Hormonal Control on Enzymes of Osmoregulation in a Teleost, Anabas Testudineus (BLOCH): an in vivo and in vitro Study

Abstract

Hormonal control of osmoregulation in teleosts is not well understood. Role of cGH, oGH, PRL, T3 and insulin on gill Na⁺, K⁺-ATPase, Mg²⁺ and Ca²⁺ ATPases was studied in A. testudineus. Short term administration of cGH, PRL or T3 significantly increased Na⁺,K⁺-ATPase, Mg²⁺ and Ca²⁺ ATPases, while oGH influenced only Mg²⁺ ATPase, and insulin stimulated Na⁺,K⁺-ATPase. Long-term treatment with cGH and PRL also significantly increased Na⁺,K⁺-ATPase activity. GH had an additive with T3 on stimulating Na⁺,K⁺-ATPase activity. In vitro addition of cGH and oGH also had definite stimulatory effect on gill Na⁺,K⁺-ATPase except for 2ng oGH. Bromocryptine treatment caused a significant reduction on Na⁺,K⁺-ATPase activity. Both in vivo and in vitro treatments of cGH and PRL independently reversed the action of bromocryptine on Na⁺,K⁺-ATPase. Combined treatment of cGH+PRL was more prominent in stimulating Na⁺,K⁺-ATPase in bromocryptine treated fish. Present study reveals that GH, PRL and T3 have definite regulatory role on enzymes of osmoregulation in the teleost Anabas testudineus.