Sertolin is a novel gene marker of cell-cell interactions in the rat testis

A novel testicular protein designated sertolin was cloned. The full-length sertolin cDNA consists of 853 base pairs with an open reading frame of 381 base pairs coding for a 127-amino acid polypeptide that shares limited identities with antaxin/josephin and thrombospondin proteins. Sertolin (calculated molecular mass, 13,759 daltons) has two mRNA transcripts of 2.3 and 1 kilobase. A 22-amino acid peptide based on the deduced amino acid sequence of sertolin (NH(2)-KKEHFNLFKAASVSHLVQVVPQ) was synthesized and used for polyclonal antibody production. Immunoblot analysis detected a 17-kDa immunoreactive band in the Sertoli cell cytosol. Using Sertoli-germ cell cocultures, sertolin expression was found to be reduced by as much as 5-fold at the time when germ cells attach onto Sertoli cells but preceding the establishment of specialized inter-Sertoli-germ cell junctions. Neither FSH nor 17beta-hydroxy-5alpha-androstan-3-one was able to affect sertolin expression, whereas estradiol-17beta and progesterone induced a significant increase in Sertoli cell sertolin expression in vitro. In addition, interleukin-1alpha, a germ cell-derived cytokine, was also able to elicit a transient but significant increase in Sertoli cell sertolin expression. Sertolin expression was also shown to increase with testicular development and is likely to be associated with the onset of spermatogenesis. In addition, sertolin expression increased in the testis when generalized inflammation was induced in adult rats by injection of fermented yeast. These results show that sertolin will be useful in characterizing cell-cell interactions in the testis.

Differential changes in alpha2-macroglobulin and hemopexin in brain and liver in response to acute inflammation

Changes in serum and cerebrospinal fluid (CSF) proteins following generalized acute inflammation induced by fermented yeast in the rat was examined by concanavalin A-blotting, immunoblotting, and radioimmunoassay. Using alpha2-macroglobulin (alpha2-M) and hemopexin (HPX) as marker proteins, the concentration alpha2-M was found to increase in serum and CSF by 150- and 5-fold, respectively, whereas the concentration of HPX increased by about 4-fold in both fluids following yeast-induced inflammation. The lesser increase in alpha2-M in the CSF versus the systemic circulation is not likely to be the result of changes in the permeability of the blood--brain barrier, since no change in the total protein content of CSF was detected in inflamed rats when compared to control animals. These results, however, illustrate the regulation of the same protein, such as alpha2-M, in two separate organs within the same animal can be drastically different. These results also suggest a possible protective role of alpha2-M in the brain during acute inflammation. Moreover, these observations are consistent with the previous observation that there is a differential response in the level of alpha2-M between the testis and the systemic circulation during inflammation.

UV inducibility of rat proliferating cell nuclear antigen gene promoter

Proliferating cell nuclear antigen (PCNA), also known as a cofactor of DNA polymerase delta, is required for eukaryotic cell DNA synthesis and nucleotide excision repair. Expression of PCNA gene is growth-regulated and UV inducible. In our previous study, we have observed that the rat PCNA promoter has the serum responsiveness. In this study, we demonstrate its UV inducibility in CHO.K1 cells. The UV induction of the rat PCNA promoter activity was dose-dependent in the cells synchronized at different phases. In addition, the sequences of the promoter responsible for the UV inducibility were delimited to the region between nucleotides -70 and +125, which contains an AP-1 site and a downstream proximal ATF/CRE site. While mutation of the AP-1 site abrogated the UV inducibility, mutation of the ATF/CRE site enhanced the UV inducibility, suggesting that the two sites play different roles in the UV induction of the promoter. In addition, the role of p53 in the UV induction of rat PCNA promoter was investigated. We found that exogenous p53 was unable to mimic the UV irradiation to induce rat PCNA promoter and that the UV induction of the rat PCNA promoter was seen in p53 deficient cells. Therefore, it is unlikely that the UV induction of the rat PCNA promoter is p53 dependent.

Development of an enzyme-linked immunosorbent assay, using a monoclonal antibody against alpha2-macroglobulin, for the diagnosis of systemic lupus erythematosus

OBJECTIVES

To develop an enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody (mab) directed against abnormally glycosylated serum alpha2-macroglobulin (alpha2-M) from patients with systemic lupus erythematosus (SLE).

DESIGN AND METHODS

Serum alpha2-M purified by HPLC from patients with SLE was injected in a Balb/c, CB6 F1 female mouse and hybrid cell lines were screened using alpha2-M Glu-C fragments derived from SLE and normal donors (NHS). A mab was selected and used to develop an ELISA by which sera from NHS (n = 14), SLE (n = 34), rheumatoid arthritis (n = 15), Sjögren's syndrome (n = 11), mixed connective tissue diseases (n = 12), and liver diseases (n = 11) were analyzed.

