Effects of juvenile hormone on polyamines of the fat body and neural tissue of the cricket Acheta domesticus

Abstract

Abstract The levels of polyamines and the activity of two of the rate limiting enzymes of their biosynthesis were studied in neural tissue and in the fat body of adult females of Acheta domesticus , submitted to different physiological experiments. Allatectomy, performed during the last larval instar, suppressed juvenile hormone production, resulted in the absence of the peak of hormone occurring in 3-day-old adult females and affected the normal pattern of polyamine distribution. As early as day 4 post-emergence, putrescine titres markedly decreased in the fat body, and spermidine levels dropped in the neural tissue. In the fat body, allatectomy depressed ornithine decarboxylase activity, but increased S -adenosylmethionine decarboxylase activity. In the neural tissue, lack of juvenile hormone depressed both ornithine decarboxylase and S -adenosylmethionine decarboxylase activities, resulting in a significant reduction of polyamine titres. Juvenile hormone injections into allatectomized females enhanced enzyme activities and increased polyamine titres. These findings suggest that the neural tissue, like the fat body, may be a target organ for juvenile hormone action. The present data reveal tissue-specific patterns of polyamine metabolism and demonstrate the action of juvenile hormone on polyamine metabolism.