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PubMed1982

Identity of ligandin in rat testis and liver.

1. One of the main problems in the field of multifunctional proteins such as ligandin is the possibility that multiple forms and isoproteins may exist. Because liver ligandin [GSH (reduced glutathione) S-transferase B] consists of equal amounts of Ya (22 000 Da) and Yc (25 000 Da) subunits, and testis ligandin, prepared by the standard technique of anion-exchange and molecular-exclusion chromatography, contains more Yc subunit than Ya, it has been claimed that testis and liver ligandin are different entities. 2. We purified testis ligandin by immunoaffinity chromatography and have obtained a product identical with liver ligandin (Yc = Ya). This suggests that the differences previously described may be due to contamination of testis ligandin by a closely related species. In fact sodium dodecyl sulphate/polyacrylamide-gel-electrophoretic analysis of testis GSH S-transferases separated by CM-cellulose chromatography showed that GSH S-transferase AA, present in large amounts, migrated in the same region as Yc subunit. 3. Testis ligandin prepared by the standard technique was similar to that reported [Bhargava, Ohmi, Listowsky & Arias (1980) J. Biol. Chem. 255, 724-727] and contained more Yc subunit than Ya. CM-cellulose chromatography of this 'pure' preparation revealed significant amounts of GSH S-transferase AA migrating as Yc subunit, in addition to ligandin consisting of equal amounts of Ya and Yc subunits. 4. Our studies show that testis ligandin is identical with liver ligandin. Previously described differences are due to a contaminant identified as GSH S-transferase AA.

Animals↗
PubMed1985

Heterogeneity of high-mobility-group protein 2. Enrichment of a rapidly migrating form in testis.

A determination of the absolute amounts of high-mobility-group proteins 1 and 2 (HMG1 and HMG2) in rat tissues demonstrated that amounts of HMG2 were low in non-proliferating tissues, somewhat higher in proliferating and lymphoid tissues, but were extremely elevated in the testis. This increase was due to a germ-cell-specific form of HMG2 with increased mobility relative to somatic HMG2 on acid/urea/polyacrylamide-gel electrophoresis. To determine if the findings in the rat were a general feature of spermatogenesis, testis (germinal), spleen (lymphoid), and liver (non-proliferating) tissues from various vertebrate species were examined for their relative amounts of HMG1 and HMG2, and for HMG2 heterogeneity. Bull, chimpanzee, cynomologus monkey, dog, gopher, guinea pig, hamster, mouse, opossum, rabbit, rat, rhesus monkey, squirrel and toad (Xenopus) tissues were analysed. Nearly all species showed relatively high contents of HMG2 in testis tissue, whereas HMG1 contents were similar in all species and tissues. Ten of thirteen species showed a rapidly migrating HMG2 subtype in testis tissue, separable by acid/urea/polyacrylamide-gel electrophoresis. Xenopus, which lacks HMG2 in somatic tissues, showed an HMG2-like protein in testis tissue. Although the rapidly migrating HMG2 subtype in species other than rat was not testis-specific, it was always enriched in the testis. This study indicates that increased amounts of HMG2 and the enrichment of a rapidly migrating HMG2 subtype are general features of spermatogenic cells.

Animals↗
PubMed1998

Isolation and identification of metallothionein isoforms (MT-1 and MT-2) in the rat testis.

It has been a long-lasting controversial issue as to whether or not the male genital organs, such as the testis and prostate, contain metallothioneins (MTs), a group of cysteine-rich heavy-metal-binding proteins that play a role in detoxifying heavy metals such as cadmium (Cd). Earlier studies reported that the rodent testis lacks MTs and concluded that this is why the testis is very susceptible to Cd, although other indirect experimental evidence suggests that MTs are present in this organ. A deficiency of MTs in the testis was originally suspected on the basis of amino acid composition analysis, since MT-like proteins isolated as Cd-binding proteins did not have a characteristic MT structure. In the present study, we demonstrate that the rat testis indeed expresses Cd-binding proteins with sequences identical to those previously described for MT-1 and MT-2, the major isoforms. To confirm that MT-1 and MT-2 are present in the rat testis, we purified and isolated Cd-binding proteins by homogenization using Cd-containing buffer, followed by sequential purification using Sephadex G-75 gel filtration chromatography and anion HPLC column chromatography, which yielded Cd-binding protein-1 (Cd-BP-1) and -2 (Cd-BP-2). After pyridylethylation, Cd-BP-1 and Cd-BP-2 were subjected to specific protein fragmentation by acids and endopeptidases, which revealed that these Cd-binding proteins have the same primary structures as MT-1 and MT-2 respectively. Thus we believe that the present results clearly resolve the long-standing debate about the presence of MTs in the testis, at least in the rodent.

