Fig. 1.

Unilateral nanoinjection of resiniferatoxin (RTX) into the medial nucleus tractus solitarius (mNTS) dose-dependently decreases brown adipose tissue (BAT) sympathetic nerve activity (SNA), BAT temperature (T_BAT), expired (Exp.) CO₂, heart rate (HR), and arterial pressure (AP). A: representative example of the effects of nanoinjection of RTX into the mNTS (0.1, 0.5, or 1 nM in 100 nl, dashed lines) on the recorded variables. B: group data (means ± SE; n = 6), showing dose-dependent effects of RTX nanoinjections into mNTS. MAP, mean arterial pressure. *Significant linear regression between different doses of RTX and BAT SNA inhibitions, reductions in T_BAT, and reductions in expired CO₂, in HR, and in MAP. C, left: photomicrograph of a partial coronal section illustrating a representative nanoinjection site in mNTS (arrowhead indicating blue bead deposit). C, right: locations of RTX nanoinjection sites (blue circles, n = 6) plotted on a schematic drawing of a partial coronal section at 13.5 to 14 mm caudal to bregma. T_SKIN, skin temperature; Gr, gracile nucleus; 12N, hypoglossal nucleus.