Prolactin size variants during pregnancy in women with ovulatory hyperprolactinemia: characterization by isoelectric focusing and lectin affinity chromatography.

Previous studies from this laboratory have demonstrated the occurrence of important changes in PRL size heterogeneity in women with ovulatory hyperprolactinemia during gestation. A similar observation has been made, in normal women, for glycosylated PRL, which shows a progressive decrease as pregnancy progresses. In this study we decided to investigate the contribution of G-PRL on PRL heterogeneity throughout gestation in women with ovulatory hyperprolactinemia. Serum samples obtained throughout gestation were analysed by SDS-PAGE followed by immunoblotting and by isoelectric focusing of gels as well. The results indicated that, independent of the stage of pregnancy, the relative amounts of G-PRL as compared with the nonglycosylated form of the hormone remained quite constant. In addition, isoelectric focusing analyses of serum samples consistently resulted in an identical isoelectric point of PRL throughout all of the gestational period. These results suggested that changes in the relative proportions of PRL size species during pregnancy were not correlated with the degree of PRL glycosylation. Moreover, these observations further extended and supported the concept that the occurrence of PRL size heterogeneity depends mainly on thiol-disulfide interchange mechanisms, among PRL molecules, at the pituitary level.

Absorption of dihydrotestosterone (DHT) after its intramuscular administration.

In order to produce a sustained release system for natural androgens, two groups of six hypogonadal males received intramuscular (IM) 40 mg crystalline dihydrotestosterone (DHT), either with particle size of less than 50 microns (DHT-M) or between 100 and 150 microns (DHT-C). Serum DHT was analyzed through 51 days of follow-up. In the DHT-M group, serum DHT was above pretreatment values for 17 days, whereas in the DHT-C group, this period was extended over 50 days. The area under the serum concentration-time curve and the half-life of absorption calculated for the DHT-C group were greater than those obtained for the DHT-M group (55.1 ng/day/ml and 21 days vs. 14.5 ng/day/ml and 6 days; P less than 0.01). The authors conclude that DHT injection appears to be an effective and convenient technique for restoring serum physiologic DHT levels. This approach is suitable for long-term substitution therapy.