Absolute Quantification of Swine Brain Glutamate Compounds Concentration using MR Spectroscopy and LCModel after Nasal Spraying Butorphanol Tartrate

The purpose of this study was to investigate whether the Central Nervous System (CNS) analgesics affect the metabolites of swine brain by nasal spraying. Single voxel proton magnetic resonance spectroscopy (¹H-MRS) was performed on 9 swine. The data were post-processed using LCModel software. Before nasal spraying butorphanol tartrate, the mean Glutamate compounds (Glx) concentration was 9.276+0.542 mmol/kg. After nasal spraying, the mean Glx concentration was 7.283plusmn0.540 mmol/kg. Using paired sample t-test we found that swine brain Glx level was significantly decreased after using nasal spray analgesic (t=2.826, p=0.022). However, there were no significant differences concerning mean NAA concentrations and mean Choline (Cho) concentrations before and after nasal spraying. Before nasal spraying, the mean NAA and Cho concentrations were 6.094+0.384 mmol/kg and 1.547+0.114 mmol/kg, respectively. After nasal spraying, the mean NAA and Cho concentrations were 5.530+0.346 mmol/kg and 1.255+0.079 mmol/kg, respectively. Our results imply that Glx are nociceptive neurotransmitters and play an important role in the analgesia.