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C Perreau

Publications and source records attributed to C Perreau.

At least 37 records · Page 2Linked to original sources
PubMed1991

Age-related changes in the function of the pituitary-gonadal axis in a sterile male rat mutant (hd/hd).

Testicular growth is depressed in the genetically sterile male rat (hd/hd) relative to its LE phenotype littermates (by 50% and 73% at 27 and 90 days of age, respectively). Within the hd/hd testis, both the tubular and seminiferous tubule tissues are affected by the mutation. In addition, there is significantly less germ cell production from the primary spermatocyte stage of spermatogenesis onwards and the total number of Sertoli cells observed is less. In the intertubular tissue, the total volume and the total number of Leydig cells per testis is significantly less, but the mean volume of an average Leydig cell is not modified. The serum gonadotropin levels are higher in the hd/hd rat, whereas from 40 days of age onwards the level of testosterone is lower. The FSH and LH binding affinity constants are unchanged by the mutation; however, the total number of FSH binding sites per 10(6) Sertoli cells is lower while that of LH per 10(6) Leydig cells is greater. Indeed, it is likely that the lesser concentration of serum testosterone in the hd/hd rat is a result of a smaller number of Leydig cells since their individual function is not modified. The testicular androgen binding protein (ABP) content and the ABP output towards the epididymis are lower as a consequence of both a lesser number and an altered function of the Sertoli cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1991

The form and function of the Leydig cells in hypophysectomized rams treated with pituitary extract when spermatogenesis is disrupted by heating the testes.

The morphology and in-vivo function of the Leydig cells were studied in rams when spermatogenesis had been disrupted by a single exposure of the testes 20 days earlier to a temperature of about 42 degrees C for 45 min. To avoid complications due to changed negative feedback from the testes to the pituitary with consequent changes in the degree of gonadotrophic stimulation, ten of the animals (five heated and five unheated) were surgically hypophysectomized when the testes were heated and then treated twice daily with pituitary extract. Six intact rams (three heated and three unheated) were also studied. The heat-affected testes were about half the size of the unheated testes, and blood plasma flow was closely related to testis weight. There were no differences in the testosterone concentrations in spermatic venous blood, testicular lymph or rete testis fluid, or in oestradiol in spermatic venous plasma from heated or unheated testes. Consequently, testosterone secretion by the heat-affected testes was markedly reduced, and the concentrations in jugular blood were also lower in the heat-affected rams than in controls. The volume of the interstitial tissue was less in absolute terms in the heat-affected rams, but it made up a greater fraction of the testes. The absolute volume of the blood plus lymph vessels, and their fraction of the interstitial tissue were lower in the heat-affected testes, although there was no effect on their volume as a fraction of the whole testis. The heat-affected testes of the hormone-treated rams had fewer Leydig cells, but each cell was larger; no equivalent difference was found in the intact rams. However, the dose of pituitary extract chosen was somewhat excessive, as there were higher than normal concentrations of FSH, LH and testosterone in jugular blood plasma, of testosterone and oestradiol in testicular venous blood plasma and of testosterone in rete testis fluid in the hormone-treated hypophysectomized rams. The testes of the unheated hypophysectomized rams increased in size by about 20% during treatment with pituitary extract, although testicular blood plasma flow was lower per unit weight of testis. The absolute volume of each Leydig cell and the total volume in absolute terms and as a fraction of the interstitial tissue was greater in the hormone-treated than in the untreated rams, but not the volume as a fraction of the whole testis. The total number of Leydig cells was higher in the hormone-treated unheated rams than in all the other rams taken together.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Comparisons of endocrinological and testis parameters in 18-month-old Ile de France and Romanov rams.

Endocrinological and testis parameters of adult 18-month-old Ile de France (IF) and Romanov (Ro) rams were compared during sexual season. Testis weights, total volumes of intertubular tissue, and of blood and lymph vessels, total seminiferous tubule length, rete testis flow rate and daily production of germ cells were significantly higher in IF than in Ro rams. These variations originated from differences in Sertoli cell numbers, which were established before puberty. When daily productions of germ cells, of ABP or of RTF were expressed per Sertoli cell, they were higher in Ro than in IF rams. Quality of spermatids, as measured by their cellular size prior to elongation, was lower in Ro than in IF. The number of FSH-binding sites per Sertoli did not differ between the two breeds but FSH plasma levels were higher in Ro than in IF rams. Total numbers of Leydig cells per testis, their individual size or their LH-binding capacity did not differ significantly between the two breeds. However, the ratio of mean testosterone upon mean LH plasma levels were greater in Ro than in IF rams while both breeds had identical LH mean plasma levels.

