The effects of progesterone (P) on the release of LRH and LH were examined in a sequential double chamber superfusion system by superfusing the medial basal hypothalamus (MBH) and/or pituitaries excised randomly from cycling female rats. Addition of 10 \g=m\lof 10\m=-\6 m oestradiol (E2) to the first chamber resulted in a gradual and significant (60\p=n-\160%) increase in LH release above the pre-injection level from the pituitary in series with MBH. Administration of 10\m=-\8m P after 10\m=-\6m E2 caused a prompt and marked increase (300%) of LH (P < 0.05), whereas 10\m=-\8m P alone had no effect. Administration of 10\m=-\6m E2, 10\m=-\8m P or E2 plus P did not significantly change LH secretion from the pituitary superfused alone. The concentration of LRH in the efflux was significantly increased (150\p=n-\200%) 150 min after 10\m=-\6m E2 administration. P administration after E2 injection produced a prompt and significant increase of LRH and the increase of LRH (300\p=n-\600%) was 2\p=n-\3-fold that produced by E2. P alone had no effect. These data clearly indicate that P enhances E2-induced LH release by increasing LRH secretion from the MBH.

Laminin secreted by implanted fibroblasts inhibited the detachment of implanted myoblasts from grafted myocardia, resulting in more permanent therapeutic effects upon myoblast sheet transplantation.

The regulation of mouse placental lactogen (mPL)-I and mPL-II secretion by activin and inhibin and the expression of activin and inhibin subunit mRNAs in the mouse decidua were examined. Activin-A at a concentration of 10 nM/l significantly inhibited mPL-II secretion by placental cells from days 9 and 12 of pregnancy. However, activin-A did not affect mPL-I secretion by cells from days 7 and 9 of pregnancy nor mPL-II secretion by cells from day 7 of pregnancy. By contrast, 10 nM/l inhibin activated mPL-II secretion by cells from day 12 of pregnancy. These effects of activin and inhibin on mPL-II secretion were dose-dependent. Follistatin, which binds to activin and blocks its bioactivity, completely eliminated the inhibitory effect of activin on mPL-II secretion. Incubation of placental cells from day 12 of pregnancy with activin-A resulted in a significant reduction of the mPL-II mRNA level assessed by Northern blot analysis. Northern blot analysis using poly(A)+RNA extracted from the decidua indicated that mouse decidua, as well as the placenta, express all activin and inhibin subunits and that their gene expressions increased during gestation. The expression of these mRNAs in the decidua was much higher than those in the placenta. These findings suggest that activin and inhibin regulate mPL-II secretion and suggest the presence of an autocrine or paracrine regulation of mPL-II secretion in mouse placenta by activin and inhibin after mid-pregnancy in vivo.

Myositis-specific antibodies (MSA) are detected in over 80% of patients with dermatomyositis (DM). 1 Anti-Mi-2 antibodies were found to be specific for DM. 2 We encountered a patient in whom anti-Mi-2 autoantibodies were detected 3 months before the clinical diagnosis of DM and in whom steroid treatment was promptly initiated when myositis developed.

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