RESULTS

The affinity of the mab for alpha2-M from SLE, but not from the other diseases, was higher compared to NHS, as demonstrated by immunoblotting and ELISA.

CONCLUSIONS

The ELISA was capable of recognizing changes of glycosylation of alpha2-M in SLE and may be useful for its differential diagnosis.

Identification and purification of proteins from germ cell-conditioned medium (GCCM)

Germ cells are known to regulate Sertoli cell and testicular function possibly through released factor(s) or via cell-cell contact. However, the identities of many of these putative biological factors are not known. The aim of this study is to present a strategy to identify and purify germ cell-derived proteins found in germ cell-conditioned medium (GCCM) at a quantity sufficient to permit protein microsequencing. The purification scheme of a novel germ cell-derived protein from GCCM designated GC-26 is presented along with several germ cell proteins using a combination of high pressure liquid chromatography (HPLC) columns. The purity of GC-26 and other germ cell proteins were confirmed by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) and silver staining. The identities of GC-26, a 26-kDa polypeptide, and other proteins were determined by direct protein microsequencing. These partial NH2-terminal amino acid sequences were compared with the existing databases at Protein Identification Resource (PIR), GenBank, and BLAST. These analyses revealed that these proteins are unique. This strategy should be useful for the micropurification of proteins from other biological samples and/or fluids.

Obstruction of the vas deferens alters protein secretion by the rat caput epididymidal epithelium in vivo

Obstruction of epididymal lumen fluid flow alters the intraluminal environment and potentially changes epididymal epithelial cell function when those functions are dependent on intraluminal regulatory molecules. This investigation tested the hypothesis that obstruction of the rat vas deferens alters caput epididymidal protein synthesis and secretion In vivo. Adult male rats were subjected to vasal obstruction or sham operation. Fourteen days later, caput epididymides were subjected to in vivo microperfusion with medium containing a [35S]-amino acid mixture. At the end of a 3-hour perifusion, micropuncture was used to obtain caput lumen fluid (LF). Tubule extract (TE) was obtained as supernatant after homogenization and centrifugation of caput tubules. Tubule extract contained all [35S]-proteins synthesized within the 3-hour experiment, and LF contained the secreted [35S]-proteins. Radioactivity of trichloroacetic acid (TCA)-precipitable proteins in LF and TE was determined, and two-dimensional electrophoresis and autoradiography of each sample were carried out. The resultant autoradiograms were evaluated densitometrically. A protein synthesis index calculated from the TCA-precipitable radioactivity data demonstrated that a significant decline in overall protein synthesis was induced by vasal obstruction. Densitometry of autoradiograms demonstrated that the total number of radiolabeled proteins detected in both the LF and TE of obstructed animals was significantly smaller than the same number in control animals (P < 0.05). Autoradiography revealed seven major, consistently appearing gene products in LF, and these were subjected to amino acid sequence analysis. Cysteine-rich secretory protein (CRISP)-1 proteins were significantly reduced in the LF of obstructed animals, which implies that these proteins are dependent on luminal regulatory molecules for their normal production.

Functional expression of sperm angiotensin II type I receptor in Xenopus oocyte: modulation of a sperm Ca2+-activated K+ channel

In addition to Ca2+ and K+ fluxes, angiotensin II (Ang II) has been shown to influence sperm motility. The present study investigated the involvement of angiotensin II type 1 receptor (AT1) in mediating the modulatory effect of Ang II on a sperm Ca2+-activated K+ channel expressed in Xenopus oocytes injected with RNAs of spermatogenic cells. Ang II at a concentration of 1 microM was found to potentiate the ionomycin-induced current, previously demonstrated to be mediated by a 'Maxi' Ca2+-activated K+ channel. However, at higher concentration, 20 microM, Ang II was found to suppress the ionomycin-induced current. Both potentiating and inhibitory effects of Ang II were blocked by losartan, a specific antagonist of AT1 receptors. Immunohistochemical studies further confirmed the presence of AT1 receptors in spermatogenic cells while expression of AT1 receptor mRNA was demonstrated by RT-PCR. These results suggest that Ang II may influence sperm motility as well as other sperm function by acting on AT1 receptors, and exerting potentiating and inhibitory effects on the Ca2+-activated K+ channels.

