A 1H-NMR Based Study on Hemolymph Metabolomics in Eri Silkworm after Oral Administration of 1-Deoxynojirimycin

Abstract

We aimed to investigate whether 1-deoxynojirimycin (DNJ) modulates glycometabolism and has toxicity in Eri silkworm (Samia cynthia ricini, Saturniidae). In this paper, hemolymph metabolites were used to explore metabolic changes after oral administration of DNJ or mulberry latex and to characterize the biological function of DNJ at the metabolic and systemic levels. Hemolymph samples were collected from fourth-instar larvae of Eri silkworm and ex-vivo high-resolution 1H nuclear magnetic resonance (NMR) spectra were acquired from the collected hemolymph samples. Then the obtained spectra were analyzed by principal component analysis (PCA) and independent-samples t-test. Metabolic pattern recognition analysis of hemolymph samples indicated that the groups of 0.25% DNJ, latex, and the mixture of 0.5% DNJ and latex (1:1) were significantly different from the control group. Moreover, compared to the control group, the groups of 0.25% DNJ, latex, and the mixture of 0.5% DNJ and latex (1:1) showed the decreased levels of citrate, succinate, fumarate, malate, and glutamine in hemolymph, the groups of 0.25% DNJ and the mixture of 0.5% DNJ and latex (1:1) showed the increased levels of trehalose and lactate. In addition, mulberry leaves exude latex was highly toxic to Eri silkworm because rich unidentified high-molecular-weight factor (s) acted as toxic substances. In our results, latex caused 20 deaths among 50 fourth-instar larvae of Eri silkmoth, but DNJ or the mixture did not caused death. All these results suggest that DNJ has a positive impact on the reverse glycometabolism by modulating glycometabolism and inhibiting glucogenesis and energy metabolism. DNJ is a secure substance as a single-ingredient antidiabetic medicine due to its nontoxicity and bioactivity.

An Evaluation of 1-Deoxynojirimycin Oral Administration in Eri Silkworm through Fat Body Metabolomics Based on1H Nuclear Magnetic Resonance

“…In our previous work, we had proved that metabolic profiles of hemolymph in Eri silkworms after oral administration of DNJ, latex, and the mixture of DNJ and latex (1 : 1) were significantly different compared with the age-matched controls. In addition, we also confirmed that only latex caused deaths of Eri silkworm, but not DNJ or the mixture [ 13 ]. However, further understanding of DNJ systematical regulation on energy metabolism in tissues of Eri silkworm has not yet been explored.…”

Comparative transcriptome analysis reveals significant metabolic alterations in eri-silkworm (Samia cynthia ricini) haemolymph in response to 1-deoxynojirimycin

“…Glycometabolism plays an important role in the physiological balance of living organisms [ 27 ]. As shown in our previous studies, the glycometabolism pathway was impaired in the haemolymph and midgut of fourth-instar larvae after oral administration of DNJ [ 18 , 19 ]. In this study, based on the KEGG database analyses, the up-regulated genes related to glycometabolism were mainly enriched in N-glycan biosynthesis, glycolysis and gluconeogenesis, starch and sucrose metabolism, and the down-regulated genes associated with glycometabolism were mainly enriched in fructose and mannose metabolism.…”

“…GABAT is a dimeric homopolymer that catalyses the first step in the conversion of the central inhibitory neurotransmitter gamma-amino butyric acid (GABA) to succinic acid [ 46 ]. As shown in our previous study, succinate levels were reduced in the haemolymph of fourth-instar eri-silkworm in response to the DNJ treatment [ 18 ]. Thus, DNJ inhibited the expression of the GABAT gene to influence succinate production.…”

“…As an alkaloid from mulberry, DNJ shows substantial inhibitory activity towards α-glucosidase in vitro , which may be beneficial for suppressing abnormally high blood glucose levels [ 3 ]. In our previous study, we used eri-silkworm as a model to study the toxic actions of DNJ via metabonomics, and DNJ modulated glycometabolism and inhibit glucogenesis and energy metabolism [ 18 , 19 ]. DNJ is reported to exert a significant inhibitory effect on the activity of α-glucosidase.…”

“…Therefore, we utilized the fifth-instar eri-silkworm haemolymph to research the toxic effects of DNJ using a transcriptomic analysis. As shown in our previous study, DNJ has a positive impact on reverse glycometabolism by modulating glycometabolism and inhibiting glucogenesis and energy metabolism in the fourth-instar eri-silkworm haemolymph [ 18 ]. In the eri-silkworm midgut, DNJ not only exerts a potent negative effect on energy metabolism and glycometabolism but also modulates lipid metabolism [ 19 ].…”