Effect of the spinal drug tramadol on the fatty acid compositions of rabbit spinal cord and brain.

Tramadol is an important spinal drug which produces analgesia following intrathecal injection. It is well known that fatty acids (FAs) play an important role in membrane fluidity of the blood-brain barrier (BBB) tissue, which blocks and/or controls the transportation of toxic substances into the brain. The aim of this study was to investigate the effect of a spinal drug (tramadol) on the concentrations and compositions of fatty acid in BBB tissues of New Zealand male rabbits. The total cellular fatty acid profiles of the tissues in three spinal cord sections (cervical, thoracal and lumbar) and in the brain of rabbits with or without drug administration were determined by gas chromatography using Sherlock Microbial Identification System (MIS) software (Microbial ID, Newark, DE, U.S.A.) with a database of FAME profiles for eukary. The relative percentage of the fatty acid methyl ester (FAME), 24 : 1 omega9c nervonic and 17 : 1 omega8c, did not change with tramadol treatments. However, there was an increase in the concentration of the FA 16 : 0, 18 : 1 omega7c DMA, 18 : 1 omega9c, sum in future 4, sum in future 8, sum in future 9, 18 : 0, 20 : 4 omega6c, sum in future 14, 22 : 4 omega6c, in contrast to a decrease in the percentages of the following FAMEs; 20 : 0, 20 : 1 omega9c. In the brain, there was an increase in the concentration of the FA 18 : 1 omega9c, sum in future 8 and 18 : 0, in contrast to a decrease in the percentages of two FAMEs, 16 : 0, 20 : 4 omega6c and 22 : 6 omega3c. The number of fatty acids were 20 in the spinal cord sections and 8 in the brain tissues of control animals compared to 15-18 fatty acids in the spinal cord section and 7 in the brain tissues of drug administered animals. The overall changes in the concentrations and numbers of FAs suggest that the spinal drug tested in this study has a side effect of disrupting of membrane fluidity of the BBB, which may cause neurotoxicity.