Human sperm endothelial nitric oxide synthase expression: correlation with sperm motility

OBJECTIVE

To characterize the pattern of endothelial nitric oxide synthase (eNOS) expression on human spermatozoa and to determine whether sperm eNOS expression correlates with sperm function.

DESIGN

Prospective, observational study.

SETTING

University infertility clinic.

PATIENT(S)

Twelve nonazoospermic infertile men.

INTERVENTION(S)

Semen samples (n=12) obtained from nonazoospermic infertile men were fractionated on discontinuous Percoll gradients. Endothelial nitric oxide synthase staining on spermatozoa was correlated with sperm motility in Percoll gradient-fractionated spermatozoa. Endothelial nitric oxide synthase protein was detected with the use of a previously characterized monoclonal antibody. Control slides were incubated with preabsorbed antibody or mouse immunoglobulin G.

MAIN OUTCOME MEASURE(S)

Localization of eNOS on human spermatozoa and correlation between the pattern of sperm eNOS expression and sperm motility.

RESULT(S)

Morphologically normal spermatozoa exhibited postacrosomal and equatorial eNOS immunostaining. However, abnormally shaped spermatozoa often exhibited aberrant staining (in the midpiece and/or head region). A significant negative correlation was observed between the percentage of sperm with aberrant eNOS immunostaining and the percentage of motile sperm (r=-.46).

CONCLUSION(S)

The specific localization of eNOS to human spermatozoa suggests that nitric oxide may be involved in normal sperm physiology. However, aberrant patterns of sperm eNOS expression are associated with decreased sperm motility, possibly through the generation of excessive cytotoxic oxidants.

Evidence for cross-talk between Sertoli and germ cells using selected cathepsins as markers

To examine whether proteases are possibly involved in cellular migration and/or spermiation when developing germ cells translocate across the seminiferous epithelium during spermatogenesis, in situ hybridization was used to localize messenger RNA (mRNA) transcripts of cathepsin L, D, and S in the epithelium at different stages of the spermatogenic cycle in the rat. Cathepsin L mRNA was found to localize almost exclusively near the basal lamina of the epithelium. At stages VI and VII of the cycle before spermiation, the signal of cathepsin L mRNA was so intense that it formed a complete dark precipitate near the basal lamina encircling the entire tubule. At stage VIII, the expression of cathepsin L was completely abolished, and no staining of cathepsin L mRNA was seen in the epithelium. The mRNA of cathepsin D and S was found near the basal lamina, a finding consistent with their localization in Sertoli cells and possibly primary spermatocytes in almost all stages, but peaked at stages VII-IX and VII-VIII of the cycle, respectively, at the time before and during spermiation. These results illustrate the possible involvement of these proteases in facilitating germ cell movement and spermiation. To examine whether germ cells express any of these cathepsin genes, spermatocytes with a purity of greater than 95% were isolated from 15-day-old rat testes by Percoll gradient centrifugation for reverse transcriptase-polymerase chain reaction. It was found that primary spermatocytes expressed multiple cathepsin genes, including cathepsin B, C, D, H, L, and S. Furthermore, the expression of cathepsin L by germ cells isolated from 15-day-old rats (largely spermatocytes and spermatogonia) can be stimulated by Sertoli cell-enriched culture medium in a dose-dependent manner, but not by germ cell-conditioned medium. These results reveal that germ cell function can be regulated by Sertoli cells. Moreover, these results suggest that germ cells may play an active role in the overall testicular protease expression. Also, we present evidence suggesting there is cross-talk between Sertoli and germ cells, since the expression of cathepsin L in each cell type is regulated by one another via either soluble factors or cell-cell contact.

Quantification of prostaglandin D synthetase in cerebrospinal fluid: a potential marker for brain tumor

Prostaglandin D synthetase (PGD-S; prostaglandin-H2 D-isomerase, EC 5,3,99,2), a 30 kDa glycoprotein also known as beta-trace protein that catalyzes the formation of prostaglandin D2 (PGD2) from PGH2, was purified to apparent homogeneity from human cerebrospinal fluid (CSF) using a two-step procedure involving HPLC on a Vydac C8 reversed-phase column and high performance electrophoresis chromatography (HPEC) using a 10% T SDS-polyacrylamide gel. The purity of PGD-S isolated from CSF was confirmed by silver stained SDS-polyacrylamide gel and direct protein microsequencing (NH2-APEAQVSVQPNFQ). A highly specific polyclonal antibody was prepared against this protein for immunoassay development. Using an ELISA, it was found that the concentration of PGD-S in CSF did not alter significantly in different pathological conditions of the central nervous system (CNS). These include dementia (n = 9), hydrocephalus (n = 4), neuropathy (n = 11), optic neuritis (n = 4), multiple sclerosis (n = 11), and demyelinating syndrome (n = 11), when compared to normal individuals (n = 12); however, the level of PGD-S in the CSF obtained from patients with brain tumor (n = 11), was reduced by as much as 2-fold when compared to control samples (n = 12) illustrating PGD-S is a potentially useful marker for brain tumor.