Amino Acid Sequence↗
PubMed2002

Temporal changes in testis weight during the past 50 years in Japan.

The ever-increasing presence of environmental toxicants and their disruptive effect on the reproductive systems of wildlife raises the question of possible damage to the human reproductive system. Using medicolegal data from over 20,000 Japanese men subjected to necropsy from 1948 to 1998, we investigated temporal changes in testis weight to find possible evidence of male reproductive disorders. We also carried out a histological examination of 747 testes collected from 1978 to 1998. Our detailed analyses of the development of testis weight over the past 50 years have revealed four clear phenomena: (i) the age at which testis weight reaches its maximum has decreased; (ii) peak weight showed a general increase until it started to decline in boys born after 1960; (iii) the decline-rate at which testis weight decreases after its peak has greatly accelerated; and (iv) the onset of increasing testis weight of boys has occurred at a progressively younger age. Our quantitative analyses of testis weight indicate the possibility of a subtle reproductive disorder in Japanese men, especially in those born after 1960. Together with the accelerated development and decline in testis weight during the past 50 years, the decline in peak weight might be indicative of a subtle interference of environmental toxicants with male reproductive organogenesis.

Adolescent↗
PubMed2001

Immunolocalization of cytochrome P450 aromatase in rat testis during postnatal development.

Aromatization of androgens into estrogens in rat testis is catalyzed by the microsomal enzyme cytochrome P450 aromatase. In this work, aromatase cellular site was investigated in prepuberal, peripuberal and postpuberal testis, from 10-, 21- and 60-day-old rats respectively. Paraffin-embedded testis sections were processed for P450arom immunostaining using a rabbit polyclonal antiserum generated against purified human placental cytochrome P450 aromatase. Next, biotinylated anti-rabbit IgG was applied, followed by ABC/HRP/complex amplification with diaminobenzidine as chromogen. Prepuberal testis sections showed a strong immunoreactivity of aromatase in Sertoli cell cytoplasm while interstitial cells were immunonegative. In peripuberal testis sections, cytoplasmic immunoreaction was weak in Sertoli cells, but it was strong in spermatocytes and sporadic in Leydig cells. Postpuberal testis sections displayed a moderate aromatase immunoexpression in spermatocytes while a strong immunostaining was observed in round and elongated spermatids, as well as in Leydig cells. These results indicate a different age-dependence of aromatase localization in rat testicular cells during gonadal development. In particular, inside the seminiferous tubules, the aromatization site moves from Sertoli cells to late germ cells, suggesting a proliferative role of aromatase in prepuberal testis and its subsequent involvement in meiotic and post-meiotic germ cell maturation.

Aging↗
PubMed1972

Biological activity of human chorionic gonadotropin released from testis binding-sites.

The effect of testicular binding of human chorionic gonadotropin upon the biological activities of the hormone was examined by comparison of the binding and activation properties of (125)I-labeled gonadotropin before and after binding to rat testis in vitro. Biologically active (125)I-gonadotropin taken up by rat testis was dissocated from testis binding-sites at low pH and evaluated for its ability to bind again to testis, adenylate cyclase activation, and stimulation of steroidogenesis during subsequent incubation with fresh testis. Binding to tissue receptor-sites for 4 hr did not impair the biological properties of gonadotropin, though hormone remaining in the incubation medium had reduced affinity for tissue binding-sites during subsequent incubation with rat testes. In comparison to the original preparation, (125)I-labeled gonadotropin previously eluted from specific binding-sites of rat testis showed significantly increased binding activity and stimulation of cyclic AMP and testosterone release during further incubation with rat testes in vitro. The enhancement of biological activity of the eluted hormone is attributable to affinity purification of the original hormone preparation by selective uptake at receptorsites. These results demonstrate that gonadotropin is not inactivated or degraded during combination with gonadotropin receptors of rat testis.

Adenylyl Cyclases↗
PubMed1997

Production of SVP-1/-3/-4 in guinea pig testis. Characterization of novel transcripts containing long 5'-untranslated regions and multiple upstream AUG codons.

