Spinal anaesthesia with gamma hydroxybutyrate. A study in a rat model

Gamma hydroxybutyric acid, a central inhibitory neurotransmitter and a cere bral metabolite of gamma-aminobutyric acid, is present in high concentratio ns in the mammalian hypothalamus and basal ganglia. Its sodium salt gamma h ydroxybutyrate has been effectively used as an intravenous anaesthetic agen t, and as an oral sedative, and in the management of the alcohol withdrawal syndrome. In an animal model, using 72 Wistar strain rats allocated to one of six groups of 12 animals each, with implanted lumbar intrathecal cathet ers, we examined whether gamma hydroxybutyrate, 20% 40 mu L (32 mg kg(-1)) administered alone or combined with fentanyl, gamma hydroxybutyrate 20% 20 mu L (16 mg kg(-1)), fentanyl 0.005% 20 mu L (4 mg kg(-1)) as an intratheca l bolus, provides intra-operative anaesthesia, comparable with that produce d by intrathecal lignocaine. We demonstrated that gamma hydroxybutyrate, gi ven by an intrathecal bolus in the rat model, produced reversible segmental antinociception, together with muscular relaxation of the abdominal wall a nd rear limbs. This is accompanied by moderate sedation without haemodynami c or respiratory depression. This agent may thus be promising for use as a spinal anaesthetic drug.