Additive effects of nicotine and high-fat diet on hepatocellular apoptosis in mice: involvement of caspase 2 and inducible nitric oxide synthase-mediated intrinsic pathway signaling.

Smoking is a major risk factor for diabetes and cardiovascular disease and may contribute to nonalcoholic fatty liver disease (NAFLD). The health risk associated with smoking is exaggerated by obesity and is the leading causes of morbidity and mortality worldwide. We recently demonstrated that combined treatment with nicotine and a high-fat diet (HFD) triggers greater oxidative stress, activates hepatocellular apoptosis, and exacerbates HFD-induced hepatic steatosis. Given that hepatocellular apoptosis plays a pivotal role in the pathogenesis of NAFLD, using this model of exacerbated hepatic steatosis, we elucidated the signal transduction pathways involved in HFD plus nicotine-induced liver cell death. Adult C57BL6 male mice were fed a normal chow diet or HFD with 60% of calories derived from fat and received twice daily IP injections of 0.75 mg/kg BW of nicotine or saline for 10 weeks. High-resolution light microscopy revealed markedly higher lipid accumulation in hepatocytes from mice received HFD plus nicotine, compared to mice on HFD alone. Addition of nicotine to HFD further resulted in an increase in the incidence of hepatocellular apoptosis and was associated with activation of caspase 2, induction of inducible nitric oxide synthase (iNOS), and perturbation of the BAX/BCL-2 ratio. Together, our data indicate the involvement of caspase 2 and iNOS-mediated apoptotic signaling in nicotine plus HFD-induced hepatocellular apoptosis. Targeting the caspase 2-mediated death pathway may have a protective role in development and progression of NAFLD.

Aging-related increased expression of inducible nitric oxide synthase and cytotoxicity markers in rat hypothalamic regions associated with male reproductive function.

UNLABELLED: We have previously demonstrated that the inducible nitric oxide synthase (iNOS) protein and total NOS activity increase in the hypothalamus and other regions of the male rat brain during aging. We have now tested the hypothesis that increased iNOS results in excessive nitric oxide (NO) and peroxynitrite production, and leads to increased apoptosis in CNS cells, including the GnRH and oxytocin hypothalamic neurons involved in the control of male reproductive function. Young (3-month-old) and old (24-month-old) male Brown Norway rats (n = 6) were perfused with 4% formalin. Adjacent coronal paraffin-embedded sections (5 microm) of preoptic area (POA), supraoptic nucleus (SON), paraventricular nucleus (PVN), and arcuate nucleus (ARC) of the hypothalamus were immunostained with antibodies for iNOS, neuronal NOS (nNOS), and nitrotyrosine (a marker of peroxynitrite formation). The intensity of immunostaining was measured using a densitometric image analysis system. Apoptosis was determined by the TUNEL assay. Double immunofluorescence staining with confocal laser scanning microscopy was used for co-localization studies. A significant increase in the iNOS immunostaining measured as optical density (OD) was found in the old compared to the young animals (SON: 0.32 +/- 0.02 vs. 0.23 +/- 0.03, p < 0.05; PVN: 0.34 +/- 0.03 vs. 0.07 +/- 0.05, p < 0.001; POA: 0.18 +/- 0.02 vs. 0.01 +/- 0.02, p < 0.001). Aging did not affect nNOS expression. Nitrotyrosine was elevated in the hypothalamic regions of old compared to young rats (SON: 0.32 +/- 0.05 vs. 0.10 +/- 0.04, p < 0.05; PVN: 0.32 +/- 0.04 vs. 0.13 +/- 0.03, p < 0.01; POA: 0.72 +/- 0.06 vs. 0.03 +/- 0.003, p < 0.001). Increased nitrotyrosine was accompanied by an elevation of the apoptotic index in the old rats (SON: 11.01 +/- 3.33 vs. 0.57 +/- 0.50, p < 0.001; PVN: 3.08 +/- 1.12 vs. 0.42 +/- 0.32; POA: 6.60 +/- 1.93 vs. 0.18 +/- 0.17, p < 0.01; ARC: 0.001 +/- 0.0001 vs. 4.33 +/- 2.33). iNOS staining co-localized with GnRH and oxytocin staining. IN CONCLUSION: The aging-related iNOS increased expression in the hypothalamus of the male rat affects regions known to control the synthesis and release of GnRH (POA, ARC) and oxytocin (PVN, SON), and the factors regulating penile erection (POA, and PVN). These observations suggest that iNOS may play a role in the reduction in GnRH and oxytocin neuronal secretion resulting in reproductive dysfunctions such as lowered serum testosterone, hypospermatogenesis, and diminished copulatory function in the aging male animal.

XXY male mice: an experimental model for Klinefelter syndrome.

