Reproduction, nutrition, developpement最新文献

In a previous study we showed that the administration of gossypol to rats for 34 days caused 2 types of modification of the epididymis: (1) the secretion of carnitine and inositol were reduced in the fluid, (2) the spermatozoa lost their motility and showed major morphological changes (head-flagella dissociation). We wished to clarify the early effects of gossypol on the epididymis. Sprague Dawley adult rats (350 g) were forced fed with gossypol at a dose of 25 mg/kg/day for 17 days. After sacrifice, the motility of spermatozoa from the cauda of the epididymis was measured and the morphology of spermatozoa from the caput of the epididymis quantified following electron microscopic examination. Carnitine, inositol and potassium were assayed in the epididymal fluid. No abnormalities of spermatozoa (motility, count, morphology, ultrastructural examination) were observed in the cauda of the epididymis. In contrast, a high percentage (63%) of spermatozoa from the caput of the epididymis were altered (vacuolization and lysis of mitochondria). Biochemical analysis of the fluid revealed no differences between treated animals and controls. Thus it appeared therefore, that after 17 days of gossypol administration, the only abnormality detected in the epididymis involved the spermatozoa from the caput. It is therefore probable that the motility disorders seen in spermatozoa from the cauda of the epididymis at 34 days cannot be explained by alterations of the secretion of fluid but rather by earlier direct lesions of testicular spermatids and/or of spermatozoa from the caput of the epididymis.

Automated and continuous recording of ammonia concentration in rumen liquor (Godeau et al., 1986) was performed on four cows around their first calving. Results suggest an insufficient concentration in early lactation.

The proteins of epididymal tissues and fluids recovered from five regions of the human epididymis were separated by polyacrylamide gel electrophoresis under denaturing conditions. Among the 60 peptides identified, eight appeared to be expressed solely in the epididymal duct when compared to serum and testis proteins. Three of these (92, 47 and 24 Kd) showed a degree of regional specificity in fluids. The 92 Kd peptide was found in the caput and proximal corpus, the 47 Kd in the distal corpus and cauda and the 24 Kd in the caput of the epididymis. Three of the specific epididymal proteins (39, 30, 26 Kd) displayed a remarkable analogy to those found in man and monkey in other conditions and which are present at the sperm surface in the epididymis cauda.

Prorenin (PR) an inactive high molecular weight form of renin normally circulates in human plasma at a concentration of about 10 times that of active renin (AR) and this proenzyme seems to be linked to the reproductive function. It has been demonstrated that AR and PR are present at high concentrations in follicular fluid when the ovaries are stimulated with gonadotropins and that the PR plasma levels increase steadily after hCG injection with a correlation between blood PR and the number of developing follicles and corpora lutea. From September 1986 we studied the profile of immunoreactive active renin (AR) and prorenin (PR) in plasma during hyperstimulated cycles for IVFET or GIFT. All women were treated with a protocol combining GnRH analog (Decaptyl Ipsen Biotech, Paris France) and human menopausal gonadotropins until injection of 5,000 IU hCG. AR has been assayed in frozen samples by specific immunoradiometry (Renin RIA code 79 795, Pasteur Diagnostic, France) using two complementary monoclonal antibodies. A second assay of total renin was carried out after trypsin activation which revealed the inactive form. Progesterone (P), estradiol (E2) were measured by radioimmuno-assays. During the follicular phase, from day 1 of hMG administration to the day before hCG, no significant difference could be found between two groups, 63 pregnant or 60 nonpregnant cycles matched for age and number of oocytes retrieved, for E2, P, PR and AR. During the periovulatory period (D - 1, Do = day of hCG injection and D 1) no difference could be found for E2, P and PR (tabl. 1). In the 2 groups the mean E2 levels increased after hCG injection, as well as P and PR. But a significant difference appeared for AR which increased in the plasma immediately after hCG administration in the pregnant group whereas it decreased in the non-pregnant group (+2.5 vs -2 pg/ml) the mean variation between Do and D + 1 being significantly different in fertile cycles and in nonfertile cycles.(ABSTRACT TRUNCATED AT 400 WORDS)

