kept in artificial freshwater). Thereafter, the level increased from day 5 resulting in hypercalcemia at day 10 and day 15. In prolactin treated fish (group D) the plasma calcium level indicated progressive increase from day 5 to day 15. In the vehicle-injected fish (group C) the AF-positive cells of corpuscles of Stannius showed accumulati
Hypophysectomy was performed on freshwater male stinging catfish, Heteropneustes fossilis. Prolactin (0.1 mg/100 g bw/day) was administered to the hypophysectomized fish for 10 days. The plasma calcium, phosphate and magnesium levels were determined on day 1, 3, 5 and 10. Hypophysectomy provoked hypocalcemia and hypophosphatemia whereas the plasma magnesium levels were not significantly altered. Administration of prolactin to hypophyesctomized fish elevated the levels of these electrolytes. These results indicate that prolactin may be involved in the regulation of calcium, phosphate and magnesium in fish.
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