Biomedical subjects

F Gaytan

Publications and source records attributed to F Gaytan.

At least 19 recordsLinked to original sources

PubMed2006

Expression of KiSS-1 in rat ovary: putative local regulator of ovulation?

Kisspeptins, the products of KiSS-1 gene, and their receptor, GPR54, have recently emerged as essential gatekeepers of reproduction, mainly through regulation of GnRH secretion at the hypothalamus. However, the profound hypogonadotropism linked to GPR54 inactivation is likely to mask additional functions of this system at other levels of the gonadal axis, in which expression of KiSS-1 and GPR54 has been preliminarily reported. We describe herein the expression of KiSS-1 gene and kisspeptin immunoreactivity (IR) in rat ovary and evaluate its developmental and hormonal regulation. KiSS-1 and GPR54 mRNAs were persistently detected in adult ovary along estrous cycle. Yet, contrary to GPR54, ovarian KiSS-1 levels fluctuated in a cyclic-dependent manner, with a robust increase in the afternoon of proestrus, i.e. preceding ovulation. In addition, kisspeptin-IR was observed in rat ovary, with strong signals in theca layers of growing follicles, corpora lutea, and interstitial gland, compartments in which modest GPR54-IR was also detected. Interestingly, the rise in ovarian KiSS-1 mRNA at proestrus was prevented by blockade of preovulatory gonadotropin surge and restored by replacement with human chorionic gonadotropin as superagonist of LH. In addition, immature ovaries showed low to negligible levels of KiSS-1 mRNA, which were significantly enhanced by gonadotropin priming. In summary, we present novel evidence for the developmental and hormonally regulated expression of the KiSS-1 gene, and the presence of kisspeptin-IR, in rat ovary. The ability of the LH surge to timely induce ovarian expression of KiSS-1 at the preovulatory period strongly suggests a previously unsuspected role of locally produced kisspeptin in the control of ovulation.

Animals↗

PubMed2005

Pattern of orexin expression and direct biological actions of orexin-a in rat testis.

Orexins, hypothalamic neuropeptides initially involved in the control of food intake and sleep-wake cycle, have recently emerged as pleiotropic regulators of different biological systems, including the reproductive axis. Besides central actions, peripheral expression and functions of orexins have been reported, and prepro-orexin and orexin type-1 receptor mRNAs have been detected in the testis. However, the pattern of expression and biological actions of orexin in the male gonad remain mostly unexplored. In this study, we report analyses on testicular prepro-orexin mRNA expression and orexin-A immunoreactivity in different experimental settings, and on direct effects of orexin-A on seminiferous tubule functions. Expression of prepro-orexin mRNA was demonstrated in the rat testis at different stages of postnatal development, with negligible levels at early juvenile period and maximum values in adulthood. Likewise, orexin-A immunoreactivity was demonstrated along postnatal maturation, with strong peptide signal in Leydig cells and spermatocytes at specific stages of meiosis. Testicular expression of prepro-orexin mRNA appeared hormonally regulated; its levels decreased after hypophysectomy and increased after gonadotropin replacement and ghrelin stimulation. Finally, orexin-A suppressed the expression of key Sertoli cell genes, such as Müllerian-inhibiting substance and stem cell factor, and inhibited DNA synthesis in specific stages of the seminiferous epithelium. In conclusion, we provide evidence for the regulated expression of orexin in the rat testis and its potential involvement in the control of seminiferous tubule functions. Together with our recent results on the expression of orexin type-1 receptor in the rat testis, our data further document a novel testicular site of action of orexins in the control of male reproductive axis.

Aging↗

PubMed2004

Expression of growth hormone secretagogue receptor type 1a, the functional ghrelin receptor, in human ovarian surface epithelium, mullerian duct derivatives, and ovarian tumors.

