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. Author manuscript; available in PMC: 2020 Oct 1.
Published in final edited form as: Brain Behav Immun. 2019 Jun 5;81:151–160. doi: 10.1016/j.bbi.2019.06.008

Figure 4.

Figure 4.

Effects of repeated immunizations with a heat-killed preparation of M. vaccae or vehicle in rats exposed to fear conditioning, fear extinction, and spontaneous recovery on overall mean Tph2 mRNA expression in the dorsal raphe nucleus (DR), median raphe nucleus (MnR), B9 supralemniscal serotonergic cell group, and pontomesencephalic reticular formation (PMRF). Each graph represents the mean (A) ± SEM or (B) + SEM of Tph2 mRNA expression, i.e., (A) mean ± SEM of Tph2 mRNA expression at each rostrocaudal level throughout the rostrocaudal extent of the DR, MnR, B9 supralemniscal serotonergic cell group, and PMRF. (B) Overall mean + SEM Tph2 mRNA expression within the DR, MnR, B9 serotonergic cell group, and PMRF. Rats received fear conditioning on Days −37 and −36, followed by immunizations with a heat-killed preparation of M. vaccae or borate-buffered saline vehicle (Vehicle) on Days −35, −28, and −21, followed by fear extinction training on Days 1-6, and spontaneous recovery 14 days later (Day 20). Rats were euthanized 24 h later on Day 21. *p < 0.05, M. vaccae versus vehicle. Rostrocaudal levels 1 through 16 correspond to those illustrated in panels A-P of Figure 3.