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Inhibition of platelet-derived growth factor actions in the embryonic testis influences normal cord development and morphology.

Platelet-derived growth factors (PDGFs) are paracrine factors with roles in mesenchymal-epithelial interactions during normal and pathologic processes. Previously, PDGF and its receptor (PDGFR) have been shown to be present in perinatal, peripubertal, and adult rat testes. The role of PDGF in embryonic testicular cord formation is not known. The hypothesis tested is that PDGFs and PDGFRs are expressed during cord formation and that inhibition of their action influences normal cord formation during embryonic testis development. Embryonic Day (E) 13 gonadal organ cultures were used. Organs were cultured for 3 days and treated daily with vehicle or a PDGFR-specific tyrosine phosphorylation inhibitor (i.e., the tyrphostin AG1295 or AG1296). Vehicle-treated testes formed normal cords, whereas tyrphostin-treated testes formed "swollen cords," a phenomenon characterized by a significant decrease in the number of cords per testis area and increased cord diameter due to fusion of cords. Expression of PDGF and PDGFR in E13, E14, E16, Postnatal Day (P) 0, and P20 testes was examined. Messenger RNAs for PDGF-A and -B and PDGF alpha- and beta-receptors were expressed in isolated testes during all developmental periods examined. Immunoreactivity for PDGF was present throughout the testicular compartment at E14, restricted primarily to testicular cords at E16, and present in cells of the testicular cords with a stronger immunoreactivity in certain interstitial cell types of P0 testis. PDGFR beta-receptor immunoreactivity was primarily localized to the mesonephros of E14 organs and the testicular interstitium of E16 and P0 testes. Tyrphostins did not affect apoptotic cell number in the testis. PDGF had no effect on cell growth in P0 testis cultures. The results show that PDGFs and PDGFRs are expressed in embryonic testis during cord formation in a tissue-specific manner. Inhibition of PDGF actions does not inhibit cord formation but does alter normal cord development and morphology. The observations provide insight into the factors involved in male sex differentiation and embryonic testis development.

Animals↗

Testis developmental phenotypes in neurotropin receptor trkA and trkC null mutations: role in formation of seminiferous cords and germ cell survival.

The objective of the present study was to determine if the neurotropin receptors trkC and trkA are involved in embryonic testis development. These receptors bind neurotropin 3 and nerve growth factor, respectively. The hypothesis tested was that the absence of trkC or trkA receptors will have detrimental effects on testis development and morphology. The trkA and trkC homozygote knockout (KO) mice generally die either at or shortly after birth. Therefore, heterozygote mice were mated to obtain homozygote gene KO mice at Embryonic Day (E) 13, E14, E17, and E19 of gestation, with E0 being the plug date. Gonads from approximately 80 embryos were collected and fixed, and each embryo was genotyped. To determine gonadal characteristics for each genotype, the number of germ cells, number of seminiferous cords, seminiferous cord area, and interstitial area were calculated at each developmental age. Germ cell numbers varied in trkA gene KO mice from those of wild-type mice at each age evaluated. In trkC gene KO mice, differences were detected in germ cell numbers when compared to wild-type mice at E17 and E19. At E19, germ cell numbers were reduced in both trkA and trkC gene KO mice when compared to wild-type animals. Apoptosis was evaluated in testes of wild-type, trkC gene KO, and trkA gene KO mice to determine if the alteration in germ cell numbers at each developmental age was influenced by different patterns of germ cell survival or apoptosis. No differences were found in germ cell apoptosis during embryonic testis development. Interestingly, trkA gene KO mice that survived to Postnatal Day 19 had a 10-fold increase in germ cell apoptosis when compared to germ cells in wild-type mice. Evaluation of other morphological testis parameters demonstrated that trkC KO testes had reduced interstitial area at E13, reduced number of seminiferous cords at E14, and reduced seminiferous cord area at E19. The trkA gene KO testes had a reduction in the number of seminiferous cords at E14. Histology of both trkA and trkC gene KO testes demonstrated that these gonads appear to be developmentally delayed when compared to their wild-type testis counterparts at E13 during testis development. The current study demonstrates that both trkA and trkC neurotropin receptors influence germ cell numbers during testis development and events such as seminiferous cord formation.

