Estradiol Affects Prolactin Producing Cells and Calcium levels in a Teleost, Heteropneustesfossilis, Kept in Different Calcium Concentrations

Abstract

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 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 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 10day. 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.

Alterations in the Prolactin Cells of Stinging Catfish, Heteropneustes fossilis Administered with Prolactin and Maintained in Artificial Freshwater or Calcium-Deficient Freshwater

“…The histological details of the prolactin cells (Fig. 2) of vehicle-injected fish (group A) are more or less similar to those of the details given by Srivastav et al (2017). These cells remain unaltered throughout the experiment.…”

“…Prolactin (PRL) is a long peptide hormone which is found in all jawed vertebrates (Saha et al, 2021). It is expressed in a variety of different organs and performs diverse physiological functions (Freeman et al, 2000;Srivastav et al, 2017;Dobolyi et al, 2020). In fish, PRL is released into circulation mainly through the definitive mass of prolactin cells present in the pituitary (Brown and Brown, 1987;Srivastav et al, 2017Srivastav et al, , 2021Saha et al, 2021).…”

“…It is expressed in a variety of different organs and performs diverse physiological functions (Freeman et al, 2000;Srivastav et al, 2017;Dobolyi et al, 2020). In fish, PRL is released into circulation mainly through the definitive mass of prolactin cells present in the pituitary (Brown and Brown, 1987;Srivastav et al, 2017Srivastav et al, , 2021Saha et al, 2021). In fishes, prolactin has been associated with many functions -(i) reproduction Ozaki et al, 2007), (ii) parental behavior (Tacon et al, 2000;Pall et al, 2004;Cunha et al, 2019), (iii) migration (Onuma et al, 2010;Whittington and Wilson, 2013), (iv) immunomodulation (Yada et al, 2004), (v) egg and larval development ( Kaneko et al, 2002;Santos et al, 2003), (vi) osmoregulation (Clarke and Bern, 1980;Kelly et al, 1999), and (vii) hypercalcemic action through inhibition of gill calcium efflux (Flik et al, 1994) and by promoting gill calcium influx (Anderson and van Itallie, 2009).…”

11-Deoxycorticosterone (DOC)’s Action on the Gill Osmoregulation of Juvenile Rainbow Trout (Oncorhynchus mykiss)

“…For the chloride, the linear range of detection was between 20-100 nmol/well. All the analytes were first evaluated and validated in the plasma from other teleost fish [28][29][30].…”