Hypertrehalosemic hormones increase the concentration of free fatty acids in trophocytes of the cockroach (Periplaneta americana) fat body

The effect of the hypertrehalosemic hormones, HTH-I and HTH-II, on free fatty acid levels in trophocytes prepared from Periplaneta americana fat body by collagenase treatment was investigated. Following a challenge from either of the hormones the content of palmitic, stearic, oleic, and linoleic acid in the trophopcytes increased. The increase in free fatty acid concentration due to the action of the synthetic hormones was generally in the range of 40-95% for each of the four fatty acids. Crude corpus cardiacum extract containing the native hormone also had a stimulatory effect, which was comparable to that of the synthetic hormones. In the intact insect the injection of synthetic hormone was followed by an increase in the level of the four fatty acids in the hemolymph. HTH-II was more potent in this respect than HTH-I. Free fatty acids in the mycetocytes and urate cells did not respond to either of the synthetic hormones. (C) 1997 Elsevier Science Inc.