The following drugs were administered intracerebrally in the study: (a) muscimol hydrobromide (0.5 μl of 2 μg/μl solution; Sigma, USA), muscimol being a GABA mimetic28 (link), (b) (2 R)-amino-5-phosphonopentanoate (AP5; 0.5 μl of 5 μg/μl solution; Sigma, USA) which is an antagonist at the glutamate NMDA receptors68 (link),89 (link),90 (link), (c) 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione (NBQX; 0.5 μl of 10 μg/μl, 20 μg/μl or 40 μg/μl solution; Tocris, USA) which is an antagonist at glutamate AMPA receptor39 (link),92 (link), and (d) lidocaine hydrochloride (0.5 μl/site of 4% w/v; Sigma, USA), a local anesthetic50 (link). The drugs were prepared in 0.5% Alcian blue dye in saline (Sigma, USA) which also acted as vehicle in control experiments. The drugs, (a) through (c), were used in experiments involving microinjection into the MS region. Intraseptal microinjections were made at one given site only, while, in comparison, lidocaine was microinjected bilaterally into the RVM.
Functionally, intraseptal microinjection of the fore-mentioned drugs at the selected concentration attenuates theta rhythmic septo- hippocampal activation28 (link),68 (link),89 (link)–91 (link). The highest concentration of NBQX used in this study is also known to strongly attenuate afferent stimulation-evoked putative AMPA current in medial septal neurons39 (link).
Free full text: Click here