EFFECTS OF MOMORDICA CHARANTIA L. NANOPARTICLES ON ENDOPLASMIC RETICULUM STRESS AND LIPOTOXICITY INDUCED BY STREPTOZOTOCIN IN RATS

Abstract

Diabetes mellitus, is a complex metabolic disease with different causative factors, and one of the cause of death among humans. It is mainly characterized by lack of insulin and/or insulin resistance. Several mechanisms have been implicated to cause insulin resistance such as lipotoxicity, inflammation, hyperglycaemia, mitochondrial dysfunction and endoplasmic reticulum stress. The mechanisms involved in the modulatory effects of Momordica charantia nanoparticles in ER-stress induced by streptozotocin (STZ) in the pancreas of rats were investigated. A total of 36 adult male Wister rats (70-150g) were acclimatized and randomly allocated into 6 groups containing 6 animals per group. Diabetes mellitus was induced by intraperitoneal (i.p) injection of 65mg/kg freshly buffered (0.1 M citrate, pH 4.5) solution of STZ to overnight fasted rats. After 72 hours, animals with blood glucose ≥200 mg/dl were selected and used for subsequent experiments. The Animals were then divided into; Diabetic control group (65 mg/kg STZ), Control group, and groups that are diabetic rats post-treated with varying dose of silver nitrate, Momordica charantia nanoparticles, metformin, and plant extract for 11 days. The Momordica charantia nanoparticles used was synthesized using the filtrate from the plant extract added to 1mM concentration of aqueous silver nitrate. The bioreduction of Ag+ ions to Ag0 was monitored using a UV-Vis spectrophotometer at 430nm. Further characterization of the nanoparticles was done using Fourier transformed infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The mRNA expression of endoplasmic reticulum (ER) stress related genes (grp78, perk, atf-4, ire-1α, chop and trb-3), lipotoxicity genes (vldlr, ppar-γ, srebp-1c, pepck, lipase, and fto), and pro-inflammatory markers (tnf-α, il-1β, tgf-β1, and il-6) were assessed on the pancreas using reverse transcriptase polymerase chain vii reaction (RT-PCR). The infrared spectrum revealing the functional groups responsible for the synthesis of the Momordica charantia nanoparticles were depicted to be 3280.1cm-1 carboxylic acids (O-H stretch), 2922.2 cm-1 alkanes (C-H stretch), 1625 cm-1 amides (C=O stretch), 1543.1 cm-1 nitro compounds (symmetrical stretch), 1319.5 cm-1 nitro compounds (asymmetrical stretch) and ethers (symmetrical and asymmetrical stretch). SEM images at magnifications of 500×, 1000× and 1500× clearly gave physical morphology and topography, revealing that the synthesized nanoparticles were stacked together, silvery in colour, and amorphous in shape. A significant increase (p<0.05) in fasting blood glucose (FBG) was observed in the STZ untreated group compared to the control group, while treatment with metformin (100mg/kg), M. charantia nanoparticles (50mg/kg) and the plant extract (100mg/kg) significantly reduced (p<0.05) FBG relative to the STZ untreated group. Moreover, the expression of Inflammatory cytokines, ER stress and lipotoxicity genes were significantly up-regulated (p<0.05) in the STZ untreated group compared to the control, while treatment with metformin (100mg/kg) and M. charantia nanoparticles (50mg/kg) significantly down-regulated (p<0.05) the expression of the genes relative to the STZ untreated group. It can be concluded that the Momordica charantia nanoparticles is effective for reversing ER stress and lipotoxicity, and could be an alternative therapy for the treatment of diabetes mellitus. However, further researches should be carried out to establish its toxicological safety at clinical stages.