Pituitary-testicular relationships in the rat embryo]

LH given to the Rat embryo at the time of hypophysectomy by decapitation (18 days of intrauterine life) will prevent the drop in androgen synthesis which normally ensues. This is regarded as definite proof that androgen synthesis is under pituitary control in the rat embryo at late gestational stages. On the other hand, the decrease in androgen synthesis following testosterone injection to the pregnant female points to the fact that there is a negative feedback of testosterone on pituitary LH secretion.     

Ultrastrukturelle Aspekte des supraoptikohypophysären Systems in der hypophysektomierten Ratte

Summary The supraoptico-hypophyseal system in the hypophysectomized rat was studied by electron microscopy. Light microscopic observations hitherto reported that, after hypophysectomy the proximal cut end of the infundibular stalk becomes reorganized into a neural lobelike organ, could be reconfirmed. The ultrastructural aspect of the supraoptic cells following hypophysectomy was also described.     

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.     

The age-dependent difference in the response of the vagina to the neonatal administration of testosterone propionate in Long-Evans female rats

Summary The ability of the vaginal epithelium to respond to testosterone propionate by producing keratin was established when female rats were 3 days of age, whereas the vaginal stroma from rats 2 days old or less was capable of responding to the androgen and might destroy the vaginal epithelium.     

Effects of hypophysectomy, bilateral adrenalectomy and hormone replacement therapy upon organ monoamine oxidase activity.

Changes in MAO activity after hypophysectomy (HX) are not due to adrenal insufficiency. ACTH failed to reverse the effects of HX and enhanced the depression of cardiac and spleenic MAO. The data suggests both facilitatory and inhibitory effects of pituitary hormones on MAO activity.     

Releasable GABA in tubular epithelium of rat kidney

The distribution of gamma-aminobutyric acid (GABA) in the rat kidney was examined by immunocytochemical techniques. GABA-like immunoreactivity (GABA-LI) was predominantly confined to the renal tubules, including the ascending parts of the distal tubules, and the loops of Henle, the collecting tubules and ducts, and the connective parts of the convoluted tubules. In GABA-positive cortical tubules, about half of the epithelial cells were labelled. The labelled cell type showed the ultrastructural features of principal cells. Depolarizing stimulation by ouabain and high K+ concentration evoked the efflux of endogenous GABA from kidney slices. The present findings, along with previous results, suggest that GABA released from renal tubular epithelium, and transported with the urine, might be involved in the modulation of contractility in the urinary tract.     

MicroRNA-29 in the adaptive immune system: setting the threshold

Recent research into the role of microRNA (miR) in the immune system has identified the miR-29 family as critical regulators of key processes in adaptive immunity. The miR-29 family consists of four members with shared regulatory capacity, namely miR-29a, miR-29b-1, miR-29b-2 and miR-29c. Being expressed in both T and B cells, as well as the main accessory cell types of thymic epithelium and dendritic cells, the miR-29 family has been identified as a putative regulator of immunity due to the predicted suppression of key immunological pathways. The generation of a series of in vivo molecular tools targeting the miR-29 family has identified the critical role of these miR in setting the molecular threshold for three central events in adaptive immunity: (1) control over thymic production of T cells by modulating the threshold for infection-associated thymic involution, (2) creating a neutral threshold for T cell polarization following activation, and (3) setting the threshold for B cell oncogenic transformation. These results identify the miR-29 family as potent immune modulators which have already been exploited through the evolution of a viral mimic and could potentially be exploited further for therapeutic intervention.     

Releasable GABA in tubular epithelium of rat kidney

Summary The distribution of gamma-aminobutyric acid (GABA) in the rat kidney was examined by immunocytochemical techniques. GABA-like immunoreactivity (GABA-LI) was predominantly confined to the renal tubules, including the ascending parts of the distal tubules, and the loops of Henle, the collecting tubules and ducts, and the connective parts of the convoluted tubules. In GABA-positive cortical tubules, about half of the epithelial cells were labelled. The labelled cell type showed the ultrastructural features of principal cells. Depolarizing stimulation by ouabain and high K⁺ concentration evoked the efflux of endogenous GABA from kidney slices. The present findings, along with previous results, suggest that GABA released from renal tubular epithelium, and transported with the urine, might be involved in the modulation of contractility in the urinary tract.     