Klinefelter syndrome (47,XXY) is the most common sex chromosome aneuploidy in men. Thus, it is important to establish an experimental animal model to explore its underlying molecular mechanisms. Mice with a 41,XXY karyotype were produced by mating wild-type male mice with chimeric female mice carrying male embryonic stem cells. The objectives of the present study were to characterize the testicular phenotype of adult XXY mice and to examine the ontogeny of loss of germ cells in juvenile XXY mice. In the first experiment the testicular phenotypes of four adult XXY mice and four littermate controls (40,XY) were studied. XXY mice were identified by either Southern hybridization or karyotyping and were further confirmed by fluorescence in situ hybridization. The results showed that the testis weights of adult XXY mice (0.02 +/- 0.01 g) were dramatically decreased compared with those of the controls (0.11 +/- 0.01 g). Although no significant differences were apparent in plasma testosterone levels, the mean plasma LH and FSH levels were elevated in adult XXY mice compared with controls. The testicular histology of adult XXY mice showed small seminiferous tubules with varying degrees of intraepithelial vacuolization and a complete absence of germ cells. Hypertrophy and hyperplasia of Leydig cells were observed in the interstitium. Electron microscopic examination showed Sertoli cells containing scanty amounts of cytoplasm and irregular nuclei with prominent nucleoli. The junctional region between Sertoli cells appeared normal. In some tubules, nests of apparently degenerating Sertoli cells were found. In the second experiment the ontogeny of germ cell loss in juvenile XXY mice and their littermate controls was studied. Spermatogonia were found and appeared to be morphologically normal in juvenile XXY mice. Progressive loss of germ cells occurred within 10 days after birth. This resulted in the absence of germ cells in the adult XXY mice. We conclude that a progressive loss of germ cells occurring in early postnatal life results in the complete absence of germ cells in adult XXY mice. The XXY mouse provides an experimental model for its human XXY counterpart, Klinefelter syndrome.

Redistribution of Bax is an early step in an apoptotic pathway leading to germ cell death in rats, triggered by mild testicular hyperthermia.

Programmed cell death occurs spontaneously during spermatogenesis and can be induced in a cell- and stage-specific manner by mild testicular hyperthermia. Studies using transgenic mice suggest the involvement of Bcl-2 proteins in regulating germ cell apoptosis. To delineate further the pathways involved, we examined the temporal changes in proapoptotic Bax and antiapoptotic Bcl-2 in rat testes after transient exposure to heat (43 degrees C for 15 min). Germ cell apoptosis, involving exclusively early (I-IV) and late (XII-XIV) stages, was activated within 6 h. Initiation of apoptosis was preceded by a redistribution of Bax from a cytoplasmic to perinuclear localization within 0.5 h of heating as assessed by immunocytochemical methods. In contrast, Bcl-2 is distributed both in the cytoplasm and nucleus in those cell types susceptible to heat-induced apoptosis. Despite the striking redistribution, Bax levels remained unchanged as determined by Western analysis; Bcl-2 levels increased significantly by 6 h after heat exposure. Reverse transcription-polymerase chain reaction analysis indicated no change in either Bax or Bcl-2 mRNA levels in response to heat, suggesting the involvement of post-transcriptional rather than transcriptional mechanisms mediating their activity. The marked subcellular redistribution of Bax prior to activation of apoptosis and the increase in Bcl-2 suggest an involvement of Bcl-2 family members in heat-induced apoptotic death of germ cells.

Reproductive aging in the Brown Norway rat is characterized by accelerated germ cell apoptosis and is not altered by luteinizing hormone replacement.

Reproductive aging in the male Brown Norway (BN) rat is characterized by decreased Leydig cell steroidogenesis associated with seminiferous tubule dysfunction. This could be a result of a combination of a primary testicular defect and a secondary hypothalamic pituitary dysfunction. In the present study, we determined in the BN rat whether germ cell loss occurred via apoptosis. We then defined the age of onset of Leydig cell dysfunction and germ cell loss and examined whether chronic luteinizing hormone (LH) replacement would delay or prevent reproductive aging. Plasma hormone levels, testicular sperm concentrations, and germ cell apoptosis were studied in 6, 9, 12, 15, 18, and 21-month-old BN rats. Beginning at 15 months, testicular weight, sperm concentration, total sperm counts, plasma testosterone, LH, and inhibin decreased, whereas the proportion of regressed testes and plasma follicle-stimulating hormone (FSH) levels increased with aging. Accelerated germ cell apoptosis involving spermatogonia, preleptotene and pachytene spermatocytes, and spermatids was evident in some tubules of the relatively normal testes from 21-month-old rats. In the regressed testes, complete cessation of spermatogenesis occurred. The apoptotic index was higher in the testes of old (21-month-old) rats in particular at stages XII-XIV when compared with younger animals. Chronic LH replacement (0.5 microg i.p. twice per day) administered to 15-month-old BN rats for 6 months did not alter plasma hormone levels, testes weight, sperm concentration or content, or the germ cell apoptotic index. In the control group, 3 out of 10 testes were regressed, whereas in the LH-replaced group, only 1 out of 12 testes was regressed. We show in this study that early reproductive aging in the BN rat began at around 15 months. Germ cell loss associated with aging occurs via apoptosis. Replacement therapy with LH for 6 months does not decrease or delay the testicular dysfunction associated with aging. It is unlikely that hypothalamic-pituitary dysregulation is the major cause of testicular aging.

