Stimulation of progesterone production by adrenocorticotropic hormone and prostaglandin E2 in rat luteal cells

The effects of adrenocorticotropic hormone (ACTH), human chorionic gonadotropin (hCG) and prostaglandin E2 (PGE2) on the progesterone secretion of luteal cells from rats were studied. Corpora lutea were harvested on Day 6 of pseudopregnancy and digested by trypsin. Homogeneous suspensions of luteal cells were used for short-term incubation. ACTH, PGE2, and hCG were added to the medium and the changes in progesterone production were measured by radioimmunoassay (RIA). Furthermore, specific ACTH-binding sites of the luteal cell membrane were studied by Scatchard analysis. ACTH, PGE2 and hCG increased synthesis of progesterone, and the combination of hCG with ACTH or PGE2 further increased production of the hormone. The effect of ACTH could be prevented by indomethacin. These effect of ACTH seem to be connected with specific ACTH-binding sites of the luteal cell membrane and with increased production of PGE2.

Effects of oxytocin and vasopressin on the ovarian blood flow, progesterone and oestradiol-17 beta secretion in oestrous rats

Oestrous rats were anaesthetized with pentobarbital, one of the femoral arteries and veins and one of the ovarian veins were cannulated, and a thin polyethylene cannula was fixed in the ovarian bursa. Five-min blood fractions were collected from the ovary for 50 min. Following the control fractions 15 mU of oxytocin, 15 mU of vasopressin or 50 microliter of 0.9% NaCl solution was given into the ovarian bursa over 10 min. Blood pressure and ovarian blood flow were continuously recorded. Progesterone (P) and oestradiol-17 beta (E2) were determined from the blood samples by RIA. Oxytocin did not alter the blood pressure, whereas the ovarian blood flow showed a short increasing tendency. Later, however, it started to decrease in parallel with the decrease in blood pressure owing to blood loss. The secretion of P and E2 remained unchanged. No changes in blood pressure were observed after vasopressin administration, although the ovarian blood flow quickly decreased in parallel with the secretion of P and E2. It is suggested that oxytocin has no direct effect on ovarian blood flow and hormone secretion in the rat. Vasopressin, however, is an effective vasoconstrictor in the rat ovary and may in this way reduce hormone synthesis.

Effect of local GABA administration on rat ovarian blood flow, and on progesterone and estradiol secretion

The effect of gamma-aminobutyric acid (GABA)--superfused onto the surface of the ovary--on ovarian blood flow and on estradiol-17-beta (E2) and progesterone (P) secretion was studied in anaesthesized, pseudopregnant rats. GABA, 0.5 mumol per 50 microliter per animal, significantly reduced the blood pressure in the femoral artery, increased ovarian blood flow, enhanced the rate of E2 release and markedly decreased P secretion. The present findings indicate that local GABAergic mechanisms may be involved in the regulation of ovarian blood flow and hormone secretion.

Study of the luteinizing hormone-induced increase of ovarian blood flow during the estrous cycle in the rat

CYF rats were anesthetized on various days of the 4-day cycle and blood samples were collected at 5-min interals from the ovarian vein before and after i.v. administration of 5 micrograms/100 g BW of luteinizing hormone (LH). Ovarian venous outflow, blood pressure and hematocrit were continuously recorded, and from the blood samples progesterone (P) and 17 beta-estradiol (E2) were determined by radioimmunoassay (RIA). Ovarian blood flow and P secretion showed a parallel increase on Day 1 (estrus), on Day 2, and on the afternoon of Day 4 (proestrous). LH increased ovarian blood flow each day of the cycle together with P and E2 secretion; however, no relationship was seen between the initial value of hormone secretion and the LH-induced increase of ovarian blood flow. Inhibition of hormone secretion by cycloheximide prevented the LH-induced increase of ovarian blood flow; moreover, a decrease in ovarian blood flow parallel with the diminution of hormone secretion was observed. Indomethacin pretreatment abolished the hyperemic effect of LH and partially inhibited the LH-induced increase of hormone secretion. Propranolol blocked the LH-induced increase of ovarian blood flow and blunted the effect of LH on hormone secretion. It was concluded that in LH-induced hyperemia, cAMP, prostaglandins and other vasoactive metabolites released during the process of hormone synthesis, and also a beta-adrenergic mechanism, are involved in the regulation of ovarian blood flow.

Increase of ovarian progesterone secretion by beta 2-adrenergic stimulation in oestrous rats

Oestrous rats were anaesthetized with pentobarbital and one of the femoral arteries, femoral veins and utero-ovarian veins were cannulated. Five min blood fractions were collected from the ovary for 50 min. Following two control fractions fenoterol, noradrenaline, isoproterenol (0.5 microgram/min) or 0.9% NaCl (0.02 ml/min) were infused iv for 40 min. In a group of oestrous animals fenoterol was given locally to the ovarian bursa. Blood pressure and the ovarian venous outflow were continuously recorded and blood levels of progesterone (P) and oestradiol-17 beta (E2) were determined by RIA. Fenoterol administered iv increased P secretion without altering ovarian blood flow, whereas noradrenaline and isoproterenol had no effect on P secretion. Fenoterol administered locally stimulated both P and E2 secretion, and this was prevented by iv infusion of propranolol. It is suggested that ovarian beta 2-adrenergic receptors have a regulatory role in ovarian hormone secretion.

