Fig. 1.

Characterisation of L^distalDq model. (a) Tetracycline (DOX)-inducible Cre-mediated recombination system specific to distal L cells resulting in DREADD-hM3Dq expression. The rtTA is expressed under the control of the Insl5 promoter. Induction with DOX (‘TET-On’) drives a Cre-mediated recombination, resulting in the excision of a stop cassette, driving expression of hM3Dq-P2A-Citrine (Citrine is a yellow GFP variant) in distal L cells. (b) Representative images from immunohistochemistry-based assessment of Citrine induction in (i, ii) colonic and (iii) pancreatic tissue from DOX-treated Insl5-rtTA×Tet-Cre×Dq mice (i) GFP (green)/INSL5 (red), (ii) GFP (green)/5-HT (red)/GCG (blue) and (iii) GFP (green)/GCG (blue). Scale bars, 10 μm. (c) Bars represent percentage of INSL5-positive cells that are positive for GFP (n = 2 mice). (d-f) GLP-1, INSL5, PYY and neurotensin secreted from mouse colonic cultures (n = 2–4, in triplicate). Data represent the mean ± SEM of the fold increase of peptide quantification (peak area) of the treated condition compared with the mean of the vehicle treated control triplicates of the same culture. Conditions: control, 10 μmol/l CNO and a combination of forskolin (10 μmol/l) 3-isobutyl-1-methylxanthine (IBMX; 10 μmol/l) and glucose (10 mmol/l) (F/I/10G). **p < 0.01 and ***p < 0.001 vs control by 1-way ANOVA with Dunnett’s post hoc test performed on log₁₀-transformed data (vs control). CAG, synthetic promoter composed of cytomegalovirus early enhancer element (C), the promoter, the first exon and the first intron of the chicken beta-actin gene (A) and the splice acceptor of the rabbit beta-globin gene (G); Insl5-P, insulin-like peptide 5 gene promoter; P2A, viral 2a ‘ribosomal stutter’ sequence; stop, stop codon; tetO, tetracycline operator sequence. Circles, vehicle; squares, CNO; diamonds, F/I/10G