Ghrelin, the endogenous ligand of the GH secretagogue receptor (GHS-R), is a newly identified, ubiquitously expressed molecule that has been involved in a wide array of endocrine and nonendocrine functions, including cell proliferation. In this context, our group recently reported the expression of ghrelin and its functional receptor, the GHS-R type 1a, in the human ovary and testis as well as several testicular tumors. Ovarian malignancies, however, remain unexplored. Notably, a vast majority of ovarian tumors derive from the surface epithelium, which originates from the celomic epithelium. Considering the proven expression of ghrelin in the human ovary, and its reported effects in the proliferative activity of different cancer cell lines, we aimed at evaluating whether the ovarian surface epithelium as well as related reproductive structures and tumors are potential targets of ghrelin. To this end, expression of GHS-R1a was analyzed by immunohistochemistry in a panel of normal, metaplastic, and neoplastic tissues. Uniform GHS-R1a immunostaining was detected throughout the ovarian surface epithelium. Likewise, ciliated cells within the fallopian tube epithelium showed strong GHS-R1a expression. In contrast, other celomic derivatives, such as endometrium and endocervix, were negative for GHS-R1a immunoreactivity. In keeping with data from normal tissues, inclusion cysts from the surface epithelium expressed GHS-R1a. Similarly, benign serous tumors resembling fallopian tube epithelium were also positive, whereas serous cystadenocarcinomas showed GHS-R1a expression only in highly differentiated specimens. In contrast, other neoplasms, such as mucinous cystadenomas and cystadenocarcinomas, endometrioid tumors, clear cell carcinomas, and Brenner tumors, did not express GHS-R1a. In conclusion, our results demonstrate that the ovarian surface epithelium and related tumors are potential targets for systemic or locally produced ghrelin because they express the functional type 1a GHS-R. Considering the relevant role of the ovarian surface epithelium in key physiological events (such as ovulation) and neoplastic transformation of the ovary, the potential actions of ghrelin in those phenomena merit further investigation.

Cervix Uteri↗

PubMed2004

Advanced vaginal opening and precocious activation of the reproductive axis by KiSS-1 peptide, the endogenous ligand of GPR54.

The awakening of the gonadotrophic axis at puberty is the end-point of a complex cascade of sex developmental events that leads to the attainment of reproductive capacity. Recently, loss-of-function mutations of the gene encoding GPR54, the putative receptor for the KiSS-1-derived peptide metastin, have been linked to hypogonadotrophic hypogonadism, both in rodents and humans. However, the actual role of the KiSS-1/GPR54 system in the timing of puberty onset remains unexplored. We report herein that chronic central administration of KiSS-1 peptide to immature female rats induced the precocious activation of the gonadotrophic axis, as estimated by advanced vaginal opening, elevated uterus weight, and increased serum levels of luteinizing hormone (LH) and oestrogen. The central effect of KiSS-1 upon LH release appeared to be mediated via the hypothalamic LH-releasing hormone. In contrast, despite the well-documented permissive role of body fat stores and the adipocyte-derived hormone leptin in puberty maturation, acute activation of the gonadotrophic axis by KiSS-1 was persistently observed in pubertal animals under food deprivation, after central immunoneutralization of leptin, and in a model of leptin resistance. Overall, the present results, together with our recent data on maximum expression of KiSS-1 and GPR54 genes in the hypothalamus at puberty, provide novel evidence for a role of the KiSS-1 system as a downstream element in the hypothalamic network triggering the onset of puberty.

Animals↗

PubMed2004

Ghrelin inhibits the proliferative activity of immature Leydig cells in vivo and regulates stem cell factor messenger ribonucleic acid expression in rat testis.

Ghrelin has emerged as putative regulator of an array of endocrine and nonendocrine functions, including cell proliferation. Recently, we provided evidence for the expression of ghrelin in mature, but not in undifferentiated, Leydig cells of rat and human testis. Yet testicular actions of ghrelin, other than modulation of testosterone secretion, remain unexplored. In the present study we evaluated the effects of ghrelin on proliferation of Leydig cell precursors during puberty and after selective elimination of mature Leydig cells by treatment with ethylene dimethane sulfonate. In these settings, intratesticular injection of ghrelin significantly decreased the proliferative activity of differentiating immature Leydig cells, estimated by 5-bromodeoxyuridine labeling. This response was selective and associated, in ethylene dimethane sulfonate-treated animals, with a decrease in the mRNA levels of stem cell factor (SCF), i.e. a key signal in spermatogenesis and a putative regulator of Leydig cell development. Thus, the effects of ghrelin on SCF gene expression were evaluated. In adult rats, ghrelin induced a significant decrease in SCF mRNA levels in vivo. Such an inhibitory action was also detected in vitro using cultures of staged seminiferous tubules. The inhibitory effect of ghrelin in vivo was dependent on proper FSH input, because it was detected in hypophysectomized rats only after FSH replacement. Overall, it is proposed that acquisition of ghrelin expression by Leydig cell precursors during differentiation may operate as a self-regulatory signal for the inhibition of the proliferative activity of this cell type through direct or indirect (i.e. SCF-mediated) mechanisms. In addition, we present novel evidence for the ability of ghrelin to modulate the expression of the SCF gene, which may have implications for the mode of action of this molecule in the testis as well as in other physiological systems.

