L-theanine is the unique amino acid found in tea plants, has antioxidant and antiinflammatory activities, and functions in mental concentration and sleep quality. In this study, it is aimed to investigate the effects of L-theanine on doxorubicin (DOX, a chemotherapeutic agent) induced nephrotoxicity in rats, especially via GSH related enzymes. 32 male Sprague Dawley rats weighing 300-400 g were randomly assigned into 4 groups (n = 8) and the substances were given intraperitoneally to them: Control group (saline for 5 days); Theanine group (200 mg/kg/day theanine for 5 days); DOX group (single dose of 20 mg/kg DOX); DOX + Theanine group (20 mg/kg DOX at first day and 200 mg/kg/day theanine for 5 days). Kidney tissues were evaluated by histopathological analysis. Serum levels of blood urea nitrogen (BUN) and creatinine by spectrophotometrically; percentage of apoptosis indexes (AI%) in the tissues by TUNEL method; caspase-3 levels, reduced and oxidized glutathione (GSH and GSSG), gamma-glutamyltransferase 1 (GGT1), glutathione reductase (GR), glutathione peroxidase (GPx), and glutathione S-transferase (GST), nuclear factor kappa B p65 (NF-kB p65) by commercial kits; malondialdehyde (MDA) by spectrophotometrically were determined in plasma and kidney tissues. According to DOX group, the DOX + Theanine group has much lower tissue and plasma GSSG, GGT1, NF-κB p65 levels and tissue AI%, whereas significantly higher GSH levels and GPx, GR, GST activities (P < 0.05). It is suggested that L-theanine may have protective effects by enhancing effects on the antioxidant system of GSH and GSH-related enzymes against DOX-induced nephrotoxicity in rats. But this finding needs to be supported with further studies.

The present study evaluated the neuroprotective and antioxidant effects of quercetin in a rat model of sciatic nerve crush injury using histopathological, morphometric and biochemical methods. A total of 48 male Sprague Dawley rats, aged 10-12 weeks old were randomly divided into eight groups, consisting of two sham groups (S‑7, S‑28), three quercetin‑treated groups (Q‑7, Q‑28; 200 mg/kg/7 days), trauma (T‑7, T‑28; 1 min sciatic nerve crush injury) and three trauma+quercetin groups (T+Q‑7, T+Q‑28; trauma+quercetin 200 mg/kg/7 days). Rats were sacrificed on day 7 or 28. Oxidant‑antioxidant biochemical parameters in nerve tissues from all groups were analyzed using histopathological staining with toluidine blue and Masson's trichrome. DNA fragmentations were identified using terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick‑end labeling in cells from each tissue sample. Degeneration of the axons and myelin sheath, the breakdown of the concentric lamellar structure of the myelin sheath and axonal swelling were observed in groups T‑7 and T‑28. Myelin sheath thicknesses, nerve fiber diameters and the number of myelinated nerve fibers decreased, while the apoptotic index (AI) increased in the T‑7 and T‑28 groups. However, it was observed that nerve regeneration began in the T+Q‑7 and T+Q‑28 groups compared with the sham groups, together with the healing of cellular damage and axonal structure and a decrease in the AI. Malondialdehyde and superoxide dismutase activity did not differ significantly between the T‑7 and S‑7 groups. However, catalase activity significantly decreased in the T‑28 group when compared with the sham 7 day group. Tissue malondialdehyde levels significantly increased, while serum catalase activity increased in the T+Q‑7 group compared with the T‑7 group. These results suggest that quercetin has beneficial effects on nerve regeneration and may shorten the healing period in crush‑type sciatic nerve injuries.