L. Gourdoux

Endocrine control of hemolymph carbohydrates in Locusta migratoria: Comparison between effects of two endogenous hormonal extracts and effects of insulin and glucagon

Abstract 1. 1. In adult male Locusta , effects of corpora cardiaca extracts, intestinal insulin-like molecule, glucagon and insulin were tested on hemolymph carbohydrates. 2. 2. Carbohydrates were separated by gas-liquid chromatography. 3. 3. CC extracts and glucagon mainly increase trehalose and melibiose levels; they have no effect upon glucose concentration. 4. 4. Intestinal insulin-like molecule and insulin decrease all hemolymph carbohydrates. 5. 5. These results suggest that in Locusta , like in mammals, hemolymph carbohydrates are controlled by a double system of regulation: a hyperglycemic system present in CC and a hypoglycemic factor localized in midgut.

Effects of honeybee insulin-immunoreactive peptide on haemolymph lipid and carbohydrate: Interaction of vertebrate somatostatin

Abstract The haemolymph lipid and carbohydrate concentrations were determined in emerging worker honeybees following injection of [ I ] saline, [ II ] a bee insulin-immunoreactive peptide ( BIRP ) and [ III ] BIRP + vertebrate somatostatin. BIRP promptly lowered trehalose, glucose, diacylglycerol and phospholipid concentrations, and increased the levels of fatty acid and triacylglycerol. It also induced a positive correlation between 1,2-diacylglycerol and short chain triacylglycerol, and completely reversed a negative correlation between long chain triacylglycerol and fatty acid, as well as a positive correlation between 1,3-diacylglycerol and steroid, both of the latter correlation appearing following treatment [ I ]. In all correlations except those between fatty acid, phospholipid and diacylglycerol, injection of vertebrates somatostatin together with BIRP partially neutralizes the specific effects of BIRP injected alone, a result similar to the action of somatostatin in vertebrates. BIRP is an endogenous intestinal insulin-like peptide whose physiological activity may be modulated by somatostatin-like molecules.

Carbohydrate metabolism in Pieris brassicae L. (Lepidoptera); variations during normal and diapausing development

Abstract 1. 1. Glycogen and trehalose metabolisms are studied with [U- 14 C] glucose during the normal and diapausing development in Pieris brassicae L. 2. 2. During pupal diapause trehalose is accumulated, its storage being accompanied with a strong turnover. If the diapausing pupae are maintained at a cold temperature (+5°C), this phenomenon is amplified. 3. 3. Diapause appears to be a period of the development where metabolic activity is very unequal; some metabolic pathways are inhibited, on the contrary others remain very active.

Hemolymph trehalose and carbohydrates in starved male adult Locust a migratoria: Possibility of endocrine modification

Abstract 1. 1. Starvation during a period from 1 to 6 days induced a strong decrease of total hemolymph carbohydrates in Locusta 25-day-old male adults. 2. 2. The trehalose concentration remained constant during the first fasting day, after which it dramatically decreased: trehalose is the most used sugar during starvation. 3. 3. Injections of saline CC extracts, during the fasting period, are always able to increase hemolymph carbohydrates, especially trehalose. The fourth-fasting-day insects have the highest reactions. 4. 4. The effects of injecting glucagon are comparable with those of CC extracts but are noticeable earlier.

Deltamethrin: In vivo effects on glucose catabolism in Locusta migratoria L

Abstract The in vivo effects of deltamethrin (a pyrethroīd insecticide) on pathways of glucose catabolism have been investigated in 20-day-old male adult Locusta migratoria. The relative contributions of the pentose cycle and the glycolytic-citric cycle were evaluated by a radiorespirometric method using d -[1-14C]glucose and d -[6-14C]glucose as substrates. The injection of nonlethal and LD50 doses of ethanolic solutions of deltamethrin significantly modified the in vivo glucose degradation. A dose-dependent stimulation of the respiratory rate was observed. The C 6 C 1 ratio and the conversion of d -[6-14C]glucose into 14CO2 were increased in both cases. In contrast, the conversion of d -[1-14D]glucose into 14CO2 was reduced, especially at the LD50 dose. Deltamethrin reduced the contribution of pentose cycle and diverted substrates toward the glycolytic pathway followed by the Krebs cycle.

