Syringic acid demonstrates an anti-inflammatory effect via modulation of the NF-κB-iNOS-COX-2 and JAK-STAT signaling pathways in methyl cellosolve-induced hepato-testicular inflammation in rats

Syringic acid (SACI) is an emerging nutraceutical and antioxidant used in modern Chinese medicine. It has potential neuroprotective, anti-hyperglycemic, and anti-angiogenic properties. Methyl cellosolve (MCEL) has been reported to induce tissue inflammation in the testis, kidney, liver, and lung. This study aimed to investigate the effect and probable mechanism of action of SACI on MCEL-induced hepatic and testicular inflammation in male rats. Compared to the control group, administration of MCEL to rats significantly increased the levels of IL-6, TNF-α, iNOS, COX-2, and NF-κB in the liver and testis. Additionally, the total mRNA expressions of JAK1 (in the liver only), STAT1, and SOCS1 were significantly increased in both the liver and testis, while testicular JAK1 total mRNA levels were significantly decreased. The expression of PIAS1 protein was significantly higher in the liver and testis. Treatments with SACI at 25 (except liver iNOS), 50, and 75 mg/kg significantly decreased the levels of IL-6, TNF-α, iNOS, COX-2, and NF-κB compared to the control group. Furthermore, the total mRNA expressions of JAK1 and SOCS1 in the liver were significantly reduced by all doses of SACI investigated, while the total mRNA levels of liver and testis STAT1 were significantly reduced by 25 and 50 mg/kg of SACI only. In the testis, the mRNA level of SOCS1 was significantly reduced by all doses of SACI compared to MCEL only. Additionally, SACI (at 75 mg/kg) significantly reduced PIAS1 protein expression in the liver, while in the testis, SACI at all investigated doses significantly reduced the expression of PIAS1. In conclusion, SACI demonstrated a hepatic and testicular anti-inflammatory effect by inhibiting the MCEL-induced activation of the NF-κB and JAK-STAT signaling pathways in rats.

Effect of syringic acid on steroid and gonadotropic hormones, hematological indices, sperm characteristics and morphologies, and markers of tissue damage in methyl cellosolve-administered rats

Methyl cellosolve (MTC) is an established gonadotoxic and hematotoxic compound that is commonly and universally utilized in herbicide, liquid soap, stain, dye, paint, and brake fluid manufacturing industries as a solvent. Due to its wide range usage, this study therefore investigated the effect of syringic acid (SYAC) on hematological indices, sperm characteristics and morphologies, and markers of tissue damage in MTC administered male Wistar rats. Thirty (30) rats divided into six groups were used. Rats in group 1 served as control, those in group 2 were administered MTC for 30 consecutive days, those in groups 3, 4, and 5 were treated with 25, 50, and 75 mg/kg body weight of SYAC respectively also for 30 consecutive days immediately after each day MTC administrations, while rats in group 6 received 75 mg/kg body weight of SYAC only throughout. Compared with control, administrations of MTC resulted in a significant decrease in spermatozoa count, number of normal and live spermatozoa, Hb count, MCH, MCHC, serum TC, and LH, while number of abnormal spermatozoa, RBC and WBC counts, activities of serum AST, ALT, GGT, LDH, and ADH were significantly increased. Treatments with 25 mg/kg of SYAC significantly reduced the RBC and WBC counts, serum activities of AST, ALT, GGT, and increased TC concentration. Treatments with 50 mg/kg SYAC significantly lowered the number of abnormal spermatozoa, RBC count, activities of serum ALT, AST, LDH, ADH, and increased the number of normal spermatozoa, MCV, MCH, and MCHC, while 75 mg/kg of SYAC significantly decreased the serum activities of AST, ALT, GGT, LDH, ADH, and increased serum TC concentration. Findings from this study have revealed the hepatoprotective effect of SYAC at all doses investigated but did not confer spermatoprotection and hematoprotection against MTC-induced toxicities, and looking at the 3 doses investigated, 50 mg/kg of SYAC yielded the best effect.

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MTC significantly decreased live sperm, sperm count, MCH, MCHC, and Hb counts.

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MTC significantly increased number of abnormal sperm, RBC and WBC counts.

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MTC significantly increased serum activities of AST, ALT, GGT, LDH, and ADH.

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SYAC significantly decreased RBC and WBC counts, AST, ALT, GGT, LDH, and ADH.

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SYAC significantly increased number of normal sperm, MCV, MCH, and MCHC counts.

Methyl cellosolve-induced renal oxidative stress and time-dependent up-regulation of pro-inflammatory cytokines, apoptotic, and oncogenic markers in rats

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MC significantly increased and decrease the kidney levels of MDA and NO respectively after 14 and 21 days.

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MC administration resulted in the disorganization of the renal redox system.

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MC significantly increased the kidney levels of TNF-α and IL-6 after 7, 14 and 21 days, and IL-1β after 14 and 21 days.

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MC significantly increased kidney p53, Bax, and caspase-3 after 14 and 21 days, and decreased Bcl-2 after 14 and 21 days.

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MC significantly increased the kidney levels of c-Myc and K-Ras after 7, 14 and 21 days.

Methyl cellosolve (MC) is used in production of textile, paints, stains, inks, surface coatings, and anti-icing additive in hydraulic fluids and jet fuel. Consequently, the present study investigated its effect on renal cells, in a time-course study in male Wistar rats. Animals were orally administered 50 mg/kg body weight of MC for a period of 7, 14, and 21 days. Following 7 days of administration of MC, there was a significant increase in the levels of K-Ras, c-Myc, TNF-α, IL-6 and NO, while GSH level and SOD activity were significantly reduced compared with control. At the end of 14 days exposure, RKW, GSH, NO, and Bcl-2 levels were significantly decreased, while levels of K-Ras, c-Myc, p53, Bax, caspase-3, TNF-α, IL-1β, IL-6, MDA and GPx activity were significantly increased compared with control. After 21 days of MC administration, RKW, GSH, NO, IL-10 and Bcl-2 levels were significantly decreased, while levels of K-Ras, c-Myc, p53, Bax, caspase-3, TNF-α, IL-1β, IL-6, MDA and GST activity were significantly increased compared with control. Exposures to MC in any way should be strictly avoided as it could trigger renal damage through the disorganization of the antioxidant system, up-regulation of inflammatory, apoptotic, and oncogenic markers in rats.