Hormonal and genetic control of germ cell apoptosis in the testis.

Programmed cell death is an evolutionarily conserved cell death process that plays a major role during normal development and homeostasis. In many cases, the ordered execution of this internal death programme leads to typical morphological and biochemical changes that have been termed apoptosis. The crucial role of this mode of cell death in the pathogenesis of diverse human diseases including cancer, acquired immunodeficiency syndrome, neurodegeneratives disorders, atherosclerosis and cardiomyopathy is now supported by a wealth of data. In adult mammals, including humans, germ cell death is conspicuous during normal spermatogenesis and plays a pivotal role in sperm output. Withdrawal of gonadotrophins and testosterone further enhances the degeneration of germ cells in the testis. The availability of a quantitative method for analysing the testicular DNA fragmentation and in situ methods to localize specific germ cells undergoing apoptosis, either spontaneously or in response to a variety of death triggering signals, opens new avenues in the understanding of the significance of germ cell apoptosis during normal and abnormal states of spermatogenesis. A growing body of evidence demonstrates that both spontaneous (during normal spermatogenesis) and accelerated germ cell death triggered by deprivation of the gonadotrophic support or moderately increased scrotal temperature in adult rats occur almost exclusively via apoptosis. Although there has been spectacular progress in the understanding of the molecular mechanisms of apoptosis in various systems other than spermatogenesis, elucidation of the biochemical and molecular mechanisms by which germ cell apoptosis is regulated has only just begun. It is likely that germ cell apoptosis is controlled in a cell-type specific fashion, but the basic elements of the death machinery may be universal. In addition, there is increasing evidence that homozygous disruption of a number of genes in mice results in infertility through accelerated germ cell apoptosis. Manipulation of spermatogenesis by survival factor(s) deprivation or increases in extrinsic death signals in loss-of-function or gain-of-function mouse models provides a basis for further attempts to define the intrinsic regulation of various death-related genes by external death signals. Such information is crucial for effective management of male factor infertility as well as more targeted approaches to male contraception.

Triptolide: a potential male contraceptive.

The antifertility effect of triptolide and other related compounds, isolated from Tripterygium wilfordii, has been demonstrated in male rats. The exact sites and mechanism of action of triptolide remain unknown. Our objectives were to determine whether triptolide at selected dose levels that induce infertility has any detrimental effects on the testes and to determine the sites and the possible mechanisms of its action. Groups of six adult male Sprague-Dawley rats were given oral administration of either vehicle (control group) or triptolide (50 or 100 microg/kg body weight) daily for 35 or 70 days. Body weight gain was normal in all treated groups. All six rats treated with a high dosage of triptolide were infertile during the second (63-70 days) mating trial. A lower dose (50 microg) of triptolide gave intermediate fertility values. Plasma levels of luteinizing hormone, follicle-stimulating hormone, testosterone, and intratesticular testosterone were not significantly different between control and triptolide-treated groups. Cauda epididymal sperm content was decreased by 68% and the motility, which averaged 58.2% in the control rat, was reduced to almost zero. No effects of triptolide were observed on testis and accessory organs weight, volumes of tubular lumen and the total Leydig cells, tubule diameter, and the number of Sertoli cells, spermatogonia, preleptotene (PL), and pachytene (P) spermatocytes. There were, however, modest but significant decreases in tubule volume and the number of round spermatids at stages VII-VIII. No changes in the germ cell apoptotic index measured at stages VII-VIII and XIV-I were noted between controls and rats rendered infertile with a high dose of triptolide. Thus, triptolide, at a dose level that induces complete infertility in the adult rats, has minimal adverse effects on the testes and acts primarily on the epididymal sperm making triptolide an attractive lead as a post-testicular male contraceptive.

Significance of apoptosis in the temporal and stage-specific loss of germ cells in the adult rat after gonadotropin deprivation.