Animals↗

Rete testis hyperplasia with hyaline globule formation. A lesion simulating yolk sac tumor.

The presence of eosinophilic, hyaline globules in association with epithelial hyperplasia was noted in the rete testis of three patients with germ cell tumors. In the more florid examples, this proliferation formed a solid and microcystic pattern that, in association with the hyaline globules, mimicked a yolk sac tumor component. However, the bland cytologic features of the cells and the conformation to the configuration of the rete testis were keys to its reactive nature. A subsequent review of 48 testicular specimens containing well-defined areas of the rete testis showed hyaline globule formation in the rete testis or tubuli recti in 16 of 27 germ cell tumors, one of five other testicular tumors (four stromal tumors and one plasmacytoma), and none of 16 nonneoplastic cases. Many of the cases that had hyaline globules also showed epithelial hyperplasia. Further analysis demonstrated an incidence of rete testis invasion by neoplasm in cases that had hyaline globules, with or without epithelial hyperplasia, that was significantly higher (p less than 0.01) than that seen in neoplastic cases lacking hyaline globules. We concluded that this pseudoneoplastic reaction developed secondary to invasion of the rete testis by tumor. Immunostains supported the nonneoplastic nature of the proliferative lesions and indicated that the globules represented various proteins that had been absorbed from the lumen of the rete testis by the epithelial-lining cells but not successfully secreted.

Albumins↗

Analysis of testis-specific transcripts in the chicken.

Sequences of candidate chicken testis-specific genes were analysed in order to develop a resource for functional genomic studies of the testis and male germ cells. Tentative consensus sequences (TC) containing expressed sequence tags expressed in testis libraries were selected from the TIGR Gallus gallus Gene Index, resulting in 292 TC. The transcriptional expression of these genes were evaluated in several chicken tissues, including testis and ovary. One hundred ten of the 292 TC were expressed in a testis-specific manner. Annotation of the TC using the Gene Ontology database terms showed that the proportion of testis-specific TC that were classified as having catalytic activity (within the molecular function branch) was higher than the proportion of total chicken TC classified in the same way. Our results may facilitate the investigation of testis-specific genes and their functional analysis in the chicken, as well as in other avian species.

Animals↗

Angiotensin converting enzyme in the testis and epididymis of mammals.

Angiotensin converting enzyme (ACE) activity has been reported in testis and epididymis of seven different animal species. Among all the species, the mouse testis and epididymis showed the highest converting enzyme activity followed by rat testis and epididymis. The lowest activity was detected in buffalo testis and rabbit epididymis. Most of the testicular enzyme was found concentrated in the 107,00 X g sediment while the epididymal enzyme was equally distributed between sediment and supernatant. ACE levels of different regions of the rat testis and epididymis was analyzed. The gradient of ACE was found increasing from caput to cauda. A major fraction of testicular and epididymal ACE activity was found in their respective fluid. ACE appeared only in mature rats, rabbits and mice testis and epididymis. Sexually stimulated rabbits showed significant ACE increase in the testis. In vitro characterization studies were conducted.

Animals↗

Effects of prolactin and bromocriptine on physiological status of testis of the musk shrew (Suncus murinus L.).

This investigation was undertaken to study the effects of prolactin and bromocriptine on the testis of the musk shrew. None of these treatments had any effect on the weight of testis or on the accessory sex organs. Treatment of prolactin or bromocriptine failed to induce any change in esterified and free cholesterol content of the testis. No significant alterations were also recorded in the levels of macromolecules and in the levels of enzymes of the testis and the prostate gland. On the other hand, bromocriptine treatment resulted in an increase in the activity of Mg2+-ATPase and phospholipid:DNA ratio of the testis with a concomitant decrease in its DNA content. The absence of any change in the content of fructose in the ampullary gland, in the activity of beta-glucuronidase of the kidney, in cholesterol content of the testis, in diameters of seminiferous tubule and Leydig cell nucleus, in activities of acid phosphatase and beta-glucuronidase of the testis and in the weight of accessory sex organs of prolactin and bromocriptine treated musk shrews suggests that prolactin does not play a significant role in regulating the testicular function of the musk shrew.

