Circadian rhythms in accessory sex gland function in the male rat

Alterations in various parameters of accessory sex gland function were monitored during two separate 24 h periods in adult male rats, and compared to fluctuations in the circulating levels of testosterone, prolactin, corticosterone and LH. Bimodal circadian rhythms in ventral prostate prolactin binding, cytosolic oestrogen binding and seminal vesicle weight could be discerned which appeared to be related to a similar rhythmicity in circulating testosterone levels, but with a phase shift of 3 h. Prostatic membrane bound adenylyl cyclase activities (basal and hormone stimulated) and prostatein concentrations followed different patterns possibly correlated to other endocrine changes.

Testicular and glandular contributions to the prolactin pool in human semen

The immunoreactive prolactin in human seminal plasma originates predominantly from two sources, the seminal vesicles and the testicular-epididymal axis. The following evidence supported a testicular-epididymal origin: Vasectomy reduced the content of prolactin in the ejaculates by 50%; the concentration of seminal prolactin was highly correlated (r = 0.54, p less than 0.003) with the concentration of sperm in a normal population of young and middle-aged men; and prolactin concentrations in the split ejaculates of normospermic men revealed a profile that corresponded to the sperm distribution pattern. Evidence supporting an additional contribution from the seminal vesicles included the following. The split ejaculate of an azoospermic individual coincided more with the distribution of the vesicular parameter fructose; vasectomy did not cause the disappearance of prolactin from the ejaculate; and split-ejaculate analyses weakened the possibility of a major prostatic source.

Estrogen receptors in stromal and epithelial fractions of the ventral prostate of rats

The cytosol from rat ventral prostates contains two estrogen-binding components that can be separated in a glycerol gradient: a high-affinity (KD = 4.2 X 10(-10) M), low-capacity (110 fmole/mg DNA) species that runs in the 8S region of the gradient, and a lower-affinity (KD = 2.4 X 10(-9) M), higher-capacity (410 fmole/mg DNA) 4S protein. Separation of prostate tissue into stromal- and epithelial-enriched fractions was associated with the disappearance of the latter component. When compared per milligram DNA stromal- and epithelial-enriched fractions contained similar amounts of the high-affinity 8S-binding protein. In vivo estrogen treatment caused a time-related disappearance of the protein from the intact cytosol presumably as a result of translocation. No major differences in the degree of binding to the high-affinity component were observed in rats of different ages. Estrogens seem to exert direct effects on both stromal and epithelial tissues of the prostate.

Two-dimensional electrophoresis of proteins in various fractions of the human split ejaculate

Two-dimensional electrophoresis of six fractions of split ejaculates from normal men (median age 23 years, n = 6) revealed large differences in the pattern of proteins found between the prostate-enriched fractions and secretions associated with the seminal vesicles. The glandular contributions were assessed using the concentrations of spermine, zinc and prostatic acid phosphatase (PAP) for prostatic secretion, and fructose and prostaglandin E for seminal vesicle secretion in the various fractions. Aside from PAP, four additional proteins were apparently associated with the prostatic fraction, one of which shared the biochemical characteristics of the specific ventral lobe protein of the rat prostate, prostatein (molecular mass 16 000, pI 4.8). The presumptive vesicular fractions contained a large number of low molecular mass proteins (10-20 000), with widely varying pI-values. The concentration of albumin and transferrin appeared to be highest in the sperm cell enriched fractions, indicating a major contribution to the ejaculate of testicular/epididymal origin.

Prolactin desensitizes the prostaglandin E1-dependent adenylyl cyclase in the rat prostate gland

Prior exposure of the rat ventral prostate to a high dose of ovine prolactin in vivo or in vitro caused the specific desensitization of the prostaglandin E1-dependent adenylyl cyclase. Maximal desensitization was achieved in vivo 6 h after exposure to 100 micrograms prolactin and complete resensitization occurred after 7 days. No heterologous desensitization of the response of the cyclase to other hormones tested was observed. Incubation of isolated secretory cells with prolactin and prostaglandin E1 desensitized the subsequent response to the same prostaglandin. Simultaneous exposure of the cells to indomethacin prevented the prolactin-induced effect. Prolactin could also induce similar changes in the prostaglandin E1-dependent cyclase of rat Leydig cell tumour cells in vivo, suggesting that this may represent a phenomenon shared by other prolactin target organs. This study supports the hypothesis that prostaglandins may constitute second messengers for prolactin effects on the prostate gland.

Seminal plasma characteristics during frequent ejaculation

Seven young men provided a semen sample every 8 h for 2 days. Citric acid, zinc, acid phosphatase , spermine, fructose and protein were measured in the samples. Despite a dramatic reduction in semen volume, the concentration of the majority of the parameters remained constant during the period of study. The protein profile of the ejaculates, as assessed by 2-dimensional electrophoresis, also did not change. Levels of citric acid, zinc and acid phosphatase were closely correlated, while spermine, which is also believed to be of prostatic origin, showed no correlation with these other parameters. The spermine concentration of the ejaculates increased significantly during the period of high ejaculation frequency and returned to normal levels after a 3 day abstinence period. In view of the fact that spermine accumulation in tissues appears to be associated with growth and protein synthesis this increase in seminal spermine may reflect a stimulation of prostatic cell activity.

Current approaches to research on prostatic function and pathology

This article describes some of the techniques and approaches currently in use in prostatic research which hopefully will provide new information and perspectives on the etiology of prostatic pathology. These techniques include a variety of methods for visualizing and quantitating protein hormone receptors, protein electrophoresis of prostatic tissue and fluids for protein markers, cell separation of the different cell populations of the prostate so that their interaction can be evaluated, and tests for the influence of low molecular weight peptides on prostatic function. Examples of the type of information which can be derived from each of the approaches are included and discussed.