Effect of quercetin and role of nitric oxide pathway in chloroquine-induced scratching

Abstract Nitric oxide (NO) is an abundant mediator which is demonstrated to be involved in pruritus. Assuming that the increased NO also mediates chloroquine-induced pruritus, which is a frequent complication seen in the chronic chloroquine treatment, the current study aimed to investigate the effect of quercetin and the role of NO in chloroquine-induced pruritus in C57BL/6 mice. Model was created with subcutaneous chloroquine (400µg/site) injection to the nape of the mice. Effect of quercetin and role of NO were investigated with administration of quercetin, and co-administration with L-NAME, 7-NI and L-arginine before chloroquine injection. Locomotor activity was assessed by activity cage and number of the scratching bouts after chloroquine injection was recorded for 30 minutes. Our results show that quercetin significantly reduced scratching bouts at the doses of 10, 20, 40 and 80 mg/kg. Locomotor activity was decreased at the 40 and 80 mg/kg doses of quercetin. Additionally, decrease of the number of scratching bouts by quercetin prevented by L-arginine treatment, while L-NAME and 7-NI enhanced the anti-pruritic effect of sub-effective doses of quercetin. Therefore, our study demonstrated that acute injection of quercetin significantly diminished chloroquine-induced scratching behavior, and this effect is partly mediated by inhibition of neuronal nitric oxide synthase enzyme.

The effect of hippophae rhamnoides extract on oral mucositis induced in rats with methotrexate

ABSTRACT Objective: To investigate the effect of HRE (Hippophae rhamnoides extract) on oral mucositis induced in rats with MTX. Material and Methods: Experimental animals were divided into groups as healthy (HG), HRE+MTX (HMTX), and control group, which received MTX (MTXC). HMTX group received 50 mg/kg HRE while MTXC and HG groups received equivolume distilled water with gavage once a day. After one hour of HRE and distilled water administration, HMTX and MTXC groups received a single dose of oral MTX 5 mg/ kg. This procedure was repeated for one month. Results: The levels of MDA, IL-1β, and TNF-α were found to be significantly higher in the cheek, lower lip, and tongue tissue of the animals receiving MTX, compared with HG and HMTX groups; however, these parameters were lower in the cheek and low lip tissue, and a milder damage ocurred in these tissues, compared with the tongue tissue in MTXC group. No histopathologic damage was observed in the cheek, lower lip, and tongue tissues of the rats treated with HRE. Conclusion: This findings indicate that HRE as a natural product is an important advantage compared with synthetic drugs for prophylaxis of oral mucositis developed due to MTX.

Effect of thiamine pyrophosphate on retinopathy induced by hyperglycemia in rats: A biochemical and pathological evaluation.

Purpose: Information is lacking on the protective effects of thiamine pyrophosphate (TPP) against hyperglycemia‑induced retinopathy in rats. This study investigated the biochemical and histopathological aspects of the effect of TPP on hyperglycemia‑induced retinopathy induced by alloxan in rats. Materials and Methods: The rats were separated into a diabetic TPP‑administered group (DTPG), a diabetes control group (DCG) and a healthy group (HG). While the DTPG was given TPP, the DCG and HG were administered distilled water as a solvent at the same concentrations. This procedure was repeated daily for 3 months. At the end of this period, all of the rats were euthanized under thiopental sodium anesthesia, and biochemical and histopathological analyses of the ocular retinal tissues were performed. The results of the DTPG were compared with those of the DCG and HG. Results: TPP prevented hyperglycemia by increasing the amount of malondialdehyde and decreasing endogen antioxidants, including total glutathione, glutathione reductase, glutathione S‑transferase and superoxide dismutase. In addition, the amounts of the DNA oxidation product 8‑hydroxyguanine were significantly lower in the retinas of the DTPG compared to the DCG. In the retinas of the DCG, there was a marked increase in vascular structures and congestion, in addition to edema. In contrast, little vascularization and edema were observed in the DTPG, and there was no congestion. The results suggest that TPP significantly reduced the degree of hyperglycemia‑induced retinopathy. Conclusions: The results of this study indicate that TPP may be useful for prophylaxis against diabetic retinopathy.