Age Factors↗

PubMed2004

Expression of ghrelin and its functional receptor, the type 1a growth hormone secretagogue receptor, in normal human testis and testicular tumors.

Ghrelin, the endogenous ligand for the GH secretagogue receptor (GHS-R), has been primarily linked to the central neuroendocrine regulation of GH secretion and food intake, although additional peripheral actions of ghrelin have also been reported. In this context, the expression of ghrelin and its cognate receptor has been recently demonstrated in rat testis, suggesting a role for this molecule in the direct control of male gonadal function. However, whether this signaling system is present in human testis remains largely unexplored. In this study we report the expression and cellular location of ghrelin and its functional receptor, the type 1a GHS-R, in adult human testis. In addition, evaluation of ghrelin and GHS-R1a immunoreactivity in testicular tumors and dysgenetic tissue is presented. The expression of the mRNAs encoding ghrelin and GHS-R1a was demonstrated in human testis specimens by RT-PCR, followed by direct sequencing. In normal testis, ghrelin immunostaining was demonstrated in interstitial Leydig cells and, at lower intensity, in Sertoli cells within the seminiferous tubules. In contrast, ghrelin was not detected in germ cells at any stage of spermatogenesis. The cognate ghrelin receptor showed a wider pattern of cellular distribution, with detectable GHS-R1a protein in germ cells, mainly in pachytene spermatocytes, as well as in somatic Sertoli and Leydig cells. Ghrelin immunoreactivity was absent in poorly differentiated Leydig cell tumor, which retained the expression of GHS-R1a peptide. In contrast, highly differentiated Leydig cell tumors expressed both the ligand and the receptor. The expression of ghrelin and GHS-R1a was also detected in dysgenetic Sertoli cell-only seminiferous tubules, whereas germ cell tumors (seminoma and embryonal carcinoma) were negative for ghrelin and were weakly positive for GHS-R1a. In conclusion, our results demonstrate that ghrelin and the type 1a GHS-R are expressed in adult human testis and testicular tumors. Overall, the expression of ghrelin and its functional receptor in human and rat testis, with roughly similar patterns of cellular distribution, is highly suggestive of a conserved role for this newly discovered molecule in the regulation of mammalian testicular function.

Adult↗

PubMed2003

Immunolocalization of ghrelin and its functional receptor, the type 1a growth hormone secretagogue receptor, in the cyclic human ovary.

Ghrelin is a novel 28-amino acid peptide identified as the endogenous ligand for the GH secretagogue receptor (GHS-R). Besides its hallmark central neuroendocrine effects in the control of GH secretion and food intake, an unexpected reproductive facet of ghrelin has recently emerged because expression of this molecule and its cognate receptor has been demonstrated in rat testis. However, whether this signaling system is present in human gonads remains to be evaluated. In this study, we have assessed the presence and cellular location of ghrelin and its functional receptor, namely the type 1a GHS-R, in the cyclic human ovary by means of immunohistochemistry using specific polyclonal antibodies. Strong ghrelin immunostaining was demonstrated in ovarian hilus interstitial cells. In contrast, ghrelin signal was not detected in ovarian follicles at any developmental stage, nor was it present in newly formed corpora lutea (CL) at very early development. However, specific ghrelin immunoreactivity was clearly observed in young and mature CL, whereas expression of the peptide disappeared in regressing luteal tissue. Concerning the cognate receptor, ovarian expression of GHS-R1a protein showed a wider pattern of tissue distribution, with detectable specific signal in oocytes as well as somatic follicular cells; luteal cells from young, mature, old, and regressing CL; and interstitial hilus cells. Of particular note, follicular GHS-R1a peptide expression paralleled follicle development with stronger immunostaining in granulosa and theca layers of healthy antral follicles. In conclusion, our results are the first to demonstrate that ghrelin and its functional type 1a receptor are expressed in the cyclic human ovary with distinct patterns of cellular location. The presence of both components (ligand and receptor) of the ghrelin signaling system within the human ovary opens up the possibility of a potential regulatory role of this novel molecule in ovarian function under physiological and pathophysiological conditions.