The major objectives of the present study were to document the temporal and stage-specific acceleration of germ cell apoptosis in adult rats after selective suppression of pituitary gonadotropins by GnRH antagonist (GnRH-A) treatment, and to examine the possibility that apoptosis is the sole mechanism of germ cell death in response to hormonal deprivation. Groups of adult male rats were given a daily injection of a vehicle for 14 days or GnRH-A (1.25 mg/kg BW) for 2, 5, 7, and 14 days. Analysis of testicular apoptotic DNA fragmentation revealed a detectable increase at Day 5 and a maximal increase at 14 days after treatment. In situ analysis of germ cell apoptosis fully corroborated the observed increase in the degree of DNA fragmentation with time and also revealed a stage-related activation of apoptosis of specific germ cells. A low incidence (0.06-0.09) of germ cell apoptosis (expressed as numbers per Sertoli cell) was detectable at stages I, IX-XI, and XII-XIV in control rats. Mean incidence of apoptotic germ cells specifically at stages VII-VIII increased significantly (0.40 +/- 0.06) by Day 5 and increased another 2.2-fold (over the 5-day treatment values) on Day 7 after GnRH-A treatment as compared to values in controls, where no apoptosis was detected. Significantly increased incidence of apoptosis at stages IX-XI (0.37 +/- 0.05) over control values (0.07 +/- 0.01) was noted by Day 7. Within the study paradigm, the highest number of dying cells occurred by Day 14, at which time a modest but significant (p < 0.05) increase in the incidence of apoptosis was also noted at stages I, II-IV, V-VI, and XII-XIV in comparison with control values. Stages VII-VIII and IX-XI still exhibited the higher number of cells undergoing apoptosis (0.97 +/- 0.22, and 1.03 +/- 0.22, respectively). Comparison between rates of apoptosis and cell degeneration measured at stages VII-VIII demonstrated an intimate association (r = 0.94; p < 0.001) between apoptosis and germ cell loss, strongly supporting the concept that germ cell death (at these stages) after removal of hormonal support in the adult rat occurs almost exclusively via apoptosis.

In the male brown-Norway (BN) male rat, reproductive aging is associated with decreased LH-pulse amplitude and area.

The Brown-Norway (BN) rat has been proposed as a rodent model for the study of human male reproductive aging. As in man, reduction in serum or plasma testosterone (T) and both testicular (primary) and hypothalamic-pituitary (secondary) reproductive dysfunction have been associated with aging in male BN rats. However, the presence of secondary testicular failure in this rodent, as indicated by low serum luteinizing hormone (LH) levels, needs further corroboration. The present study was designed to determine whether age-related differences in the pulsatile patterns of pituitary LH and follicle-stimulating hormone (FSH) secretion occur in gonad-intact male BN rats. Three age groups were examined: young (3-4 months), middle aged (12-13 months), and old (21-22 months). Using intra-atrial cannulae, serial 5-minute blood samples were withdrawn from conscious, unrestrained animals. Plasma LH concentrations were determined by a supersensitive immunofluorometric assay (FIA) and FSH and T by radioimmunoassay (RIA). Mean T levels were different among groups (young > middle age > old). In young rats, T levels were higher in the late morning/early afternoon than in the late afternoon: this variation was not found in older rats. Mean FSH concentrations were higher in the old than in the middle-aged and young rats. Significant differences in mean LH levels were not found among groups. Compared to young rats, shortened pulse interval and reduced area of pulses characterized the secretory pattern of both gonadotropins in old rats. In addition, LH-pulse amplitude and total area of LH pulses were also significantly lower in old than in young rats. Besides the well-recognized primary testicular failure that occurs in the old BN rat, this study confirms a hypothalamic-pituitary deficiency that makes this rodent model ideal for studying human male reproductive aging.

Reproductive aging in the male brown-Norway rat: a model for the human.

