Journal of Endocrinology and Reproduction

Dafina Wilfred ¹, Valsa S. Peter ², Subash Peter ¹

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram – 695581, Kerala, IN
2 Inter-University Centre for Evolutionary and Integrative Biology, University of Kerala, Kariavattom, Thiruvananthapuram – 695581, Kerala, IN

Abstract

Being the principal estrogen, estradiol 17β (E₂) is essential for normal ovarian function in the vertebrates including fishes. Besides its primary role in reproduction, E₂ is also known for its role in many other physiological processes including water and mineral balance. However, it is uncertain, how E₂ regulates ion-specific ATPases that drive Na⁺, K⁺, H⁺, Ca²⁺ and Mg²⁺ transport in fish brain. We, therefore, examined the short-term in situ action of E₂ on ion transporter function in the brain segments of freshwater female Mozambique tilapia Oreochromis mossambicus. Tilapia were perfused with increasing doses of E₂ (10^-9, 10^-8 and 10^-7 M) for 20 min and sampled for determining Na⁺/K⁺-ATPase, H⁺-ATPase, Ca²⁺-ATPase, and Mg²⁺-ATPase activities in the prosencephalon (PC), mesencephalon (MC) and metencephalon (MeC) segments of brain. Dose-dependent increase in Na⁺/K⁺- and Ca²⁺-dependent transporter activities after E₂ perfusion were found in PC. In MC, E₂ treatment, however, produced significant increase in Mg²⁺, Ca²⁺ and H⁺ transport activities in mitochondria but decreased Na⁺/K⁺- and νH⁺ transporter activities. On the contrary, in MeC, E₂ administration while producing increase in Na⁺/K⁺-, mitochondrial- and νH⁺-transport, lowered cytosolic and mitochondrial Ca²⁺ transport. Taken together, the data indicate that E₂ has rapid and direct action on ion transporter function that corresponds to the differential activation/inactivation of neuronal clusters in the brain segments of female freshwater tilapia.

Keywords

Na⁺/K⁺-ATPase, Estradiol 17β, Fish, Ion Transporter, Ionoregulation, Tilapia brain.

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