Antibody Specificity↗

PubMed1997

Role of prolactin in the regulation of macrophages and in the proliferative activity of vascular cells in newly formed and regressing rat corpora lutea.

The proliferative activity of vascular cells and the number of macrophages were studied in corpora lutea of cycling and pregnant rats after prolactin (PRL) administration or depletion with the dopaminergic agonist CB154. Pregnant rats showed a higher proliferative activity of the vascular cells in newly formed corpora lutea than did cycling rats in metestrus. When cycling rats were treated with PRL, the proliferative activity was equivalent to that of pregnant rats. Treatment of pregnant rats with CB154 decreased the proliferative activity of vascular cells to the level in cycling rats. Otherwise, the proliferative activity was not modified in cycling rats after CB154 treatment. This indicates that the increase in the proliferative activity of vascular cells in the corpus luteum of pregnancy was due to the twice-daily PRL surges induced by mating. Treatment of cycling rats with CB154 decreased the number of macrophages in both newly formed and regressing corpora lutea, whereas PRL treatment increased the number of macrophages in regressing corpora lutea. In pregnant rats, treatment with CB154 decreased the number of macrophages in both newly formed and regressing corpora lutea. These results suggest that both the preovulatory and the twice-daily PRL surges regulate the macrophage population in newly formed and regressing corpora lutea.

Animals↗

PubMed1996

Proliferative activity in the different ovarian compartments in cycling rats estimated by the 5-bromodeoxyuridine technique.

The ovary is one of the most active proliferating tissues, and several methods for assessing cellular proliferation have been used to study follicular kinetics during the estrous cycle in the rat. In this study, we have estimated the proliferative activity of the different ovarian tissue compartments by using the 5-bromodeoxyuridine (BrdU) technique. Adult cyclic rats were studied 1 h after pulse-labeling with BrdU. Follicles were divided by size as small (mean diameter < 275 micrograms) or large (mean diameter > or = 275 micrograms). Small follicles were recorded into five classes: 1) primordial follicles (formed by flattened pre-granulosa cells), 2) unilaminar primary follicles (which ranged from having at least one enlarged pre-granulosa cell up to having a complete layer of cuboidal granulosa cells), 3) multilaminar class a (having 1-2 layers of granulosa cells and measuring up to 75 micrograms in diameter), 4) multilaminar class b (76-150 micrograms), and 5) multilaminar class c (151-274 micrograms). Large follicles were recorded into classes 1-5 according to previous classifications [Osman P. J Reprod Fertil 1985; 73:261-270]. Primordial follicles and about 70% of unilaminar primary follicles were unlabeled, whereas all of the remaining classes of small and large follicles were labeled. The labeling index (percentage of BrdU-positive cells) increased in parallel with follicle size but showed a progressive decrease in large preovulatory follicles and a centripetal pattern of cell proliferation. Atretic follicles showed a significantly lower number of labeled cells than healthy follicles of the same size. The number of proliferating cells was not related to follicle size but was inversely correlated with the degree of atresia. Cyclic CL showed intense proliferative activity that was well correlated with functional activity. The number of labeled cells was maximal in metestrus, decreased in the succeeding days, and was very low in proestrus. Proliferating cells seemed to correspond to vascular cells lining blood vessels. These results indicate that the BrdU technique is a useful, accurate, and sensitive method for assessing cellular proliferation in the rat ovary.

