Effect of sodium barbital dependence on chronic spinal rats monitored by spontaneous hind leg movements

Sodium barbital was administered to intact and chronic spinal rats at the maximally tolerable dose subcutaneously three times a day for two weeks and then abruptly terminated. During withdrawal, the animals' behavior was monitored continuously for 80 hours. Spontaneous hind leg movements (SLMs) were measured in chronic and acute spinal rats every four hours for 144 consecutive hours. Tonic-clonic convulsions developed in withdrawing animals. SLMs developed in each withdrawing chronic spinal rat but were absent in acute spinal, control chronic spinal, and those rats receiving an acute single dose of barbital (140 mg/kg, sc). Administration of barbital (70 mg/kg, sc) or (3 gm/kg, po) but not saline during withdrawal completely arrested any further SLMs. The T 1/2β of barbital in both chronic spinal and intact rats following chronic dosing was 18 hours. In conclusion, this study reports characteristics of sodium barbital withdrawal on behavior and SLMs in intact and chronic spinal rats.