Previous studies in the Sprague-Dawley rat have demonstrated that male reproductive aging is primarily a neuroendocrine dysfunction characterized by decreased pulsatile LH secretion leading to low serum testosterone (T) levels, whereas sperm production is relatively well maintained. In contrast to the Sprague-Dawley rat, the Brown-Norway (BN) rat has a longer life span, does not become obese, and experiences fewer age-related tumors of the endocrine or reproductive system, thus providing a disease-free model for studying male reproductive aging. We studied the changes in serum hormone levels and related these alterations to testicular T production, Leydig cell morphometry, and spermatogenesis in young (6 months), aging (22 months), and old (30 months) BN rats. Low serum T levels were associated with decreased LH levels in the 22-month-old (T, 0.58 +/- 0.08 ng/ml; LH, 0.45 +/- 0.06 ng/ml) and 30-month-old rats (T, 0.63 +/- 0.10 ng/ml; LH, 0.34 +/- 0.04 ng/ml) compared to those in young rats (T, 1.35 +/- 0.30 ng/ml; LH, 0.79 +/- 0.10 ng/ml). In vitro Leydig cell T production, basally and after stimulation by LH, was similar in young and old rats. The total testicular T content was lower in 30- than in 6-month-old rats. Testicular morphometry showed smaller Leydig cell volume in the old (857 +/- 97 microns3) than in the young rats (1387 +/- 103 microns3), although their number per testis remained unchanged (6 months, 22.7 +/- 1.6 x 10(6)/testis; 30 months, 25.2 +/- 3.1 x 10(6)/testis). In contrast, a marked (68.4%) reduction in the total number of Sertoli cell per testis was noted in the 30-month-old rats. The proportion of the testis occupied by seminiferous tubules was also reduced in the old rats. Significant (P < 0.05) age-related reductions occurred in tubule diameter, length of tubules, and volume of tubules and their lumens. The testicular sperm concentration and total sperm production were significantly reduced in the 22- and 30-month-old rats. These changes in seminiferous tubule function in the old rats were associated with low serum and testicular inhibin and high serum FSH levels. We conclude that aging in the reproductive axis of the BN rat is manifested by 1) lower serum T levels due to decreased pituitary LH stimulation of endogenous T production, and 2) decreased seminiferous tubule function accompanied by elevated FSH levels indicative of a primary testicular disorder.(ABSTRACT TRUNCATED AT 400 WORDS)

Temporal and stage-specific changes in spermatogenesis of rat after gonadotropin deprivation by a potent gonadotropin-releasing hormone antagonist treatment.

GnRH antagonists (GnRH-As) rapidly and reversibly inhibit testicular functions in a variety of experimental models as well as man. Their potential for human male contraception is currently being tested in many centers, including our own. This study was undertaken to provide comprehensive quantitative information on the testes and to document the temporal and stage-specific changes in the kinetics of germ cell degeneration in rats treated daily with the Nal-Glu GnRH-A (1250 micrograms/kg body wt) for up to 4 weeks. Plasma levels of testosterone (T) and the concentrations of testicular T declined to 20.7% and 5.4% of control values, respectively, by 1 week and remained suppressed throughout the treatment period. Preleptotene and pachytene spermatocytes, and step-7 and step-19 spermatids at stage VII were the first germ cells to degenerate soon after (1 week) GnRH-A treatment. Germ cell counts at stage VII also revealed a significant (P < 0.05) reduction in number of preleptotene (25.6%), pachytene (35.4%), and step-7 spermatids (29.1%) in comparison with controls. The number of homogenization-resistant advanced spermatids decreased by 70%. A further progressive loss of spermatogenic activity occurred with time. Treatment with GnRH-A for 4 weeks caused advanced spermatids to decline to nearly undetectable, Step-7 spermatids to decline to 17.7% of the normal level, and the P and PL to decline to 28.6% and 67.7%, respectively, of control values. The number of Sertoli cells and A1 spermatogonia remained unchanged throughout the experimental period. The effects of GnRH-A treatment on spermatogenesis were identical to that of hypophysectomy. These results suggest that: 1) early deprivation of gonadotropins and/or intratesticular T by GnRH-A treatment is followed by stage-specific degeneration of germ cells; 2) pituitary secretions other than LH and FSH have little primary influence on spermatogenesis during early regression; and 3) the GnRH-A-treated rat would be an excellent animal model for studying the targeted effects of LH, FSH, and T on the regulation of spermatogenesis.

Sentinels of Leydig cell structural and functional changes in golden hamsters in early testicular regression and recrudescence.

The seasonally breeding hamster model was used to assess changes associated with Leydig cell activity and inactivity. Specifically, parameters of Leydig cell structure and function were studied to determine the early changes seen in seasonally breeding golden hamsters in photoperiod-induced gonadal regression and photoperiod-induced gonadal recrudescence. Time intervals used to characterize early regression and recrudescence were selected with the objective of determining the most sensitive parameters characterizing functional transitional states. In early regression, plasma levels of follicle-stimulating hormone (FSH) but not luteinizing hormone (LH) or testosterone were reduced significantly. Regressive structural changes included decreases in volume of the interstitium, total number of Leydig cells, blood vessels, and the seminiferous tubules and tubular lumen. A decrease in volume, but not numbers of Leydig cells, was accompanied by decreases in volume of Leydig cell tubular smooth endoplasmic reticulum (t-ER), Golgi complex, and the peroxisomes and decreases in surface area of the inner mitochondrial membrane and t-ER, suggesting that early Leydig cell changes are restricted primarily to organelles associated with steroid biosynthesis. In early recrudescence, at a time when there was an increase in the number of germ cells in the basal compartment, blood levels of LH, FSH and testosterone were all increased. There were increases in testicular weight, volume, seminiferous tubular lumen, blood vessel and interstitial volumes. Leydig cells increased in size as a result of increases in nuclear, nucleolar and cytoplasmic volumes, while Leydig cell numbers did not increase. At the subcellular level there were increases in the surface areas of the cell, mitochondrial membranes and cisternal endoplasmic reticulum (sparsely populated with ribosomes). Unlike the changes seen in early degeneration when steroid synthetic organelles were initially affected, the changes in early recrudescence indicate that Leydig cells must first rebuild their synthetic machinery (nucleus, nucleolus and rough endoplasmic reticulum) that, at a later time, will reconstitute the cell's steroidogenic machinery. Correlation of hormonal parameters with structural parameters did indicate a relationship between hormonal parameters and steroid secreting organelles. Correlations were strongest with testosterone but, surprisingly, plasma FSH levels correlated more strongly with many structural parameters of the Leydig cell than did the levels of LH. Since FSH receptors are not present on Leydig cells, these data add to the growing data suggesting a role for factors originating from the seminiferous tubule in modulation of Leydig cell function.

