Comparison between serum LH and FSH levels in male and female rats during the perinatal period]

In the newborn female Rat, no transient LH and FSH serum surges were observed between 0 and 2 hrs., as compared with the newborn male. In the newborn female, a progressive increase in serum gonadotropins was observed between 2 and 6 hrs. These results indicate that, at birth, the pituitary-gonadal axis reacts in a different way in male and female Rats.     

Stimulation of pituitary LH and FSH secretion after immunoneutralization of endogenous substance P in the cycling rat]

In the cycling female Rat, administration of substance P antisera performed at noon on the proestrous day provokes a significant increase in LH and FSH serum level, right before or after the preovulatory surges, but had no effect on its occurrence or magnitude. These results suggest that substance P has a normal physiological inhibitory role in gonadotropin regulation.     

Vitamin A consumption in pregnant and non pregnant rats, and in castrated rats receiving or not receiving estradiol or pregnenolone; relation to tocopherol and cytochrome P-450]

Consumption of vitamin A and cytochrome P 450 by pregnant Rat is more important than in non pregnant and ovariectomised Rat. Estradiol implant in ovariectomised female has some, but slighter, influence only on retinol. These physiological situations have no action on the hepatic levels of tocopherols (total and alpha). These results are discussed.     

Reduction of isoprenaline induced tachycardia in pregnant rats. Role of a serum factor]

The in vivo isoprenaline (50 microgram/kg) induced tachycardia (beta 1 adrenergic stimulant effect) was decreased in pregnant (20th day) Rats compared to non pregnant Rats. The in vitro positive chronotropic effect of isoprenaline (10 ng/ml) on cultured Rat heart cells was abolished by pregnant Rat serum whereas progesterone (0.10 to 5 microgram/ml) or oestradiol (0.1 to 25 microgram/ml) were ineffective. The decreased beta 1 adrenergic responsiveness in pregnant Rats could be related to a seric factor, different from these two hormones.     

Increase in serum testosterone in newborn rats]

The changes in serum testosterone and dihydrotestosterone concentrations have been measured in the newborn Rat, before, during and up to 6 hrs after birth. A sudden and transient increase of serum testosterone has been found between 0 and 2 hrs. At 4 hrs, the value returns to that found in the foetus at the end of gestation.     

Combined effects of testosterone and estradiol on the ventral lobe of the rat postate in organ culture]

After organ culture without hormone, the epithelial gland cells of Rat veantral prostate undergo atrophic changes, whereas the interstitial stroma components tend to increase. Estradiol (1-1,000 nM),added to the culture medium, is ineffective. On the contrary, testosterone (1-100 nM) maintains epithelial cells and prevents the increase of interstitial stroma. When estradiol (1-1,000 nM) is combined with a physiological concentration of testosterone (1-4 nM), the epithelial cells are well maintained, but the inhibitory action of testosterone on the stroma is counteracted so that the glandular epithelium and the interstitial stroma are both stimulated. However, when testosterone is used at supraphysiological (10-100 nM) concentrations, estradiol is completely ineffective and the structure of the prostate is identical to the one given by the androgen alone.     

Production of prostaglandins in mixed lymphocyte cultures (MLC) between allograft donors and recipients]

A prostaglandin-like activity, as evaluated by a bio-assay using the fundus of Rat stomach, has been demonstrated in supernatants of lymphocyte cultures. This activity undergoes a striking increase in supernatants of mixed cultures of allograft donor and recipient cells, when compared with control supernatants of donor or recipient cells cultured alone. This phenomenon is observed after 24 hrs. of culture. It disappears if the supernatant is dialyzed. Little or no increase in prostaglandin-like activity is found in supernatants of primary mixed lymphocyte cultures (without previous allograft), at lest in the first two days of culture.     

Increases in frequency of sister chromatid exchange following tumor grafts in different immunocompetent hosts]

Measurement of sister chromatid exchanges (SCEs) frequency of inbred Rat or nu/nu Mice bone marrow cells, following tumour grafts, have been developed. Increase of SCEs was observed in hosts which present or not metases and with reduced survival rates after malignant tumour grafts. These results suggest a remote control of tumoral tissue by a diffused matter effect.     

Species-specific differences in the mitogenic activity of heparin-binding growth factors in the sera of various mammals

Sera from different mammalian species displayed great differences in mitogenic activity, as measured by stimulation of DNA synthesis in BALB/c 3T3 cells (3T3 cells). Among the sera examined, fetal bovine serum was least active, and increasing activity was detected in calf serum, human serum, rat serum and mouse serum, in that order. Rat and mouse sera exhibited extremely high mitogenic activity with 3T3 cells, but when TIG-1 human fetal lung fibroblasts were used for the DNA assay instead, the activity levels of all of the sera were lower, and the differences between them were smaller. To determine the reasons for these differences, the heparin-binding growth factors in each serum were separated on a heparin affinity column. Five peaks of DNA-stimulating activity were obtained. Three of these were found in all sera examined, with both 3T3 cells and TIG-1 cells. Two other peaks were found only with 3T3 cells; one was peculiar to rat and mouse sera, with extremely high activity in the rat, and the other was specific to fetal serum. The dependence of the activity of these peaks on the cells used for the test was confirmed using normal rat lung fibroblasts and immortalized rat kidney cells. These findings adequately explain the species-specific differences in mitogenic activity of whole sera, and the variation in activity depending on the cells used for assay of DNA synthesis.     