Rat prostaglandin D2 synthetase: its tissue distribution, changes during maturation, and regulation in the testis and epididymis

The changes in glutathione-independent prostaglandin D2 synthetase (PGD-S) during maturation in the rat were determined in selected organs by an RIA using PGD-S purified from rat cerebrospinal fluid and a monospecific anti-rat PGD-S polyclonal antibody. In a survey of its tissue distribution in various organ extracts and biological fluids, it was found that the concentration of PGD-S was highest in the epididymis-about 6- and 80-fold greater than that in the brain and testis, respectively. During maturation, PGD-S concentration increased steadily in the testis and epididymis; this is in contrast to the pattern of changes in the brain and liver, which showed a general trend of decline. Reverse transcription-polymerase chain reaction and Southern blotting were used to demonstrate the presence of PGD-S mRNA transcript in the testis and in Sertoli and germ cells. In the epididymis, the steady-state PGD-S mRNA level was highest in the caput, followed by the cauda and corpus. Orchiectomy induced a drastic reduction of PGD-S concentration in all three epididymal compartments. Administration of dihydrotestosterone (DHT) failed to restore the reduced epididymal PGD-S level except in the caput epididymis, where 4 days after DHT treatment the level of PGD-S was restored to about 50% of the pre-orchiectomized level; this suggests that the epididymal PGD-S level is not entirely regulated by androgen and that another yet to be identified testicular factor(s) is likely to be involved in its regulation. Germ cell-conditioned medium was also shown to stimulate PGD-S expression in the Sertoli cell. These results illustrate that PGD-S is an important molecule in testicular and epididymal function and that it is likely involved in spermatogenesis and sperm maturation.

Testin secreted by Sertoli cells is associated with the cell surface, and its expression correlates with the disruption of Sertoli-germ cell junctions but not the inter-Sertoli tight junction

Testin is a testosterone-responsive Sertoli cell secretory product. In the present study, we demonstrated that the amount of testin secreted by Sertoli cells in vitro was comparable with several other Sertoli cell secretory products. However, virtually no testin was found in the luminal fluid and cytosols of the testis and epididymis when the intercellular junctions were not previously disrupted, suggesting that secreted testin may be reabsorbed by testicular cells in vivo. Studies using Sertoli cells with and without a cell surface cross-linker and radioiodination in conjunction with immunoprecipitation illustrated the presence of two polypeptides of 28 and 45 kDa, which constitute a binding protein complex that anchors testin onto the cell surface. The 28- and 45-kDa peptide appear to be residing on and inside the cell surface, respectively. Immunogold EM studies illustrated testin was abundantly localized on the Sertoli cell side of the ectoplasmic specialization (a modified adherens junction) surrounding developing spermatids. In contrast, very few testin gold particles were found at the site of inter-Sertoli tight junctions. When the inter-Sertoli tight junctions were formed or disrupted, no significant change in testin expression was noted. This is in sharp contrast to the disruption of Sertoli-germ cell junctions, which is accompanied by a surge in testin expression. These results demonstrate the usefulness of testin in examining Sertoli-germ cell interactions.

Lysergic acid diethylamide (LSD) is a partial agonist of D2 dopaminergic receptors and it potentiates dopamine-mediated prolactin secretion in lactotrophs in vitro

The hallucinogenic effects of lysergic acid diethylamide (LSD) have mainly been attributed to the interaction of this drug with the serotoninergic system, but it seems more likely that they are the result of the complex interactions of the drug with both the serotoninergic and dopaminergic systems. The aim of the present study was to investigate the functional actions of LSD at dopaminergic receptors using prolactin secretion by primary cultures of rat pituitary cells as a model. LSD produced a dose-dependent inhibition of prolactin secretion in vitro with an IC50 at 1.7x10(-9) M. This action was antagonized by spiperone but not by SKF83566 or cyproheptadine, which indicates that LSD has a specific effect on D2 dopaminergic receptors. The maximum inhibition of prolactin secretion achieved by LSD was lower than that by dopamine (60% versus 80%). Moreover, the fact that LSD at 10(-8)-10(-6) M antagonized the inhibitory effect of dopamine (10(-7) M) and bromocriptine (10(-11) M) suggests that LSD acts as a partial agonist at D2 receptors on lactotrophs in vitro. Interestingly, LSD at 10(-13)-10(-10) M, the concentrations which are 10-1000-fold lower than those required to induce direct inhibition on pituitary prolactin secretion, potentiated the dopamine (10(-10)-2.5x10(-9) M)-mediated prolactin secretion by pituitary cells in vitro. These results suggest that LSD not only interacts with dopaminergic receptors but also has a unique capacity for modulating dopaminergic transmission. These findings may offer new insights into the hallucinogenic effect of LSD.