Further observations of stage-specific effects seen after short-term hypophysectomy in the rat.

Although hypophysectomy has been a popular tool to study the effects of hormone deprivation as well as concomitant or subsequent hormone supplementation, there is relatively little morphological information available on the structural manifestation of pituitary removal on the testis. In the report, changes, in addition to those previously reported after short-term (6 days) hypophysectomy in the rat (Russell and Clermont, 1977), are described. Membrane-bound vacuoles (primarily) appeared within the basal region of the Sertoli cell at approximately the level of Sertoli-Sertoli junctions. In stages VIII through XI elongating spermatids were abnormal and manifested manchette indentation of the nucleus, a variety of other abnormal head shapes, acrosomal breaks and enlargement of the subacrosomal space. These defects were interpreted as the effect of declining hormonal levels in stage VII on spermatids that had survived the stage VII hormone sensitivity known to occur with severe hormone depletion. Abnormalities in the flagellum involving the mitochondrial sheath and fibrous sheath were detected. Preleptotene spermatocytes degenerated and could be identified in the process of doing so near the base of the seminiferous epithelium. The contact of preleptotene spermatocytes with the basal lamina was also significantly reduced. The results show that both Sertoli cell and germ cell abnormalities were present although germ cell abnormalities could be a secondary consequence of lack of appropriate stimulation of the Sertoli cell. Degeneration of basal compartment germ cells shows that germ cells other than those located in the adluminal compartment are vulnerable to hormonal withdrawal. The question of how hormone effects are mediated in the testis at midcycle to produce these effects is discussed.

Golden hamster myoid cells during active and inactive states of spermatogenesis: correlation of testosterone levels with structure.

Myoid cells were examined quantitatively in adult golden hamsters with active spermatogenesis and compared with hamsters in which the testes were regressed due to a modification in the light-dark cycle. A detailed morphometric study was undertaken utilizing animals previously examined. The cell-surface area and volumes of most organelles were not significantly different in animals which were gonadally active as compared with regressed animals. A slight, but significant, increase in nuclear volume (31%) and a slight, but significant, decrease (28%) in cell volume were recorded for regressed animals. The total volume of pinocytotic vesicles was increased dramatically (approximately threefold) in active animals in comparison with inactive animals (P less than 0.01), indicating that an increase in non-specific transport across the myoid cell is associated with spermatogenic activity. Intravascularly injected horseradish peroxidase was capable of entering pinocytotic vesicles in both active and inactive animals. Plasma luteinizing hormone (LH) as well as plasma and testicular testosterone levels were weakly (r = 0.64, 0.68, and 0.65, respectively), but significantly (P less than 0.05), correlated with cell size. Plasma and testicular testosterone were correlated with the total volume of pinocytotic vesicles (r = 0.74 and 0.68, respectively). The data indicate that although the rat myoid cell possesses receptors for testosterone, there are few structural manifestations of the hamster myoid cell that correlate well with testosterone levels. Thus, the hamster myoid cell differs from two other hormone-responsive somatic cells in the testis, the Sertoli cell and the Leydig cell, that show dramatic structural alterations with changes in gonadal activity and striking correlations of structural features with functional measures.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative study in twelve mammalian species of volume densities, volumes, and numerical densities of selected testis components, emphasizing those related to the Sertoli cell.