The LH receptor was solubilized from porcine testis homogenates by different detergents. Non-ionic detergents appeared to be the best ones regarding solubilization yield and recovery of active receptor after elution from hCG affinity gels. However, the final yield was not greater than 1-2% of the starting receptor activity. We also investigated the effect of added phospholipids (75% phosphatidylcholine + 25% phosphatidylethanolamine) on the yield of the overall purification process. It was shown that the best p value [i.e. the ratio of (detergent concentration - critical micellar concentration) to phospholipids] upon solubilization was congruent to 1.1 for a non-ionic detergent such as Nonidet P-40, while a higher p value was better upon elution. The stability of the solubilized receptor versus pH and SDS has been studied. The receptor exhibited two pKa's of denaturation congruent to 3.8 and 11.1, while the [125I]hCG-receptor complex dissociated with a pKa congruent to 3.8 and 10.3 SDS concentrations as low as 0.05% denatured rapidly and apparently, irreversibly, the solubilized LH receptor. The stability of different affinity gels was checked and it was found that the best yield for receptor elution (congruent to 10%) was obtained with an immunoaffinity anti-hCG support. The obtention of two monoclonal antibodies is mentioned, as well as their competition with the binding of [125I]pLH to testis homogenates.

The aim of the present study in the pig was to describe the biliary and pancreatic secretory component of the migrating myoelectric complex (MMC) during the interdigestive period and after feeding, and to examine the effects of the extracorporal diversion of biliary or pancreatic secretions on the MMC and on the cyclical variation of intraduodenal pH. In a first trial six pigs (50.6 +/- 1.6 kg) were fitted with a permanent catheter in the common bile duct (3 pigs) or in the pancreatic duct (3 pigs) to control the flow of these secretions. They also had a duodenal catheter to return the secretions, and antral and duodenal electrodes for simultaneous recording of motility in fasting conditions. In a second trial ten pigs (50.8 +/- 1.5 kg) underwent a similar surgical preparation (5 bile duct and 5 pancreatic duct fistulations). They had, in addition, a duodenal T-shaped cannula (19 cm distal to the pylorus) allowing continuous intraluminal pH recording parallel to the motility recording. Experiments included 4 situations: secretions returned under fed or fasted conditions; by-passed secretions in fed or fasted pigs. The flow of bile and pancreatic juice was very high during irregular spiking activity phases (ISA), peaking at the beginning of regular spiking activity phases (RSA); it was minimal during quiescent phases. The duration of the duodenal MMC and of its 3 constitutive phases was not modified by total extracorporal diversion of bile or pancreatic secretion either in the fed or fasted state. During the interdigestive period the pH was significantly reduced under bile diversion (quiescence: 6.17 vs 7.15; ISA: 4.91 vs 5.94; RSA: 5.40 vs 6.52) as well as under pancreatic juice diversion (quiescence: 5.56 vs 7.18; ISA: 4.21 vs 5.97; RSA: 5.14 vs 6.72). In fed pigs only bile diversion resulted in a small acidification during the postprandial pattern (5.07 vs 5.44) and the consecutive MMC cycles (quiescence: 5.81 vs 6.61; ISA: 4.66 vs 4.92; RSA: 5.11 vs 5.78). Nevertheless the periodicity of pH variation along the MMC cycle was unaffected in bile or pancreatic juice-deprived animals. It is concluded that a true biliary and pancreatic secretory component of MMC exists in the pig, and that these 2 secretions strongly contribute to the neutralization of the duodenal contents. However, the major determinant of the cyclical variation of the intraduodenal pH appears to be the periodicity of the acid gastric outflow.