Animals↗

PubMed1996

In vivo manipulation (depletion versus activation) of testicular macrophages: central and local effects.

Testicular macrophages are a relevant cell type for the regulation of Leydig cell steroidogenesis. The availability of liposome technology allows in vivo manipulation of macrophages in order to analyze their role in the regulation of the hypothalamic-pituitary-testicular axis. In this study, adult (70 days of age) and prepubertal (22 days of age) rats were injected intratesticularly with liposomes containing either dichloromethylene diphosphonate (C12MDP) to deplete testicular macrophages or muramyl tripeptide (MTP-PE) to activate them. Control rats were injected with the corresponding volumes of 0.9% NaCl. Animals were killed 10 days after treatment. Adult rats injected bilaterally or unilaterally with C12MDP liposomes showed increased serum LH and testosterone concentrations, as well as increased testosterone concentrations in the testicular interstitial fluid. In unilaterally injected rats, testosterone concentrations in the interstitial fluid were higher in the macrophage-containing testes than in the contralateral, macrophage-depleted testes. Adult rats treated bilaterally with MTP-PE liposomes showed increased numbers of testicular macrophages, whereas the number of Leydig cells was unchanged. Serum LH concentrations were decreased, but no changes were found in testosterone concentrations. Prepubertal rats treated bilaterally with C12MDP liposomes showed decreased numbers of Leydig cells. However, serum LH and testosterone concentrations were increased. Otherwise, prepubertal rats treated bilaterally with MTP-PE liposomes showed increased numbers of macrophages and Leydig cells, as well as increased serum testosterone concentrations. These data suggest that testicular macrophage-derived factors act at two different levels in the pituitary-testicular axis: first, at a central level by inhibiting LH secretion, and secondly, at a local level by stimulating Leydig cell steroidogenesis.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1995

Response to Leydig cell apoptosis in the absence of testicular macrophages.

Removal of apoptotic cells from the tissues appears to be a major function of resident tissue macrophages. In order to investigate further the role of testicular macrophages after massive Leydig cell death, adult rats were injected intra-testicularly with liposome-entrapped dichloromethylene diphosphonate (Cl2MDP-lp, right testis) to deplete testicular macrophages, and with NaCl (left testis) as control. Ten days later, the animals were injected intraperitoneally with ethylene dimethane sulphonate (EDS) to induce Leydig cell apoptosis. In macrophage-containing testes there was a 2-fold increase in the number of macrophages on days 1-3 after EDS treatment and Leydig cells were completely eliminated from the interstitium by the second day after treatment. The main differences in the response to Leydig cell death in macrophage-depleted testes were: (1) an early rise in the concentration of small mononuclear, lymphocyte-like cells, (2) a greater influx of circulating monocytes, (3) the existence of variable inflammatory infiltrates on days 3-4, and (4) the disappearance of infiltrating monocytes by day 10. These results suggest that resident macrophages prevent the inflammatory reaction elicited by massive Leydig cell death.

Animals↗

PubMed1995

Pituitary-testicular axis in rats lacking testicular macrophages.

Testicular macrophages were depleted selectively in adult rats by intratesticular injections of liposome-entrapped dichloromethylene diphosphonate (Cl2MDP-Lp), whereas control animals received intratesticular injections of phosphate-buffered saline-containing liposomes or 0.9% NaCl. The absence of macrophages in Cl2MDP-lp-injected rats was confirmed histologically. Rats lacking testicular macrophages showed significantly increased (twofold on average) serum concentrations of luteinizing hormone at 5 and 10 days after treatment. Serum luteinizing hormone concentrations drop to control values at 15 days after treatment. Serum testosterone concentrations were increased significantly (twofold on average) at 5, 10 and 15 days after treatment. No significant changes were found for follicle-stimulating hormone serum concentrations, or for the weights of the testes and sex accessory organs. Testicular histology was unchanged, except for the absence of testicular macrophages in Cl2MDP-lp-treated animals. Rats treated with NaCl or Cl2MDP-lp were injected with 100 IU of human chorionic gonadotrophin and sacrificed 2 h later. Serum testosterone concentrations increased 8.6- and 3.5-fold in NaCl and Cl2MDP-lp-treated rats, respectively, in response to acute human chorionic gonadotrophin treatment. These results point out the relevance of testicular macrophages for the regulation of the pituitary-testicular axis.