Animals↗
PubMed1990

Evidence for LH-inhibiting activity in ovine peripheral and testicular blood.

Intracellular cyclic AMP and testosterone productions by purified mature rat Leydig cells were stimulated by oLH (25 micrograms/l) 18- and 12-fold, respectively, after a 5-h incubation period. The replacement of the incubation medium by charcoal-treated testicular venous plasma (40%, v/v) from adult rams in the breeding season induced an inhibition of cyclic AMP and testosterone productions (82 and 66%, respectively, of oLH-stimulated values). Testicular arterial plasma is less effective than testicular venous plasma, even when it originates from non-breeding season rams; in that case, testicular venous and arterial plasma strongly inhibit testosterone productions (84 and 67%, respectively of oLH-stimulated values), which probably indicates that the inhibitory activity is higher in the non-breeding season. The addition of peripheral plasma leads to a testosterone production equal to 35 and 65% of the oLH-stimulated values, respectively, for ram blood collected in non-breeding and breeding seasons. The same concentration of ovine testicular lymph or rete testis fluid is without significant effect on cyclic AMP production; however, testosterone is slightly decreased by lymph but enhanced by rete testis fluid. Increasing amounts of venous or arterial testicular blood induce a dose-related decrease of the specific binding of labelled hCG in both rat and ram testicular membranes. This inhibiting factor is present in peripheral and testicular blood of either control or hypophysectomized or castrated rams, is a protein in nature, heat-sensitive, and has an apparent molecular weight higher than 10,000 daltons.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

A parallel between two techniques of extraction of connective tissue macromolecules.

A method of extraction of the collagen and noncollagen proteins from deep dermis of young adult rabbits using a 0.1 M tartaric acid solution was set up. The tartaric acid extraction, together with the preliminary neutral salt extraction, solubilized 95% of the total collagen and 98% of the noncollagen proteins, far more than the 6 M guanidinium Cl solution used for comparison. Elastin was not extracted. Studies on the fibrillation of the extracted collagen in neutral solution at 25 degrees C or on the results of pepsin digestion in acidic solution at +4 degrees C showed that the tartaric acid-extracted collagen was in a nondenatured form, whereas that extracted by guanidinium Cl was largely denatured. Polyacrylamide gel electrophoresis (PAGE) indicated that most of the collagen was of type I and that many noncollagen proteins were present, mostly in the molecular weight range of 40 kDa. Bidimensional PAGE gave a reproducible pattern of these noncollagen proteins, showing that several additional proteins were present in tartaric acid extracts and not in guanidinium chloride extracts.

Animals↗
PubMed1988

Effect of continuous low-dose gamma-irradiation on rat Sertoli cell function.

Continuous low-dose gamma-irradiation of mature rats induced a progressive degeneration of the germ cells. Blood FSH increased by 127, 176 and 214%, respectively, after 55, 70 and 85 days of treatment when compared to FSH levels in control rats (8.50 +/- 0.60 ng/ml); conversely, serum LH and testosterone levels were unchanged. The Sertoli cell function was affected by the treatment from 70 days on, as attested by androgen binding protein (ABP) and transferrin secretions which diminished 35-40%. Serum ABP levels were not altered, whatever the duration of irradiation, even though epididymal ABP contents (as well as concentrations) diminished 34-60% when compared to those of the controls. Moreover, in purified Leydig cells, LH-stimulated intracellular cAMP levels, which were decreased by seminiferous tubule medium (STM) from control rats, were enhanced in presence of STM from treated animals. Testosterone output was stimulated 9-fold in presence of oLH and further increased (46-76%) from stages XIV-V by STM prepared from control and irradiated rats, respectively. After 85 days the STM effects on both cAMP and testosterone syntheses were zero. These results demonstrate a probable alteration of Sertoli cell function after irradiation, but also a role of the germ cells in the regulation of the synthesis of ABP, transferrin and Sertoli cell paracrine factors.

Androgen-Binding Protein↗
PubMed1987

Testicular growth and hormonal parameters in the male Snell dwarf mouse.

