Progesterone binding in the immature mouse and rat uterus

The use of a highly active progestin, 17, 21-dimethyl-19-nor-4, 9-pregnadiene-3, 20-dione (R 5020), as a tag has established that progesterone binds to a specific “7–8S” uterus cytosol component in both the immature mouse and rat.     

Rod sensitivity of neonatal mouse and rat

We have measured the sensitivity of rod photoreceptors isolated from overnight dark-adapted mice of age P12 (neonate) through P45 (adult) with suction-pipette recording. During this age period, the dark current increased roughly in direct proportion to the length of the rod outer segment. In the same period, the flash sensitivity of rods (reciprocal of the half-saturating flash intensity) increased by approximately 1.5-fold. This slight developmental change in sensitivity was not accentuated by dark adapting the animal for just 1 h or by increasing the ambient luminance by sixfold during the prior light exposure. The same small, age-dependent change in rod sensitivity was found with rat. After preincubation of the isolated retina with 9-cis-retinal, neonatal mouse rods showed the same sensitivity as adult rods, suggesting the presence of a small amount of free opsin being responsible for their lower sensitivity. The sensitivity of neonate rods could also be increased to the adult level by dark adapting the animal continuously for several days. By comparing the sensitivity of neonate rods in darkness to that of adult rods after light bleaches, we estimated that approximately 1% of rod opsin in neonatal mouse was devoid of chromophore even after overnight dark adaptation. Overall, we were unable to confirm a previous report that a 50-fold difference in rod sensitivity existed between neonatal and adult rats.     

Symplasma formation and decidualization in the pseudopregnant rabbit after intraluminal instillation of tricaprylin.

A pure neutral triglyceride, tricaprylin, was injected (Day 0) into isolated segments of the uterus of rabbits in which pseudopregnancy had been induced by i.v. injection of hCG 6 days before. The animals were killed in groups of 3 on Days 1, 2, 3, 4 and 6. Saline, simple ligation of the uterus or uterine trauma were used as control treatments in other uterine segments in the same animals. Extensive symplasma formation in the uterine epithelium of the tricaprylin-treated segments was observed on Days 2 and 3; this had degenerated by Day 4 and was absent by Day 6. Decidualization of the stroma began on Days 3 and 4 and was absent by Day 6. The symplasma formed earlier on the antimesometrial side than it did laterally or mesometrially. Decidualization was maximal mesometrially, intermediate laterally, and absent antimesometrially. Ligation with saline and trauma, but not ligation alone, produced symplasma formation. Decidualization occurred after trauma but not after saline injection or ligation alone.     

Characterization and expression of the mouse pregnant specific uterus protein gene and its rat homologue in the intestine and uterus

The pregnant specific uterus protein gene (Psup) is a novel mouse gene expressed in pregnant uterus. This paper describes the identification and expression of the rat homologue of Psup. The gene is highly expressed in the duodenum. Expression decreases in a proximal-distal gradient in the small intestine and was not detected in the cecum and colon. The pattern of expression in the mouse was similar. Expression of Psup in the mouse was localized to the epithelial cells in the intestine and pregnant uterus by in situ hybridization. The data show tissue-specific expression of Psup.     

Unique sensitivity to alpha-galactosylceramide of NKT cells in the uterus

It was previously reported that NKT cells, which are mainly present in the liver of mice, are also present in the uterus and that these uterine NKT cells are associated with abortion under overactivated conditions. In this study, we further examined their phenotypic and functional properties. In parallel with the progression of pregnancy, the number of uterine lymphocytes increased. This increase accompanied an increase in the number of TCRalphabeta(+) T cells and NKT cells in the uterus, although the number of NKT cells decreased at late pregnancy. Approximately one-third of the TCRalphabeta(+) cells were NKT cells at the early pregnant stage, while this ratio decreased toward late pregnancy. These uterine NKT cells were found to respond to alpha-galactosylceramide (alpha-GalCer) differently in comparison with liver NKT cells. In contrast to the apoptotic response of liver NKT cells on day 1 after alpha-GalCer injection, uterine NKT cells expanded prominently without such apoptosis. The majority of liver NKT cells were CD4(+). In contrast, almost all of the uterine NKT cells were double negative CD4(-)8(-). However, similar to liver NKT cells, uterine NKT cells used an invariant chain of Valpha14Jalpha281 gene for TCRalpha. The resistance against apoptosis might be due to the high expression of bcl-2 on uterine NKT cells after alpha-GalCer activation. Other evidence was that macrophages which existed in the pregnant uterus carried an activation marker, CD69, and could potentially produce many cytokines by their activation. The present results suggest that uterine NKT cells and surrounding macrophages are quite different in function from those in the liver.     

