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C Jean

Publications and source records attributed to C Jean.

At least 19 recordsLinked to original sources
PubMed1992

Adrenodemedullation does not impair the beneficial effect of physical training in streptozotocin-diabetic rats.

This study was designed to ascertain if the improvement in glucose homeostasis found in diabetic animals submitted to physical training is due to an increased secretion of epinephrine by the adrenal medullae. Male Wistar rats were surgically adrenodemedullated (ADM group) or sham-operated (SHAM group). After a 3-week recovery period, a bolus of streptozotocin (40 mg/kg) was injected intravenously (IV), and the animals presenting 1 week later with a blood glucose value between 14 and 22 mmol/L were retained in the protocol and randomly assigned to a sedentary (SHAM-DS and ADM-DS) or trained (SHAM-DT and ADM-DT) group. Physical training was done on a treadmill according to a 10-week progressive program. An IV glucose tolerance test (0.5 g/kg) was performed in previously cannulated rats, 64 hours after the last bout of exercise. Pancreatic insulin and glucagon content was also determined. In sedentary diabetic rats, adrenodemedullation had no effect on plasma glucose, insulin, or glucagon levels, neither in the basal state nor following the glucose load. Basal glucose levels were diminished by training in both SHAM (16.1 +/- 1.5 v 21.8 +/- 0.4 mmol/L; P less than .01) and ADM (12.4 +/- 1.7 v 21.1 +/- 1.2 mmol/L; P less than .01) groups, with values lower in ADM-DT than in SHAM-DT rats (P less than .05). After glucose loading, the glucose levels were significantly lower (P less than .01) throughout the test in both SHAM-DT and ADM-DT rats than in their sedentary counterparts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗
PubMed1992

The genomic organization and DNA sequence of the mouse vas deferens androgen-regulated protein gene.

The gene for mouse vas deferens protein (MVDP) is expressed, under androgenic control, exclusively in the epithelial cells of the deferent duct. As a first step in correlating cell-specific and hormonal regulations with the structure of the gene, the complete sequence of the MVDP gene (11 kb) and 0.5 kb of the 5' flanking region have been determined. The size range for the 10 exons is 78 to 168 bp, whereas that of introns is 292 to 2833 bp. A major site of transcription is located on an A residue 46 nucleotides upstream from the A of the ATG initiation codon. A TATA (CATAA) box, a CAAT box, a GC-rich motif and a (5'-TGTTCT-3') element that closely resembles the consensus sequence of the androgen response elements are present in the 5' flanking region of the MVDP gene.

Aldehyde Reductase↗
PubMed1992

In vitro androgenic induction of a major protein in epithelial cell subcultures from mouse vas deferens.

Pure epithelial cell cultures, obtained from primary culture of vas deferens tissue collected from 20- to 30-day-old mice, were amplified by subculturing the cells over 3T3 feeder layer in a serum-free defined medium. Adhesion and proliferation of epithelial cells did not require androgens, but a minimal concentration of 5.10(-7) M hydrocortisone. In that system, epithelial cells expressed cytokeratin but failed to produce the tissue specific mouse vas deferens protein (MVDP) in response to androgens. Various culture procedures and medium compositions were assayed for induction of MVDP expression. Culture onto microporous membrane inserts, which allow polarization of cells, is absolutely required for androgenic induction of MVDP. Androgen action did not require the presence of hydrocortisone, insulin, triiodothyronine, pituitary extracts, epidermal growth factor and acetylcholine. A minimal supplemented medium was then defined in which the expression of MVDP by epithelial cells in response to androgens was dose dependent. It has also been shown that this response at each concentration of dihydrotestosterone was heterogeneous at individual cell level. Highly reproducible results were obtained from epithelial cell cultures between 8th to 16th passages, showing that subcultured cells have maintained their ability to differentiate and express specialized functions.

Acetylcholine↗
PubMed1991

Androgen dependence during development of the mouse vas deferens protein mRNA.

The mRNA encoding a major protein of the mouse vas deferens (MVDP) was first detected in 10-day-old males and its concentration increased sharply between 10 and 20 days, reaching adult levels at 40 days. This increase was not associated with an increase in tissular androgen concentrations. In 30-day-old mice castrated at birth or treated with cyproterone acetate over 29 days, MVDP mRNA levels were not abolished and were similar to those measured in 10- and 20-day-old controls. These results suggest that the neonatal expression of MVDP gene is independent of androgens. In addition, precocious accumulation of MVDP mRNA could be induced by injection of excess amounts of androgens in 20- but not in 10-day-old animals. The prepubertal increase in MVDP mRNA levels is androgen-dependent but other factors may be necessary for MVDP expression.