Morphometric studies were performed on 12 mammalian species (degu, dog, guinea pig, hamster, human, monkey, mouse, opossum, rabbit, rat, stallion, and woodchuck) to determine volume density percentage (Vv%), volume (V), and numerical density (Nv) of seminiferous tubule components, especially those related to the Sertoli cell, and to make species comparisons. For most species, measurements were taken both from stages where elongate spermatids were deeply embedded within the Sertoli cell and from stages near sperm release where elongate spermatids were in shallow crypts within the Sertoli cell. Montages, prepared from electron micrographs, were used to determine Vv% of Sertoli cell components in seminiferous tubules. Excluding the tubular lumen, the Sertoli cell occupied from a high of 43.1% (woodchuck) to a low of 14.0% (mouse) of the tubular epithelium. There was a strong negative correlation (r = -0.83; P less than 0.005) of volume occupancy of Sertoli cells with sperm production. Nuclear volume, as determined by serial reconstruction using serial thick sections, ranged from a high of 848.4 microns 3 (opossum) to a low of 273.8 microns 3 (degu). There was no correlation (r = 0.02) of nuclear volume with volume occupancy (Vv%) in the tubule. Sertoli cell volume was determined by point-counting morphometry at the electron-microscope level as the product of the nuclear size and points determined over the entire cell divided by points over the nucleus. Sertoli cell V ranged from 2,035.3 microns 3 (degu) to 7,011.6 microns 3 (opossum) and was highly correlated (r = 0.85; P less than 0.001) with nuclear size. However, there was no significant correlation between the Sertoli cell size (V) and volume occupancy (Vv%; r = 0.13) or sperm production (r = -0.21). Stereological estimates of the numerical density (Nv) of Sertoli cells ranged from a high of 101.9 x 10(6) (monkey) to a low of 24.9 x 10(6) (rabbit) cells per cm3 of testicular tissue. There was no correlation of numerical density of Sertoli cells with sperm production (r = 0.002). A negative correlation was, however, observed between the numerical density of the Sertoli cells and the Sertoli cell size (r = -0.79; P less than 0.002). Data from the present study are compared with those previously published. This is the first study to compare Sertoli cell morphological measurements using unbiased sampling techniques. Morphometric data are provided which will serve as a basis for other morphometric studies.

Changes in the testicular microvasculature during photoperiod-related seasonal transition from reproductive quiescence to reproductive activity in the adult golden hamster.

The structure and permeability of the testicular microvasculature in the adult golden hamster during different phases of gonadal activity was examined. After 12 weeks of exposure to a short photoperiod (SD; 6L:18D), maximal testicular regression with over tenfold reduction in size was achieved as compared with active testes of animals maintained in long photoperiod (LD; 16L:8D). Testes weights and volumes in regressed testes were not significantly different from the values measured in animals undergoing early recrudescence (transfer from SD to LD for 1 or 2 weeks). The volume density of testicular blood vessels and their lumina did not differ significantly between fully gonadally active, fully regressed animals or those transferred from SD to LD for 2 weeks. However, in animals transferred for 1 week from SD to the stimulatory LD, the density of testicular blood vessels and vascular permeability to the endothelial tracer horseradish peroxidase were significantly increased, as compared to all other groups. An angiogenic process was observed by electron microscopy, which was initiated in the regressed gonad and which was prominent 1 week after transfer from SD to LD, but it was less conspicuous 2 weeks after transfer from SD to LD. The angiogenic process was characterized by activated developing blood vessels with a basal lamina and a lumen, which was formed by dilatation of an interendothelial space. There were two types of endothelial sprouts: the first with one layer of basal lamina, indicating true neovascularization, and the second with additional layers of basal lamina. In the latter, the presence of a superfluous basal lamina indicates that regeneration takes place along the path of old vessels. In fully regressed animals isolated basal-lamina-like structures were observed. Basal laminae are known to survive endothelial cell death, and these basal laminae later appear to serve as a scaffold for regeneration of new vessels. The rapid renewal of the testicular microvasculature under physiological stimuli suggests that the recrudescing testis of the golden hamster can be viewed as a physiological model of angiogenesis.

Morphometric studies on hamster testes in gonadally active and inactive states: light microscope findings.