The GP1G gene of the guinea pig codes for three of the four abundant seminal vesicle secretory proteins produced in this species. This gene is expressed at highest efficiency in the seminal vesicle (SV) from a promoter that contains a canonical TATA box and CCAAT box. However, GP1G gene transcripts and proteins have also been identified in other tissues. To investigate the structure of GP1G transcripts produced in the testis, cDNA clones were isolated by screening a testis library. Three unique cDNAs (TSM1-3) were isolated. Each of these clones contained a 3'-untranslated region (UTR) and coding region identical to that of the seminal vesicle transcript. However, the 5'-UTRs of the testis transcripts were significantly longer than that found on the SV mRNA (416-646 nucleotides compared with only 23 nucleotides for the SV). Each of these alternatively spliced 5'-UTRs incorporated the SV promoter elements into transcribed sequence, and each contained multiple upstream AUG codons predicted to abolish translation of the major open reading frame. Nevertheless, each of the testis transcripts was capable of directing the synthesis of GP1G-related proteins in vitro. Analysis of the translation products suggests that the extended 5'-UTR of the testis transcripts regulate both the choice of translation start site and the efficiency of translation in this system. Western blot analysis of testis proteins revealed that the protein products of GP1G are also synthesized by the testis in vivo.

Animals↗
PubMed1997

Spermatid-specific overexpression of the TATA-binding protein gene involves recruitment of two potent testis-specific promoters.

The gene encoding the TATA-binding protein, TBP, is highly overexpressed during the haploid stages of spermatogenesis in rodents. RNase protection analyses for mRNAs containing the previously identified first, second, and eighth exons suggested that most TBP mRNAs in testis did not initiate at the first exon used in somatic cells (here designated exon 1C). Using a sensitive ligation-mediated cDNA amplification method, 5' end variants of TBP mRNA were identified, and the corresponding cDNAs were cloned from liver and testis. In liver, a single promoter/first exon is used to generate a steady-state level of roughly five molecules of TBP mRNA per diploid cell equivalent. In testis, we detect modest up-regulation of the somatic promoter and recruitment of at least five other promoters. Three of the alternative promoter/first exons, including 1C and two of the testis-specific promoter/first exons, 1D and 1E, contribute roughly equivalent amounts of mRNA which, in sum, account for greater than 90% of all TBP mRNA in testis. As a result, round spermatids contain an estimated 1000 TBP mRNA molecules per haploid cell. Testis TBP mRNA also exhibits several low abundance 5' end splicing variants; however, all detected TBP mRNA leader sequences splice onto the common exon 2 and are expected to initiate translation at the same site within exon 2. The precise locations of the three major initiation exons are mapped on the gene. The identification of the strong testis-specific promoter/first exons will be important for understanding spermatid-specific tbp gene regulation.

Animals↗
PubMedDate not supplied

Expression of claudin-1 in mouse testis.

In testis, tight junctions (TJs) between adjacent Sertoli cells are important for the formation of the blood-testis barrier (BTB) and crucial for spermatogenesis. The present study aimed to find postnatal changes in the expression of claudin-1, one of the TJ genes in mouse testis. By semiquantitative RT-PCR, it was found that claudin-1 expression in testis increased up to a peak at 10 days after birth and decreased thereafter. Western blot analysis showed abundant expression of 21-kDa protein in testis, lung, and brain from the adult mouse. The developmental change in the expression of claudin-1 protein in testis coincided with that from the RT-PCR. Testosterone treatment significantly increased claudin-1 expression in immature Sertoli cells, suggesting the possible regulation of claudin-1 expression by androgen in mouse Sertoli cells. Claudin-1 expression appears to be developmentally regulated in the mouse testis.

Animals↗
PubMed2000

Molecular characterization of a voltage-gated potassium channel expressed in rat testis.

Potassium (K(+)) channels are present in both mammalian testis and spermatozoa. Immunofluorescent detection of sperm-bound biotinylated charybdotoxin, an inhibitor of Ca(2+)-activated and of delayed rectifier K(+) channels, indicated that these ion channels are uniformly distributed over the surface of both heads and tails of unfixed rat epididymal spermatozoa. Reverse transcription-polymerase chain reaction (RT-PCR) analysis on rat testis RNA with PCR primers, based on known nucleotide sequences of different classes of K(+) channels, amplified sequences homologous to delayed rectifier K(+) channels. In-situ RT-PCR on rat testis sections showed that these K(+) channel transcripts are present in the cytoplasm of primary spermatocytes and post-meiotic elongating spermatids. Northern blot analysis of various rat tissues identified multiple K(+) channel transcripts, some of which were observed only in testis. An attempt to obtain a full length rat testis K(+) channel cDNA sequence gave an assembled sequence of 2693 base pairs with >90% homology to a delayed rectifier K(+) channel, Kv1.3. A method for rapid amplification of cDNA ends was employed to amplify the 5' sequences of the rat testis cDNA but a unique sequence could not be obtained. DNA sequencer traces suggest that multiple related K(+) channels which differed at their 5' ends were amplified in rat testis.

