Olive cake reduces glycaemia and lipemia and increases antioxidant enzymes in STZ-induced diabetes in rat erythrocytes and tissues

Abstract

Purpose The purpose of this study is to determine the effect of olive cake (CO) on glycaemia and lipemia and lipid peroxidation and antioxidant enzymes activities in erythrocytes and tissues, in streptozotocin (STZ)-induced diabetic rats. Design/methodology/approach Diabetes was induced by a single intraperitoneal injection of STZ (55 mg/kg BW). In total, 12 diabetic D rats, weighing 260 ± 20 g, were divided into two groups fed a casein diet supplemented (D-OC) or not (D) with OC (7.5 per cent), for four weeks. Findings In D-OC compared with D, glycaemia, total cholesterol and triglycerides values (−40 per cent; p = 0.007, 27 per cent; p = 0.007 and −27 per cent; p = 0.0019). In erythrocyte, liver, kidney, heart, muscle and brain, thiobarbituric acid reactive substances contents were respectively, (−19 per cent; p = 0.03, −32 per cent; p = 0.002, −20 per cent; p = 0.04, −68 per cent; p = 0.003, −74 per cent; p = 0.0003 and −38 per cent; p = 0.04). In erythrocyte, SOD, GSH-Px and CAT activities were respectively, (+14 per cent; p = 0.01, +74 per cent; p = 0.012 and +34 per cent; p = 0.0009). In the liver, kidney, heart and muscle, SOD activity was respectively, (+31 per cent; p = 0.004, +12 per cent; p = 0.038, +43 per cent; p = 0.001 and +23 per cent; p = 0.18). GSH-Px activity was respectively, (+121 per cent; p = 0.0009, 89 per cent; p = 0.0006, + 95 per cent; p = 0.008, +71 per cent; p = 0.02 and +26 per cent; p = 0.01), in the liver, kidney, heart, muscle and brain. Catalase activity was (+21 per cent; p = 0.008) in the liver, (+88 per cent; p = 0.0002 in the kidney, +53 per cent; p = 0,002 in the heart and 83 per cent; p = 0.00004 in the muscle). Originality/value In diabetic rats, OC reduces hyperglycaemia induced by STZ and attenuates triglyceridemia and cholesterolemia. This residue is able to decrease the oxidative stress by increasing the antioxidant enzymes activity in erythrocytes and tissues. The high contents of phytoconstituents present in OC are considered to be responsible for this effect.