Dwarf mice show delayed testicular growth and their adult testis weights are half the normal value. The aims of the present work were firstly, to compare the developmental profiles of plasma gonadotropins and of testicular cell multiplication and differentiation in dwarf vs normal mice and secondly, to determine the effect of hMG supplementation on dwarf mice. In the dwarf mice no pubertal rise in plasma FSH was observed, and the adult values remained very low when compared with those of normal mice; plasma LH decreased after 40 days of age and remained equal to half the normal values. In adults, testicular testosterone content was greatly increased in dwarf mice compared with normal mice, whereas plasma testosterone and accessory gland weights were reduced. At 24 days of age, the total numbers per testis of Leydig and Sertoli cells were reduced in dwarf vs normal mice, whereas in adult mice their differentiation, but not their total numbers, was reduced. This resulted in lower daily production of leptotene primary spermatocytes and of round spermatids in dwarf than in normal mice. hMG supplementation promoted Leydig and Sertoli cell multiplication, but did not produce full differentiation, resulting in increased daily production of round spermatids. In conclusion, in adult dwarf mice a deficiency in plasma gonadotropins prevents full differentiation of Leydig and Sertoli cells without affecting the number of these cells.

Animals↗
PubMed1985

Effects of flutamide or of supplementation with testosterone in prepubertal male rats prenatally treated with busulfan.

Male rats treated prenatally with busulfan in order to render them aspermatogenic were treated between 23 and 38 days of age either with testosterone, or flutamide. In such aspermatogenic rats, testosterone supplementation stimulated the growth of accessory sex organs, markedly decreased the secretion of gonadotrophins (by 61% for LH and 83% for FSH), decreased testicular weight (-60%) as well as all parameters relating to testicular histology. Flutamide treatment decreased the weight of accessory sex organs, stimulated the secretion of both LH (+200%) and FSH (+63%) by inhibition of the negative feedback of testosterone; endogenous testosterone secretion was increased by 363%. Testicular weight was increased by 44% and the total volume and the cytoplasmic and nuclear area of Leydig cells were increased by 254 and 28%, respectively, but their number per testis was unchanged. The number of Sertoli cells per testis was increased by 49%, but their nuclear area was not modified. In aspermatogenic prepubertal rats, the large increase in plasma FSH demonstrated that FSH release was partly under the control of inhibin, secreted by Sertoli cells when germinal cells were present. Nevertheless, FSH levels after testosterone (inhibition) or flutamide treatment (stimulation) clearly demonstrated that, in the growing rat, FSH secretion is also partly dependent on the negative feedback of testosterone. In the absence of germ cells, FSH was able to re-initiate Sertoli cells mitoses, but not their functional activity. LH secretion was solely controlled by the negative feedback of androgens and, even in the absence of germinal cells, Leydig cells were able to respond to LH stimulation by an increase in testosterone secretion.

Anilides↗
PubMed1985

Photoperiodic variations of somatic and germ cell populations in the Soay ram testis.

Seasonal changes in the Leydig, Sertoli and stem cells (undifferentiated A0 and cyclic A1) spermatogonia and the daily spermatid production were analysed in the testes of adult Soay rams exposed to short days (8L:16D) or long days (16L:8D) for 12 weeks. The total numbers of Leydig, Sertoli and stem cells (A0 + A1) were not affected by the treatments, but the size of the Leydig and the Sertoli cells, the efficiency of spermatogenesis (i.e. the number of male gametes produced by an A1 spermatogonium) and the daily sperm production were all significantly reduced in the rams exposed to long days. There was a positive correlation between the concentration of FSH and testosterone and many of the cytological changes consistent with a causal role for these hormones in mediating the effects of photoperiod on the testicular function in the ram.

Animals↗
PubMed1984

Relationship between rete testis fluid secretion and testicular structure in the ram.

A rete testis cannulation technique was used to compare the secretion of rete testis fluid with the production of spermatozoa and histological testicular parameters in Ile-de-France rams. Thirteen testes were cannulated and rete testis fluid variables were compared to histological variables of the same testis. The rate of flow of rete testis fluid was significantly (P less than or equal to 0.05%) correlated with testicular size, the area of the walls of the seminiferous tubules and the volume of the Leydig cells. These two latter factors accounted for 66% of the variation in the flow of rete testis fluid.

Animals↗
PubMed1984

Variations in the plasma levels of gonadotrophin and testosterone and in Leydig and Sertoli cell populations between birth and adulthood in Romanov lambs born in spring or autumn.

Plasma gonadotrophin and testosterone levels during the prepuberal period have been compared in spring and autumn-born Romanov lambs; the somatic and germ cell populations of these lambs have also been compared at birth and at adulthood. At 1 and 3 months of age, the number of LH pulses per hour and mean plasma LH levels were significantly higher in spring than in autumn lambs. In adults, no such differences were observed. Similarly, at 1 and 3 months of age, the number of testosterone pulses per hour was higher in spring than in autumn animals. In the prepuberal period, the ratio of the levels of mean plasma testosterone to LH was higher in autumn than in spring lambs. The highest ratio was observed in adults but there was no variation according the season of birth. At 1 month of age, mean plasma FSH levels were higher in autumn than in spring lambs; this difference did not persist later on. Despite these endocrinological differences, testis weight, total Sertoli and Leydig cell numbers per testis, total number of gonocytes per testis at birth and daily production of round spermatids per testis in adult rams were similar in spring and autumn-born animals.

