Alterations in the insulin-like growth factor system during the menstrual cycle in normal XXXX .

@entity172 @entity1 @entity1420 @entity2301 @entity442 @entity10116 @entity7828 @entity5100 @entity53
OBJECTIVES: To evaluate the effects of endogenous @entity172 and @entity7828 on the IGF-system during the normal menstrual cycle in healthy premenopausal @entity1 not using contraceptive drugs. METHODS: Nine @entity1 had fasting blood samples obtained at 2-3 days intervals during a 5 week study period. Plasma levels of @entity442 , @entity5100 , IGFBP-I, @entity2301 , @entity53 and @entity1420 were measured by radioimmunoassay (RIA) in each sample. @entity2301 was also evaluated by Western ligand blot (WLB) and immunoblot. Any differences between the menstrual phase (defined as day 1-5), follicular and luteal phases (separation based on plasma @entity53 and @entity1420 values) were evaluated by the Friedman test. RESULTS: A small but significant difference in plasma levels of @entity442 (P < 0.01) and IGFBP-d (P < 0.05) measured by RIA between the three phases were seen with the highest levels found during the follicular phase. No change in plasma levels of @entity10116 and @entity5100 was found and immunoblots did not reveal any alteration in the ratio of fragmented to intact @entity2301 during the menstrual cycle. A positive correlation between plasma levels of @entity442 and @entity53 was seen in 8 out of 9 @entity1 (P = 0.012). CONCLUSIONS: The finding of a slight but significant higher level of plasma @entity442 in the follicular and luteal phases compared with the menstrual phase suggests plasma @entity53 may influence the level of this growth factor. This hypothesis is further supported by the finding of a correlation between plasma levels of @entity442 and @entity53 but not @entity1420 in individual @entity1 at different times during the menstrual cycle.