This study provides quantitative information on the testes of seasonally breeding golden hamsters during active and regressed states of gonadal activity. Seminiferous tubules occupied 92.5% of testis volume in adult gonadally active animals. Leydig cells constituted 1.4% of the testicular volume. The mean volume of an individual Leydig cell was 1092 microns 3, and each testis contained about 25.4 million Leydig cells. The volume of an average Sertoli cell nucleus during stage VII-VIII of the cycle was 502 microns 3. A gram of hamster testis during the active state of gonadal activity contained 44.5 million Sertoli cells, and the entire testis contained approximately 73.8 million Sertoli cells. Testes of the hamsters exposed to short photoperiods for 12-13 wk displayed a 90% reduction in testis volume that was associated with a decrease in the volume of seminiferous tubules (90.8% reduction), tubular lumena (98.8%), interstitium (72.7%), Leydig cell compartment (79.3%), individual Leydig cells (69.7%), Leydig cell nuclei (50.0%), blood vessels (85.5%), macrophages (68.9%), and Sertoli cell nuclei (34.1%). The diameter (61.1%) and the length (36.8%) of the seminiferous tubules were also decreased. Although the number of Leydig cells per testis was significantly lower (p less than 0.02) after short-photoperiod exposure, the number of Sertoli cells per testis remained unchanged. The individual Sertoli cell in gonadally active hamsters accommodated, on the average, 2.27 pre-leptotene spermatocytes, 2.46 pachytene spermatocytes, and 8.17 round spermatids; the corresponding numbers in the regressed testes were 0.96, 0.20, and 0.04, respectively. The striking differences in the testicular structure between the active and regressed states of gonadal activity follow photoperiod-induced changes in endocrine function and suggest that the golden hamster may be used as a model to study structure-function relationships in the testis.

Quantitative analysis of germ cells and Leydig cells in rat made infertile with gossypol.

This study utilized improved methods of fixation and plastic embedding to quantitatively evaluate the effects of gossypol on germ cells and Leydig cells in testes of rats made infertile with gossypol. Rats were fed by gavage with 10, 20 or 30 mg/kg per day of gossypol for 9 weeks; control animals received the vehicle alone. Numbers of A spermatogonia, preleptotene and pachytene spermatocytes, and step 7 or 8 spermatids per Sertoli cell were counted in stages VII-VIII of the cycle of the seminiferous epithelium. Although high doses (30 mg/kg) of gossypol produced a significant decrease in the relative number of germ cells compared with vehicle-treated controls, no significant deviation in the relative number of germ cells was noted between controls and rats made infertile with 10 or 20 mg/kg/day of gossypol. Stereologic techniques were used to assess the changes in the Leydig cells. No significant deviation in the Leydig cell morphology, cell number, or cell volume was noted as a result of gossypol treatment at the dose levels employed. It appears that germ cell depletion, such as that caused by high doses of gossypol, is not mediated by a change in Leydig cell function. The present report emphasizes the importance of studies to determine the minimal effective doses for gossypol's antifertility activity in animal models as well as in man.

Effects of diazacholesterol dihydrochloride (SC-12937), an avian antifertility agent, on rat testis.

The present study was undertaken to evaluate the effectiveness of an avian chemosterilant, 20, 25-diazacholesterol dihydrochloride (SC-12937), on the rat testis. Adult male rats were injected intraperitoneally with 10 mg (Group 1) or 30 mg (Group 2) of SC-12937/kg/d or with vehicle alone (Group 3) for 10 days, and were killed 24 hours after the last injection. A wide range of variation in the appearance of affected seminiferous tubules was observed in the testis of SC-12937-treated rats at both dose levels. This ranged from apparently normal-looking seminiferous tubules to almost completely atrophied tubules with no cells. Affected tubules exhibited intraepithelial vacuoles of varying size, multinucleated giant cells, germ cell exfoliation, and tubular atrophy. The presence of severely damaged and entirely normal seminiferous tubules adjacent to one another in the same section was noteworthy. The changes appeared to be dose-related. A greater number (34.6%) of affected tubules were observed in rats receiving 30 mg of SC-12937 compared with the ones receiving 10 mg of this compound (19.6%). The Sertoli cells also were affected by this drug and exhibited cytoplasmic vacuolation, a marked increase in the accumulation of lipid droplets and myeloid bodies. Necrotic Sertoli cells also were observed in the severely affected tubules. The possible mechanism of antispermatogenic action of SC-12937 in rats has been discussed briefly.

Effect of DL-6-(N-alpha-pipecolinomethyl)-5-hydroxyindane maleate (PMHI) on the reproductive system of a wild rat, Bandicota bengalensis. II. Epididymis and accessory sex glands.

The effect of PMHI on the epididymis and accessory sex glands (ventral prostate, seminal vesicle, and coagulating gland) was studied in a wild rodent, the bandicoot rat. Animals were given a single subcutaneous injection of PMHI (150 mg/kg body wt) and were killed 2, 10, or 30 days later. Treatment of PMHI resulted in severe alterations in the epididymis of the bandicoot rat with no apparent effect on accessory sex glands except for a transitory decrease in epithelial height of the seminal vesicle and in peripheral acini of the ventral prostate. Changes in the epididymis included a marked involution of the caput, Zone I in particular, formation of sperm granulomata, and the distension of the "clear" cells in the caudal portion of the duct. Sperms progressively disappeared from the lumen and by Day 30, the cauda epididymis became completely azoospermic. It appears that the epididymal lesions produced by this compound may play a contributory role to induce infertility in the bandicoot rat.