Rat testicular extracellular superoxide dismutase: its purification, cellular distribution, and regulation

Using multiple HPLC steps, we have identified and purified a 68-kDa polypeptide (as estimated by gel permeation HPLC) to apparent homogeneity, from primary Sertoli cell-enriched culture medium, that consisted of two monomers of 35 (alpha chain) and 33 kDa (ss chain) on SDS-polyacrylamide gel running under reducing conditions. Partial N-terminal amino acid sequence analysis of these two monomers revealed sequences of NH2-DXGESGVDLADRL (SODEX-alpha) and NH2-XXDTGESGVDLADXL (SODEX-ss), which are identical to rat extracellular superoxide dismutase (SODEX) with the exceptions that SODEX-alpha and SODEX-ss are missing, respectively, four (Trp-Thr-Met-Ser) and two (Trp-Thr) amino acids from their N-termini, compared to rat SODEX, suggesting that the cleavage sites of the SODEX gene in the testis are different from that of other organs. Studies by sequential use of reverse transcription and polymerase chain reaction (PCR) using two SODEX primers have demonstrated the expression of SODEX in the heart, brain, lung, kidney, epididymis, testis, Sertoli, and germ cells, with low expression in the liver and ovary and no expression in the uterus, spleen, or thymus. Nucleotide sequence analysis of this 447-base pair PCR product from Sertoli cells revealed that its sequence is equivalent to the sequence of previously published rat SODEX. During testicular maturation, the SODEX steady-state mRNA level increased significantly from 20 to 60 days of age and then declined at 90 days of age. Such an increase in the testicular SODEX expression during maturation is not likely a result of an up-regulation by germ cells, since germ cells isolated from either 20- or 60-day-old rats when cocultured with Sertoli cells failed to elicit an increase in SODEX expression in the cocultures. Using primary Sertoli cell cultures in vitro, it was found that Sertoli cell SODEX expression was stimulated by interleukin-1alpha but not by either interferon-gamma or basic fibroblast growth factor. These results illustrate that Sertoli cells as well as germ cells synthesize and/or secrete a testicular variant of SODEX that may provide essential clues to understanding superoxide radical-mediated damage in the gonad.

C-alkylated spiro[benzofuran-3(2H),4'-1'-methyl-piperidine-7-ols] as potent opioids: a conformation-activity study

Among a series of C-alkylated analogs of the weak mu opioid ligand spiro[benzofuran-3(2H),4'-1'-methylpiperidine-7-ol] (1), the 2-methyl, 2-ethyl, and cis 3'-methyl analogs, namely compounds (+/-)2, (+/-)-3, and (+/-)-4, showed much enhanced mu-affinities, with (+/-)-4 being almost as potent as (-)-morphine; while the trans 3'-methyl analog (+/-)-5 remained a weak mu-binder. Energy calculations and nmr data indicated that compounds 2-4 favor phenyl-axial conformations, while compounds 1 and 5 favor phenyl-equatorial conformations.

Regulation of alpha2-macroglobulin expression in rat Sertoli cells and hepatocytes by germ cells in vitro

Germ cells isolated from rat testes by trypsinization have been shown to yield unwanted artifacts in biological assays, since conditioned media derived from these germ cells (germ cell-conditioned media [GCCM]) can modulate Sertoli cell secretory function because of the presence of residual trypsin. To determine whether germ cells themselves can modulate Sertoli cell function, we isolated germ cells from tubules by a mechanical procedure and assessed the effect of these cells on Sertoli cell alpha2-macroglobulin (alpha2-MG) steady-state mRNA level. It was found that germ cells indeed could stimulate Sertoli cell alpha2-MG expression. This effect is probably mediated by a soluble factor(s) released from germ cells, since GCCM fractionated by HPLC contained multiple fractions that can stimulate Sertoli cell alpha2-MG expression dose-dependently. These results illustrate that germ cells play a role in regulating testicular alpha2-MG expression. Since Sertoli cells synthesize and secrete many of the serum proteins behind the blood-testis barrier that are also produced by hepatocytes, we sought to ascertain whether germ cells can affect hepatic alpha2-MG expression. When germ cells were cocultured with hepatocytes isolated from adult rats, the hepatocyte alpha2-MG steady-state mRNA level was shown to be stimulated by germ cells dose-dependently. Using different pools of fractions derived from GCCM after their fractionation by a preparative anion-exchange HPLC column, GCCM was found to contain a factor(s) that stimulated hepatocyte alpha2-MG expression dose-dependently. More importantly, the fractions that stimulated hepatocyte alpha2-MG expression had a retention time different from that of the factor(s) that affected Sertoli cell alpha2-MG expression. These data illustrate that germ cells secrete multiple biological factors capable of regulating alpha2-MG expression in the testis and the liver. In summary, this study reveals a possible physiological link between the testis and the liver in that germ cells may release a factor(s) capable of modulating alpha2-MG expression in both organs.