Acid Phosphatase↗

Expression of insulin receptor substrates 1-3, glucose transporters GLUT-1-4, signal regulatory protein 1alpha, phosphatidylinositol 3-kinase and protein kinase B at the protein level in the human testis.

Insulin receptor substrates (IRS) mediate the biological actions of insulin, growth factors and cytokines. This action is via receptor-mediated tyrosine phosphorylation of IRS proteins. The aim of present study was to demonstrate the distribution of IRS-1-3, the glucose transporter class I subfamily (GLUT-1-4), signal regulatory protein 1alpha (SIRP1alpha), protein kinase B (PKB) and phosphatidylinositol kinase (PI3-K) in the human testis to determine whether signal transduction mediated by these proteins is active in testicular cells. In the present study, the expression of IRS-1-3, GLUT-1-4, SIRP1alpha, P13-K and PKB was studied in the human testis at the protein level using immunohistochemistry and western blotting. A positive immunoreaction for IRS-1 was found in the human testis in peritubular myoid cells and macrophage-like interstitial cells. A positive immunoreaction for GLUT-3 was found in the human testis in Sertoli cells, peritubular myoid cells, early spermatocytes, macrophage-like interstitial cells and cells in the small vessels walls. Western blotting demonstrated IRS-1, IRS-2 and GLUT-3 proteins in the human testis. Expression of IRS-3, GLUT-1, GLUT-2, GLUT-4, SIRP1alpha, P13-K and PKB was not detected in the human testis. The results of the present study suggest that proteins like insulin and certain cytokines using IRS-1, IRS-2 and GLUT-3 in their signal transduction pathways can have effects on different cell types of the testis in humans.

Antigens, Differentiation↗

Fixation of a single testis: always, sometimes or never.

If it is necessary to perform an orchiectomy for an intravaginal testicular torsion it is the usual practice of surgeons to fix the contralateral testis. When faced with a child with only one testis for another reason it is our practice to fix this single testis to eliminate the small but disastrous risk of a torsion. We were interested to see whether this practice was usual and therefore sent out a questionnaire to the 67 consultant paediatric surgeons and urologists in Great Britain. Sixty-six surgeons replied. Seven surgeons (11%) always fix the single testis, 28 (42%) sometimes and 31 (47%) never fix a single testis. Five surgeons had looked after 6 patients who had a torsion of a second unfixed testis after losing the first for a reason other than intravaginal torsion. Four of these patients had initially had a neonatal supravaginal torsion, 1 had a torsion of an undescended testis and the sixth had severe testicular atrophy following an inguinal herniotomy. In our opinion the devastating loss of these solitary testes makes contralateral testicular fixation after an orchiectomy for whatever reason mandatory.

Attitude of Health Personnel↗

Testis-specific transcription initiation sites of rat farnesyl pyrophosphate synthetase mRNA.

A variety of rat tissues were screened at low stringency with a rat farnesyl pyrophosphate (FPP) synthetase cDNA. In testis, an FPP synthetase-related RNA was detected that was larger than the liver FPP synthetase mRNA and was present at very high levels comparable with liver FPP synthetase RNA levels obtained from rats fed diets supplemented with cholestyramine and mevinolin. Sequence analysis of testis cDNA clones, together with primer extension and S1 nuclease experiments, indicated that testis FPP synthetase transcripts contain an extended 5' untranslated region. The 5' extension contained one or two out-of-frame upstream ATGs, depending on the site of transcription initiation. Protein in vitro translation studies indicated that the extended 5' untranslated region may play a role in regulating the translation of the FPP synthetase polypeptide in rat testis. Southern blot analysis with a probe containing both testis and liver 5' untranslated sequences provided evidence that both liver and testis transcripts derive from the same gene. The data suggest that an upstream testis-specific promoter results in the abundant production of FPP synthetase transcripts that are translated at low efficiency; another promoter functions in liver and other somatic tissues and directs the regulated synthesis of shorter discrete transcripts.

