Phospholipase A2 sensitivity of the dorsal root and dorsal root ganglion.
METHODS
This study was designed to characterize the effects of phospholipase A2 on the neural response of dorsal root and dorsal root ganglion in the anesthetized New Zealand White rabbit.


OBJECTIVE
To examine the effects of phospholipase A2 on the neural response of somatosensory neurons at the dorsal root ganglion level.


BACKGROUND
Phospholipase A2 may be an irritating component of disc tissue that is present in high concentration in painful herniated discs, in synovial fluids, and in sera of rheumatoid arthritis patients. Phospholipase A2 is inflammatory; however, its effects on dorsal roots and dorsal root ganglion response have never been demonstrated.


METHODS
Surgically isolated dorsal roots and dorsal root ganglia from New Zealand White rabbits were investigated by electrophysiologic techniques. Phospholipase A2 doses ranging from 100 to 400 U were applied on the mechanically sensitive segments of the dorsal root ganglia, and responses to varying doses were evaluated in relation to elapsed time.


RESULTS
The application of phospholipase A2 on the dorsal root ganglion resulted in possible neurotoxicity at doses more than 375 U, with no significant effect at lower doses except for recruitment of "silent units" at doses ranging from 200 to 340 U.


CONCLUSIONS
Phospholipase A2 doses comparable to serum concentrations in human rheumatoid arthritis appeared to be neurotoxic when applied to dorsal root ganglia. At lower doses, silent units become activated that were not active before the phospholipase A2 application. These results suggest that dorsal roots and dorsal root ganglion may be impaired by phospholipase A2, leading to sciatica and low back pain.
Ozaktay
A C
AC
Wayne State University, Bioengineering Center, Detroit Michigan, USA.
Kallakuri
S
S
Cavanaugh
J M
JM
D000704:Analysis of Variance; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005727:Ganglia, Spinal / Q000187:drug effects / Q000503:physiopathology; D008297:Male; D010741:Phospholipases A / Q000008:administration & dosage / Q000494:pharmacology / Q000633:toxicity*; D054467:Phospholipases A2; D011817:Rabbits; D012815:Signal Processing, Computer-Assisted; D013126:Spinal Nerve Roots / Q000187:drug effects* / Q000503:physiopathology
D010741:Phospholipases A; D054467:Phospholipases A2