Animals↗

PubMed1995

Testicular serotonin is related to mast cells but not to Leydig cells in the rat.

Testicular serotonin (5HT) concentrations were determined by HPLC in the testes of rats treated neonatally with oestradiol benzoate (EB) and in adult rats treated with the Leydig cell cytotoxic ethylene dimethane sulphonate (EDS). 5HT concentrations were related to mast cell numbers. EB-treated rats showed an accumulation of mast cells in the testes at 35 and 70 days of age and increased 5HT concentrations in both the interstitial fluid and the testicular capsule, whereas no increases in 5HT concentrations or in the number of mast cells were found for the ventral prostate of these animals. On the contrary, 5HT concentrations were not related to the number of Leydig cells. In EB-treated rats, in which Leydig cells were nearly absent at 35 days of age, 5HT concentrations were significantly increased. Furthermore, EDS-treated rats did not show significant changes in 5HT concentrations, in spite of the elimination of Leydig cells. These data suggest that mast cells are a major source of serotonin in the rat testis.

Animals↗

PubMed1995

Role of testicular macrophages in the response of Leydig cells to gonadotrophins in young hypophysectomized rats.

The Leydig cells of young hypophysectomized rats are highly sensitive to the stimulatory effects of exogenous pituitary hormones. The aim of this study was to analyse the role of testicular macrophages in the response of Leydig cells to different hormones. Male rats were hypophysectomized at 28 days of age and 10 days later they were injected intratesticularly with dichloromethylene diphosphonate-containing liposomes (right testis) to deplete testicular macrophages, and with 0.9% NaCl (left testis). One week later, the animals were treated daily with 1 IU rat GH (rGH)/rat, 5 IU recombinant human FSH (recFSH)/rat, 10 IU human chorionic gonadotrophin (hCG)/rat, or vehicle for 7 days. The animals were killed on the day after the last injection. The animals treated with rGH showed increased body weight and increased number and size of testicular macrophages in the left testes, but no significant effects on Leydig cells were found. Treatment with recFSH induced a significant increase in testicular weight and tubular diameter in both testes. In the left testes, the number and size of macrophages were increased; the number of Leydig cells was not changed, although they showed a significantly increased cross-sectional area. This effect was abolished in the right (macrophage-depleted) testes. However, the effect of recFSH on the growth of the seminiferous tubules was not modified by the absence of macrophages. Rats treated with hCG showed increased testicular weight and serum testosterone levels, as well as an increased weight of the ventral prostate. In the left testes, the number and size of both macrophages and Leydig cells were increased. Otherwise, the number of Leydig cells was unchanged in the absence of macrophages, whereas the increase in the size of Leydig cells was partially abolished. These data indicate that testicular macrophages are needed for the response of Leydig cells to gonadotrophin treatment.

Animals↗

PubMed1994

Pituitary adenylate cyclase-activating peptide (PACAP) immunolocalization in lymphoid tissues of the rat.

Pituitary adenylate cyclase activating peptide (PACAP) is a novel peptide isolated from the ovine hypothalamus. PACAP exists in 2 molecular forms with 27 (PACAP27) or 38 (PACAP38) amino acid residues. PACAP localization was studied by immunohistochemical methods in central (bone marrow and thymus) and peripheral (spleen, lymph nodes and duodenal mucosa) lymphoid tissues with antisera raised against PACAP27 or PACAP38. PACAP-positive cells were found in all lymphoid tissues examined. These cells were highly positive for PACAP38 but were negative for PACAP27. Morphologically, they were small mononuclear cells with relatively scarce cytoplasm and lymphocyte-like features. PACAP38-positive cells were abundant in peripheral lymphoid tissues (i.e., mesenteric lymph nodes). In the duodenal mucosa, PACAP38-positive cells were located either in the lamina propria or epithelium. These results suggest that PACAP38-positive cells are present within lymphoid tissues and may represent a lymphocyte-like cell subpopulation that has a potential role in cell-to-cell interactions in the immune system and in the integrated communication between neuroendocrine and immune systems.