5' Untranslated Regions↗
PubMed2001

Insulin modifies the proliferation and function of chicken testis cells.

We investigated whether insulin plays a role in the proliferation and androgen production of chick testis cells. Testes from 18-d-old chick embryos or newly hatched chickens were dissociated and precultured in the presence of fetal bovine serum (FBS) for 24 h. After this period, testis cells from 18-d-old chick embryos were cultured in serum-free medium for 1 h with 0, 10, 50, or 100 microg/mL of insulin and were then exposed to human chorionic gonadotropin (hCG) for 3 h. In addition, some cells were incubated for 18 h with only insulin or insulin plus hCG. Androgens were measured by radioimmunoassay in the spent media. To study the influence of insulin on testis cell proliferation, cells were exposed to insulin for 18 h. A pulse of 3H-thymidine was added thereafter. We found that 18-d-old embryonic testis cells responded to hCG, increasing androgen production. Incubation with insulin for 1 h did not affect basal androgen production but modified the subsequent response to hCG. The addition of insulin plus hCG for 18 h resulted in important downregulation of the hCG effect. In addition, insulin significantly increased the proliferation of embryonic testis cells. The cells from testes of newly hatched chickens were precultured as described for embryonic cells and then exposed to insulin for 1 h in a serum-free medium. This treatment significantly increased the basal androgen production. Insulin also significantly enhanced the response to hCG of the testis cells from newly hatched chickens. These results strongly suggest that insulin has a role in the activity and in the proliferation of cultured testis cells throughout the perinatal period.

Androgens↗
PubMed2003

Testis-specific expression of rat mitochondrial glycerol-3-phosphate dehydrogenase in haploid male germ cells.

Mitochondrial glycerol-3-phosphate dehydrogenase (mGPDH) is regulated by multiple promoters in a tissue-specific manner. We characterized the testis-specific promoter C of the mGPDH gene and investigated the cellular localization of mGPDH within the testis. Electrophoretic mobility shift experiments identified a cAMP-response element (CRE) site at -57 that was active in the testis. An in vitro-translated CRE modulator (CREM) protein was able to bind this CRE site, and an anti-CREM antibody interfered with this complex. Ectopic expression of the testis-specific transcriptional activator CREMtau and protein kinase A in human hepatocarcinoma HepG2 cells activated a promoter C-driven luciferase construct in transient transfection experiments. Furthermore, mGPDH expression was undetectable in testis of CREM-deficient mice. The cellular localization of mGPDH expression and translation in adult rat testis was determined by in situ hybridization and immunohistochemistry techniques. The mGPDH transcripts were detected solely in postmeiotic germ cells. Expression of mGPDH was restricted from round spermatids to early elongating spermatids. The mGPDH protein was delayed in postmeiotic germ cells, restricted from late elongating spermatids to mature spermatids. Our results indicate that rat mGPDH is expressed by a testis-specific promoter from haploid male germ cells in a stage-specific manner.

Animals↗
PubMed2003

Expression of estrogen receptors alpha and beta in the fetal baboon testis and epididymis.

Although studies in transgenic mice suggest that estrogen is important for development of the testis, very little is known about the potential role of estrogen in maturation of the primate fetal testis. Therefore, as a first step to determine whether estrogen regulates maturation of the fetal primate testis, we used immunocytochemistry to determine estrogen receptor (ER) alpha and beta expression in the fetal baboon testis. Second, we established methods to quantify ERbeta mRNA levels by competitive reverse transcription-polymerase chain reaction in Sertoli cells isolated by laser capture microdissection (LCM) from the fetal baboon testis. ERbeta protein expression was abundant in the nuclei of Sertoli, peritubular, and interstitial cells in baboon fetuses at mid (Day 100) and late (Day 165) gestation (term is 184 days). ERbeta mRNA level was 0.03 attomole/femtomole 18S rRNA in Sertoli cell nuclei and associated cytoplasm isolated by LCM. ERalpha was expressed in low level in seminiferous tubules and in moderate level in peritubular cells on Day 165. Germ cells expressed very little ERalpha or ERbeta protein, whereas the baboon fetal epididymis exhibited extensive ERalpha and ERbeta immunostaining at mid- and late gestation. In contrast to the robust expression of ERbeta, androgen receptor protein was not demonstrable within the cells of the seminiferous cords but was abundantly expressed in epididymal epithelial cells of the fetal baboon. In summary, the results of this study show that the fetal baboon testis and epididymis expressed the ERalpha and ERbeta, and we suggest that our nonhuman primate baboon model can be used to study the potential role of estrogen on maturation of the fetal testis.