Study on the role of maternal sex steroid production and metabolism in the embryotoxicity of para-xylene

CFY rats were exposed to inhalation of clean air or air containing para-xylene (3000 mg/m3) on the 10th, and 9th and 10th days of gestation. Uterine and ovarian venous blood flow, fetal weight, ovarian progesterone and 17 beta-oestradiol secretion, and the progesterone and 17 beta-oestradiol level of peripheral blood (uterine and femoral veins) were measured on the 11th day of gestation. Exposure to para-xylene decreased the weight of the fetuses and the progesterone and 17 beta-oestradiol levels of peripheral blood, but it did not influence the uterine and ovarian venous outflow and the ovarian progesterone and 17 beta-oestradiol secretion rate. It is concluded that para-xylene, by inducing the hepatic monooxygenase system, facilitates the biotransformation of progesterone and 17 beta-oestradiol, which is metabolized by this enzyme system. The decrease in the sex hormone level of peripheral blood is supposed to play a role in the embryotoxicity (retarding and lethal effects) of para-xylene.

[Structure of adrenal glands removed for hyperandrogenism and their hormone production in tissue culture]

Authors studied the surgically removed adrenals of a 16 year old girl with hyperandrogenism in tissue culture. The majority of cells in the initial culture was similar to the cells of the normal human adrenal. In the 6 weeks tissue culture the morphology of the cells has shown an alteration. The majority of them contained a small number of lipid droplets, abundant quantity of lysosomes and autophage vacuole. At this period in the media the progesterone level appeared to be elevated. Two months later in the tissue culture numerous transformed cells could be seen and the progesterone level of the media was low. It is believed that alteration of the biosynthesis of progesterone may have a role in the increased production of testosterone and in virilization.

Rejection of tumor cells in vitro: morphological studies on killer T cells and damaged tumor cells

The in vitro destruction of a methylcholanthrene-induced guinea pig sarcoma (MC-D) by killer T lymphocytes was investigated by light and electron microscopy. Various degrees of cell damage ranging from slight to extensive were observed. In cells with slight injury, dilatation, vesiculation, fragmentation and degeneration of the rough surfaced endoplasmic reticulum were the most characteristic findings. In cells with extensive injury, widespread nuclear and cytoplasmic alterations were evident and many of these cells were fragmented into smaller portions and finally transformed into granular membranous and amorphous debris. Cytoplasmic vacuoles filled with electron-lucent material were frequent in extensively damaged cells. Killer lymphocytes resembled closely antibody-forming plasma cells when examined with light microscopy but lacked the extensive network of rough surfaced endoplasmic reticulum, and did not produce immunoglobulin. It is suggested that these extensively differentiated T-derived killer cells are end cells similar to those of B lymphocyte-derived plasma cells. Viral particles resembling closely C-type viruses were observed in mixed killer cell MC-D cultures.

A radioimmunoassay for tetanus antibodies using protein A - containing Staphylococcus aureus

To measure tetanus antibodies a trace amount of 125I-labeled tetanus toxin is mixed with appropriate dilutions of human serum or blood. The labeled antigen-antibody complexes are adsorbed to heat-killed staphylococci (Cowan I) via their surface protein A. The radioactivity of the washed solid phase is a function of the initial antibody concentration. The test allows the measurement of 6 X 10(-0) U of tetanus antitoxin in a volume of 0.03 ml. In order to avoid possible interferences, serum has to be diluted 20-fold before use. Taking that into account, the real border limit of sensitivity is 4 X 10(-3) U/ml serum. Antibodies may be measured in serum, in plasma, and even in heparinized blood. As to its sensitivity, the test compares well with the toxin neutralization procedure. It is superior to the previous radioimmunologic, enzymoimmunologic, and hemagglutination techniques with respect to sensitivity and reproducibility. It reflects the values obtained in the toxin neutralization test better than the other in vitro procedures, as shown by parallel assays of 17 sera.

Competitive protein binding assay of oestradiol-17 beta and oestrone using uterine cytosol prepared from HCG-treated rabbits

Uterine cytosol was prepared from rabbits after treatment with human chorionic gonadotrophin (HCG) and used for the determination of oestradiol-17 beta and oestrone by competitive protein binding (CPB) assay. The so obtained uterine cytosol gave higher percentage of binding and proved to be more stable when stored at --20 degrees C than cytosol obtained from the pregnant uterus.

Cytological changes and antigen capture in chicken spleen during the secondary immune response to homologous and cross-reacting antigens

It was demonstrated by autoradiography using 125I-labeled antigens that in the secondary response to bovine serum albumin (BSA), a considerable amount of antigen is localizing in the germinal centers (GC) of chicken spleen prior to the onset of antibody production. A similar early antigen capture, although of a lesser degree, was also noted when birds originally immunized with BSA were injected with human serum albumin (HSA) on a second occasion. Early antigen localization in GCs was scarcely demonstrable in the primary response. Since antigen capture requires specific antibodies, it was concluded that the antigen binding cells correspond with B lymphocytes of GCs formed during the primary immune response or with their descendants. On antigenic stimulus, these cells transform to antibody producing cells after one or more mitoses. GCs can therefore be regarded as memory units composed of cells committed to one and the same antigen. Cells of the thymus-system probably play a cooperative role in the antigen-induced formation of GCs.

Responsiveness of the ovary to gonadotrophins in pre- and perinatal life: oestrogen secretion in tissue and organ cultures

Secretion of oestrogen by the ovaries of foetal (15-19 days of gestation) and newborn rats in organ and tissue culture was not detectable by fluorometry when the ovary was taken from foetuses before folliculogenesis had occurred. In organ cultures of ovaries, the time of folliculogenesis corresponded with the normal timing of folliculogenesis in vivo. In tissue cultures the process of formation of follicles was delayed. Oestrogens were present in the medium when folliculogensis was fully established in the cultured foetal ovaries. Secretion began spontaneously and did nto depend on the addition of gonadotrophins to the medium. The addition of gonadotrophins the the culture medium did not effect the level of oestrogen secreted by the foetal and newborn rat ovaries during the period of incubation (2-3 weeks).