Objective To research the effect of radiosurgery in combination of temozolomide therapy in vitro on invasion and endocrine function of rat pituitary adenoma cells.Methods Rat pituitary adenoma cell lines GH3 and MMQ were divided into control group,10 Gy irradiation group,20 Gy irradiation group,temozolomide treatment group,and radiosurgery in combination of temozolomide group;cells without exposure were used as control group,cells treated with gamma knife radiation respectively with marginal doses of 10 and 20 Gy (all to the 99％ isodose line) were used as 10 Gy irradiation group and 20 Gy irradiation group,cells treated with 250 μmol/L and 615 μmol/L temozolomide for 24 h after 20 Gy radiation were used as radiosurgery in combination of temozolomide group,and cells treated with 250 μmol/L and 615 μmol/L temozolomide for 24 h were used as temozolomide treatment group.Real time-PCR and Western blotting were employed to measure the mRNA and protein expressions of matrix metalloproteinase (MMP)-9 and vascular endothelial growth factor (VEGF);and secretion of prolactin (PRL) and growth hormone (GH) was detected by ELISA.Results As compared with the control group,the 10 Gy irradiation group and 20 Gy irradiation group had significantly lower mRNA and protein expressions of MMP-9 and VEGF,and secretion of PRL and GH (P＜0.05);and these levels in the 20 Gy irradiation group were significantly lower than those in the 10 Gy irradiation group (P＜0.05);As compared with the 10 Gy irradiation group,20 Gy irradiation group,and temozolomide treatment group,the radiosurgery in combination of temozolomide group had significantly lower mRNA and protein expressions of MMP-9 and VEGF,and secretion of PRL and GH (P＜0.05) Conclusion Gamma knife radiosurgery combined temozolomide could significantly inhibit the invasive ability and endocrine function of rat pituitary adenoma cell lines GH3 and MMQ,which has better effect than radiotherapy or temozolomide treatment alone.