Amino Acid Sequence↗

The testis-determining autosomal trait, Tda-1, of C57BL/6J is determined by more than a single autosomal gene when compared with DBA/2J mice.

The putative Tda-1 or testis-determining autosomal trait of the C57BL/6J mouse strain came to attention when the Y chromosome from the poschiavinus variety of Mus musculus domesticus was introduced into C57BL/6J by backcross matings. The F1 generation expressed normal testis development in XY individuals with the poschiavinus Y chromosome. In the backcross and subsequent crosses to C57BL/6J females, XY individuals expressed ovaries bilaterally or various combinations of an ovotestis with a contralateral ovary or testis or bilateral ovotestes and a few had testes bilaterally. Some of the previous breeding data appeared to support the hypothesis that C57BL/6J had an autosomal recessive factor that differed from the poschiavinus strain and, in the homozygous state, caused incomplete testis development with the poschiavinus Y chromosome. Subsequent attempts to map the Tda-1 factor, using a recombinant inbred strain approach, failed to localize Tda-1 and this suggests it might map to different chromosomes depending on which strain pairs are used. We constructed two strains of C57BL/6J and DBA/2J that are congenic for the poschiavinus Y chromsome. In the C57BL/6J. Y-POS congenic strain, liability to express incomplete testis development is normally distributed and thresholds in development specify the probability (or areas under the normal distribution) of different classes of ovary, ovotestis, and testis combinations. Testis development is normal in the DBA/2J. Y-POS congenic strain. With the two congenic strains and their normal parental strains we were able to conduct standard crosses to examine the reciprocal F1 and four types of backcross generations to the C57BL/6J strain in which all XY individuals have the poschiavinus Y chromosome.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Anatomical relationships between testis and epididymis during the fetal period in humans (10-36 weeks postconception).

OBJECTIVE: To determine the anatomy of the epididymis and its relationship with the testis during the fetal period in normal individuals. METHODS: We studied bilaterally 146 testes and epididymides taken from 73 normal fresh human fetuses ranging in age from 10 to 36 weeks postconception. The epididymal anatomy was classified in six types: type I: the epididymis is connected to the testis by its head and tail and the epididymal body is separated from the testis; type II: the epididymis is completely attached to the testis; type III: the epididymis is attached to the testis only by its head; type IV: the epididymis is attached to the testis only by its tail; type V: the epididymis is completely detached from the testis; type VI: segmental atresia of the epididymis. RESULTS: Normal epididymal anatomy, considered type I and type II, was found in 89.72% and in 7.53% of the cases, respectively. Type III and type IV epididymal anatomy was found in only 2.05% and 0.68% of the cases, respectively. We did not find types V and VI epididymal abnormalities. CONCLUSIONS: Our results show that irrespective of testicular position during the fetal period, the incidence of epididymal abnormalities in normal fetuses is very low (2.75%) when compared with previous reports in patients with cryptorchidism and/or with a patent processus vaginalis (36-79%).

Embryonic and Fetal Development↗

The androgen microenvironment of the human testis and hormonal control of spermatogenesis.

