Gastrin, yemwe amadziwikanso kuti pepsin, ndi mahomoni am'mimba omwe amapangidwa makamaka ndi ma G cell am'mimba antrum ndi duodenum ndipo amagwira ntchito yofunikira pakuwongolera magwiridwe antchito am'mimba ndikusunga dongosolo la m'mimba.Gastrin imatha kulimbikitsa katulutsidwe ka asidi m'mimba, imathandizira kukula kwa maselo am'mimba a mucosal, komanso kukonza zakudya komanso magazi a mucosa.Mu thupi la munthu, kuposa 95% ya biologically yogwira gastrin ndi α-amidated gastrin, yomwe makamaka imakhala ndi ma isomers awiri: G-17 ndi G-34.G-17 ikuwonetsa zomwe zili pamwamba kwambiri m'thupi la munthu (pafupifupi 80% ~ 90%).Kutulutsa kwa G-17 kumayendetsedwa mosamalitsa ndi pH ya m'mimba antrum ndipo kumawonetsa malingaliro oyipa omwe amagwirizana ndi asidi am'mimba.