Endocrine Abstracts

Background Ovarian follicles contain a specialised extracellular matrix (ECM), the basal lamina, separating granulosa cells (GC) and theca cells. An important gonadotrophin-regulated gene in ECM remodeling is LOX, which catalyses cross-linkage of collagen and elastin within ECM. Pro-LOX is proteolytically cleaved to active LOX by bone morphogenetic protein-1 (BMP-1), which also cleaves pro-collagens to mature forms. BMP-1 action is enhanced by procollagen C-proteinase enhancer (PCPE). Glucocorticoids have widespread roles in ECM remodelling and presence of 11βhydroxysteroid dehydrogenase isoforms that reversibly activate Corticosterone (CORT) suggests glucocorticoid modulation of intraovarian LOX. Here we ask if gonadotrophins and CORT impact on LOX and related regulatory components in GC. Methods: GC were isolated from immature female rats to provide immature GC (IGC) or after treatment with pregnant mare serum gonadotrophin (10 IU; i.p.) to produce mature GC (mGC). After 48 h serum-free culture with test substances total RNA was extracted for real-time RT-PCR and LOX enzyme activity determined in spent medium. Results: IGC. CORT (10⁻⁶) suppressed BMP-1 mRNA (P<0.01). Paradoxically, CORT increased LOX activity (P<0.05), but not LOX or PCPE mRNA. Follicle-stimulating hormone (0.01IU/ml) with or without CORT had no statistically significant effect on any mRNA expression, but tended to increase (non-significantly) LOX enzyme activity. MGC. CORT stimulated LOX mRNA (P<0.05), reflected in a trend towards increased LOX enzyme activity. Luteinising hormone (LH) (0.01IU/ml) decreased PCPE mRNA (P<0.02) expression and addition of CORT caused further reduction (P<0.001). LH alone had no effect on the expression of LOX or BMP-1 mRNA, or on LOX activity. LH plus CORT tended to increase LOX and BMP-1 mRNA expression, which was mirrored by LOX activity. Conclusion: Anti-inflammatory glucocorticoids are likely to modulate key components of the collagenous ECM synthetic pathway in GC, most notably causing up-regulation of LOX mRNA and/or enzyme activity. MRC supported.