Paraspinal muscle abscess after Chinese Kong Fu practitioner manipulation--a case report

Paraspinal infection is a rare condition. Modes of infection include transcutaneous infection of the deep tissue by needles or catheters, surgery, blunt trauma, and hematogenous spread from distant sites. Chiropractic manipulation is a noninvasive procedure but is sometimes associated with vascular or neurologic insults resulting in hematoma or cerebrovascular accidents. We report a paraspinal muscle abscess in a healthy young man 7 days after Chinese Kong Fu practitioner manipulation for back pain without definite infection sources. The local paraspinal tenderness as demonstrated by the patient should be considered to be a sign of infection. Paraspinal infection often subjects to delayed diagnosis and this delay may be disastrous. In the management of low back pain or treating spinal disorders, physicians should be aware of the possibility of such a condition particularly in patients whose back pain has been managed with chiropractic manipulation to avoid misdiagnosis.

Rat testicular N-cadherin: its complementary deoxyribonucleic acid cloning and regulation

Using primer sets specific for mouse N-cadherin and rat testicular RNA for RT-PCR, a full-length complementary DNA (cDNA) coding for rat testicular N-cadherin was isolated. The deduced amino acid sequence of rat N-cadherin yielded a 883-amino acid polypeptide that displayed a 98.6% identity with the mouse homolog. N-Cadherin was found to be expressed by Sertoli and germ cells in the rat testis by RT-PCR. Using Sertoli-germ cell cocultures, it was found that the N-cadherin expression increased with time in culture. To assess whether this is due to a soluble factor(s) released from germ cells that affects Sertoli cell N-cadherin expression, germ cell-conditioned media (GCCM) were fractionated by preparative anion-exchange HPLC, and the resulting fractions were divided into 14 pools. Pool 4 was found to contain a factor(s) that induced a dose-dependent stimulation on Sertoli cell N-cadherin expression with a maximal stimulation at 2 microg protein/dish/4.5 x 10(6) Sertoli cells. At higher doses between 12 and 32 microg protein/dish, this pool relinquished its effect on Sertoli cell N-cadherin expression suggestive of a biphasic effect. This biphasic effect was confirmed using increasing doses of crude GCCM on Sertoli cell cultures. Since nonviable germ cells failed to stimulate Sertoli cell N-cadherin expression, it illustrates the observed stimulatory effect by GCCM is likely to be mediated via a soluble factor(s) releasing from viable germ cells. These results reveal the presence of a stimulatory factor(s) in GCCM that can modulate Sertoli cell N-cadherin expression in vitro. Since N-cadherin plays a crucial role in facilitating invasive capacity of metastatic tumor cells, the observation of germ cell-released factor(s) in affecting Sertoli cell N-cadherin expression may suggest its possible role in facilitating germ cell migration during spermatogenesis.

Synthesis of 2,3,4a,11b-tetrahydro-oxazino[2,3-c]benzopyran-9-carbonitriles as ATP-sensitive potassium channel openers

A series of optically active tetrahydro-oxazino[2,3-c]benzopyran derivatives have been synthesized and evaluated for potassium channel opening activity. (4aR,11bR)-1-Benzoyl- 5,5-dimethyl-2,3,4a,11b-tetrahydro-oxazino[2,3-c]benzopyran-9-carb onitrile ((-)-11e) was identified as a bladder-selective potassium channel opener (IC50, bladder = 8.15 microM, IC50, portal vein = 34.5 microM).