Demonstration of testosterone secretion by testicular tissue of hypophysectomized boar as affected by HCG in organ culture]

Boar Leydig cells undergo a strong atrophy from 1 to 3 months after hypophysectomy but can be reactivated by the gonadotropin HCG in organ culture conditions. This reactivation which appeared at histological and ultrastructural level was evidenced by the capacity of testicular tissue to synthesize testosterone as judged by radioimmunoassay. Both synthesis in the tissue and release into the medium increased according the incubation time with HCG; the adjonction of 17 alpha-OH-pregneolone to culture medium led to increase the intra and extra-tissular concentration of testosterone.     

Beta-adrenergic stimulation of androgen production by fetal mouse Leydig cells in primary culture

The responsiveness of fetal mouse Leydig cells to catecholamines (epinephrine, norepinephrine), a beta-agonist agent (L-isoproterenol) and hCG was investigated in vitro. Fetal Leydig cells when freshly isolated were unable to respond to L-isoproterenol (10(-5) M). However, L-isoproterenol, epinephrine and norepinephrine significantly stimulated androgen production by fetal Leydig cells after 24 h of primary culture. Androgen production was increased in both conditions and to a greater extent by hCG. Propranolol blocked the stimulatory effect of L-isoproterenol and epinephrine. It is concluded that catecholamines can regulate fetal testosterone biosynthesis.     

Evaluation of signal transduction pathways mediating the nuclear exclusion of the androgen receptor by melatonin

The intracellular signaling pathways mediating the nuclear exclusion of the androgen receptor (AR) by melatonin were evaluated in PC3 cells stably transfected with the AR. The melatonin-induced nuclear exclusion of the AR by melatonin (100 nM, 3 h) was blocked by LY 83583 (an inhibitor of guanylyl cyclases). 8-Bromo-cGMP (a cell-permeable cGMP analog), mimicked the effect of melatonin, as did ionomycin (a calcium ionophore) and PMA [an activator of protein kinase C (PKC)], and their effects were blocked by GF-109203X (a selective PKC inhibitor). BAPTA (an intracellular calcium chelator) blocked the effects of melatonin and 8-bromo-cGMP but not of PMA. Inhibition or activation of the protein kinase A pathway did not affect basal or melatonin-mediated AR localization. We conclude that the melatonin-mediated rise in cGMP elicits AR nuclear exclusion via a pathway involving increased intracellular calcium and PKC activation. These results define a novel signaling pathway that regulates AR localization and androgen responses in target cells. Received 31 July 2001; received after revision 18 September 2001; accepted 30 October 2001     

«Colony-stimulating activity» im Serum und der Milz nach Rauscher Virusinfektion

Summary Colony-stimulating activity (CSA) of serum and spleen was studied in CBA/J mice 1–5 days after Rauscher virus infection, using the agar culture system with normal mouse bone marrow cells as target cells. A sharp increase of CSA was observed with a peak after 2 days in both sites; after 5 days control levels are reached.

---

---

Mit Unterstützung der Deutschen Forschungsgemeinschaft (SFB 112, Zellsystemphysiologie).     

Circadian variation of adrenocortical cyclic nucleotides (cyclic AMP and cyclic GMP) in hypophysectomized rats

The existence of a circadian variation in the adrenocortical concentrations of cyclic AMP and cyclic GMP in male adult Wistar rats examined 10 days after hypophysectomy is demonstrated. The results suggest that the circadian variations of adrenocortical cyclic nucleotides observed previously in intact rats might not entirely depend upon pituitary corticotrophin.     

Acute effect of hypophysectomy on the natriuresis following saline infusion in dogs.

The natriuresis following an i.v. isotonic saline loading corresponding to 10% of body wt. was markedly decreased after acute hypophysectomy, due to lowered urinary sodium concentration, in anaesthetized dogs. A role of the pituitary in such a homeostatic natriuresis is suggested.     

