Sexual differences and steroid‐induced changes in metabolic activity in toadfish sonic muscle

Keith R. Pennypacker, Michael L. Fine, Richard R. Mills

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Since the male oyster toadfish (Opsanus tau) is more active in sound production than the female, we hypothesized that sonic muscles of the male are biochemically specialized to perform more work. In order to categorize the muscle biochemically and test for sexual differences, we measured the activity of two anaerobic enzymes, 3‐phosphoglyceraldehyde dehydrogenase (3PG) and lactic dehydrogenase (LDH), and two aerobic enzymes, malate dehydrogenase (MDH) and glutamic oxaloacetic transaminase (GOT). Males exhibited greater 3PG and GOT activity than females (p < 0.05). Both MDH and LDH showed little activity in either sex. High 3PG and low LDH levels indicate a substained level of glycolysis, with pyruvate shuttled into aerobic metabolism, and high GOT activity indicates a high level of aerobic metabolism. From this and other data, we conclude that toadfish sonic muscle can be classified as fast‐twitch oxidative glycolytic or fast‐twitch fatigue resistant. The endocrine basis for these sexual differences was examined by implanting steroid pellets into ovariectomized females. Testosterone induced a doubling of 3PG activity (p < 0.02), and dihydrotestosterone induced an eight‐fold increase (p < 0.0005) in GOT concentration over controls. The steroids had no effect on LDH and MDH activities. Hormones, therefore, trigger one of the fundamental sexual differences underlying toadfish communication, namely a difference in metabolism, providing the male with the capacity for increased sound production.

Original languageEnglish
Pages (from-to)259-264
Number of pages6
JournalJournal of Experimental Zoology
Volume236
Issue number3
DOIs
StatePublished - Dec 1985

ASJC Scopus subject areas

  • Animal Science and Zoology

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