Fig. 1.

Distribution of clonidine injection sites superimposed onto evenly spaced serial cross-sections of the pons. The sections were stained with Neutral Red and immunostained for TH. Closed circles: clonidine injections placed within 0.4 mm from the center of the “loose” part of the A7 group; open circles: clonidine injections placed at a distance of 0.5–1.2 mm from the A7 group; dotted circles: injections placed at intermediate distances, 0.4–0.5 mm; triangles: control clonidine injections made into the A7 region following microinjections of RS-79948, an α₂-adrenoceptor antagonist, placed at the same site. The injections were made on either the left or right side and their location was then redrawn at the corresponding sites on one side of the pons. Abbreviations: A5, NE A5 group; A7, NE A7 group; LC, locus coeruleus; Mo5, trigeminal motor nucleus; PnC, nucleus pontis caudalis; PnO, nucleus pontis oralis; scp, superior cerebellar peduncle; SubCA, nucleus subcoeruleus, alpha part; VT, ventral tegmental nucleus.