Animals↗

PubMed1994

Effects of growth hormone and prolactin on testicular macrophages in long-term hypophysectomized rats.

Long-term hypophysectomized (LTHX) rats were treated for 1 week with growth hormone (rGH, 600 micrograms/kg body wt.), prolactin (rPRL, 600 micrograms/kg body wt.), combined rGH/rPRL or vehicle, to study the effects of these hormones on testicular macrophages. Growth hormone and, to a lesser extent, prolactin significantly increased the number and size of testicular macrophages. The in vivo phagocytic capacity of testicular macrophages was tested by their ability to clear the testicular interstitium of dead Leydig cells after treatment with the specific cytotoxic reagent ethylene dimethane sulphonate (EDS). In vehicle- or rPRL-treated rats, abundant EDS-killed Leydig cells (about 50% of the pre-existent population) remained in the testicular interstitium 72 h after EDS treatment, whereas clearance of the testicular interstitium of dead Leydig cells was largely achieved in rGH- or rGH/rPRL-treated rats. These results indicate that growth hormone and prolactin have stimulatory effects on testicular macrophages in LTHX rats.

Animals↗

PubMed1994

Selective depletion of testicular macrophages and prevention of Leydig cell repopulation after treatment with ethylene dimethane sulfonate in rats.

Testicular macrophages were selectively eliminated with dichloromethylene diphosphonate-containing liposomes (Cl2MDP-lp) to study the role of these cells in the repopulation of Leydig cells after treatment with ethylene dimethane sulfonate (EDS). Right testes were injected with Cl2MDP-lp to deplete macrophages and left testes were injected with sodium chloride and served as controls. Injection of Cl2MDP-lp produced a 97% reduction in the number of macrophages 10 days after treatment. Twenty-one days after destruction of the existing Leydig cells with EDS, abundant differentiating Leydig cells were present in the left (macrophage-containing) testes. On the contrary, in the right (macrophage-depleted) testes, differentiating Leydig cells were scarce, and was 3% of that found in the control testes. The inhibition of Leydig cell repopulation in macrophage-depleted testes was more evident at 30 days after EDS treatment, when the number of Leydig cells in the right testes was 1% of that found in control testes. The lack of Leydig cell development was also indirectly shown by the lower mass and more atrophic seminiferous epithelium of the right testes, as well as the decreased weight of the ipsilateral epididymis compared with the left testes. These results indicate that testicular macrophages are central to the proliferation and differentiation of new Leydig cells after EDS treatment, and point out the significance of paracrine regulatory mechanisms in rat testes.

Animals↗

PubMed1994

Requirement for testicular macrophages in Leydig cell proliferation and differentiation during prepubertal development in rats.

Testicular macrophages in rats were selectively depleted by an intratesticular injection of liposomes containing dichloromethylene diphosphonate into the right testis to study the possible role of these macrophages during the prepubertal development of Leydig cells. The contralateral testes were injected with 0.9% NaCl and served as controls. The animals were injected with the liposomes and NaCl at 5, 10, 15, 20 or 25 days of age. In macrophage-depleted testes, Leydig cell development was inhibited in the animals injected at 5, 10 or 15 days of age. At 35 days of age, the testis was repopulated with macrophages and Leydig cells also developed. Rats treated at 20 or 25 days of age, when Leydig cells were already present in low numbers, did not show any further increases in the number of Leydig cells up to 35 days of age. To study whether the effects of gonadotrophins on Leydig cell development require the presence of macrophages, 21-day-old rats, injected 3 days before with liposomes (right testis) and NaCl (left testis), were treated with 75 iu human FSH kg-1 bodymass day-1, 10 iu hCG per rat day-1, combined hFSH and hCG, or vehicle (PBS with 0.5% BSA) for 6 days. Treatment with hCG induced a sevenfold increase in the number of Leydig cells in the left (macrophage-containing) testis, whereas no increase was found in the right (macrophage-depleted) testis. These results indicate that macrophages are needed for Leydig cell development and for the Leydig cell response to hCG during postnatal maturation.

Animals↗