Thyroid hormone and anti-Mullerian hormone (AMH) on Leydig cell differentiation: studies using C57BL/6 mice and AMH over expressing mice.

Although the thyroid hormone has stimulatory effects and anti-Mullerian hormone (AMH) has inhibitory effects on prepubertal Leydig cell (LC) differentiation, it is important to find out whether the stimulatory effect of thyroid hormone could overcome the inhibitory effect of AMH on postnatal LC differentiation. Therefore, the objective of the present study was to use the anti-Mullerian hormone overexpressing mouse (AMH++) model to understand the simultaneous effects of AMH and thyroid hormone on postnatal LC differentiation, proliferation, maturation and function and to test whether the inhibitory effect of AMH could be overcome by the stimulatory effect of the thyroid hormone. Four age groups (7, 21, 40, 90 days) of control (C57BL/6; C) and AMH++ were used.

Spermatogenetic but not immunological defects in mice lacking the τCstF-64 polyadenylation protein.

Alternative polyadenylation controls expression of genes in many tissues including immune cells and male germ cells. The τCstF-64 polyadenylation protein is expressed in both cell types, and we previously showed that Cstf2t, the gene encoding τCstF-64 was necessary for spermatogenesis and fertilization. Here we examine consequences of τCstF-64 loss in both germ cells and immune cells.

Comparison of testis structure, function and thyroid hormone levels in control C57BL/6 mice and anti-mullerian hormone over expressing mice.

Anti-Mullerian hormone (AMH) is considered as a negative regulator of postnatal Leydig cell (LC) differentiation, because AMH over expressing mice (Mt-hAMH mice) testes are deficient in LC. Therefore, in the present study Mt-hAMH mice was used as a model to examine the process of postnatal LC differentiation. Testis structure-function studies were performed in age-matching Mt-hAMH and C57BL/6 (controls) mice; testicular components were quantified and circulating testosterone and thyroid hormone levels (thyroxine/T4 and triiodothyronine/T3; necessary for postnatal LC differentiation) were determined.

Effects of photo stimulation and nonstimulation of golden hamsters (Mesocricetus auratus) from birth to early puberty on testes structure and function.

We tested whether puberty in golden hamsters is photoperiodically controlled. Hamsters were raised under 14:10 hours Light:Dark (14L) and 1:23 hours Light:Dark (1L) respectively, from birth to 28 days and tested for various parameters. Body weight, Leydig cell (LC) size and testicular testosterone secretion were greater and plasma thyroxin (T4), testicular androstenedione secretion and LC number were lower (P<0.

Differentiation of Leydig cells in the Mongolian gerbil.

Information on postnatal Leydig cell (LC) differentiation in the Mongolian gerbil has been unavailable. Therefore, current investigation was designed to examine LC lineage differentiationin this rodent, from birth to adulthood. Gerbil testes at 1 day, 1-7 weeks (w), 2 and 3 months of age were conventionally processed by light and transmission electron microscopy.

Alteration in testicular cell components following transiently induced ischaemia in prepubertal bulls.

The aim of the present study was to evaluate transient testicular ischaemia (induced using elastrator bands) in Jersey calves on testicular morphology and development. Treatments (at 27 +/- 5 days of age) consisted of control (0 h banding) and banding for 2, 4 or 8 h (n = 4 in each group). After castration (at 60 +/- 5 days of age), the right testis was used for calculation of cell components per testis according to the point-counting method.

Effects of hypothyroidism on anti-mullerian hormone expression in the prepubertal rat testis.

Differentiation of adult Leydig cells (ALC) in the prepubertal rat testis is stimulated by thyroid hormone (Thy) and inhibited by the Anti-Mullerian Hormone (AMH) produced by the immature Sertoli cell (SC). As Thy induces SC maturation in the prepubertal rat testis, we hypothesized that Thy stimulation of ALC differentiation is mediated via inhibition of AMH production by the SC with their maturation. If this hypothesis is true, AMH production by the prepubertal Sertoli cells in hypothyroid rats should not decline immediately after birth as in euthyroid rats, but should be maintained throughout the hypothyroid period at a similar or higher level to that of day 1 rats.

Changes in the testis seminiferous tubules and interstitium in prepubertal bull calves immunised against inhibin at the time of gonadotropin administration.

