Interaction between intrathecal gabapentin and adenosine in the formalin test of rats.
Spinal gabapentin and adenosine have been known to display an antinociceptive effect. We evaluated the nature of the interaction between gabapentin and adenosine in formalin-induced nociception at the spinal level. Male Sprague-Dawley rats were prepared for intrathecal catheterization. Pain was evoked by injection of formalin solution (5%, 50 microL) into the hindpaw. After examination of the effects of gabapentin and adenosine, the resulting interaction was investigated with isobolographic and fractional analyses. Neither gabapentin nor adenosine affected motor function. Gabapentin or adenosine decreased the sum of the number of flinches during phase 2, but not during phase 1 in the formalin test. Isobolographic analysis, in phase 2, revealed an additive interaction between gabapentin and adenosine. Taken together, intrathecal gabapentin and adenosine attenuated the facilitated state and interacted additively with each other.
Yoon
Myung Ha
MH
Department of Anesthesiology and Pain Medicine, Chonnam National University, Medical School, Gwangju, Korea. mhyoon@chonnam.ac.kr
Choi
Jeong Il
JI
Park
Heon Chang
HC
Bae
Hong Beom
HB
D000241:Adenosine / Q000008:administration & dosage / Q000378:metabolism / Q000627:therapeutic use; D000588:Amines / Q000008:administration & dosage / Q000378:metabolism / Q000627:therapeutic use; D000700:Analgesics / Q000008:administration & dosage / Q000378:metabolism / Q000627:therapeutic use; D000818:Animals; D003509:Cyclohexanecarboxylic Acids / Q000008:administration & dosage / Q000378:metabolism / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D005557:Formaldehyde / Q000633:toxicity*; D000077206:Gabapentin; D007278:Injections, Spinal; D008297:Male; D009043:Motor Activity / Q000502:physiology; D010147:Pain Measurement; D051381:Rats; D017207:Rats, Sprague-Dawley; D005680:gamma-Aminobutyric Acid / Q000008:administration & dosage / Q000378:metabolism / Q000627:therapeutic use
D000588:Amines; D000700:Analgesics; D003509:Cyclohexanecarboxylic Acids; D005557:Formaldehyde; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin; D000241:Adenosine