We used our previously described technique for laser capture microdissection (LCM) of central nervous system (CNS) tissue [26]. Mice underwent intracardiac perfusion with 10 cm3 ice-cold 0.9% NaCl after CO2 asphyxiation followed by brain harvest. Brainstems were rapidly dissected, embedded in optimal cutting temperature medium, and stored at −80°C until sectioning. Later, 15-μmol/l sections were cut using a cryostat, placed on slides and rapidly dehydrated through ethanol and xylene. Each slide contained about six sections. The slides were then brought directly to the PixCell LCM instrument (Arcturus, Mountain View, California, USA), with a 15-μm laser spot diameter, power of 40 mW and 500-μs pulse duration to transfer tissue to the CapSure matrix (Arcturus). Each cap was used until 80−90% of the surface contained transferred tissue. Tissue was harvested from the amygdala, dorsal raphe, and periquaductal gray nuclei using standard brain atlases to guide the process. The RNA was extracted using the PicoPure (Arcturus) RNA spin column purification kit according to manufacturer's directions followed by mRNA amplification. It has been shown by our laboratory and others that amplification of laser-captured RNA
