Article Figures & Data
Figures
- Figure 1.
Immunofluorescence identifies the presence of CB1Rs and MOPRs throughout the PBN. The bright-field image (top row, middle panel) shows the tissue section in which preabsorbing the CB1R primary antibody with the control peptide completely blocked immunofluorescence for CB1Rs, indicating the specificity of the antibody for this protein (top row, right panel). Green CB1R-like immunoreactivity (FITC conjugate) can be seen throughout the PBN (middle row, left panel). Red MOPRs (TRITC conjugate) are found throughout as well (middle row, right panel). Overlaying the images revealed some small areas of overlap (yellow; middle row, right panel). In the higher-power images (bottom row), open arrows indicate what appear to be neuritic processes. Filled arrows indicate what appear to be cell bodies. Overlaying the images reveals only partial areas of potential colocalization (yellow; bottom row, right panel). Infusion sites were located within the black circle in the central lateral PBN (top row, left panel).
- Figure 2.
GTPγS autoradiography reveals G-protein coupling stimulated by 2-AG in the central lateral PBN in vitro is blocked by the CB1R antagonist AM251. Left shows typical autoradiograms for 2-AG (50 μm), AM251 (50 μm), and the combination of 2-AG and AM251. All tissue was incubated in the presence of the adenosine A1 antagonist DPCPX (1 μm) to reduce adenosine-mediated basal activity. Right shows values in optical density units + SEM for incorporation of [35S] GTPγS for tissue from four rats studied in vitro. **p < 0.01 indicates significant differences between value of 2-AG and all of the other conditions; ##p < 0.01 indicates significant differences between value for 2-AG and the combination of 2-AG with AM251 (BOTH); ANOVA followed by Student–Newman–Keuls test. Area of quantification is within the white square (2-AG panel).
- Figure 3.
2-AG stimulated feeding of high-fat/sucrose pellets during the first 30 min after infusion into the central lateral PBN. 2-AG stimulated the intake of high fat/sucrose pellets by 30 min after infusion (n = 7). *p < 0.05 and **p < 0.01 indicate significant differences between values of 2-AG and vehicle.
- Figure 4.
The orexigenic actions of 2-AG are blocked by CB1R antagonism. The CB1R antagonist AM251 (1 nmol) completely blocked the actions of 2-AG (n = 5). In a separate group of animals (n = 8), AM251, at all concentrations tested, failed to alter the intake of high-fat/sucrose pellets (inset). **p < 0.01 indicates significant differences between value for 2-AG versus vehicle. ##p < 0.01 indicates significant differences between value of 2-AG and AM251 (BOTH) versus 2-AG alone; ANOVA followed by Student–Newman–Keuls test.
- Figure 5.
2-AG failed to alter intake of high fat/sucrose pellets in off-target anatomical controls. The concentration of 2-AG that gave maximal stimulation of high fat/sucrose pellets intake (1 nmol; see Fig. 3) was infused ∼400–700 μm caudal to infusions successfully stimulating intake (n = 6). In these anatomical controls, 2-AG failed to alter intake at any time point.
- Figure 6.
2-AG increased intake of pure fat (Crisco) and pure sucrose (pellets). 2-AG (0.25 and 1 nmol) increased fat intake by 30 min after infusion (n = 6; left). Additionally, 2-AG (2 nmol) increased sucrose pellet intake at 0.5 and 2.0 h (n = 6; right). *p < 0.05 indicates significant differences between values of 2-AG versus vehicle; ANOVA followed by Student–Newman–Keuls test.
- Figure 7.
2-AG failed to alter intake of ad libitum fed standard chow, regardless of baseline intake. In animals fed with ad libitum access to standard chow (adlib), 2-AG failed to alter intake at any time point tested (n = 7). 2-AG also failed to alter intake in a separate group of animals maintained on a schedule with rationed feeding (ration), in which their baseline intakes approximated those of animals eating high fat/sucrose pellets (n = 7).
- Figure 8.
Stimulating parabrachial MOPRs with DAMGO (2 nmol) increased feeding of both high fat/sucrose pellets (HFS) and standard chow (SC) at later time points. Data represent mean of two groups of six rats each, with each rat infused with vehicle and DAMGO. *p < 0.05 and **p < 0.01 indicate significant differences between values of DAMGO versus vehicle; ANOVA followed by Student—Newman–Keuls test.