The aim of the present study was to evaluate the effects of gonadotropin administration at initiation of inhibin passive immunisation in Jersey bull calves (age 27 +/- 5 days) on testicular morphology and development. Primary treatments consisted of control (keyhole limpet haemocyanin, KLH; n = 9) or immunisation against inhibin (INH; n = 9). Subsets of calves were randomly assigned within primary treatments (TRT) to receive saline ( n = 3 per TRT), follicle-stimulating hormone (FSH; n = 3 per TRT) or gonadotrophin-releasing hormone (GnRH, n = 3 per TRT).

Expression of insulin-like peptide 3 in the postnatal rat Leydig cell lineage: timing and effects of triiodothyronine-treatment.

Fetal (FLC) and adult Leydig cells (ALC) secrete insulin-like peptide 3 (INSL3), which is linked to cryptorchidism in the newborn rat. Its gene regulation appears to be independent of that for most steroidogenic enzymes, and may thus be a marker for other aspects of ALC differentiation. Our study examined the following on INSL3 peptide expression in ALC lineage (i) timing, (ii) which cell stage, and (iii) effects of triiodothyronine (T3).

Detection of platelet-derived growth factor-alpha (PDGF-A) protein in cells of Leydig lineage in the postnatal rat testis.

Platelet-derived growth factor-A (PDGF-A) is a locally produced growth factor in the rat testis secreted by both Sertoli cells and Leydig cells. It has been suggested that PDGF-A may be involved in modulation of testosterone production and may be essential to Leydig cell differentiation, however it is not known at what stage of differentiation PDGF-A begins to be expressed in the cells of Leydig lineage in the postnatal rat testis. Therefore, the objectives of this research were to determine at what postnatal age and in which cell type is PDGF-A first expressed in cells of the adult Leydig cell lineage, and does PDGF-A expression coincide with expression of 3beta-hydroxysteroid dehydrogenase (3beta-HSD), an indicator of steroid hormone synthesis.

Detection of anti-Mullerian hormone receptor II protein in the postnatal rat testis from birth to sexual maturity.

Anti-Mullerian hormone (AMH) produced by the immature Sertoli cells negatively regulates the postnatal Leydig cell (i.e. adult Leydig cells/ALC) differentiation, however, the mechanism is sparsely understood.

Leydig cells, thyroid hormones and steroidogenesis.

Leydig cells are the primary source of androgens in the mammalian testis. It is established that the luteinizing hormone (LH) produced by the anterior pituitary is required to maintain the structure and function of the Leydig cells in the postnatal testis. Until recent years, a role by the thyroid hormones on Leydig cells was not documented.

Effects of thyroid hormones on Leydig cells in the postnatal testis.

Thyroid hormones (TH) stimulate oxidative metabolism in many tissues in the body, but testis is not one of them. Therefore, in this sense, testis is not considered as a target organ for TH. However, recent findings clearly show that TH have significant functions on the testis in general, and Leydig cells in particular; this begins from the onset of their differentiation through aging.

Changes in the testis interstitium of Brown Norway rats with aging and effects of luteinizing and thyroid hormones on the aged testes in enhancing the steroidogenic potential.

We tested the possibility of using LH and thyroxine (T(4)) to restore the testicular steroidogenic ability in aged Brown Norway rats. Three-, 6-, 12- (n = 8 per group), and 18-mo-old (n = 32; 3M, 6M, 12M, and 18M, respectively) rats were used. The 18M rats were divided into four groups (n = 8 per group) and implanted subdermally with Alzet mini-osmotic pumps containing saline (control), LH (24 microg/day), T(4) (5 microg/day), and LH+T(4) (24+5 microg/day), respectively, for 4 wk (to 19 mo [19M] of age).

Differentiation of the adult Leydig cell population in the postnatal testis.

Five main cell types are present in the Leydig cell lineage, namely the mesenchymal precursor cells, progenitor cells, newly formed adult Leydig cells, immature Leydig cells, and mature Leydig cells. Peritubular mesenchymal cells are the precursors to Leydig cells at the onset of Leydig cell differentiation in the prepubertal rat as well as in the adult rat during repopulation of the testis interstitium after ethane dimethane sulfonate (EDS) treatment. Leydig cell differentiation cannot be viewed as a simple process with two distinct phases as previously reported, simply because precursor cell differentiation and Leydig cell mitosis occur concurrently.

Effects of thyroid hormone on Leydig cell regeneration in the adult rat following ethane dimethane sulphonate treatment.

We tested the effects of thyroid hormone on Leydig cell (LC) regeneration in the adult rat testis after ethane dimethyl sulphonate (EDS) treatment. Ninety-day-old, thyroid-intact (n = 96) and thyroidectomized (n = 5) male Sprague-Dawley rats were injected intraperitoneally (single injection) with EDS (75 mg/kg) to destroy LC. Thyroid-intact, EDS-treated rats were equally divided into three groups (n = 32 per group) and treated as follows: control (saline-injected), hypothyroid (provided 0.

