Insulin deprivation leads to deficiency of Sp1 transcription factor in H-411E hepatoma cells and in streptozotocin-induced diabetic ketoacidosis in the rat.

Members of the family of Sp transcription factors include Sp1, Sp3, and Sp4 and are important regulators of eukaryotic gene expression. We previously reported that Sp1 mediated stimulation of rat calmodulin I gene expression in response to insulin. To test whether other members of the Sp family are direct targets of insulin action, we compared the levels of Sp1 and Sp3 proteins from nuclear extracts obtained from both insulin-treated and untreated rat hepatoma (H-411E) cells. We demonstrated by Western blot analysis that levels of Sp1 and Sp3 proteins were increased more than 2-fold in the insulin-treated group. Additionally, the up-regulation of both Sp1 and Sp3 transcription factors by insulin was antagonized by tumor necrosis factor-alpha, a known inhibitor of insulin action. Immunohistochemical analysis demonstrated that H-411E cells treated with insulin (10,000 microU/ml) had a marked increase in demonstrable Sp1 in the nucleus compared with cells incubated in insulin-free medium. We extended these in vitro observations to in vivo studies in the streptozotocin-diabetic rat model. We demonstrated in rat liver tissue by both Western blot and immunohistochemical staining with anti-Sp1 antibody that 1) livers of fully diabetic streptozotocin rats have low levels of Sp1 transcription factor; and 2) insulin treatment of the diabetic rat rapidly reversed this process by markedly stimulating accumulation of Sp1 in rat liver. Studies of the signal transduction mechanisms involved in insulin's effect on Sp1 demonstrate a facilitating role for phosphoinositol 3-kinase and an inhibitory role for cyclic nucleotides. In summary, insulin stimulates Sp1 protein, a transcription factor that is shown to regulate calmodulin gene expression and most likely other, as yet untested, genes.

Post-coital test in subfertile men.

Twenty-two patients with border-line spermiograms (moderate oligoasthenozoospermia or asthenozoospermia) were studied by the post-coital test (PCT) to determinate the behaviour in vivo of semen with modest dysspermia (spermatozoa counts between 10 and 20 million/ml, with 20-40% forward motility). All the female partners were normal morphologically and functionally. The PCT were always carried out when the cervical mucus was favorable (mean score 12.2-12.3) and the endocervical pH was 7.25-7.30. The positive results for the asthenozoospermic semen samples were 6.75% and for the oligozoospermic one 10%, when the classification were based on the W.H.O. criteria. When the semen samples were classified according to Kremer's criteria positive results were found in 37.5% and 40% of the cases respectively. The effects of both cervical mucus properties and pH on the results of the PCT were found to be important. The high percentage of the favorable results emphasizes the usefulness of completing studies of border-line spermiograms with an in vivo test, since it is difficult to define normality and predict the fertility potential from semen examination alone.