3-Hydroxysteroid Dehydrogenases↗
PubMed1993

Immunoreactive arginine vasopressin in the testis: immunocytochemical localization and testicular content in normal and in experimental cryptorchid mouse.

The presence of arginine vasopressin (AVP)-like peptide(s) and AVP receptors has been previously demonstrated in the testis of several species. In this study we examined the immunocytochemical localization of AVP and of its associated neurophysin (NPII) within the mouse testis, and the testicular immunoreactive (IR)-AVP content in normal pubertal and adult mice and in unilaterally cryptorchid animals. Immunostaining was conducted on fresh frozen adult testicular sections and on cultured testicular cells using the avidin-biotin immunoperoxidase technique. Immunoreactivities for AVP and NPII were localized at the periphery of the seminiferous tubules. Staining for AVP and NPII was reduced in testes showing impaired spermatogenesis. AVP and NPII immunoreactivities were present in cultured Sertoli cells, but staining was undetectable in cultured Leydig cells. Negative controls were obtained by applying antiserum that had been preabsorbed with excess peptides in place of primary antiserum. Mouse testes were found to contain IR-AVP, which co-eluted with synthetic AVP on HPLC and diluted in parallel in a specific RIA for AVP. Levels of IR-AVP expressed as pg/mg wet-weight testis were significantly higher (p < 0.05) in pubertal (36.6 +/- 1.5) than in adult animals (27.4 +/- 1.5). Experimental unilateral cryptorchidism in adult animals resulted 2 wk later in a marked reduction (p < 0.01) in IR-AVP levels in the abdominal testis (18.1 +/- 1.0 pg/mg testis) as compared to the contralateral scrotal testis (29.8 +/- 1.1 pg/mg testis).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Characteristics of A spermatogonia and preleptotene spermatocytes in the vitamin A-deficient rat testis.

The proliferative activity and other characteristics of germ cells in the vitamin A-deficient (VAD) rat testis were investigated. In the VAD testis, A spermatogonia and preleptotene spermatocytes were found. The A spermatogonia in the VAD testis showed a bromodeoxyuridine (BrdU) labeling index of 6.6 +/- 1.1% and a mitotic index of 2.8 +/- 0.5%. After continuous labeling with BrdU for up to four days, the ultimate labeling index of A spermatogonia was 11.6 +/- 2.5%, which is less than expected. It is concluded that in the VAD rat testis, many of the proliferating A spermatogonia degenerate. During the first 18 h after administration of vitamin A, no increase was observed in either the labeling index or the mitotic index of the A spermatogonia. However, after 24 h the first wave of A spermatogonia in S phase was found, and the first wave in mitosis was found after 48 h. Furthermore, in the VAD testis the DNA content of most of the A spermatogonia was similar to that of Sertoli cells, i.e., 2n. It is concluded that in the VAD situation, nearly all A spermatogonia are arrested before the S phase of the A1 spermatogonia. The hypothesis is put forward that in the VAD testis, the remaining A spermatogonia are the undifferentiated spermatogonia that are unable to differentiate into A1 spermatogonia. The preleptotene spermatocytes in the VAD testis showed a BrdU labeling index of 20.3 +/- 3.5%, while the DNA content of most of these cells was between 3n and 4n.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

A unique variant of a homeobox gene related to Drosophila cut is expressed in mouse testis.