Aldehyde Reductase↗
PubMed1991

Plasma epinephrine in chronically adrenodemedullated rats: lack of response to acute or chronic exercise.

Even if it is well established that epinephrine is a hormone originating from the adrenal medullae, the reappearance of circulating epinephrine has been reported in rats a few days after adrenodemedullation. To verify if the extra-adrenal tissue responsible for this epinephrine production can be stimulated, sham-operated or adrenodemedullated rats, either trained or kept sedentary, were submitted to an acute exercise stimulation test. Blood sampling was done before and after the test in precannulated rats for the determination of plasma epinephrine, norepinephrine, and corticosterone levels. Basal epinephrine levels were significantly reduced in trained and sedentary adrenodemedullated rats compared with their sham-operated counterparts. In response to exercise, there was no significant rise in epinephrine levels in both groups of adrenodemedullated rats. The norepinephrine levels in the basal state and in response to exercise were not altered by adrenodemedullation nor by physical conditioning. Basal corticosterone levels were similar between adrenodemedullated and sham-operated animals, either trained or kept sedentary. In response to exercise, corticosterone levels increased significantly in each group of rats but to a lesser extent in both groups of adrenodemedullated animals. These data indicate that the extra-adrenal epinephrine secretion that develops in the absence of adrenal medullae is not influenced by acute exercise nor by physical training.

Adrenal Medulla↗
PubMed1991

Lack of expression of the mRNA encoding a major protein of the mouse vas deferens after neonatal exposure to oestrogens.

We have previously characterized an androgen-inducible secretory protein from the mouse vas deferens (MVDP), and a cDNA to its mRNA has been obtained. This report describes altered MVDP gene expression after neonatal exposure to oestrogens. As shown by immunohistochemistry and Western blot analysis, MVDP was missing in the vas deferens from adult mice neonatally exposed to oestrogens. Northern blot analysis showed that the expression of MVDP mRNA was also suppressed. Exogenous testosterone was unable to stimulate MVDP production (either message or protein) in neonatally oestrogenized males. The results suggest that the alterations in gene expression in the oestrogen-exposed vas deferens reflect changes in the programme of differentiation of the organ itself.

Aldehyde Reductase↗
PubMed1991

[Characterization of cDNA and of the gene corresponding to androgen-dependent protein of the vas deferens in mice].

A 34.5 kDa abundant protein named MVDP (Mouse Vas Deferens Protein) is produced and secreted by vas deferens epithelial cells from adult mice. Steady-state levels of MVDP and its 1.4 kb mRNA are markedly decreased 30 days after castration. Testosterone treatment for 2 weeks is necessary to completely reverse the effect of castration. A cDNA encoding MVDP has been cloned and entirely sequenced. A protein of 316 amino acids encoded by an open reading frame of 948 nucleotides shows 82% homology with a human placental aldose reductase. A gene corresponding to MVDP cDNA has been recently isolated ans characterized. The gene extends over approximately 11 kb and consists of 10 exons. Its structure is very similar to that of the human aldose reductase gene. The promotor region of MVDP gene contains an androgen responsive element consensus located 97 nucleotides upstream the transcription initiation site.

Aldehyde Reductase↗
PubMed1991

Developmental and hormonal regulation of specific proteins in mouse vas deferens and seminal vesicle.

This paper is concerned with hormonal regulation of the developmental pattern of major proteins of the mouse vas deferens (mouse vas deferens protein: MVDP, 34.5 kD) and seminal vesicle (15.5, 120 and 140 kD) whose expression is regulated by testosterone at adulthood. The ontogeny of these proteins, studied by SDS-polyacrylamide gel electrophoresis, appeared to be uncoordinated. MVDP was not accumulated until animals were 20 days old and its concentration increased sharply from 20 to 30 days of age. In seminal vesicle, the 15.5 kD protein did not accumulate before day 30 whereas 120 and 140 kD proteins appeared and accumulated between 30 and 40 days. In 30-day-old mice castrated at birth or treated with cyproterone acetate over 29 days, MVDP levels were not abolished and were similar to those measured in 20-day-old males. Testosterone administration, from 1 to 10 days of age, did not induce precocious expression of MVDP. These results suggest that the neonatal expression of MVDP is independent of androgens. In seminal vesicle, the first expression of the 3 proteins studied was dependent upon testicular androgens as shown by neonatal castration and injection experiments. The marked increase in the levels of the 4 proteins studied, during sexual maturation, was not associated with quantitative or qualitative changes in tissular androgen concentrations, suggesting that other factors may be necessary for protein expression. Whereas thyroxine may induce a precocious accumulation of MVDP, prolactin had no stimulatory effect on the accumulation of proteins from vas deferens and seminal vesicle. The results suggest that during sexual maturation gene activation by androgens was progressive.

