Urethane and ketamine were tested for their ability to alter the caudally directed binding and scratching response elicited by the intrathecal (i.t.) injection of excitatory amino acids (EAAs) or substance P (SP). EAAs, such as N-methyl-D-aspartate (NMDA), kainate acid and quisqualic acid, but not SP, were inhibited by subanesthetic doses of urethane. In contrast, SP was more sensitive than NMDA to the inhibitory effect of (+)-ketamine. (-)-Ketamine produced much less inhibition of the SP-induced behaviors than the (+)isomer. These results have important implications regarding the use of urethane and ketamine as anesthetics for studies in which these excitatory compounds are potential mediators.
Bibliographical noteFunding Information:
This research was supported by Umted States Pubhc Health Servace Grants NIDA00124, NIDA04090 and NIDA04190 The authors would hke to thank Drs Stephen R Slolhng and Chnstropher W Murray for their excellent e&tonal assistance in the preparation of ttus manuscript
- Excitatory amino acids
- Substance P