It is well established for both rat and man that the total testosterone concentration within the testis is far higher than that in serum. We know for the rat that intratesticular testosterone can be reduced by 50-60% without an adverse effect on spermatogenesis but that the required intratesticular testosterone concentration is still 10-fold greater than serum testosterone concentration. This kind of information, if available for the human, could prove invaluable for understanding and treating select men with infertility and in the development of male hormonal contraceptives. Unfortunately, we know little about the androgen content of intratesticular fluid within the human testis and nothing about the relationship between intratesticular androgens and human spermatogenesis. Using a newly developed minimally invasive technique for repetitive testicular sampling, our recent studies of the human have demonstrated that, as in the rat, there is a gradient between the concentration of testosterone in serum and within the testis; intratesticular testosterone levels were found to be 100-fold higher than serum testosterone levels in normal men. Using liquid chromatography tandem mass spectroscopy, we have shown that intratesticular 5alpha-dihydrotestosterone (DHT) levels are only 2% that of testosterone and, thus, despite greater affinity for the androgen receptor, intratesticular DHT is not significant in normal men. In order to assess how much of the testosterone within the human testis is bioactive, we adapted a highly sensitive recombinant protein mammalian cell-based bioassay to measure androgen bioactivity. The androgen bioactivity in the normal human testis is roughly two-thirds that of the total testosterone measurable by radioimmunoassay, despite the fact that the concentrations of the major androgen-binding proteins (sex hormone-binding globulin- and androgen-binding protein) are insufficient to account for this difference. This finding suggests that androgens may bind to other, as-yet-unknown molecules in the human testis. How, or if, this relates to spermatogenesis in the rat, or to man-to-man differences in the response to hormonal contraceptives, is not clear. We do not yet know how much testosterone is required within the human testis to either maintain or restore quantitatively normal spermatogenesis because, as yet, experimental studies comparable to those performed in the rat have not been feasible for the human.

Androgens↗

In the adult male rhesus monkey (Macaca mulatta), unilateral orchidectomy in the face of unchanging gonadotropin stimulation results in partial compensation of testosterone secretion by the remaining testis.

This study examined, in adult monkeys, the role that gonadotropin-independent mechanisms play in compensation of testosterone (T) secretion by the testis that remains after unilateral orchidectomy (UO). We employed a model (testicular clamp), in which endogenous gonadotropin secretion was abolished with a GnRH receptor antagonist, and the gonadotropin drive to the testes was concomitantly replaced with an invariant iv pulsatile infusion of recombinant human LH and FSH (1-min pulse every 2.5 h: LH, 0.08-0.12 IU/kg.pulse; FSH, 0.12-0.32 IU/kg.pulse) that provided the Leydig cells with a physiological stimulus. Within 5 h of UO (n = 5), circulating T concentrations had declined to 43% of pre-UO levels. By d 4, however, loss of the first testis was partially compensated, as reflected by the finding that circulating T had reached a plateau of 67% of the pre-UO level, where it remained for the duration of the study (39 d). That the recovery in circulating T was the result of increased T secretion by the remaining testis was suggested by the finding that the pulsatile pattern and decay of T during the intergonadotropin pulse interval before and after UO were indistinguishable. Interestingly, inhibin B production by the remaining testis also showed a delayed, albeit, minor, compensation (13% on d 10-11; P > 0.05) after loss of the first testis. These results suggest that compensation in T production by the remaining testis after UO in adult monkeys may be achieved in part by a gonadotropin-independent mechanism that probably involves direct neural inputs to the primate testis.

Adaptation, Physiological↗

Angiotensin-converting enzyme in the testis and epididymis: differential development and pituitary regulation of isozymes.

Angiotensin-converting enzyme (ACE, EC 3.14.5.1) is found in particulate fractions of the epididymis but not in soluble epididymal fractions or in the testis of 4-week-old rats. [3H]Captopril autoradiography of testis and epididymis from 4-week-old rats confirms the association of ACE with epididymal ducts but not the testis. ACE appears in the testis between 4 and 6 weeks of age. Soluble ACE is not detectable in the epididymis until 6-7 weeks of age. Within the epididymis, regions closest to the testis develop soluble ACE activity about 1 week before those nearest to the vas deferens. Hypophysectomy of 10 week-old-rats depletes greater than 95% of ACE activity from the testis and soluble fractions of the epididymis, with little change in ACE levels from particulate fractions of the epididymis. [3H]Captopril autoradiography after hypophysectomy reveals luminal and epithelial ACE in the epididymis. The presence of particulate ACE in the epididymis under conditions where there is no testicular ACE indicates that the two forms are synthesized separately. However, soluble ACE from the epididymis might be derived from the membrane-associated ACE of the testis. Such a relationship is supported by the lag of 1 week between the development of ACE in the initial segment of the epididymis and the tail of the epididymis, and by the occurrence of soluble epididymis ACE only in those animals with testicular ACE activity.

