FEEDING EFFECTS ON GENE-EXPRESSION OF THE HYPERTREHALOSEMIC HORMONE IN THE COCKROACH, BLABERUS-DISCOIDALIS

Feeding effects on hypertrehalosemic hormone (HTH) transcript levels i n corpora cardiaca (CC) of adult females of the cockroach, Blaberus di scoidalis were measured using dot blot hybridization. HTH transcript l evels were nearly doubled in CC from females withheld from food and wa ter for ten days compared to CC from fed females. The increase in HTH- mRNA was a response to starvation, not dehydration, and reversed withi n 2 days after exposure to food. HTH-mRNA was elevated in CC from fed insects that had their recurrent nerve severed, but low fecal output b y insects with severed nerves indicated that feeding and digestion wer e impaired. Thus, the increased HTH synthesis likely resulted from sta rvation rather than disruption of neural regulation. CC from starved f emales that were refed with either solutions or agar that contained gl ucose did not show down-regulation of HTH-mRNA. Likewise, injections o f glucose or trehalose did not suppress HTH-mRNA levels in CC of starv ing insects. Down-regulation of the starvation-related increase in HTH -mRNA appears to be a response to consumption of a complex of nutrient s and not to increased carbohydrates or mechanical aspects of feeding. (C) 1998 Elsevier Science Ltd. All rights reserved.