Chromosome aberrations in cattle raised on bracken fern pasture

Thirteen cows maintained on natural bracken fern (Pteridium aquilinum) were analyzed cytogenetically. The frequency of structural chromosome aberrations detected in peripheral blood cells was significantly higher when compared to that detected in animals raised on pasture containing no bracken fern. We discuss the clastogenic action of fern and its synergistic action with infection by type 2 and 4 papilloma virus in the same animals.     

Species-specific differences in the mitogenic activity of heparin-binding growth factors in the sera of various mammals.

Sera from different mammalian species displayed great differences in mitogenic activity, as measured by stimulation of DNA synthesis in BALB/c 3T3 cells (3T3 cells). Among the sera examined, fetal bovine serum was least active, and increasing activity was detected in calf serum, human serum, rat serum and mouse serum, in that order. Rat and mouse sera exhibited extremely high mitogenic activity with 3T3 cells, but when TIG-1 human fetal lung fibroblasts were used for the DNA assay instead, the activity levels of all of the sera were lower, and the differences between them were smaller. To determine the reasons for these differences, the heparin-binding growth factors in each serum were separated on a heparin affinity column. Five peaks of DNA-stimulating activity were obtained. Three of these were found in all sera examined, with both 3T3 cells and TIG-1 cells. Two other peaks were found only with 3T3 cells; one was peculiar to rat and mouse sera, with extremely high activity in the rat, and the other was specific to fetal serum. The dependence of the activity of these peaks on the cells used for the test was confirmed using normal rat lung fibroblasts and immortalized rat kidney cells. These findings adequately explain the species-specific differences in mitogenic activity of whole sera, and the variation in activity depending on the cells used for assay of DNA synthesis.     

In situ observations of spontaneous contractions of the peripheral lymphatic vessels in the rat mesentery: effects of temperature

By means of an intracellular glass microelectrode, action potential changes were successfully recorded in situ from the endothelial cells of rat mesenteric lymphatics over the temperature range of 27-40 degrees C. The frequency of action potential and the lymphatic contraction rate correlated well with temperature.     

Receptor potential of rat taste cell to potassium benzoate.

Rat taste cells responded to relatively low concentrations of K-benzoate with a hyperpolarization and to the high concentrations with a depolarization. During both responses the membrane resistance of a taste cell decreased. Depolarization elicited by application of a combination of 0.25 M NaCl and 0.05 M K-benzoate was smaller than that by the NaCl alone, indicating a depressant action of K-benzoate.     

Receptor potential of rat taste cell to potassium benzoate

Summary Rat taste cells responded to relatively low concentrations of K-benzoate with a hyperpolarization and to the high concentrations with a depolarization. During both responses the membrane resistance of a taste cell decreased. Depolarization elicited by application of a combination of 0.25 M NaCl and 0.05 M K-benzoate was smaller than that by the NaCl alone, indicating a depressant action of K-benzoate.     

In situ observations of spontaneous contractions of the peripheral lymphatic vessels in the rat mesentery: Effects of temperature

Summary By means of an intracellular glass microelectrode, action potential changes were successfully recorded in situ from the endothelial cells of rat mesenteric lymphatics over the temperature range of 27–40°C. The frequency of action potential and the lymphatic contraction rate correlated well with temperature.     

Effects of repeated administration of potassium canrenoate (SC-14266) on serum gonadotrophin,prolactin, testosterone and progesterone in male rats

Summary Chronic administration of potassium canrenoate (SC-14266), a water-soluble anti-aldosterone agent, increased serum LH levels in male rats without altering serum levels of FSH, prolactin, testosterone and progesterone. The increase in serum LH may be due to the anti-androgenic effect of potassium canrenoate.Acknowledgments. The authors thank the Rat Pituitary Hormone Distribution Program, NIAMDD, NIH and Dr A.F. Parlow for radioimmunoassay materials.     

Stimulation of the secretion of LH and FSH and increase in testicular weight at birth in rats]

The evolutions of serum LH and FSH concentrations and of testicular weight have been measured in the newborn Rat before, during and up to 24 hrs. after birth. A sudden and transient increase of LH and FSH is observed at birth. The testicular weight rises rapidly between 2 and 4 hrs.     

Effect of cell proliferation on the condensation of X chromosomes in the form of Barr-bodies, in human 46 XX fibroblast cultures with different serum concentrations]

The frequency of Barr-bodies in cultivated 46 XX human fibroblasts considerably increases when in confluent monolayer cultures the cells no longer divide. Or, independently of cell contact, when the cells are grown in medium with low serum content, which will slow down or entirely arrest further growth. The frequency of Barr-bodies again diminishes when after the administration of culture medium with sufficient serum concentration, the cells start growing again, indicating that the condensation of the X chromosome is reversible under control of the cell proliferation.     

Pharmacological study of para-aminoclonidine, an alpha sympathomimetic]

Para-aminoclonidine is a more potent alpha-adrenergic agent than clonidine; in vitro on Rat aorta it is 150 times more active than NE, in vivo on pithed Rat it is still twice as active. The hypotensive action of paraaminoclondine is only manifested when given intraventricularly. In the conscious Rat, it has a diuretic action when given per os. Following IV injection in the anaesthetized Dog, the para-aminoclonidine induces an essentially hydric diuresis which is independet of its hypertensive action.     

Histamine production in mixed culture between allograft donor and recipient lymphocytes]

An increased production of histamine has been demonstrated during mixed cultures between allograft donor and recipient lymphocytes. This phenomenon could result from the action of a non-dialysable factor released by recipient cells in the presence of donor cells. This factor is able to increase histamine production from normal spleen cells. Little or no increase in histamine production is found during primary and mixed lymphocyte cultures (without previous allograft).