Effects of dietary monosodium glutamate on the acetylcholinesterase, specific acetylcholinesterase and total protein concentrations in the brain regions of domestic fowl (<i>Gallus domesticus</i>) layers

Abstract

This study investigated the effect of varied levels of monosodium glutamate (MSG) on acetylcholinesterase, specific acetylcholinesterase and total protein concentrations in the brain of laying hens. A total of 300 point-of-lay (POL) 16 weeks old Isa Brown pullets were randomly allotted to six dietary treatments containing 0.00 (control), 0.25, 0.50, 0.75, 1.00 and 1.25 g MSG/kg diet. Two birds were kept in a cage for the feeding trial in a completely randomized design and lasted for 16 weeks. At the end of the trial, the hens were slaughtered and their brains were harvested. Homogenized samples from the medulla oblongata, olfactory lobe, optic lobe and cerebellum were analyzed to determine acetylcholinesterase, specific acetylcholinesterase and total protein concentrations. Result showed that MSG did not affect any of the brain regions of hens fed 0.25 – 0.50 g MSG/kg. However, the medulla oblongata was significantly (p<0.05) influenced at inclusion level of 1.25g MSG/kg diet. Total protein concentration was significantly (p<0.05) higher in pineal gland, medulla oblongata and cerebellum brain regions of the hens fed 0.25 g MSG/kg. Total protein concentration in the optic lobe region of the brain of the hens fed the control diet were significantly (p<0.05) higher than those on the treatment diets. The SAChE activities of the optic lobe and medulla oblongata region of the brain were not influenced (P≥0.05) by dietary MSG although the group of layers fed with 1.25gMSG/Kg were affected. Significant changes were observed in the SAChE activities of the cerebellum while olfactory lobe and pineal gland regions of the brain were statistically unaffected. This study concluded that dietary MSG inclusion in layers’ diets above 0.50 g/kg diet increased the activities of acetylcholinesterase concentration in the optic lobe, cerebellum and olfactory lobe and reduced the total protein in the different regions of the brain with tendency to impair brain function.

Keywords: Monosodium glutamate, acetylcholinesterase, total protein, specific acetylcholinesterase