Reappearance of HCG-receptors in immature rat ovary after HCG-treatment is not due to receptor synthesis.

In 24-day-old rats the reappearance of ovarian HCG-receptors after the injection of 200 IU HCG in independent of protein synthesis. The reutilization of occupied receptors in immature female rats is due to dissociation of the receptor-hormone complex.     

HCG-insensitivity of the postnatal rat ovary is due to the lack of a specific receptor

Summary Rat ovary is insensitive to luteinizing hormone and human chorionic gonadotrophin till to the 8th to 10th day of postnatal development. This insensitivity is due to the lack of a specific hormone receptor.This work was supported in part by the Deutsche Forschungsgemeinschaft (SFB 46). Purified HCG was a gift of Schering AG, Berlin-West. We thank Dr F. Peters for performing the iodination of HCG.     

Fine structural differentiation of steroid-producing cells in the ovary of immature rat

Zusammenfassung Steroid-produzierende Zellen wurden in der Theca folliculi der geschlechtsunreifen Ratten vom 10. Lebenstag an elektronenmikroskopisch gefunden.     

Reappearance in vivo of neuraminidase-sensitive sialic acid in L 5222 rat leukemia cells

Summary Cell electrophoretic data and quantitative sialic acid determination show that, 16 to 20h after i.p. implantation of neuraminidase-treated L 5222 rat leukemia cells, the original sialic acid content at the cell periphery is reconstituted.This investigation was performed within the EORTIC Cell Surface Project Group and supported by the Swiss National Science Foundation, Grant No. 3.901.72, and by the Zürich Cancer League.     

In situ aging of auricular chondrocytes is not due to the exhaustion of their replicative potential

Summary Multiplication of chondrocytes during growth of rabbit auricular cartilage was estimated on the basis of total DNA determination and compared with the population doubling level reached by these chondrocytes in vitro. The results indicate that the in situ aging of auricular chondrocytes is caused by factors other than the intrinsic depletion of their growth potential.     

Induction of the synthesis of thymidine kinase by aldosterone in the kidney of the immature male rat

Thymidine kinase activity was studied in kidneys from immature male rats after administration of aldosterone. Kinetic studies showed that the enzyme activity reached its maximum level 24 h after aldosterone injection. That increase was specific for aldosterone and could be related to the synthesis of new molecules of enzyme.     

Induction of the synthesis of thymidine kinase by aldosterone in the kidney of the immature male rat

Summary Thymidine kinase activity was studied in kidneys from immature male rats after administration of aldosterone. Kinetic studies showed that the enzyme activity reached its maximum level 24 h after aldosterone injection. That increase was specific for aldosterone and could be related to the synthesis of new molecules of enzyme.     

The reduction of genic activity in the tetraploid amphibianOdontophrynus americanus is not due to loss of ribosomal DNA

Summary Genic activity in tetraploid members of the amphibian speciesOdontophrymus americanus is reduced to that of diploid ones. Loss of ribosomal genes, a mechanism suggested by others as a means of decreasing genetic activity, could be ruled out. The diploids and the tetraploids have almost identical proportions of their genomes complementary to (28s+18s) ribosomal RNA.     

Accelerated synthesis of dopamine in the rat brain after methadone

Riassunto Nei ratti, ild, l-metadone fa aumentare significativamente i livelli di acido omovanillico e stimola il turnover della dopamina nei gangli della base. Il destro isomero è inattivo.     

Target organs of131I-chorionic gonadotrophine in immature female rat

Zusammenfassung Die Einlagerung von¹³¹I-HCG und¹³¹I-Serumalbumin in einige Organe unreifer Rattenweibchen wurde gammaradiometrisch gemessen. Eine signifikant erhöhte Akkumulation der Radioaktivität nach¹³¹I-HCG-Verabreichung wurde im Ovarium, dem Uterus, der Hypophyse und der Schilddrüse festgestellt.     

The involvement of serotonin in induced ovulation in the immature rat

Summary In pregnant mare's serum gonadotropin (PMS) treated immature rats the cortex, cerebellum, caudate nucleus and hypothalamus were isolated and analyzed for their serotonin (5-HT) content at 6-h intervals for 72 h. Results showed a general trend of significant variation occurring in days 1 and 3 after PMS injection with no major variations observed on the second day. The results obtained suggest a possible involvement of 5-HT in the control of ovulation.     

The involvement of serotonin in induced ovulation in the immature rat.

In pregnant mare's serum gonadotropin (PMS) treated immature rats the cortex, cerebellum, caudate nucleus and hypothalamus were isolated and analyzed for their serotonin (5-HT) content at 6-h intervals for 72 h. Results showed a general trend of significant variation occurring in days 1 and 3 after PMS injection with no major variations observed on the second day. The results obtained suggest a possible involvement of 5-HT in the control of ovulation.     

Activation-induced cellular accumulation of histamine in immature but not mature murine mast cells

Mast cell activation involves the rapid release of inflammatory mediators, including histamine, from intracellular granules. The cells are capable of regranulation and multiple rounds of activation. The goal of this study was to determine if there are changes in the content of pre-formed mast cell mediators after a round of activation. After 24 h, the histamine content of bone marrow-derived mast cells (BMMC), but not that of peritoneal mast cells, exceeded the amount in resting cells. Accumulation of histamine in BMMC peaked at 72 h of activation, and returned toward preactivation levels by 96 h. The increase in histamine content was accompanied by an increase in the gene expression of histidine decarboxylase. No increases in beta hexosaminidase or murine mast cell protease-6 were observed. These findings indicate that BMMC respond to activation by increasing total cell-associated histamine content. This increase may be important to the response of these cells upon subsequent exposure to antigens.     

Protein synthesis and cyclic GMP content in rat cardiac muscle after swimming exercise

Rats were exercised for 6 h by swimming. Phenylalanine incorporation into myocardial proteins was increased when 2 h had elapsed after the termination of exercise. Cyclic GMP concentration did not change during the experiment, which indicates that cyclic GMP does not act directly as a trigger of myocardial protein synthesis in volume overload.