Effects of thyroid and luteinizing hormones on the onset of precursor cell differentiation into leydig progenitor cells in the prepubertal rat testis.

Leydig cells in the adult rat testis differentiate during the neonatal-prepubertal period. However, the stimulus for the initiation of their differentiation is still not clear. In the present study our objectives were to test the effects of thyroid hormone and LH on the initiation of precursor cell differentiation into Leydig cells in the prepubertal rat testis.

Effects of tri-iodothyronine on testicular interstitial cells and androgen secretory capacity of the prepubertal Rat.

The main objective of the study was to investigate the effects of hyperthyroidism on the rat testis interstitium during prepuberty, which is not well understood at present. Male Sprague Dawley rats were injected subcutaneously daily with saline (controls) or tri-iodothyronine (T(3), 50 microg/kg body weight; hyperthyroids) from postnatal Day 1. Rats were killed at Days 5, 7, 9, 12, 16, and 21.

Peroxisomes and intracellular cholesterol trafficking in adult rat Leydig cells following Luteinizing hormone stimulation.

The present study was designed to explore the intracellular cholesterol trafficking in Leydig cells of adult rats following Luteinizing hormone (LH) injection. Histochemical techniques were used to demonstrate distribution of free cholesterol in Leydig cells of control and LH-injected rats. Two groups of sexually mature male Sprague Dawley rats (n=4/group) were used.

Differentiation of adult Leydig cells in the neonatal rat testis is arrested by hypothyroidism.

The effects of propyl thiouracil (PTU)-induced hypothyroidism on testicular interstitial cells and androgen secretion in vitro in the neonatal rat were investigated using Sprague Dawley rats of 1, 7, 14, and 21 days. The results revealed that the fetal Leydig cell (FLC) number per testis was unchanged between and within treatment groups at all ages tested. FLC size was 50% smaller in 21-day controls than in all other groups.

The effect of chronic luteinizing hormone treatment on adult rat Leydig cells.

We investigated the chronic effects of luteinizing hormone (LH) treatment on adult rat Leydig cell structure and function. Two groups of sexually mature male Sprague-Dawley rats were used; controls and rats implanted subdermally with LH-filled Alzet miniosmotic pumps (delivers 24 micrograms of LH per day). After 2 weeks of LH treatment, testes of these rats were fixed by 2.

Luteinizing hormone on Leydig cell structure and function.

The effects of luteinizing hormone (LH) and human chorionic gonadotrophic hormone (hCG) on Leydig cell structure and function are reviewed in this paper under two main headings; responses to LH and hCG stimulation and responses to LH deprivation. With acute LH stimulation, up to 2 hours following the LH injection, there was no change in the volume of a Leydig cell. However, Leydig cell peroxisomal volume and intraperoxisomal SCP2 content showed a rapid and transient change.

Cell-cell interactions in the testis of teleosts and elasmobranchs.

In this paper we present the state of knowledge on cell-cell interactions in the testis of two groups of anamniote vertebrates--teleosts and elasmobranchs--which include most fish. In these fish, the structural organization of the testis differs fundamentally from that which characterizes amniotes in which the germinal tissue is located in tubules open at both ends and consists of a permanent population of Sertoli cells associated with successive stages of germ cell development. In fish, the spermatogenic unit of testis is the spermatocyst, which corresponds to one germ cell or to a clone of isogenetic germ cells, enclosed by one or several Sertoli cells, which form the wall of the cyst.

Signs of aging are apparent in the testis interstitium of Sprague Dawley rats at 6 months of age.

The present study investigated the effects of aging in the testis interstitium in Sprague Dawley rats. Rats of 3, 6 and 24 months of age were used. Testes of rats (n = 5) were fixed by whole body perfusion using a fixative containing 2.

Peroxisomes and sterol carrier protein-2 in luteal cell steroidogenesis: a possible role in cholesterol transport from lipid droplets to mitochondria.

In the present investigation, we have studied peroxisomes and sterol carrier protein-2 (SCP2) in control and luteinizing hormone stimulated rat luteal cells. Superovulated immature rats in mid-luteal phase (8 days after ovulation) were divided into two groups (n = 4/group) and treated with vehicle (0.2 ml saline), or luteinizing hormone (LH, 20 micrograms/rat).