Mammalian homologues of the Drosophila cut homeobox gene encode transcriptional repressors that are involved in tissue-specific and developmental gene regulation. We examined the expression of a murine cut homologue (Cux-1) in the adult mouse. In many somatic tissues, Cux-1 was expressed as a 13-kb transcript. However, the highest expression of Cux-1 was in the testis, where a unique 2.4-kb splice variant was identified. Less abundant transcripts of 5 kb, 6.5 kb, and 8.5 kb were also detected only in the testis. The nucleotide sequence of the 2.4-kb Cux-1 transcript was identical to the 13-kb transcript in the region of overlap, but the testis-specific transcript encoded a truncated protein that contained only one Cut repeat in addition to the Cut-related homeodomain. Studies of mice homozygous for the atrichosis (at/at) mutation suggested that the 2.4-kb transcript was expressed in germ cells in the testis. In situ hybridization verified that Cux-1 was transiently expressed in post-meiotic germ cells at the round spermatid stage. Immunoblot analysis of nuclear extracts showed that the testis-specific Cux-1 transcripts encoded a 55-kDa protein. These results demonstrate that multiple products of a cut-related homeobox gene are expressed in the testis. The highly restricted pattern of expression of Cux-1 in the testis suggests that it may be involved in regulation of postmeiotic gene expression.

Amino Acid Sequence↗
PubMed1998

Localization of specific relaxin-binding cells in the ovary and testis of pigs.

It is not known whether relaxin has physiological roles in the gonads in mammalian species. Limited evidence indicates that relaxin may act locally to regulate ovarian function in pigs. The possibility of a role for relaxin in testicular function in pigs has not been investigated. A major initial step toward the establishment of direct effects of relaxin on the ovary and/or testis is to demonstrate that relaxin binds with specificity to the gonads. Accordingly, the first objective of this study was to employ an immunohistochemical localization technique to determine whether relaxin-binding cells are present in the ovaries and/or testis of pigs. Once they were found to be present, the second objective was to determine whether relaxin-binding sites noticeably change either within the ovary at different stages of the estrous cycle and pregnancy, or within the testis at sexual maturity. Ovaries were collected from four stages of the estrous cycle (midfollicular, late follicular, early luteal, and midluteal) and three stages of the pregnancy (Day 40, Day 80, and Day 110). Two gilts were used for each of the stages of the estrous cycle and pregnancy. Testes were collected from a 5-mo-old immature boar and a 36-mo-old mature boar. Tissues were cut into cubes (3-4 cm3), frozen in liquid nitrogen, and cryosectioned (8 microm). Specific cell types that bind relaxin were identified by sequential application of a biotinylated relaxin probe, antibiotin immunoglobulin G conjugated to 1 nm colloidal gold, and silver for signal amplification. In the ovary, specific relaxin-binding sites were localized in both the theca and granulosa cells of developing follicles, luteal cells, and blood vessels. In the testis, specific relaxin-binding sites were localized in the Leydig cells. There were no apparent differences in relaxin-binding distribution within the ovary at different stages of the estrous cycle and pregnancy in gilts, or within the testis at sexual maturity in boars. We conclude that the specific relaxin-binding cells within the ovary and testis of the pig may contain relaxin receptors. Therefore, relaxin may have effects in the ovary and testis of pigs.

Animals↗
PubMed2001

Retinoid receptors involved in the effects of retinoic acid on rat testis development.

We have previously shown that retinoic acid (RA) is able to act on the development of Leydig, Sertoli, and germ cells in the testis in culture (Livera et al., Biol Reprod 2000; 62:1303-1314). To identify which receptors mediate these effects, we have now added selective agonists and antagonists of retinoic acid receptors (RARs) or retinoid X receptors (RXRs) in the same organotypic culture system. The RAR alpha agonist mimicked most of the effects of RA on the cultured fetal or neonatal testis, whereas the RAR beta, gamma, and pan RXR agonists did not. The RAR alpha agonist decreased the testosterone production, the number of gonocytes, and the cAMP response to FSH of fetal testis explanted at 14.5 days postconception (dpc). The RAR alpha agonist disorganized the cords of the 14.5-dpc cultured testis and increased the cord diameter in cultured 3-days-postpartum (dpp) testis in the same way as RA. All these RA effects could be reversed by an RAR alpha antagonist and were unchanged by an RAR beta/gamma antagonist. The RAR beta agonist, however, increased Sertoli cell proliferation in the 3-dpp testis in the same way as RA, and this effect was blocked by an RAR beta antagonist. The RAR gamma and the pan RXR agonists had no selective effect. These results suggest that all the effects of RA on development of the fetal and neonatal testis are mediated via RAR alpha, except for its effect on Sertoli cell proliferation, which involves RAR beta.

Animals↗