ROLE OF THE THYROID GLAND IN REGULATION OF METABOLIC RATE IN AN AIR-BREATHING SILUROID FISH, HETEROPNEUSTES FOSSILIS (BLOCH)

Abstract

SUMMARY Studies on cyclic activity of the thyroid and seasonal variations in oxygen consumption (V̇o2) under experimental conditions in which surfacing was either allowed or prevented were made in H. fossilis to try to establish a relationship between these measures and to ascertain the possible role of the thyroid in the regulation of metabolic rate. A good correlation was found between the activity of the thyroid and V̇o2 in this species. This finding was further confirmed by the administration of l-thyroxine or thiouracil to this fish. The thyroxine-and thiouracil-treated animals showed significantly higher (P < 0·05) and lower (P < 0·01) rates of V̇o2 respectively, thus indicating the probable role of the thyroid in the regulation of metabolic rate.