Prostaglandin metabolism by human testis

Prostaglandin E2 (PGE2) is a testicular peritubular cell-derived factor involved in human testicular homeostasis

In man, blockage of prostaglandin (PG)-production e.g. by non-steroidal anti-inflammatory drug (NSAIDs) may have negative testicular side effects, implying beneficial actions of PGs in the testis. We examined human testicular samples and isolated human testicular peritubular cells (HTPCs) to explore sites of PG-synthesis and targets. HTPCs express cyclooxygenase 1 (COX1) and secrete PGE2. Receptors (EP1, 2, 4) were specifically identified in peritubular cells. In HTPCs PGE2 significantly increased mRNA levels of the contractility protein calponin, but did not induce contractions. PGE2, as well as EP1 and EP4 receptor agonists, significantly increased glia cell line derived neurotrophic factor (GDNF) mRNA and/or protein levels. Importantly, the NSAID ibuprofen reduced PGE2 and this action also lowered SMA and calponin mRNA levels and levels of secreted GDNF protein. The results reveal an unknown PGE2 system in the human testis, in involving peritubular cells, which may be prone to interference by NSAIDs.

Constitutive expression of prostaglandin-endoperoxide synthase 2 by somatic and spermatogenic cells is responsible for prostaglandin E2 production in the adult rat testis

Prostaglandins (PGs), particularly PGE(2), have been implicated in the control of testicular steroidogenesis, spermatogenesis, and local immunity. However, virtually nothing is known about the expression or activity of the prostaglandin-endoperoxide synthases (PTGSs; also referred to as the cyclooxygenases), the specific rate-limiting enzymes responsible for PG production, in the adult testis. This activity was investigated in rats under normal conditions and during lipopolysaccharide-induced inflammation using quantitative real-time PCR, in situ hybridization, Western blotting, and PGE(2) measurements by ELISA. The mRNA for both the "constitutive" Ptgs1 and the "inducible" Ptgs2 forms was detected in multiple testicular cell types. Testicular Ptgs2 expression was substantially higher than that of Ptgs1, and testicular production of PGE(2) in vitro was found to be suppressed by a specific PTGS2 inhibitor (NS-398), but not by an inhibitor of PTGS1. Further investigation indicated that 1) PGE(2) production in the adult testis is attributable to constitutive expression of PTGS2 by somatic (Leydig cells and Sertoli cells) and spermatogenic cells; 2) testicular macrophages constitutively produce relatively low levels of PTGS2 and PGE(2) but are the only cell type to respond significantly to an inflammatory stimulus by increasing production of PGE(2); and 3) testicular PTGS2 expression and intratesticular PGE(2) levels are only marginally affected by acute inflammation. These data point toward a previously unanticipated maintenance role for the "inducible" PTGS2 enzyme in normal testicular function, as well as an anomalous response of testicular PTGS2 to inflammatory stimuli. Both observations are consistent with the reduced capacity of the testis to initiate and support inflammatory reactions.

Sertoli-cell prostaglandin synthesis. Effects of (follitropin) differentiation and dietary vitamin E

The synthesis of prostanoids by the Sertoli cell was assessed as part of a study on the role of vitamin E in maintaining spermatogenesis. Analyses of eicosanoid synthesis from endogenous substrate were carried out using freshly isolated Sertoli-cell-enriched preparations from both pre-pubertal and adult rats fed purified diets with and without vitamin E, as well as cells carried in primary culture. Freshly isolated cells from both the immature and fully differentiated adult testes produced PGI2 (prostaglandin I2) and PGE2, but PGF2 alpha was produced only by cells of the adult vitamin E-deficient rat. Cells from adult controls synthesized PGF2 alpha after primary culture. In contrast with other hormone responses of this cell, which are refractory in the adult, FSH (follitropin) potentiated prostaglandin production by freshly isolated cells of both immature and adult rats. The FSH response of Sertoli cells from immature animals did not change after primary culture. Adult cells were refractory to the hormone after culture, but the total amounts of prostaglandins produced by these cells were 10-fold higher than by either freshly isolated or cells of the immature in culture. Analogues of cyclic AMP did not potentiate prostaglandin synthesis. However, mepacrine, a phospholipase inhibitor, blocked the FSH effect. The finding that Sertoli cells synthesize prostaglandins and FSH enhances prostaglandin production implicates a potential role for eicosanoids in spermatogenesis and suggests that vitamin E may affect intratesticular regulators.

Role of seminal prostaglandins in male fertility. II. Effects of prostaglandin synthesis inhibition on spermatogenesis in man

The effect of prostaglandin biosynthesis inhibition has been studied in two groups of infertile oligozoospermic patients with high or normal-low seminal prostaglandin (PG) levels. PGE and 19-OH PGE were assayed by means of a gas chromatographic method and the most important seminal parameters (volume, concentration, motility and morphology of spermatozoa) were evaluated in basal conditions and at the end of indomethacin treatment, at a daily oral dose of 100 mg for thirty days. A drop in prostaglandin levels following indomethacin was observed in both groups of patients but only in the group with high concentrations of prostanoid derivates the prostaglandin inhibition was correlated with a significant improvement in sperm count and motility.

On the origin of prostaglandins in human seminal fluid

To evaluate the origin of seminal prostaglandins, genital tract fluids were analysed for prostaglandin content in two clinical situations. Six patients delivered semen samples before and after vasectomy. In these patients the prostaglandin concentration remained essentially unchanged although sperm density decreased to zero. In another patient secretory products from the testis and epididymis, and the ejaculate representing mainly the secretion of the seminal vesicles and the prostate gland, were collected separately. Secretions obtained from the testis and epididymis did not contain detectable amounts of prostaglandins, whilst in the ejaculate from the same patient the concentration was within normal limits. The results of the study show that the testis and epididymis do not contribute significantly to the prostaglandin content of human seminal fluid. The previous assumption that the seminal vesicles are the main source of seminal prostaglandins is thus supported.

A comparison of the lipoprotein profiles in male trout (Salmo gairdneri) before maturity and during spermiation

1. The distribution and concentration of blood lipoproteins were determined in three groups of male rainbow trout (Salmo gairdneri) each, fed the same diet and reared at a temperature of 17-18 degrees C. 2. The three groups (A, B and C) differed as to age (A and B were 1 yr old, while C was 3 yr old) and to degree of sexual maturity (A was sexually immature, while B and C were in spermiation). 3. Total serum lipoprotein levels reached high values in A, B and C (1900, 2400 and 1500 mg/100 ml. respectively) but their distribution depended largely on the degree of sexual maturity of the fish. 4. Very low density lipoproteins (VLDL) and low density lipoproteins (LDL) were predominant in juvenile trout, whereas high density lipoproteins (HDL) accounted for more than 50% of the total lipoproteins in spermiating trout. 5. In the latter class of lipoproteins, the phospholipid comprised 70% of the total lipid. 6. Essential 22:6 (n-3) was the main polyunsaturated fatty acid in all the lipid fractions of each of the lipoprotein classes; it was found in higher percentages in structural lipid, phospholipid and cholesterol ester, comprising between 35 and 40% of the total fatty acids. 7. These findings support the hypothesis that the production and utilization of lipoproteins in trout are related to the annual formation of gonadal tissue. The lipoproteins might be vehicles for cholesterol and essential fatty acid 22:6 (n-3), incorporated into gonadal tissue during gametogenesis.