Production of tissue inhibitors of metalloproteinases (TIMPs) by pig ovarian cells in vivo and the effect of TIMP-1 on steroidogenesis in vitro

Abstract

Precisely which ovarian cells produce tissue inhibitors of metalloproteinases (TIMPs) is unclear. Although granulosa cells are reported to produce TIMPs, thecal TIMP production has not been investigated nor has the influence of TIMPs on theca cells. Furthermore, although periovulatory follicles have been examined, little is known about smaller ovarian follicles. Follicles >/= 2 mm in diameter were collected from Large White hybrid gilts on the day before predicted oestrus (n = 3) or after hCG treatment (n = 3) and divided into 1 mm size classes. Small (2 to < 5 mm) follicles were kept intact, whereas follicles >/= 5 mm were separated into follicular fluid, granulosa and theca cell compartments. After homogenization, TIMP-1, -2 and -3 were detected by reverse zymography. Theca cells (50 x 10(3) per well) were cultured with TIMP-1 (10, 100 or 200 ng ml(-1) with or without long-R3 insulin-like growth factor I (IGF-I)) in a serum-free system to investigate the effect on steroidogenesis and the number of cells. Both large and small pig follicles produced TIMPs and TIMP-1, -2 and -3 were detected in follicular fluid, granulosa and theca cell samples. There was a phase x tissue type interaction for the presence of both TIMP-1 and -2 (P < 0.03, P < 0.05, respectively), and TIMPs were detected in more granulosa and theca cell samples after hCG than during the follicular phase. The concentrations were influenced by the type of tissue (TIMP-1, P < 0.005; TIMP-2, P < 0.005, TIMP-3, P > 0.05), and the highest concentrations occurred in the theca tissue. There were tissue type x follicle size interactions for the presence of both TIMP-1 and -2 (P < 0.001). In vitro, TIMP-1 increased thecal steroidogenesis after 144 h (oestradiol, P < 0.05, progesterone, P < 0.001) but reduced the number of viable cells (P < 0.001). In conclusion, TIMP-1, -2 and -3 were present in large and small pig follicles and were produced by both granulosa and theca cells, although concentrations differed with the type of tissue. Production was regulated by factors including follicle size and phase of the oestrous cycle. In addition to controlling tissue remodelling, TIMP-1 may also regulate steroidogenesis.