Gluconeogenesis from some amino acids and its endocrine modification in Tenebrio molitor L. (Coleoptera)

Abstract 1. 1. In adult Tenebrio molitor , gluconeogenesis from three [U- 14 C] amino acids was investigated. 2. 2. In fed adults, incorporation of labelled carbons derived from amino acids, into carbohydrates occurs. 3. 3. [U- 14 C]alanine is the best precursor, and trehalose is the main neoformed carbohydrate. 4. 4. This provides preliminary evidence that gluconeogenesis from amino acids occurs in Tenebrio molitor . 5. 5. This phenomenon is under hormonal control: hormonal factors modify the incorporation of radioactivity of [U- 14 C] alanine into carbohydrates. 6. 6. Corpora cardiaca (CC) extracts increase gluconeogenesis, intestinal insulin-like molecule reduces this pathway.

Utilisation comparee du cycle des pentoses en fonction des variations thermǐques chez deux lepidopteres Bombyx mori L. et Pieris brassicae L.

Abstract 1. 1. The variations of temperature induce modifications in the respiratory quotient of Bombyx and Pieris at all the stages of their development. 2. 2. The specific activity of the respiratory 14CO2 breathed out after the injection of glucose 1 14C and 6 14C is deeply altered in relation to the imposed temperature. 3. 3. The evolution of C6/C1 (ratio of the radioactivities of the respiratory 14CO2 after injection of the glucose 1 14C or 6 14C) seems to be greatly dependent upon temperature.

Differential hormonal control of hemolymph carbohydrates in Pieris brassicae L.

Abstract 1. 1. In last larval instar of Pieris brassicae , hemolymph carbohydrates were separated and identified by gas-liquid chromatography. Their individual variations were tested after injection of hyperglycemie and hypoglycemie insect and mammal factors. 2. 2. Trehalose level was affected by both hyper- and hypoglycemie insect and mammal factors. This showed a thin regulatory hormonal system in this species, especially for trehalose. 3. 3. Other carbohydrates could be divided into two groups according to their response to hormonal actions: the first one with melibiose, was chiefly hyperglycemie reacting carbohydrates and did not vary with hypoglycemie factors. The second one with glucose and sucrose, appeared to be mainly affected by hypoglycemie insect and mammal factors.

In vivo glucose catabolism in male adult Locusta migratoria: Effects of corpora cardiaca

1. 1. The effects of CC extracts on glucose catablism of male adult Locusta migratoria are evaluated in vivo by a radiorespirometric method. 2. 2. Whole corpora cardiaca extracts strongly divert glucose from the pentose phosphate pathway and the glucose oxidation is reduced. Neurohemal lobes of CC (CCN) extracts have no effect; glandular lobes of CC (CCG) extracts have the same effect than whole CC. 3. 3. The time-course of the effect of CCG extracts is evaluated. The injection of CCG has an immediate and durable effect on the pentose cycle. The decrease of CO2 formation from C6 of glucose in glycolysis-Krebs cycle is later.

Effects of Deltamethrin on Glucose Catabolic Pathways in the Isolated Fat Body of Adult Male Locusta migratoria

The effects of various doses (non-lethal, LD15, LD25, LD50, LD75) of the pyrethroid insecticide deltamethrin were investigated on glucose catabolism pathways in the isolated fat body of starved 25-day-old male adult Locusta migratoria. Two methods of poisoning with deltamethrin were used. In the first case, the insecticide was injected into the locust in vivo and then the fat body was dissected either 30 min or 1hr after injection. The orientation of glucose with respect to its catabolic pathways was estimated in isolated fat body by means of radio-respirometric method using [1-14C]glucose and [6-14C]glucose. Deltamethrin reduced the relative participation of the pentose pathway, and this effect was maximal 1hr after insecticide treatment. Glucose degradation in the glycolysis-Krebs cycle was increased only 30 min after treatment. Deltamethrin significantly modified the orientation of glucose between the catabolic pathways. In the second case, deltamethrin was added directly into the fat body incubation medium after its sampling in in vitro conditions. Labeled glucose was added either simultaneously or 30 min after the insecticide dose. In both cases, deltamethrin diverted glucose from the pentose cycle; this effect was larger with simultaneous injections. The relative participation of the glycolysis-Krebs cycle was slightly increased, and this effect was observed only when the injections were separated by 30 min. A direct dose-dependent response was observed only on the pentose cycle. An indirect action of deltamethrin on glucose catabolism pathways in fat body might be the most probable explanation, but we cannot eliminate the possibility of a direct effect on these catabolic pathways.