Änderung der Wachstumskinetik von Ehrlich-Aszitestumoren verschiedener Ploidie nach Röntgen-Bestrahlung

Summary The effect of irradiation (500 R) on the cell cycle of the diploid (EAT_dipl.) and the hypertetraploid (ELT) Ehrlich ascites tumor growing in the peritoneal cavity of male NMRI mice has been studied autoradio-graphically by the double labelling technique (H³- and C¹⁴-thymidine) and the method of labelled mitoses. The results suggest that the proliferation kinetics of tumor cells after irradiation depends on the type of tumor cell strain tested. Identical results were obtained after application of the alkylating agent cyclophosphamide (100 mg/kg).     

Elektrische Eigenschaften von Glasmikroelektroden nach Membranpotentialmessungen an Zellkulturen

Summary On KB cancer cells in the cover-glass culture with glass micro-electrodes we measured a middle membrane-potential of minus 11–13 mV. It is possible that the electrical qualities of the glass micro-electrodes may alter after some hundred makings of cell-points. An enlargement of the potential on the peak of the electrode (tip-potential) to — 30 mV has no influence on the result of the measuring.     

Ovulation and the role of the ovarian surface epithelium.

Epon sections from all tissue layers of the rabbit ovary, including the often neglected surface or germinal epithelium, were studied to elucidate the mechanism of follicle rupture. Scanning electron microscopy showed cells covering preovulatory follicles increased clearly in size up to 8 hours after human chorionic gonadotropin (HCG) injection. These showed an increasing number of large, intracellular structures with prominent rounded contours. Transmission electron microscopy showed large, electron dense, lysosomelike bodies in some cells 4 hours after HCG. These membrane-surrounded structures increased in size up to 8 hours after HCG, then decreased markedly. These obviously corresponded to the bodies found by light microscopy and scanning electron microscopy. Histochemistry revealed many represent lysosomes. During the last 2 hours before rupture, the dense bodies of the surface epithelium considerably decrease, signs of material emptying into vacuoles is found, and sometimes there is open communication from vacuoles towards the unerlying tunica albuginea. An extracellular edema appeared under the epithelium with degenerated fibroblasts and disintegrated collagen; these changes gradually proceeded inwards. Blood capillaries close to the membrana granulosa gradually showed small pores and close to ovulation the endothelial cells had gaps up to 3 mcm in diameter. The preovulatory follicles grew rapidly and an augmenting edema occupied the whole ovary. In the last hours before ovulation the membrana granulosa gradually dissociated. Whatever the net effect of the prostaglandins, prostaglandin F2alpha appears to be essential for follicle rupture since intrafollicular injections of antiserum blocked ovulation. Prostaglandin E1 promotes vascular permeability and lysosommal enzymes released extracellularly may be coupled to collagen degration. The enzyme synthesis and lysosomal growth in the surface epithelium of preovulatory follicles may be due to the high local concentration of sex steroids.     

Changes in major liver constituents following hypophysectomy in goldfish (Carassius auratus).

The increase in the size of goldfish (Carassius auratus) liver following hypophysectomy is due to a net accumulation of glycogen and the addition of water to maintain a constant proportion with no change in the absolute amount of either protein or lipid.     

Hypophysectomy exerts a radioprotective effect on frog lens

Summary Exposure to X-rays usually causes cataracts in frogs. These cataracts are always preceded by misalignment of the structures called meridional rows (MR). When cell division is completely halted by hypophysectomy, however, irradiation no longer disturbs the orientation of the MR. Since the MR are the structures formed as lens epithelial cells differentiate into lens fibres it is reasonable to propose that radiocataractogenesis depends upon a mitosis-driven formation of pathological fibres from epithelial cells that have been rendered abnormal by exposure to X-rays.This research was supported by: NIH grant No. EY 02492-02 (HR); NIH grant No. EY 02648-02 (BVW).     

Caryométrie des cellules réticulaires thymiques de rat: Influence des hormones somatotrope et corticotrope

Summary GH stimulates thymic epithelial secreting cells; ACTH inhibits these cells. Thymic involution following hypophysectomy is due to GH and/or corticosteroid deficiency.

---

Caryométrie des cellules réticulaires thymiques de rat: Influence des hormones somatotrope et corticotrope

---

Les auteurs remercient le NIAMD pour l'envoi de la GH de rat.