Aldehyde Reductase↗
PubMed1990

Androgen regulation of the mRNA encoding a major protein of the mouse vas deferens.

A cDNA encoding the major mouse vas deferens protein (MVDP) has been cloned and characterized. Using in situ hybridization we have identified the epithelial cells of the vas deferens as the site of synthesis of MVDP mRNA. Northern blot analysis suggests that a high level of an mRNA corresponding to the MVDP gene is present in the mouse vas deferens whereas the amount of MVDP mRNA in vas deferens of other species studied, or in other mouse tissues, even if present, is undetectable. Steady-state levels of MVDP mRNA are decreased by approximately 42% 3 days after castration but a significant hybridization signal is still observed even 50 days after castration. Testosterone treatment for 2 weeks is necessary to completely reverse the effect of castration. In vitro transcription assays on isolated nuclei showed that the hormonal induction of the MVDP gene is achieved mainly at transcriptional level.

Aldehyde Reductase↗
PubMed1990

Neonatal exposure to oestrogens alters the protein profiles and gene expression in the genital tract of adult male mice.

After neonatal administration of supraphysiological doses of oestradiol, the concentration of tissue proteins, in adult mice, was significantly reduced by 39, 45 and 56% in epididymis, vas deferens and seminal vesicle respectively. The protein profiles showed persistent alterations. In epididymis, 4 protein bands were differentially increased (14.4, 43 and 67 kDa) or reduced (24 kDa) in oestrogenized males. In vas deferens, 4 proteins were increased (14.4, 49,67 and 76 kDa) and one (34 kDa) virtually absent. In seminal vesicle, about 20 proteins of varying molecular weights (12-140 kDa) were differentially increased or decreased. Testosterone substitution, at adulthood, was unable to reverse these effects. Treatments with oestradiol during adult life induced persistent alterations in the protein profiles of the 3 organs but, in contrast to neonatal treatment, these alterations could be reversed by androgen therapy. A cDNA library has been constructed with RNA prepared from adult seminal vesicle and screened by differential hybridization. Neonatal oestrogenization strongly reduced the abundance of some mRNA species. Eleven recombinants containing putative oestrogen-sensitive sequences were isolated. Two of them, having an insert of about 500 base pairs, were used for dot-blot hybridization. Results showed that the two clones contained sequences which were differently regulated by androgens.

Aging↗
PubMed1990

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Aged↗
PubMed1979

Percentage binding of testosterone and dihydrotestosterone and unbound testosterone and dihydrotestosterone in rabbit maternal and fetal plasma during sexual organogenesis.

The percentages of bound testosterone (17 beta-hydroxy-4-androsten-3-one; T) and dihydrotestosterone (17 beta-hydroxy-5 alpha-androstan-3-one; DHT) and their unbound concentrations were determined in pregnant rabbits and their fetuses from the 18th day of gestation to birth. T and DHT were also measured in fetal testes. In the testis, the total T/total DHT ratio, very high at 22 days (73.7 +/- 15.2), decreased until birth (6.7 +/- 0.8). In male fetuses the concentrations of total and unbound circulating T and DHT were always low and did not show any peak during sexual organogenesis. The percent binding of T (from 73.0 +/- 0.5 to 77.6 +/- 0.6) and DHT (from 76.5 to 83.7 +/- 1.1) in fetuses were similar in both sexes and significantly lower than those measured in mothers (T: from 87.2 +/- 0.6 to 91.6 +/- 0.9; DHT: from 87.3 +/- 0.9 to 93.8 +/- 0.9).

Animals↗
PubMed1979

Effect of luteinizing hormone-releasing hormone on plasma testosterone in immature and adult male rabbits.

1 microgram/100 g body weight of synthetic luteinizing hormone-releasing hormone (LHRH) was administered to immature (25, 35 and 55 days of age) and adult (180 days) male rabbits. Testosterone was measured by radioimmunoassay in plasma samples taken just before and 30 min after LHRH injection. At all stages studied, LHRH significantly increased plasma testosterone. Expressed as a percent of over basal levels, the plasma testosterone was increased by 2,695% at 25 days, 3,955% at 35 days, 6,032% at 55 days and 3,766% at 180 days. Expressed in absolute amounts, the plasma testosterone levels showed an increase of 520 pg/ml at 25 days, 604 pg/ml at 35 days, 1,189 pg/ml at 55 days and 7,596 pg/ml at 180 days. The exact interpretation of the data was difficult since it is dependent on the mode of expression used. Nevertheless, the results support the observation that the hypophyso-testicular axis is functional in immature rabbits.

