Differences in the activity of prolactin cells in male and female fresh water teleost Mastacembelus armatus (Lacepede) during gonadal cycle

Abstract

Abstract Objective To determine the differences in the activity of pituitary prolactin cells between male and female fresh water teleost Mastacembelus armatus ( M. armatus ) during their reproductive cycle. Methods Fishes were sampled every month throughout the year. They were dissected, gonads weighed for the determination of GSI. Blood samples were collected for estimation of plasma calcium, 17 β-estradiol of females and testosterone of males and prolactin. Nuclear diameter of PRL cells, diameter of oocyte and testicular lobule was measured by image analyzer microscope. An experiment was also conducted in which female and male fishes were injected with 17 β-estradiol and 17 alpha-methyltestosterone respectively and the blood samples were analyzed for plasma calcium, prolactin and sex steroids levels. Results Negligible change in plasma calcium and prolactin level and little variation in nuclear diameter of PRL cells were recorded throughout the year in relation to testicular cycle as well as after 17 alpha-methyltestosterone administration in male. Variations in level of plasma calcium and prolactin and a large range of difference in nuclear diameter of PRL cells were noted during ovarian cycle as well as after 17 β-estradiol administration in female. Conclusion Difference in the activity of PRL cells was noted between male and female M. armatus. It act as hypercalcemic factor in females whose level increase along with maturation of ovary with the influence of increasing level of 17 β-estradiol from ovarian follicles to fulfill the increased demand of calcium for vitellogenesis and thus directly effecting reproduction. No such role of prolactin was observed for male fishes.