Oxidative metabolism in a teleost,Anabas testudineus Bloch: effect of testosterone and estradiol-17β on hepatic enzyme activities.

Testosterone (T) administration to maleAnabas testudineus significantly stimulated the activities of cytochrome oxidase, α-glycerophosphate dehydrogenase (α-GPDH) and Mg(2+) adenosine triphosphatase (Mg(2+) ATPase) and inhibited lactate dehydrogenase (LDH), cytosolic and mitochondrial malate dehydrogenases (MDH). The activities of succinate dehydrogenase (SDH), glucose-6-phosphate dehydrogenase (G-6-PDH) and catalase were unaffected by testosterone treatment. Administration of estradiol-17β (E2) in female fish, significantly stimulated cytochrome oxidase activity, inhibited Mg(2+) ATPase, SDH, catalase and cytosolic and mitochondrial MDH activity, and was without effect on other enzymes studied.The simultaneous injections of actinomycin D or chloramphenicol and T or E2 prevented the hormonal influence on hepatic enzyme activities. The present study demonstrates that inA. testudineus sex steroids influence hepatic oxidative metabolism by a mechanism sensitive to the action of inhibitors of protein synthesis.