In the adult, muscle metabolism represents a large drain of energetic substrates. The newborn has to provide additional energy to its muscles in order to ensure a rapid growth. However, since during the neonatal period the newborn is fed with a high-fat low-carbohydrate diet, i.e., milk, the newborn must also spare glucose for organs which are obligatory glucose consumers such as the brain. Thus, regulation of energetic substrate utilisation by muscle is of upmost importance for postnatal metabolic homeotasis. In the human, fibre types at birth can already be histochemically classified as adult types and the proportional distributions of each fibre-type approximate those seen in the adult. On the other hand, glycolytic and oxidative maximal enzyme activities are lower than adult levels. In the rat, the capacity for glucose utilisation in muscles is low at birth, reaches a peak at weaning and subsequently decreases. During the suckling period, the concentration of lipid-derived substrates is high as well as the muscle capacity for their oxidation; moreover, insulin concentration is low and insulin sensitivity of muscle glucose utilization is also reduced. Thus, during the suckling period, fuel availability and insulin concentrations, as well as tissue sensitivity towards the hormone, favour the limitation of glucose utilisation by skeletal muscles.

The bovine conceptus produces numerous signals during early pregnancy but at the present time only one protein (PSPB; pregnancy specific protein B) is detectable in the peripheral blood during the first 30 days of pregnancy. Validation criteria of the RIA for bovine PSPB have been described by Sasser et al. (1986). This review presents the results obtained in ruminants with this assay. In the bovine PSPB concentrations rise continuously during pregnancy. This protein is found in all pregnant animals at 30 days post Al. Among cows with late embryonic mortality (i.e. with high progesterone concentrations on day 21-24) only 30% present detectable PSPB concentrations between 24 and 30 days post Al. When Al are performed before 70 days post-partum, residual post- partum PSPB concentrations (from the previous pregnancy) the day of Al lowers the accuracy of positive results when PSPB RIA is used as a pregnancy test. In sheep and goat the PSPB profiles throughout pregnancy are very similar to the profile observed in the cattle. In these species the PSPB RIA may be used as a pregnancy test after 26 days post Al. In ruminants, measurement of both progesterone and PSPB in peripheral blood plasma or serum can be very useful to study the way in which various factors may chronologically affect embryonic mortality.

The effects of reserpine (catecholamine depletor) and LHRH analogues on gonadotropin secretion, spermiation and ovulation of common carp were investigated. Injections of reserpine alone at a dose of 1 or 7 mg/kg of body weight stimulated spermiation, and reserpine at a dose of 1 mg/kg of body weight in combination with (D-Arg6, Trp7, Leu8, Pro9, NEt)-LHRH (s-GnRH-A) or with (D-Ala6, Pro9)-LHRH (LHRH-A) at a dose of 50 micrograms/kg of body weight caused an increase of plasma gonadotropin levels, spermiation and ovulation in 80-90% of the females. Simultaneous injection of reserpine and LHRH analogues was as effective as injection of reserpine followed by injection of LHRH analogues 6 h later.

Using an in vitro system of pig Leydig cells (LC) and Sertoli cells (SC) we have demonstrated that: 1) LC contained specific receptors for both somatomedin-C/insulin-like growth factor I (Sm-C/IGF-I) and insulin, whereas SC contained only Sm-C/IGF-I receptors; 2) pretreatment of LC with insulin or Sm-C/IGF-I increased hCG receptor number and the cAMP and testosterone responses to this hormone. The enhanced steroidogenic capacity was related to an increased activity of several enzymes of the steroidogenic pathway. At physiological concentrations Sm-C/IGF-I was more potent than insulin, but the effects of the latter peptide at micromolar concentrations were similar to those produced by nanomolar concentrations of Sm-C/IGF-I. However, at maximal concentrations of both peptides, there was no additive effect; 3) the specificity of the effect of Sm-C/IGF-I was proven by the fact that all the effects induced by this peptide, but not by insulin, were blunted by an anti-Sm-C/IGF-I antibody; 4) pretreatment of SC with Sm-C/IGF-I at nM concentrations or with insulin (but only at microM concentrations) enhanced the stimulatory effect of FSH on cAMP production and the secretion of plasminogen activator; 5) in both LH and SC, Sm-C/IGF-I had small mitogenic effects but potentiated the mitogenic action of fibroblast growth factor (FGF). The effect of insulin was observed only at microM concentrations; 6) SC secreted a factor which had physico-chemical and biological properties similar to that of Sm-C/IGF-I. The secretion of this factor was stimulated by FGF and EGF.