Mouse brain concentrations of 3-methoxytyramine and normetanephrine: a comparison of methods of sacrifice.

The identification of sacrifice methods that produce reliable measures of baseline central nervous system neurotransmitter concentrations poses a challenge to analytical neurochemical investigation. In the present study, microwave irradiation (MWVI) was compared with in situ freezing, cervical dislocation, and simple decapitation, in an effort to examine their effects on whole mouse brain concentrations of 3-methoxytyramine (3MT) and normetanephrine (NMN), the O-methylated catecholamine metabolites believed to be sensitive indicators of release of CNS dopamine and norepinephrine, respectively. Both high-energy (6 kW, 0.3 s) and low-energy (2.5 kW, 1.5 s) MWVI produced the lowest mouse brain concentrations of 3MT and NMN when compared with other methods of sacrifice within experiments. In situ freezing resulted in values of 3MT and NMN that were slightly, yet significantly, higher than MWVI within experiments. The concentrations of 3MT and NMN obtained following either cervicle dislocation or simple decapitation were up to 9-fold greater than those produced by either of the two previous methods.