The development of estrogen-induced pituitary prolactinoma in Fischer 344 (F344) 
rats is associated with enhanced neovascularization. Based on the significance 
of matrix metalloproteinases (MMPs) for tumor growth and angiogenesis, we have 
studied the effect of batimastat (BB-94), a synthetic MMPs inhibitor (MMPI) on 
the progression of prolactin-secreting pituitary adenoma in rats. Pituitary 
tumors were induced in male F344 rats by s.c. implantation of Silastic tubes 
containing diethylstilbestrol (DES). The effects of chronic treatment with BB-94 
(30 mg/kg b.w.) on pituitary weight, cell proliferation, apoptosis and vascular 
density were evaluated. We have stated that chronic treatment with batimastat 
caused a significant reduction in the pituitary weight. Batimastat has been 
found to decrease cell proliferation evaluated by a number of PCNA-positive 
stained cell nuclei. A marked increase in the apoptotic index within the 
pituitary was observed in the study group. Moreover, the density of microvessels 
identified by CD31 was reduced in the group treated with BB-94. The results of 
our study provide evidence for an inhibitory effect of batimastat, a synthetic 
MMPI, on the growth and angiogenesis in an experimental model of human 
prolactinoma. The ability of BB-94 to suppress established pituitary tumor 
growth suggests a possible application of MMPIs in the treatment of pituitary 
adenomas.