• The glucagon-like peptide-1 receptor (GLP1R) is a receptor protein found on beta cells of the pancreas and on neurons of the brain. It is involved in the control of blood sugar levels by enhancing insulin secretion. 
• Gene targeting strategy for B-hGLP1R mice plus. The exon 1 and part of intron 1 of the mouse Glp1r gene were replaced by human CDS of GLP1R, containing the human intron 2. The chimeric GLP1R expression was driven by endogenous mouse Glp1r promoter, while mouse Glp1r gene will be disrupted. 
• Human GLP1R mRNA was detectable only in homozygous B-hGLP1R mice plus but not in wild-type mice. And human GLP1R protein was detectable only in homozygous B-hGLP1R mice plus but not in wild-type mice. 

Strain-specific analysis of GLP1R mRNA expression in wild-type C57BL/6 mice and B-hGLP1R mice plus by RT-PCR. Various tissue RNA were isolated from wild-type C57BL/6 mice (+/+) and homozygous B-hGLP1R mice plus (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human GLP1R primers. Mouse Glp1r mRNA was detectable only in wild-type C57BL/6 mice. Human GLP1R mRNA was detectable only in homozygous B-hGLP1R mice plus but not in wild-type mice. 

Representative human GLP1R expression in different tissues of B-hGLP1R mice plus by IHC. Tissues were stained with human-specific antibodies GLP1R (B-L). The spleen of wild-type C57BL/6JNifdc mice was tissue-negative control (A). Pancreas stained with PBS in B-hGLP1R mice plus was negative (B). The islet of the pancreas, striatum septum of the brain, alveolar and bronchial epithelial cells of the lung, gastric mucosal layer and myenteric plexus of the stomach, partial blood vessels the kidney, the muscularis propria nerve plexus of both large intestine and small intestine, and the interstitial cells of the small intestine mucosal layer of B-hGLP1R mice plus show human GLP1R positive (C, D, E, F, G, K, L). Liver, adipose, and skeletal muscle of B-hGLP1R mice plus show human GLP1R negative. Original magnification ×200. Abbreviations: IHC, immunohistochemistry. 

Representative mouse GLP1R expression in different tissues of B-hGLP1R mice plus by IHC. Tissues were stained with mouse-specific antibodies GLP1R (B-H). The human pancreas tissue was negative control (A). The pancreas and brain of wild-type C57BL/6JNifdc mice showed mouse GLP1R positive (C, D). The lung tissue of wild-type C57BL/6JNifdc mice showed mouse GLP1R negative (E). The pancreas, brain, and lung of B-hGLP1R mice plus showed mouse GLP1R negative (F, G, H). Original magnification ×200. Abbreviations: IHC, immunohistochemistry. 

Study of Orforglipron and Semaglutide in B-hGLP1R mice plus food intake. B-hGLP1R mice plus (6-7 weeks old) were acclimated for QD PO dosing with vehicle for 4 days, and mice were grouped by body weight and daily food intake. All animals will be placed in clean cages and fasted overnight, mice will be dosed with vehicle or test compound in the morning (before 10 AM). All group's food will be added 15 minutes post-dosing, and food remaining will be recorded at 2-, 4-, 6-, and 8 hours post-dosing. Values are expressed as mean ± SEM. Significance was determined by the 2 way ANOVA. (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001).

PF-06882961 improved glucose tolerance and promoted insulin secretion in B-hGLP1R mice plus. B-hGLP1R mice plus (12-13 weeks old) were treated with PF-06882961 for 3 mg/kg, s.c. (-15 min). Then at 0 min, the glucose tolerance test was performed in C57BL/6 and B-hGLP1R mice plus for 2 g/kg D-Glucose was administered by intraperitoneal injection (IPGTT). (A) Blood glucose. (B) Plasma insulin. As shown, glucose tolerance was improved by PF-06882961 in B-hGLP1R mice plus but not in wild-type C57BL/6 mice, and promoted plasma insulin secretion in B-hGLP-1R mice plus. Values are expressed as mean ± SEM. Significance was determined by the 2 way ANOVA. (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001).

Orforglipron improved glucose tolerance and promoted insulin secretion in B-hGLP1R mice plus. B-hGLP1R mice plus (12-13 weeks old) were treated with Orforglipron for 1 mg/kg, p.o. (-30 min). Then at 0 min, the glucose tolerance test was performed in C57BL/6 and B-hGLP1R mice plus for 2 g/kg D-Glucose was administered by intraperitoneal injection (IPGTT). (A) Blood glucose. (B) Plasma insulin. As shown, glucose tolerance was improved by Orforglipron in B-hGLP1R mice plus but not in wild-type C57BL/6 mice, and promoted plasma insulin secretion in B-hGLP-1R mice plus. Values are expressed as mean ± SEM.