Age Factors↗
PubMed1979

Changes in the testosterone to dihydrotestosterone ratio in plasma and testes of maturing rabbits.

Testosterone (T) and dihydrostestosterone (DHT) were radioimmunologically assayed in the testes and plasma of rabbits at 1, 10, 20, 40, and 60 days of age and at 3, 4, 5, and 8 months. In the testis (nanograms per 100 mg testis) and plasma (picograms per ml), both hormones are low at birth, reach their maxima between 60--90 days, and then decline and remain low after 120 days. In the testes, the T:DHT ratio is very high from birth (4.2 +/- 0.4) to 60 days (8.8 +/- 1.1). A significant decrease (P less than 0.001) occurs between 60 (8.8 +/- 1.1) and 90 (1.2 +/- 0.1) days. The T:DHT ratio is always less than or equal to unity after 90 days. From 1--60 days, T is the dominant testicular hormone, while the levels of DHT are greater than or equal to those of T after 60 days. The mean value of the plasma T:DHT ratio is always greater than unity from birth (1.7 +/- 0.4) to adulthood (2.6 +/- 0.7). The dominant circulating hormone, at all ages, is T. Our results show that sexual maturation in rabbits is characterized by an inversion of the T:DHT ratio in the testes but not in the plasma.

Aging↗
PubMed1979

Developmental patterns of the testicular response to experimental modifications of circulating androgen levels in the fetal rabbit.

The circulating level of free androgens in fetal and newborn rabbits was reduced by active immunization of mothers against testosterone (T) or was increased by injecting dihydrotestosterone (DHT) into the mothers. After immunization, about 100% of the circulating T and DHT in fetuses was bound. After maternal injection of DHT, the circulating level of this hormone in fetuses was increased 2- to 120-fold. The effects of these treatments were evaluated by determining testicular levels of T, a physiological index of circulating gonadotropin. From 20--23 days of gestation, testicular T content was modified neither by circulating antibodies nor by an increase of blood DHT. The same overloads of circulating DHT, which were ineffective between 20--23 days, significantly reduced testicular T content between 25--29 days. Testicular T content was significantly increased in newborns from immunized mothers. These results suggest that the appearance of the negative feedback action of circulating androgens takes place relatively late, at 24 or 25 days, after differentiation of the genital tract.

Animals↗
PubMed1978

Developmental patterns of plasma and testicular testosterone in mice from birth to adulthood.

Male mice were raised in cohabitation with females from birth to 90 days. Testosterone was measured every 10 days in plasma and testes. Sex difference in body weight was related to the pre-pubertal increase of testosterone levels in males. The weight of the seminal vesicle was positively correlated with circulating testosterone levels between 1 and 40 days but not between 50 and 90 days. Testosterone concentrations in the plasma and testes were high at birth: 630 pg/ml and 58.0 +/- 17.7 ng/100 mg; they subsequently decreased during the first days of life and remained low until day 20:240 +/- 110 pg/ml and 0.1 +/- 0.03 ng/100 mg. The testosterone levels then increased rapidly between days 20 and 30 and especially between 30 and 40 reaching their maxima: 5770 +/- 1720 pg/ml and 123.7 +/- 18.3 ng/100 mg testis. This increase was transitory and testosterone levels fell after day 40. By 90 days, the testosterone levels, 440 +/- 65 pg/ml and 43.2 +/- 5.5 ng/100 mg testis, were comparable to those measured at birth. Plasma testosterone and age were positively correlated between 1 and 40 days, and negatively between 50 and 90 days. The first fertile matings occurred at age 40 days.

Age Factors↗
PubMed1978

The effect of unilateral castration on plasma and testicular testosterone in rabbits from birth to 60 days.

Male rabbits were hemigonadectomized every 10 days from 1 to 50 days of age and were sacrificed 10 days after the operation. Non-operated controls were sacrificed at the same stages. Plasma and testicular testosterone were quantified by radioimmunoassay. Compensatory testicular hypertrophy was not observed in hemicastrated rabbits. Hemicastration has variable effects on testicular and plasma testosterone levels as a function of age. When it is performed at birth, there is a significant increase in testicular and plasma concentrations of testosterone. Similar results are obtained if the operation is performed at 30 days. Unilateral castration performed at 10, 20 and 50 days reduces testicular and plasma testosterone levels. When hemicastration is performed at 40 days or at the adult age, testicular and plasma testosterone levels are not modified.

Age Factors↗