FUNCTIONAL RECOVERY OF ISOLATED INJURED RAT SCIATIC NERVE BY APPLYING SONICATED LIPID EMULSIONS

Abstract

According to their severity, mechanical trauma indu ce reversible/irreversible changes of nervous conduction due to the membrane pore formation at the injury site followed by the loss of nerve membran e integrity and function. The present study was aimed at assessing functional recovery of peripheral ner ves subjected to in vitro injury by severe compression after local application of sonicated lipid emulsion (SLE). METHODS: Sciatic nerves isolated from Sprague Dawley rats (250-350g) were randomly assigned to 2 group s: Controls (n = 6) and SLE treated group (n = 6). Iso lated sciatic nerves were incubated and electricall y stimulated using Ag/AgCl electrodes (I=1mA) in double sucrose gap recording chamber. Both groups were subjected to severe injury by continuous compression with a glas s rod vertically manipulated by an electrical micromanipulator. The compression was maintained 15 sec. after the cessation of electrical nerve respo nse known as the compound action potential (CAP). In SLE treated group 2, the lipid emulsion was applied a t the site of injury for 4 minutes. After inducing the se vere lesion sciatic nerves in Controls were incubat ed in saline solution for a similar time interval. The evaluatio n of functional recovery was performed using electrophysiological recordings for 2 hours. RESULTS: In all injured nerves from the SLE group, 30-40 minutes following lipid application, an electrical response (CAP) was recorded. The CAP signal showed a trend for increasing its amplitude during the first hour post -injury, followed by a plateau which was maintained for the rest of the experiment. For each nerve the pre-inj ury CAP amplitude was considered as a marker of nerve conduction. Functional recovery was expressed as pe rcentage (%) by normalizing the final post-injury C AP amplitude to the pre-injury value. At the end of t he post-injury evaluation period in SLE treated gro up, CAP amplitude recovery ranged between 2-16% from the pre-injury value (100%). In Controls there was no rec overy during the 2 h period of post-injury follow-up. CON CLUSION: In this in vitro model of severe periphera l nerve compression, application of a sonicated lipid emuls ion allows the partial recovery of acutely injured sciatic nerves.