Animals↗

Characterization of angiotensin converting enzyme (ACE) in the testis and assessment of the in vivo effects of the ACE inhibitor perindopril.

Angiotensin converting enzyme (ACE) was characterized by radioligand studies utilizing the potent ACE inhibitor 351A, a derivative of lisinopril. Ligand binding characteristics were similar for ACE derived from testis, lung, and kidney, despite known differences in structure between ACe from these sources. This observation suggests that the ACE active enzymatic site is similar in different tissues. The effect of the orally active ACE inhibitor perindopril was studied ex vivo in tissues of the rat after oral gavage. Radioligand bound to tissue ACE was reduced after perindopril treatment, in tissue homogenates of lung and kidney, but not testis. Autoradiographs of radioligand binding to tissue sections obtained ex vivo after oral perindopril showed inhibition of ACE in the aorta, lung, and kidney, but did not reveal any inhibition of ACE in the testis. ACE in small vessels of the testis was inhibited as in the aorta, while at the same time testicular ACE was unaffected. ACE in rat testis appears to have a similar enzymatic binding site to ACE from the lung and kidney. Perindopril inhibited ACE in the lung and kidney but did not affect ACE in the testis, suggesting the drug is limited in testicular penetration by the blood-testis barrier. This may explain the lack of any reports of adverse effects of ACE inhibitors on testicular function.

Angiotensin-Converting Enzyme Inhibitors↗

Changes in retinoic acid receptor messenger ribonucleic acid levels in the vitamin A-deficient rat testis after administration of retinoids.

Recently, we have reported that retinoic acid (RA), similarly to retinol acetate, is able to reinitiate spermatogenesis in vitamin A-deficient rats. Here, we investigated the expression of RA receptors RAR alpha, RAR beta, RAR gamma, and retinoid X receptor RXR alpha by Northern blot analysis of poly(A)+ RNA of testes of vitamin A-deficient rats before and after reinitiation of spermatogenesis induced by injection of retinol acetate or RA and testes of 21-day-old and 10-week-old normal rats. In the testis of vitamin A-deficient rats 1.9-, 2.8-, and 3.8-kilobase (kb) transcripts of RAR alpha; 2.8- and 3.3-kb transcripts of RAR beta; 1.8-, 2.8-, and 3.4-kb transcripts of RAR gamma; and two transcripts of RXR alpha of 2.5 and 4.8 kb are expressed. When vitamin A-deficient rats receive RA or retinol acetate, a 3-fold increase in the amount of poly(A)+ RNA per testis can be observed after 8 h, while the amounts of glyceraldehyde-3-phosphate dehydrogenase and sulfated glycoprotein-1 mRNA hardly change. Also, the expression of several transcripts of each RAR type is significantly increased from 1.8- up to 3.6-fold. Moreover, additional transcripts of RAR beta and RXR alpha (1.8 and 1.0 kb, respectively) can be detected. In the testes of 21-day-old rats, three transcripts of each RAR type and two RXR alpha transcripts are expressed. In contrast, in the normal adult rat testis the expression of all RARs, if present, is lower than that in the 21-day-old rat testis or the adult vitamin A-deficient rat testis. The expression of all transcripts of each RAR in the testis of 21-day-old rats shows great similarity with the expression in the testis of the vitamin A-deficient rat after replacement of retinol acetate or RA. These changes in expression indicate that RARs and RXR alpha may play a role in the process of proliferation and differentiation of A spermatogonia, which is induced in vitamin A-deficient rats shortly after replacement of RA or retinol acetate.

