High concentration of MSG alters antioxidant defence system in lobster cockroach Nauphoeta cinerea (Blattodea: Blaberidae)

Interplay between diphenyl diselenide and copper: Impact on D. melanogaster survival, behavior, and biochemical parameters

Copper (Cu2+) is a biologically essential element that participates in numerous physiological processes. However, elevated concentrations of copper have been associated with cellular oxidative stress and neurodegenerative diseases. Organo‑selenium compounds such as diphenyl diselenide (DPDS) have in vitro and in vivo antioxidant properties. Hence, we hypothesized that DPDS may modulate the toxicity of Cu2+ in Drosophila melanogaster. The acute effects (4 days of exposure) caused by a high concentration of Cu2+ (3 mM) were studied using endpoints of toxicity such as survival and behavior in D. melanogaster. The potential protective effect of low concentration of DPDS (20 μM) against Cu2+ was also investigated. Adult flies aged 1-5 days post-eclosion (both sexes) were divided into four groups: Control, DPDS (20 μM), CuSO4 (3 mM), and the combined exposure of DPDS (20 μM) and CuSO4 (3 mM). Survival, biochemical, and behavioral parameters were determined. Co-exposure of DPDS and CuSO4 increased acetylcholinesterase (AChE) activity and the generation of reactive oxygen species (ROS as determined by DFCH oxidation). Contrary to our expectation, the co-exposure reduced survival, body weight, locomotion, catalase activity, and cell viability in relation to control group. Taken together, DPDS potentiated the Cu2+ toxicity.

The investigation of the effects of monosodium glutamate on healthy rats and rats with STZ-induced diabetes

Monosodium glutamate (MSG, E621) is a flavor-enhancing food additive used widely in the food preparation industry and consumed regularly. It is considered that long-term consumption of MSG causes metabolic syndrome and obesity. Diabetes mellitus (DM) is a chronic metabolic disease characterized by high blood sugar, polyuria, polydipsia, and polyphagia, in which insulin secreted from pancreatic β cells is inadequate for maintaining blood glucose homeostasis. Rats were application 65 mg/kg streptozotocin (STZ) solution intraperitoneally and a diabetes model was created. For this purpose, freshly prepared STZ was injected into the peritoneum. Tumor necrosis factor-α, interleukin (IL)-10, IL-6, and IL-1β levels in STZ, MSG, and STZ + MSG groups were found to be significantly increased in inflammation parameters measured on the 28th day of administration when compared to the Control Group (p < 0.001). Also, although malondialdehyde (MDA) levels increased significantly in the STZ + MSG group when compared to the control group (p < 0.001), glutathione (GSH), and superoxide dismutase (SOD) levels were significantly decreased in the STZ, MSG, and STZ + MSG groups when compared to the control group (p < 0.001). Also, although glucose levels increased significantly in STZ and STZ + MSG at the end of the 28th day (p < 0.01), insulin levels decreased in STZ, MSG, and STZ + MSG groups when compared to the control groups (p < 0.01). As a result, it was found that STZ and MSG application significantly increased cytokine production, increased MDA, which is an oxidant parameter in pancreatic tissue, and decreased antioxidants (GSH and SOD) when compared to the control groups. It was also found that MSG disrupted the normal histological structure in pancreatic cells, and the damage was much more in both exocrine and endocrine pancreatic areas in the STZ + MSG group when compared to the STZ and MSG groups. It was considered that with the increased use of MSG, the susceptibility to DM might increase along with tissue damage significantly in diabetic groups, therefore, MSG must be used in a limited and controlled manner.

Effect of Solanum vegetables on memory index, redox status, and expressions of critical neural genes in Drosophila melanogaster model of memory impairment

African eggplant (Solanum macrocarpon L) (AE) and Black Nightshade (Solanum nigrum L) (BN) leaves are green leafy vegetables with nutritional and ethnobotanical values. We have previously characterized the vegetables via HPLC/LC-MS to reveal notable phenolic acids, flavonoids and alkaloids. In this present study, we addressed the efficacy of the two vegetables in mitigating mercuric chloride (HgCl₂)-induced neurotoxicity and memory impairment in Drosophila melanogaster. Flies were exposed to HgCl₂ (0.30 mg/g) alone or in combination with the vegetables (0.1 and 1.0%) of both samples in their diets for seven days. The results showed that HgCl₂ (Hg)-exposed flies had significantly reduced survival rate and memory index, which were ameliorated in the Hg-exposed flies fed AE or BN. This was accompanied by increased reactive oxygen species (ROS) levels, reduced total thiol, as well as catalase, glutathione transferase (GST) and acetylcholine esterase (AChE) activities in Hg-exposed fly heads, but ameliorated in Hg-exposed flies fed dietary inclusions of the vegetables. In addition, the Hg-induced alterations in SOD, NF-ҝB/Relish, Dronc and Reaper mRNA levels were statistically indistinguishable from controls in Hg-treated flies fed diets containing AE or BN. Normalization of cnc/Nrf2 and FOXO were observed only in Hg-treated flies fed BN. These findings suggest that dietary AE or BN leaves offer protection against Hg-induced memory impairment and neurotoxicity in D. melanogaster, and further justify them as functional foods with neuroprotective properties.