The sensitivity of one-cell mouse embryos to pyruvate and lactate

One-cell mouse embryos were cultured in several concentrations of pyruvate and lactate. Maximum development to blastocysts occurred when one-cell ova were cultured in media containing 0.25 mM pyruvate during the first cleavage division and 30.00 mM lactate plus 0.25 mM pyruvate after the first cleavage division. The unusual sensitivity of one-cell ova to both the kind and quantity of energy source was not evident on day 2 of development; normal appearing two-cell ova were formed under extreme conditions of up to 100.00 mM pyruvate and 90.00 mM lactate. The data demonstrate that the successful development of one-cell ova in vitro depends on satisfying separate requirements for the first cleavage division versus development after the first cleavage division. The formation of morphologically normal two-cell ova cannot be used as the sole criterion for satisfying the requirements of the first cleavage divison.     

The sensitivity of the mouse testis to the mutagenic action of triethylenemelamine

Summary The low dose of 0.2 mg/kg TEM allows the production of viable zygotes from the most sensitive stage of spermatogenesis. The frequency of translocations among offspring conceived during this peak period of sterility at 10–14 days p.i. is greater than among those conceived earlier, so that as the fertility of the treated males decreases (i.e. the percentage of dominant lethals increases) the frequency of translocations among their offspring increases. The results provide presumptive evidence that the spermatids are more sensitive to the mutagenic action of TEM than are the mature spermatozoa. A comparison of the incidence of translocations induced by TEM with that induced by X-rays is made and the significance of the occurrence of sterile animals among the F₁ is discussed.     

The sensitivity of the thoracolumbar spinal cord of the mouse to hyperthermia

Twelve millimeters of the thoracolumbar spinal cord of mice has been treated with a radiofrequency heating system which has been shown previously to produce localized and controllable elevation of temperature. The severity of neurological damage was assessed by measuring the reduction in the reflex leg extension of the hind legs of the mice from video-recorded images and by scoring the performance of the mice by a negative geotaxis test. The response to treatment was rapid with maximum paralysis occurring within a few days after treatment. Only minor symptoms were observed in those animals which had not developed paralysis within 2 weeks. A 40% reduction in the reflex leg extension was chosen as an end point, and the percentage of mice having reached the end point for different thermal doses was determined in groups of nine mice. The ED50 for heating for 1 h was 43.1 degrees C and for heating at 45 degrees C was 10.8 min. An increase in temperature by 1 degree C required a decrease in time by a factor of 2.25 to produce the same effect. Thermotolerance was observed 24 h after preheating at 45 degrees C for 1.9 min with a thermotolerance ratio of 1.7. The rapid response and high sensitivity of the spinal cord will have to be taken into consideration in the clinical application of hyperthermia.     

The microcirculatory bed of the normal rat uterus and in exposure to laser radiation

By means of scanning electron microscopy of corrosive casts angioarchitectonics of mucous and muscular membranes of the white rat uterus has been studied at diestrus phase, normal and under influence of laser irradiation with exposition of 1 min and 1 h. The morphometric investigation performed has proved presence of local peculiarities in organization of the uterine capillary bed. After irradiation for 1 min a noticeable increase in transversal diameter and capillary density is observed, numerous protrusions appear on their walls. When irradiation lasts for 1 h a relative loose of the uterine capillary network is observed, which is especially manifested in endometrium: capillaries demonstrate an increased convolution and decreased diameter.     

Response of the mouse uterus to nafoxidine stimulation: agonism and antagonism

Nafoxidine (NAF) acts as an estrogen agonist or antagonist depending on the animal model used. In the CD-1 mouse uterus, a three-day uterine bioassay of NAF produced a bell-shaped dose response curve with a maximal uterine wet weight increase at 200 micrograms/kg; this dose produced only a fractional increase in uterine dry weight. Combination treatment with NAF and estradiol antagonized estradiol stimulation of both wet and dry weight parameters. The time course of uterine wet weight stimulation following a single injection of NAF had an early pattern (0-10 h) similar to that of estradiol. However, at later times after stimulation, the patterns changed dramatically: the low NAF dose (200 micrograms/kg) returned to control levels by 24 h; estradiol and the high dose NAF (1.7 mg/kg) showed sustained stimulation, which peaked at 36 h with NAF compared to 24 h for estradiol. Nuclear estrogen receptor (ER) levels were measured after a single injection of 1.7 mg/kg NAF and showed a bimodal pattern similar to that seen with estradiol, with increases at 1 h and 8 h, although the overall ER levels were elevated above those seen with estradiol. Cytosolic ER levels with NAF decreased by 1 h and remained low up to 48 h. NAF treatment did stimulate uterine DNA and RNA synthesis, with a delayed time course compared to estradiol. DNA synthesis following a single 1.7 mg/kg dose of NAF was 2.5 times higher than that produced by 20 micrograms/kg estradiol. NAF treatment resulted in hypertrophy and hyperplasia in the luminal epithelium but not in the glandular epithelium. Long-term exposure to estradiol for 5 wk resulted in development of uterine cystic glandular hyperplasia and increased secretory activity; long-term exposure to NAF produced a more significant tissue hyperplasia but no secretions. These studies show that NAF stimulates some of the receptor-mediated responses attributed to an estrogen agonist in the mouse uterus; but, when co-administered with estradiol, NAF antagonizes some aspects of estrogen action.     

response of relaxin-treated rat uterus to prostaglandins and oxytocin

Paired segments of rat uterus were treated with relaxin (W1164-3, 150 GPU/mg) until the amplitude of contraction was reduced to at least 50% of the pre-treatment amplitude. Test segments then received 100 ng of either PGE₁, PGE₂, PGF_2α or 250 uU of oxytocin. Control segments remained untreated. There was a significant increase in contraction amplitude in response to the spasmogens (P < 0.05) but no increase was seen in controls.     

