*2.6. Measurement of Brain Urea*

Brain Urea was calculated using GLDH—UV-kinetic diagnostic kit with the SEMI MICRO METHOD from United Diagnostics Industry (UDI, Dammam, Saudi Arabia). Urea is a primary end product of protein nitrogen metabolism. The urea reagent was reconstituted with 3 mL of distilled water, then 1000 µL of reconstituted reagent was pre-warmed at 37 ◦C for 2 min followed by mixing with 10 µL of the sample. Absorbance was measured every 30 s for 90 s at 340 nm against distilled water, and eventually, ∆A/min was determined. One urea unit was defined as micromoles of NADH decomposed per minute using molar absorbance of 6.22 <sup>×</sup> <sup>10</sup><sup>3</sup> <sup>×</sup> <sup>M</sup>−<sup>1</sup> Cm−<sup>1</sup> .
