Lipid metabolism in Tenebrio larval fat body has been studied in vitro. Lipid release required the presence of diluted hemolymph in the incubation medium, This time-dependent release of lipid was strongly stimulated in a dosedependent manner by Tenebrio corpora cardiaca (CC) extracts or synthetic adipokinetic hormone (AKH I). Furthermore, some glycerol was released when larval fat body was incubated without hemolymph, and this phenomenon was also dose dependent for added CC extracts. Lipid synthesis was estimated i n vitro by following the incorporation of radioactivity from [6-14C] glucose into fatty acids. Lipogenesis occurred in the absence of added carbohydrates in the medium, but it was stimulated by the addition of glucose, and especially trehalose (10 mg ml-'). Intestinal insulin-like peptide (ILP) also stimulated in vitro lipogenesis in a dose-dependent fashion. We conclude that lipolytic and lipogenetic activities of larval mealworm fat body in vitro are effectively under hormonal control.
Glucose metabolism by Tenebrio molitor larval fat body tissue was studied in vitro by means of a microradiorespirometric method and the effects of either natural or synthetic catabolic hormones were evaluated. The use of this microradiorespirometric method allowed us to measure glucose catabolism in small pieces of tissue with good sensitivity.The metabolic modifications (relative and absolute) induced in the activities of the pentose cycle and glycolysis-Krebs cycle, by larval mealworm Corpora cardiaca (CC) purified extracts, were compared with those produced by synthetic locust AKH I and mammalian glucagon. These metabolic variations were evaluated by measuring total C02 and by using either [l-14Clglucose or [6-'4Clglucose molecules as substrates. The kinetics of 14C02 production and the dose-response curves of hormones were determined. The total expired COz increases significantly (17-26%) during treatment with all of the hormones studied.Modifications to the kinetics of the specific radioactivity and the cumulative yields of 14C02 derived from [l-14C]glucose and [6-'4Clglucose under the influence of each of the hormones were recorded. CC extracts and AKH I rapidly (15 min) diverted glucose from pentose cycle ( -45%); glucose oxidation was increased ( + 26%), this effect appearing later (75 m i d . Mammalian glucagon rapidly and durably increased glucose catabolism both via the pentose cycle ( + 35%) and by the glycolytic pathway ( + 200%). o
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.