Streptozotocin activates inflammation-associated signalling and antioxidant response in the lobster cockroach; Nauphoeta cinerea (Blattodea: Blaberidae)

Streptozotocin exhibits tropism to insulin-producing beta-cells in mammals and has been used to model diabetes-like phenotypes in insects. We have previously shown increased brain glucose levels and oxidative stress in STZ-treated nymphs of Nauphoeta cinerea. Here, we validate Nauphoeta cinerea as an experimental organism for studying STZ-induced metabolic disruptions by investigating the potential changes in the expression of inflammation and antioxidant related genes. Cockroaches were injected with 0.8% NaCl, 74 and 740 nmol of STZ. mRNA extracted from the head of cockroaches was used to estimate the RT-qPCR expression of inflammation and antioxidant genes. STZ-treatment upregulated the target genes of the JNK pathway (early growth factor response factor and reaper) but had no effect on PDGF-and VEGF-related factor 1. TOLL 1, the target gene of TOLL/NF-kB pathway was up regulated, while both the activator and target gene of the UPD3/JAK/STAT pathway [unpaired 3 and Suppressor of cytokine signalling at 36E] were upregulated. mRNA levels of primary antioxidants (superoxide dismutase and catalase) were increased in STZ treated nymphs but there was no effect on thioredoxins and Peroxiredoxin 4. Likewise, STZ treatment did not affect the expression of the delta class of the glutathione S-transferase gene family, but the sigma and theta classes of the GST family were upregulated. The STZ-induced N. cinerea gene expression modification demonstrates the involvement of primary antioxidants and the GST detoxification system in the cockroach oxidative stress response and buttresses the proposed crosstalk between inflammatory and redox pathways.

Streptozotocin induces brain glucose metabolic changes and alters glucose transporter expression in the Lobster cockroach; Nauphoeta cinerea (Blattodea: Blaberidae)

The development of new models to study diabetes in invertebrates is important to ensure adherence to the 3R's principle and to expedite knowledge of the complex molecular events underlying glucose toxicity. Streptozotocin (STZ)-an alkylating and highly toxic agent that has tropism to mammalian beta cells-is used as a model of type 1 diabetes in rodents, but little is known about STZ effects in insects. Here, the cockroach; Nauphoeta cinerea was used to determine the acute toxicity of 74 and 740 nmol of STZ injection per cockroach. STZ increased the glucose content, mRNA expression of glucose transporter 1 (GLUT1) and markers of oxidative stress in the head. Fat body glycogen, insect survival, acetylcholinesterase activity, triglyceride content and viable cells in head homogenate were reduced, which may indicate a disruption in glucose utilization by the head and fat body of insects after injection of 74 and 740 nmol STZ per nymph. The glutathione S-transferase (GST) activity and reduced glutathione levels (GSH) were increased, possibly via activation of nuclear factor erythroid 2 related factor as a compensatory response against the increase in reactive oxygen species. Our data present the potential for metabolic disruption in N. cinerea by glucose analogues and opens paths for the study of brain energy metabolism in insects. We further phylogenetically demonstrated conservation between N. cinerea glucose transporter 1 and the GLUT of other insects in the Neoptera infra-class.

Potassium bromate cytotoxicity in the Wister rat model of chronic gastric ulcers: Possible reversal by protocatechuic acid

The interaction between ingested xenobiotics and the gastrointestinal epithelium influences the possibility of gut epithelial cytotoxicity and systemic toxicity. Potassium bromate (KBrO₃ ) has been shown to perturb the central nervous system and it may be carcinogenic, albeit it is used as a food additive. This highlights the need to understand KBrO₃ 's effect on the stomach epithelium. Here, we report the cytotoxic potential of KBrO₃ in an ulcerated stomach, as well as possible cytoprotection by the polyphenol - protocatechuic acid. Potassium bromate (12.5 mg/kg) and protocatechuic acid (120 mg/kg) were administered orally while omeprazole (20 mg/kg) was used as standard. Potassium bromate exacerbated gastric ulcers, increased malonaldehyde levels, catalase, and sodium pump activities, but reduced nitric oxide levels. Potassium bromate further increased mast cell count in the muscularis mucosa, while inducing chronic inflammation and moderate angiogenesis in the gastric mucosa. Our results delineate KBrO₃ -induced gastric epithelial cytotoxicity that is ameliorated by protocatechuic acid. PRACTICAL APPLICATIONS: Potassium bromate is a known food additive in the baking, brewing, and cheese-making process. Conversely, protocatechuic acid (3,4-dihydroxybenzoic acid) is the polyphenolic content of plants like Hibiscus sabdariffa L that are commonly consumed as herbal drink, food, spices, and used in folk medicine. This study reports the cytoprotective effect of protocatechuic acid against gastric mucosa ulceration that has been aggravated by potassium bromate.