In vivo monitoring of rat brain endocannabinoids using solid-phase microextraction.

Aim: Solid-phase microextraction is proposed to measure concentrations of anandamide and 2-arachidonoyl glycerol in live rat brains in response to stress. Materials & methods: Solid-phase microextraction fibers were prepared from steel with 1.5 mm extraction coating. 24 male rats were divided into groups based on brain region, stria terminalis or posterior hypothalamus and loud noise or control groups. The fibers were desorbed in acetonitrile-water (75:25) and analyzed by ultraperformance LC-MS/MS. The linear range of the method was 0.05-50 ng/ml and the in vivo concentrations were found to be between 0.3 and 40 ng/ml. Conclusion: The new approach was successfully used to determine the concentrations of anandamide and 2-arachidonoyl glycerol in vivo and could be used in the future to measure other endogenous compounds.