Blockade of the development of morphine tolerance by U-50,488, an AVP antagonist or MK-801 in the rat hippocampal slice

1. In this study, we investigated the effects of different drugs (a kappa-opioid receptor agonist U-50,488, a vasopressin receptor antagonist dPTyr(Me)AVP or an N-methyl-D-aspartate (NMDA) receptor antagonist MK-801) on the development of morphine tolerance in rat hippocampal slices. 2. Hippocampal slices (450 microm) of Sprague-Dawley rats (250-300 g) were used. Slices were continuously superfused with artificial CSF or drugs at 1 ml min(-1). Nichrome wire electrodes were placed in the Schaffer-collateral pathway and used to deliver biphasic 0.2 ms pulses of 5-30 V (0.033 Hz). A glass microelectrode was placed in the CA1 area to record population spikes. 3. When the slices were superfused with 10 microM morphine, the amplitude of population spikes increased 2-3 fold in 30-40 min. However, this effect of morphine decreased, i.e. tolerance developed after continuous superfusion of morphine for 2-6 h. 4. When either U-50,488 (200 nM) or dPTyr(Me) AVP (500 pM) or MK-801 (500 pM) was co-superfused with morphine (10 microM), it significantly blocked the development of morphine tolerance. Nor-BNI (a kappa-opioid receptor antagonist, 200 nM) significantly reversed the inhibitory effect of U-50,488 but not those of dPTyr(Me)AVP or MK-801 on the development of morphine tolerance. 5. These data indicate that kappa-opioid receptors, AVP receptors and NMDA receptors are all involved in the development of morphine tolerance. The suppression of kappa-opioid receptor activity after chronic morphine may occur before the activation of AVP receptors or NMDA receptors during the development of morphine tolerance.

Enhanced antinociception of clonidine in spontaneously hypertensive rats involves a presynaptic noradrenergic mechanism

We and others previously reported that the antinociceptive effect of clonidine, measured by the hot plate method, was greater in spontaneously hypertensive rats (SHRs) than in Wistar-Kyoto rats (WKYs). In the present study, we found that the difference in clonidine-induced analgesia between these two strains was abolished after lesioning the presynaptic noradrenergic neurons with N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4). Previous studies indicated that clonidine increases tissue norepinephrine (NE) content by inhibiting NE release. We found that the basal NE concentration in locus coeruleus (LC), as measured by HPLC-ECD, was not different between WKYs and SHRs. Systemic application of clonidine (0.69 mg/kg, I.P.) significantly increased the tissue content of NE in the SHRs, but not in WKYs. Using pressure microinjection and high-speed chronoamperometric recording techniques, we found that local application of KCl to the LC brain slices increased extracellular NE levels in both strains. Perfusion of slices with clonidine (1 microM) selectively attenuated KCl-evoked NE release in SHRs, suggesting that clonidine-induced presynapitc inhibition is more effective in SHRs than in WKYs. In conclusion, our data indicate that SHRs possess augmented sensitivity to clonidine to inhibit presynaptic NE release, which may be responsible for the enhanced antinociceptive effect of clonidine in this strain.

An increase in the carbohydrate moiety of alpha 2-macroglobulin is associated with systemic lupus erythematosus (SLE)

Using lectin blots in conjunction with peptide mapping, alpha 2-macroglobulin micropurified from systemic lupus erythematosus (SLE) patients was shown to become abnormally glycosylated suggesting the occurrence of complex glycosylation in this pathological condition. To confirm there is indeed a quantitative increase in specific monosaccharides in this protein; alpha 2-macroglobulin was micropurified from a battery of 37 serum samples which included 6 normal donors (3 male and 3 female), 23 SLE patients, 6 rheumatoid arthritis patients, 1 mixed connective tissue disease patient, and 1 Sjogren's syndrome patient; for carbohydrate analysis. It was noted that the concentration of total monosaccharides in alpha 2-macroglobulin micropurified from serum samples of SLE patients is significantly higher than normal donors with a mean +/- SD of 188 +/- 410 micrograms/mg protein (SLE, n = 23) versus 14.5 +/- 4 micrograms/mg protein (normal, n = 6) even though there was a high variation in the level of monosaccharides among the SLE patients. An increase in oligosaccharides in alpha 2-macroglobulin from SLE patients compared to normal subjects was confirmed by concanavalin A (Con A) blots using peptide fragments derived from the micropurified protein. Since the interaction of peptide fragments derived from alpha 2-macroglobulin with Con A requires the presence of mannose and/or glucose residues, we have also examined if there are any correlations between the levels of mannose and glucose in alpha 2-macroglobulin and SLE. The concentration of mannose (38 +/- 60 micrograms/mg protein) in alpha 2-macroglobulin derived from SLE patients was significantly higher than normal donors (mannose, 4.8 +/- 1 micrograms/mg protein) however, the concentration of glucose in alpha 2-macroglobulin derived from SLE patients when compared to normal donors was not statistically significant, 18 +/- 20 micrograms/mg protein in SLE versus 2 +/- 0.5 micrograms/mg protein in normal donors due to high variation between samples. Also, the concentration of galactose in alpha 2-macroglobulin from SLE patients was significantly higher than normal donors (45.7 +/- 173 micrograms/mg protein versus 0.13 +/- 0.03 microgram/mg protein). These results illustrate quantification of carbohydrate in selected glycoproteins such as alpha 2-macroglobulin may be a novel and alternative clinical marker for SLE.

