J Korean Pain Soc.  2000 Nov;13(2):137-142.

The Effect of Intracerebroventricular Gabapentin on the Formalin Test in Rats

• Yoon MH
• Kwak SH
• Chung SS
• Yoo KY
• Jeong CY
• Im WM

Abstract

BACKGROUND: Systemic or intrathecal administration of gabapentin has been shown to reverse various pain states. However, until now, the effect of intracerebroventricular (ICV) gabapentin to noxious stimuli has not been reported. The authors' aim of this study was to determine the effect of ICV gabapentin on the inflammatory nociceptive model, formalin test, in rats.
METHODS
ICV catheters were implanted under halothane anesthesia. For the nociceptive test, 50 micro l of 5% formalin was subcutaneously injected into the hindpaw. The effect of ICV gabapentin, administered 10 min before formalin injection, were examined on flinching, mean arterial pressure and heart rate evoked by a injection of formalin.
RESULTS
Injection of formalin into the paw resulted in a biphasic flinching and cardiovascular response. ICV gabapentin produced a dose-dependent suppression of the flinching and mean arterial pressure response during phase 1. In contrast, in phase 2, ICV gabapentin did not attenuate the pain behavior. ICV gabapentin did not affect on the baseline mean arterial pressure and heart rate.
CONCLUSIONS
ICV gbapentin was effective for the acute noxious stimulus but it had no effect on the facilitated states induced by tissue injury.

Keyword

Analgesics, intracerebroventricular gabapentin; Pain acute noxious stimulus; facilitated state

MeSH Terms

Anesthesia
Animals
Arterial Pressure
Catheters
Formaldehyde*
Halothane
Heart Rate
Pain Measurement*
Rats*
Formaldehyde
Halothane