Animals↗

Novel expression of luteinizing hormone subunit genes in the rat testis.

The two gonadotropins, LH and FSH, are thought to be synthesized and secreted solely by the anterior pituitary. We present here evidence for expression of the LH beta and common alpha-subunit (C alpha) genes in the rat testis. The LH beta and C alpha-subunit messenger RNAs (mRNAs) were detected by reverse transcriptase-polymerase chain reaction in the rat testis and pituitary with primer pairs producing 247- and 199-base pair complementary DNA (cDNA) fragments, corresponding to nucleotides 154-400 of LH beta and nucleotides 250-448 of C alpha cDNA, respectively. The specificity of the cDNA species generated was verified by Southern hybridization using nested [32P]cDNA or oligonucleotide probes, and identity with the published rat LH beta and C alpha-subunit gene structures was determined by sequencing. The mRNA bands with specific hybridization to complementary RNA (cRNA) probes corresponding to nucleotides 154-368 of the rat LH beta cDNA and nucleotides 250-448 of the rat C alpha cDNA were found in the rat pituitary and testis by Northern hybridization. The major C alpha mRNA had a size of 0.8 kilobases (kb) in the pituitary and testis. The major LH beta transcripts were 0.8 and 2.7 kb in the pituitary and testis, respectively. To further characterize the larger testicular LH beta-subunit transcript, rapid amplification of the 3'-end of cDNA (3'-RACE) was performed using an oligo(deoxythymidine-17) adapter and a specific 5'-primer. Southern hybridization of the 3'-RACE product of rat testicular RNA with a LH beta [32P]cDNA probe had the same size as the 3'-RACE product of pituitary RNA. The pituitary and testicular RNAs were then cut into two segments using oligonucleotide-directed ribonuclease H digestion and subjected to Northern hybridization using a cRNA probe specific to the 5'-end segment. The digested 5'-end segments of the pituitary and testicular mRNAs were 0.4 and 2.3 kb, respectively, indicating that the testicular LH beta mRNA has a 1.9-kb 5'-extension, compared to the cognate pituitary mRNA. This was further verified by Northern hybridization using a cRNA probe corresponding to nucleotides -790 to -10 upstream of the pituitary initiation site of LH beta gene transcription. Specific hybridization of a 2.7-kb mRNA transcript was found in the rat testis, but none in the pituitary. Hence, the 3'-end polyadenalytion site of the LH beta mRNA is the same in rat pituitary and testis, and the different transcript sizes are due to a difference at the 5'-end.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Expression of peroxisome proliferator-activated receptor alpha messenger ribonucleic acid and protein in human and rat testis.

Peroxisome proliferator-activated receptor a (PPARalpha), a member of the steroid hormone receptor superfamily, has been linked to lipid homeostasis and tumorigenesis in tissues with high expression of receptor protein. On the other hand, the role of PPARalpha in tissues with a lower expression is not well known. Here we demonstrate the localization of PPARalpha messenger RNA (mRNA) and protein in developing and adult rat testis. Additionally, we demonstrate the expression of PPARalpha protein in adult human testis. Our experiments with Northern analysis, in situ hybridization and immunocytochemistry reveal a complex distribution of PPARalpha in tubular and interstitial cells of both adult and developing rat testis. The overall expression is rather low but may be modified by exogenous or endogenous stimuli. An up-regulation of PPARalpha mRNA could be observed after stimulation with FSH. In the developing rat testis, a clear expression of PPARalpha mRNA was present from the first days after birth. Additionally, PPARalpha mRNA and protein increased toward adulthood. In adult human testis PPARalpha immunoreactivity (IR) was present in interstitial Leydig cells and tubular cells. In the seminiferous epithelium of adult human testis the expression of PPARalpha-IR could be seen in meiotic spermatocytes, spermatids and myoid peritubular cells. The findings of our study suggest that PPARalpha may be involved in the regulation of growth and differentiation of tubular and interstitial cells in rat and human testis.

Adult↗