ABSTRACT
The aim of this study was to investigate the effects of taurine administration (100, 200 and 400 mg/kg) on behavioural, haematological and biochemical responses of mice and Wistar rats subjected to acute restraint stress (1 hour/day for 14 days) and chronic restraint stress (6 hour/day for 21 days). The treatments were administered once daily by oral gavage. Forty eight (48) Wistar rats, divided into four groups of six rats each and 48 mice divided into four groups of six mice each were used for this study. Learning and memory in both the acute and chronic restraint-stressed animals was assessed using step-down passive-avoidance test in Wistar rats and elevated plus-maze memory for mice. Exploratory activity in mice was accessed using hole-board method while motor coordination was accessed using beam-walk assay. Total and differential leucocyte counts, red blood cell count (RBC), platelet count (PLT), packed cell volume (PCV), haemoglobin concentration (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration and osmotic fragility (EOF) test were evaluated using automatic haematological assay analyzer. Serum total protein and albumin concentration was estimated using Bio-Rad protein assay kit based on the principle of Bradford. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were determined by the method of Reitman and Frankel. Serum alkaline phosphate activity (ALP) was assayed as described by Bassey. The concentration of malondialdehyde was evaluated in the fore brain homogenate samples using the method of Draper and Hadley. The brain acetylcholinesterase (AChE) activity was conducted as decribed by Ellman. Activity of superoxide dismutase in the rat brain was assessed using the NWLSSTM SOD activity assay kit. Catalase activity was viii analyzed using the NWLSSTM CAT activity assay kit. Glutathione peroxidase activity was assessed using NWLSSTM cGPx (Gpx1) Enzyme-linked immunosorbent assay (ELISA) assay kit. The results showed that taurine improved learning and memory in both acute and chronic restraint-stressed Wistar rats that received 200 and 400 mg/kg taurine, in acute (216.67 ? 8.73s and 228.50 ? 9.98s) and chronic (230.67 ? 10.72s and 223.17 ? 7.84s). Elevated plus-maze showed decreased acquisition time (34.67?4.52s) and short retention time (19.50?7.29s) in group that received 400 mg/kg taurine in the acute restraint-stressed group. Short acquisition (47.50?12.50s) and retention (21.83?15.28s) time were observed in group that received 400 mg/kg taurine in chronic restraint-stressed groups. Exploratory activity in mice was increased in both acute (22.00 � 1.24s) and chronic (18.17 � 1.49s) restraint-stressed group that received 200 mg/kg taurine. The acute restraint-stressed group showed significant decrease in white blood cell count (11.15 ? 1.59 x109/L), neutrophil (17.67 ? 0.25 %) and lymphocyte (58.12 ? 1.06 %) counts at 100 mg/kg taurine. The neutrophil/lymphocyte ratio (N/L) showed increase (0.35 ? 0.69) group that received 400 mg/kg taurine in chronic restraint-stressed group. There is significant increase in PLT in the acute group that received 200 mg/kg taurine (512.83 ? 6.00 x109/L) and significant increase in the chronic group that received 100 mg/kg taurine (568.67 ? 92.86 x109/L). There is significant decrease (5.65 ? 0.72 x1012/L) in RBC count at 100 mg/kg taurine in the chronic restraint-stressed group. 400 mg/kg taurine showed significant decreased in MCV (51.85 ? 0.85 fl) and MCH (17.72 ? 0.17 pg) in the chronic restraint-stressed group. There was no significant difference in the EOF test in both the acute and chronic restraint-stressed groups. AChE activity was increased (24.17 ? 0.75 nmol/mg) in the acute group 200 mg/kg taurine and in chronic.