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. 2018 Mar 28;315(1):R134–R143. doi: 10.1152/ajpregu.00049.2018

Fig. 3.

Fig. 3.

Section of the cervical or the subdiaphragmatic gastric vagi attenuates the sympathoinhibitory effects evoked by nanoinjection of resiniferatoxin (RTX) in the medial nucleus tractus solitarius (mNTS). A: representative example showing that following cervical vagotomy (VagX), nanoinjection of RTX (1 nM in 100 nl, dashed line) into the mNTS has minimal effects on all measured variables. AP, arterial pressure. B: with a subdiagphragmatic VagX of the anterior and posterior vagal branches, RTX injection into mNTS evokes changes in heart rate (HR) and mean arterial pressure (MAP) but not in brown adipose tissue (BAT) sympathetic nerve activity (SNA) or BAT temperature (TBAT). C: group data (means ± SE, n = 8 in the intact vagus group, n = 6 in each vagotomized group) show that cervical VagX and subdiaphragmatic (SD) VagX are effective in preventing the BAT thermogenic inhibition evoked by RTX in NTS but that cervical VagX is significantly more effective than SD VagX in attenuating cardiovascular responses to RTX injection in NTS. *P < 0.005, significant difference (least significant difference post hoc comparison between each group following significant ANOVA). For all variables, the RTX-evoked responses were significantly different between the intact vagus group and the cervical VagX group. The RTX-evoked responses in BAT SNA, TBAT, and expired CO2 differed significantly between the intact vagi and SD VagX groups; in contrast, the RTX-evoked changes in HR and MAP were not significantly different between the intact vagus and SD VagX groups, (ns, P > 0.05). The RTX-evoked responses in BAT SNA, TBAT, and expired CO2 were not significantly different (ns, P > 0.05) between the cervical and the SD VagX groups. The HR and MAP responses to RTX were significantly different between the cervical and the SD VagX groups. D and E: photomicrographs of representative RTX nanoinjection sites in mNTS in a rat with a cervical VagX (D, arrowhead indicates blue bead deposit) and one with a SD VagX (E, arrowhead indicates blue bead deposit) and schematic representations of the respective RTX nanoinjection sites (blue circles, n = 6 in each group) plotted on schematic drawings of a partial coronal section at 13.5 to–14 mm caudal to bregma. Gr, gracile nucleus; 12N, hypoglossal nucleus.