Metastasis-stimulating activity in the mouse uterus

Mouse uterine luminal proteins are thought to play important roles in inducing diapausing blastocysts to implant into the uterine wall. Employing a syngeneic teratocarcinoma cell line (402AX), we demonstrate that neoplastic cells are better able to invade and metastasize if they are coinjected with uterine fluid from pregnant or estrogen-primed mice. This metastasizing activity of uterine fluid was partially purified by using disc polyacrylamide electrophoresis and gel filtration chromatography. Preliminary experiments indicate that the post-albumin and albumin bands contain most of the bioactivity. Furthermore, these bands contain smaller molecular weight proteins (less than 14,000) than can be separated by detergent and mild acetic acid (0.1 N) treatment.     

The gelatinolytic activity of rat uterus collagenase

The collagenase produced by rat uterine cells in culture has been examined for its ability to degrade denatured collagen. Acting as a gelatinase, rat uterus collagenase was able to successfully degrade the denatured chains of collagen types I through V. In addition, the enzyme produced multiple cleavages in these chains and displayed values for Km of 4-5 microM, compared to values of 1-2 microM when native collagen was used as substrate. Furthermore, rat uterus collagenase degraded the alpha 2 chain of denatured type I collagen at a significantly faster rate than the alpha 1 chain, as previously observed for human skin fibroblast collagenase. In contrast to the action of human skin collagenase, however, the rat uterus enzyme was found to be a markedly better gelatinase than a collagenase, degrading the alpha chains of denatured type I guinea pig skin collagen at rates some 7-15-fold greater than native collagen. Human skin collagenase degrades the same denatured chains at rates ranging from 13-44% of its rate on native collagen. Rat uterus collagenase, then, is approximately 50 times better a gelatinase than is human skin collagenase. In addition to its ability to cleave denatured collagen chains at greater rates than native collagen, the rat uterus collagenase also attacked a wider spectrum of peptide bonds in gelatin than does human skin collagenase. In addition to cleaving the Gly-Leu and Gly-Ile bonds characteristic of its action on native collagen, rat uterus collagenase readily catalyzed the cleavage of Gly-Phe bonds in gelatin. The rat enzyme was also capable of cleaving Gly-Ala and Gly-Val bonds, although these bonds were somewhat less preferred by the enzyme. The cleavage of peptide bonds other than Gly-Leu and Gly-Ile appears to be a property of the collagenase itself and not a contaminating protease. Thus, it appears that the collagenase responsible for the degradation of collagen during the massive involution of the uterus might also act as a gelatinase to further degrade the initial products of collagenolysis to small peptides suitable for further metabolism.     

Development and characteristics of an oestrogen sulphotransferase in placenta and uterus of the pregnant mouse. Comparison between mouse and rat.

The mouse placenta possesses a soluble oestrogen sulphotransferase activity which increases markedly from at least 12 days of gestation until term. At about 16 days of gestation, a similar activity is found in the uterus. This activity also increases until term and disappears rapidly post partum. The uterine enzyme activity appears to require the presence of the foetal unit for its onset, since unoccupied horns, whether their endometrial stromal cells are differentiated to decidual cells or not, are essentially devoid of it. Uterine cytosols from non-pregnant mice are also inactive in this respect. In late gestation, the uterine sulphotransferase is confined to the decidua basalis, the areas to which the placentas are attached. The sulphotransferase(s) of placenta and uterus has an absolute requirement for 3'-phosphoadenosine 5'-phosphosulphate, and possesses little activity in the absence of exogenous thiol groups. Stimulation is also seen in the presence of Mn2+, Mg2+ or Ca2+. Oestrone and oestradiol, and to a lesser degree oestriol, are substrates for the enzyme(s), whereas testosterone, cortisol and dehydroepiandrosterone are not. Oestrone and oestradiol at higher concentrations (1.0-1.5 microM) completely inhibit the enzyme(s). These enzymes could play a role in altering tissue concentrations of active oestrogens during gestation in the mouse. Oestrogen sulphotransferase activity is low or absent in reproductive tissues of the pregnant rat.     

Hyperosmotic instillation of rat stomach.

Instillation of equally hyperosmotic solutions (1000 m0sm/kg) of NaCl, KCl, MgCl₂, or dextrose depressed the electrical potential difference and the spontaneous acid secretion of rat stomachs. Luminal osmolality declined only slightly after hyperosmotic dextrose instillation, but loss of luminal chloride followed hyperosmotic salt instillation. Comparable losses of luminal sodium or potassium were observed. These changes result from a hyperosmotic alteration of ion transport through the gastric mucosa.