Fig 2: Co-distribution of GPR103-like immunoreactivity (LI) with insulin, glucagon and somatostatin in the human pancreas. (A and B) Consecutive sections treated with the GPR103 antibodies and insulin antibodies reveal that the histological distribution of GPR103-LI (A) is closely related to that of insulin (B). (C and D) Consecutive sections treated with the GPR103 antibodies and glucagon antibodies suggesting that, in some cases, glucagon-positive cells (arrow) (D) display GPR103-like immunoreactivity (arrow) (C). (E and F) Consecutive sections treated with the GPR103 antibodies and somatostatin antibodies suggesting that, in some cases, somatostatin-positive cells (arrow) (F) display 26RFa-like immunoreactivity (arrow) (E). Scale bars: 25 µm.

Fig 3: Distribution of 26RFa-like immunoreactivity in the human pancreas. (A and B) Low magnification photomicrograph showing that the 26RFa labeling is present in the endocrine islets, whereas the exocrine tissue is virtually devoid of 26RFa-like immunoreactivity (A). A higher magnification reveals that almost all the cells of the islet are strongly labeled with the 26RFa antibodies (B). (C and D) Similarly, the pancreatic islets are strongly labeled with the GPR103 antibodies (C). However, a higher magnification of the islets reveals that some islet cells are strongly labeled (arrows), whereas others are devoid of immunostaining (arrowheads) (D). (E and F) Photomicrographs showing that preincubation of the 26RFa antibodies with synthetic human 26RFa (10-6 M) results in a total loss of the immunostaining in the pancreatic islets (F). (G and H) Similarly, substitution of the GPR103 antibodies with Tris buffer results in a total loss of the immunostaining in the pancreatic islets (H). Scale bars: (E, F, G and H), 200 µm; (A and C), 50 µm; (B and D), 10 µm.

Fig 4: Distribution of 26RFa- and GPR103-like immunoreactivity in the human ileum and colon. (A and B) In the ileum, 26RFa-immunolabeling is present in scattered enterocytes and goblet cells of the villosities (A). A higher magnification photomicrograph shows that a number of villosities are, indeed, devoid of immunostaining (B). (C and D) Similarly, GPR103-immunolabeling is present in a few enterocytes and goblet cells of the ileum (C), but when the cells are labeled, the immunostaining is intense (D). (E and F) In the colon, most of the villosities are devoid of 26RFa-immunolabeling (E). However, in some cases, weakly immunostained enterocytes can be found (F). (G and H) Distribution and localization of the 26RFa receptor in the colon is very similar to that observed in the ileum with an intense immunostaining in the enterocytes and goblet cells of some villosities. Scale bars: (A, C, E and G), 200 µm; (B), 50 µm; (F and H), 25 µm; (D), 10 µm.

Fig 5: Distribution of GPR103-like immunoreactivity in the human stomach. (A) Low magnification photomicrograph showing a dense immunolabeling in the gastric glands. (B, C and D) Higher magnification photomicrographs reveal that, in the surface epithelium cells, the immunostaining for the 26RFa receptor is restricted to the basal pole of the cells (B and C). In the neck part of the gastric glands, GPR103-positive cells are large and exhibit a round shape identifying them therefore as parietal cells (D). (E and F) Control sections showing that substitution of the GPR103 primary antibodies with Tris buffer saline results in a total loss of the immunostaining. Scale bars: (A), 200 µm; (E and F), 50 µm; (B and D), 25 µm; (C), 10 µm.