Relaxin inhibits prostacyclin release by the rat pregnant myometrium

Porcine relaxin (30 μg/ml) when incubated with separated myometrial tissue from 20 day pregnant rats inhibited basal prostacyclin output by 50%. However, relaxin did not inhibit the increased prostacyclin output observed when myometrial tissue was incubated with the prostaglandin precursor, arachidonic acid (10 μg/ml). When prostacyclin release was stimulated by incubation with oxytocin (10 mU/ml), however, relaxin completely inhibited the increased output. The results suggest that relaxin interferes with basal and oxytocin-stimulated prostacyclin formation in pregnant myometrial tissue by inhibiting the action of the enzyme phospholipase A₂ which is responsible for liberating the precursor arachidonic acid endogenously.     

Relaxin in the male

Relaxin, a hormone usually associated with pregnancy, has been found in the semen plasma of many species. The prostate gland appears to be a source of relaxin. Relaxin stimulates sperm motility from suboptimal samples and increases sperm penetration into oocytes. Thus, relaxin may be an effective therapeutic agent in male infertility.     

Relaxin

1. Relaxin is a hormone of reproduction that appears to affect parturition, uterine accommodation, and sperm motility to varying degrees in many species. 2. All relaxins have the same two chain, disulfide-linked insulin-like structure and two arginine residues in the midregion of the B chain. 3. The active relaxin molecule is produced by excision of a connecting peptide from the prohormone. 4. The biosynthetic pathways of insulin and relaxin are alike, but the relaxin prohormone is about twice as large as the corresponding proinsulin. 5. The primary structures of relaxins from apparently closely related species differ significantly in their amino acid compositions and do not fit into the traditional scheme of molecular evolution.     

Location of the angiogenic activity in the pregnant human uterus

Angiogenic activity was known to be intensely dynamic during pregnancy with a geometric orientation towards the site of implantation. Therefore this study was designed to test whether the uterine lining of pregnancy, the decidua, induces angiogenic activity on the chorioallantoic membrane (CAM). Twenty-three decidual specimens obtained during legally induced abortions were implanted into the 9-day-old chick CAM. All decidual specimens showed strong angiogenic activity as measured by 9-fold increase in radial blood vessels, with a geometrical formation of 'spokewheel' pattern extending over a range of 1.2 cm within 48 h.     

Identification of sources of cerebral activity in the cat

The identification of sources of cerebral activity is investigated, and the resulting methodology is applied to the simple case of hippocampal afterdischarges in the cat. We develop an “imagery” technique which consists in defining, in a preliminary step, the number and the power spectrum density of unknown sources (identification of sources) assumed to emit independent signals in the ill-defined noisy cerebral medium. The technique assumes the medium to be quasilinear and quasistationary, and these assumptions have to be checked. It is based upon the interspectral matrix and its diagonal form. It makes it clear that (1) the problem of estimating the number of sources is closely dependent on the estimation method used to assess the power spectrum density, and (2) the coherence matrix should be preferred to the interspectral matrix for reasons linked with the estimation variance of its elements and the proximity of the sources and sensors. In order to assess the validity of the methodology, a source of hippocampal afterdischarges has been created by threshold stimulation of the ventral hippocampus of the cat. The resulting EEG signals are used to show that there is a single source and to estimate its power density spectrum, which can then be compared with the true one.     

Pacemaker activity in distal parts of the cat ureter

Existence of two types of uncoordinated spontaneous activities of the cat ureterbladder area was shown: spikes and slow waves. The oscillation frequency of this area is two-fold lesser than the rhythm of renal waves. The activity concordance of these pacemakers occurs under conditions of ureter dissection in the middle. Normally pacemakers of this area seem to be a reserve mechanism of urine pushing through.     

Adenosine triphosphatase activity in the carotid body of the cat

Summary Three kinds of nucleoside phosphatases were demonstrated histochemically in the cat carotid body with nucleoside triphosphate, nucleoside disphosphate and nucleoside monophosphate as substrates. Each of these enzyme activities exhibited the substrate specificity respectively. The nucleoside triphosphatase activity showed specific localization in association with the parenchymal cells of the carotid body.The electronmicroscopy revealed that the reaction product was located on and between the two apposing plasma membranes of type I and type II cells, of a type II cell and its wrapping axons and of the intricate basal infolding of a type II cell itself.Some possible functions of the adenosine triphosphatase in the carotid body are discussed.     

Relaxin enhances the collagenolytic activity and in vitro invasiveness by upregulating matrix metalloproteinases in human thyroid carcinoma cells

In this study, we identified differential expression of immunoreactive matrix metalloproteinase 2 (MMP2)/gelatinase A, membrane-anchored MT1-MMP/MMP14, and human relaxin-2 (RLN2) in human benign and malignant thyroid tissues. MMP2 and MT1-MMP were detected in the majority of thyroid cancer tissues and colocalized with RLN2-positive cells. MMP2 was mostly absent in goiter tissues and, similar to RLN2, may serve as a marker for thyroid cancer. MMP2 and MT1-MMP were identified as novel RLN2 targets. RLN2 caused a significant downregulation of tissue inhibitor of MMP (TIMP) 3 protein levels but did not change the expression levels of MMP13, and TIMP1, TIMP2, and TIMP4 in human thyroid carcinoma cells. RLN2 failed to affect the expression of MMP1, 3, 8, and 9 in the thyroid carcinoma cells investigated. Stable RLN2 transfectants secreted enhanced levels of bioactive MMP2 which contributed to the increased collagenolytic activity and in vitro invasiveness into collagen matrix by human thyroid cancer cells. Three-dimensional reconstitution of confocal fluorescent microscopy images revealed larger-sized invadopodia, with intense MT1-MMP accumulation at the leading migrating edge in RLN2 transfectants when compared with enhanced green fluorescent protein clones. In RLN2 transfectants actin stress fibers contributed to pseudopodia formation. In conclusion, enhanced tumor cell invasion by RLN2 involves the formation of MT1-MMP-enriched invadopodia that lead to increased collagenolytic cell invasion by human thyroid cancer cells.