Animals↗
PubMed1984

A comparison of the changes in LH, FSH and testosterone in spring-born ram lambs of two different breeds.

LH, FSH and testosterone variations were compared during the prepubertal period in Romanov and Ile-de-France ram lambs born in the spring. Mean plasma LH levels increased significantly between the 1st and 8th week of age in the Romanov and between the 1st and 12th week of age in the Ile-de-France. At 1 month of age, the number of LH and testosterone pulses per hour was higher in Romanov than in Ile-de-France lambs. The mean plasma testosterone levels, higher in the Romanov, increased from 1 week of age onwards. Mean plasma FSH levels increased from the first neonatal week till the 8th week in the Romanov and till the 12th week in the Ile-de-France. The levels of FSH did not differ significantly between the two breeds. The higher and earlier secretion of LH and production of testosterone in the Romanov might be a cause of its better reproductive performance.

Age Factors↗
PubMed1984

Effect of prenatal treatment with busulfan on the hypothalamo-pituitary axis, genital tract and testicular histology of prepubertal male rats.

Female Wistar rats were treated with busulfan or with solvent on Day 20 of pregnancy. Thirty male offspring of each group were killed at 38 days of age. In busulfan-treated rats, compared to controls, hypothalamic LH-RH content was decreased by 52%, whereas pituitary LH and FSH concentrations were increased by 60 and 43% respectively. Plasma LH and FSH were increased by 112 and 275% respectively. Prolactin concentrations were not changed, but plasma testosterone concentration was decreased by 48%. The total number of Leydig cells per testis was decreased by 52%, and LH binding sites per testis were decreased by 70%. The total number of Sertoli cells was decreased by 44%, while FSH binding sites per testis were decreased by 62%. Spermatogenesis was practically absent after prenatal exposure to busulfan. These data demonstrate that on Day 20 of pregnancy all the dividing cells in the fetal testes were depleted by an antimitotic treatment. The stimulation of the hypothalamo-pituitary axis could have been partly induced by the decrease in testosterone production, and by the aplasia of germ cells involving modifications of the remaining Sertoli and Leydig cells.

Animals↗
PubMed1984

Effect of season of birth and of hemicastration on the histology of the testis of 6-month-old lambs.

Season but not hemicastration affected the cellular composition of the testis. Despite similar weight, the testicular histology differed markedly with season of birth. The number of Leydig cells and of Sertoli cells was greater in summer- than in winter-born lambs by factors of 2 and 1.5 respectively. Similarly the number of spermatogonia and their rate of production increased substantially in summer-born lambs. The rate of spermatid production was affected by both hemicastration and season. Season of birth exerted more modifications to testicular histology than did hemicastration.

Animals↗
PubMed1983

Endocrinological and histological changes induced by flutamide treatment on the hypothalamo-hypophyseal testicular axis of the adult male rat and their incidences on fertility.

Adult male Wistar rats were treated with flutamide from 90 to 105 days of age. In a first experiment, testis and accessory sex organs were weighed. In the same animals, hypothalamic LRH content, pituitary gonadotrophin concentrations, plasma LH, FSH, prolactin and testosterone levels, and testicular gonadotrophin receptors were evaluated. In a second experiment, fertility was tested at the end of the treatment, and histology of the testis was performed. All the results were compared to those obtained in control animals of the same age. Accessory glands of genital tract were significantly lower in flutamide-treated animals (P less than 0.01). Hypothalamic LRH, pituitary and plasma FSH, and prolactin concentrations were unchanged, while pituitary and plasma LH level and especially plasma testosterone concentration were increased (P less than 0.001). Flutamide therefore exerted a strong inhibition on testosterone-dependent organs, and blocked the negative feedback of testosterone on the hypothalamo-pituitary axis, increasing the LH levels. Testis weight, intertubular tissue volume, total number and total volume of Leydig cells/testis, as well as total length and diameter of seminiferous tubules were unchanged in flutamide treated rats. However number of LH receptors/Leydig cell, nuclear area of Sertoli cells, number of FSH receptors/Sertoli cell, number of leptotene spermatocytes and of round spermatids per cross section, and yield of spermatogonial divisions were decreased after treatment. Flutamide treatment also decreased fertility by 48% (P less than 0.05). This lowered fertility is likely the result of impaired spermatogenesis and/or a dysfunction of accessory sex organs.

Anilides↗