Figure 1.
Differential effect of ghrelin on food intake and GH secretion in high and low-responders.
(A) Cumulative 0–4 h food intake and (B) GH peak of secretion in individual mice injected i.p with saline (circles), 30 nmol of ghr (squares), ghr+hOb (triangles) or ghr+hObQ90L (inverted triangles) (30 nmol). 4 hours after ghrelin injection, 59% of mice increased their food consumption over a threshold of 0.42 g (high responders, closed symbols) whereas 41% of mice did not (low responders, open symbols) responders. The dotted line represents the threshold for ghrelin response. Bar represents mean of data. ***P<0.0001 vs saline.
Figure 2.
Effect of native (hOb) and Q90L obestatin (hObQ90L) on ghrelin-induced (Ghr) cumulative food intake and meal pattern in high responders C57BL/6 mice.
(A) Mean cumulative 4 h food intake after the different treatments in high responders. (B–D) Meal number, size and duration within 4 h following the injections in high responders. Data represent mean±SEM. **P<0.01 vs saline, ***P<0.001 vs saline, ###P<0.001 vs ghr.
Figure 3.
Effect of native (hOb) and Q90L obestatin (hObQ90L) on ghrelin-induced (Ghr) GH secretion in high responders C57BL/6 mice.
(A) Mean GH secretion in response to the different treatments in high responders. (B) Area Under the curve of GH secretion over 40 minutes in high responders. Data represent mean±SEM. **P<0.01 vs saline, ***P<0.001 vs saline, #P<0.05 vs ghr+hOb.
Figure 4.
Effect of native (h/rOb) and Q90L obestatin (hObQ90L) on ghrelin-induced (Ghr) cFos immunoreactivity in C57BL/6 mice in the arcuate nucleus (ARC) and in the nucleus tractus solitarius (NTS).
(A and C) Representative confocal photomicrophotographs of the cFos staining after each treatment in coronal sections at 1.9 mm of the interaural line in the ARC and −3.78 mm of the interaural line in the NTS ; (B and D) Average of cFos-positive nuclei per section after the different treatments between 2.2/1.6 mm of the interaural line for the ARC and between −3.78/−3.98 mm of the interaural line for the NTS. Data represent mean±SEM. ***P<0.001 vs saline, *P<0.05 vs saline, #P<0.05 vs ghr. Scale bar represents 100 µm in the ARC and 50 µm in the NTS. 3V: third ventricle, ME: median eminence, DMH: Dorsomedial Hypothalamic nucleus, VMH: Ventromedial Hypothalamic nucleus, ARC: Arcuate nucleus, NTS: Nucleus Tractus Solitarius, AP: Area Postrema, 10N: Dorsal Motor Nucleus of Vagus, cc: central canal.
Figure 5.
Effect of native (h/rOb) and Q90L obestatin (hObQ90L) on ghrelin-induced (Ghr) cFos immunoreactivity in arcuate nucleus (ARC) NPY neurons in C57BL/6 mice.
(A) Representative confocal photomicrophotographs of hypothalamic coronal sections showing the merged images containing cFos staining in red and NPY-GFP cells in green after each treatment at 1.9 mm of the interaural line in the ARC. (B) Quantification of NPY-GFP positive cell bodies expressing cFos in the ARC after the different treatments. Data represent mean±SEM. ***P<0.001 vs saline, #P<0.05 vs ghr, $P<0.01 vs ghr+hOb. Scale bar represents 100 µm, 3V: third ventricle, ME: median eminence.
Figure 6.
Effect of native (hOb) and Q90L obestatin (hObQ90L) on the ghrelin-induced (Ghr) decrease of evoked GABA synaptic responses in GHRH neurons.
Dose response curves for hOb and hObQ90L (10, 30, 100 and 300 nM) represented on a semi-logarithmic scale. Ghrelin was applied at 300 nM. Data represent mean±SEM. The dotted line represents the EC50 values, 18 µM and 66.4 µM for hObQ90L and hOBhOb respectively. The two curves show significant differences (comparing best fit values of two groups using Student T-test, P<0.001).