Haptoglobin is a Sertoli cell product in the rat seminiferous epithelium: its purification and regulation

Using multiple HPLC steps, a protein of 67 kDa (estimated by gel permeation HPLC) was purified from Sertoli cell-enriched culture medium that consisted of two dissimilar subunits of 9 (alpha chain) and 24 (beta chain) kDa on SDS-polyacrylamide under reducing conditions. Direct protein sequence analysis of the 9-kDa subunit revealed a sequence of NH2-VELGNDATDIEXD, which is identical to the alpha subunit of the rat haptoglobin (Hp). Hp is a 67-kDa tetrameric serum acute-phase protein consisting of two alpha and two beta subunits (alpha2beta2) of 8.5 kDa and 24.5 kDa, respectively. Using a 351-bp cDNA coding for Hp for northerns and two Hp primers for RT-PCR, we have demonstrated the expression of Hp in Sertoli and Leydig cells, germ cells, and the testis, but not in the epididymis. In contrast to the hepatic haptoglobin, an acute-phase protein whose steady-state mRNA level increased by as much as fivefold during induced inflammation, the testicular homolog reduced by fourfold within 24 hours following induced inflammation, suggesting that this gene is regulated differently in the testis and in the liver. Moreover, the testicular steady-state Hp mRNA level increased steadily after birth during maturation, suggesting its involvement in spermatogenesis. Using primary Sertoli cell cultures in vitro, it was found that the Sertoli cell Hp expression was not regulated by either FSH, testosterone, estradiol, dexamethasone, interleukin-1beta (IL-1beta), IL-6, interferon-gamma (INF-gamma), transforming growth factor-beta (TGF-beta), lymphocyte inhibitory factor (LIF), or germ-cell-conditioned medium (GCCM). Since transferrin secreted by Sertoli cells is an important molecule in maintaining the crucial iron level necessary for spermatogenesis, the identification of haptoglobin as a Sertoli and germ cell product adds a new member to the growing family of metal transporters in the testis that are likely to play an important role in iron metabolism in the testis.

Interactions of proteases and protease inhibitors in Sertoli-germ cell cocultures preceding the formation of specialized Sertoli-germ cell junctions in vitro

The biochemical mechanism(s) by which germ cells can form specialized junctions with Sertoli cells in the seminiferous epithelium at various stages of the spermatogenic cycle is unknown. This study sought to examine the biochemical changes that are involved when germ cells are cocultured with Sertoli cells in vitro preceding the establishment of specialized Sertoli-germ cell junctions. While isolated germ cells were allowed to attach to Sertoli cells, media from both the apical and basal compartments of bicameral units were collected to assess serine and cysteine protease activity. The expression of selected serine and cysteine proteases and their corresponding inhibitors in these Sertoli-germ cell cocultures was also examined by RT-PCR. Using an [125I]-collagen film assay, a transient but significant increase in serine protease activity was noted in both the apical and basal compartments when germ cells began to settle onto the Sertoli cell monolayer preceding the formation of intercellular junctions. A specific tryptase (RNK-Tryp 2, a serine protease formerly cloned from a rat granular lymphocyte leukemia cell line, RNK-16, cDNA expression library) was shown to be expressed exclusively by Sertoli cells and not germ cells. Furthermore, Sertoli cell tryptase expression as well as urokinase plasminogen activator (u-PA, also a serine protease) increased significantly when germ cells were adhering to Sertoli cells. The decline in total serine protease activity when Sertoli-germ cell junctions were being formed was accompanied by a concomitant increase in alpha2-macroglobulin (alpha2-MG, a nonspecific protease inhibitor) expression. No significant changes in cysteine protease activity in either the apical or basal compartment were noted. However, there was a transient but significant increase in cathepsin L expression when germ cells were adhering to Sertoli cells preceding cell junction formation. The subsequent reduction in cathepsin L expression after this transient increase was accompanied by a concomitant increase in cystatin C expression. These results suggest that proteases and their corresponding inhibitors are working synergistically and are likely to be involved in the adherence of germ cells to Sertoli cells and the subsequent formation of intercellular junctions.