Oxytocic Hormone Research Articles

Myometrial response to neurotropic and musculotropic spasmolytic drugs in an extracorporeal perfusion model of swine uteri

To compare the effects of neurotropic and musculotropic spasmolytic drugs in isolated swine uterus specimens, 80 swine uteri were perfused using an established model for preserving a viable organ that responds to oxytocic hormones and spasmolytic drugs. An intrauterine catheter was used to record pressure changes. Following initiation of rhythmic uterine contractions and recording of spontaneous rhythmic contractions, spasmolytic drugs (butylscopolamine, atropine, denaverine, morphine, metamizole, pethidine and celandine) were administered at various concentrations. The musculotropic relaxant denaverine in particular showed significant results ( P ⩽ 0.05) for all dosages and parameters investigated. In terms of muscle physiology, musculotropic agents (denaverine and celandine) have clear advantages in comparison with neurotropic (butylscopolamine and atropine) or musculoneurotropic (morphine, metamizole and pethidine) spasmolytic drugs for inhibiting contractions. Experiments with pethidine (Dolantin) also showed promising results; with celandine (Paverysat), an initial increase in contractions was observed that may suggest ways of promoting rapid directed sperm transport. Denaverine and pethidine in particular may in the future be able to play an important role in improving the pregnancy rate after IVF. Uterine contractions are important not only for labour, but also for the transport of semen and the oocyte. Contraction inducing-medicaments, such as oxytocin or the various prostaglandins, are used in everyday practice. These medicaments, however, interact with the arterial pressure which can be of utmost importance in hypertonic or pre-eclamptic patients. Using perfused swine uteri, which we obtained from the slaughterhouse, we were able to examine which substances can be safely used to influence the uterine contractility with the lowest rise in the arterial pressure. In these experiments we examined a group of drugs known as spasmolytic drugs. Denaverine and pethidine (Dolantin) showed promising results. In view of the latest research, the physiology of the menstrual cycle and the standard embryo-transfer technique, it appears that a combination of different drugs that are capable of positively reducing uterine contractions currently provides the best conditions for preparing the uterus sufficiently for embryo implantation. Denaverine and pethidine may in the future be candidates for improving the pregnancy rate after IVF.

The extracorporeal perfusion of the swine uterus as an experimental model: The effect of tocolytic drugs

Objective Comparison of the effect of tocolytic drugs on isolated swine uterus preparations. Study design Forty swine uteri were perfused with the aim to preserve a viable organ, which should be responsive to oxytocic hormones and tocolytic pharmaca. An intrauterine catheter recorded the pressure changes. After initiation of rhythmical uterine contractions we administered known tocolytic drugs (fenoterol, ritodrine, terbutaline, propofol, acetylsalicylic acid, alcohol, atosiban, verapamil, and glyceryl trinitrate) in various concentrations. Results Perfusate pH and lactate, partial oxygen and carbon dioxide tensions, and oxygen saturation in the perfusate showed good preservation of the organ for up to 8 h. All substances showed a tocolytic effect on the swine uterus. The effect varied substantially with regard to the length of the contraction free intervals, which was our main effect parameter. Fenoterol, acetylsalicylic acid, and alcohol showed the most and glyceryl trinitrate the least powerful effect. Conclusions A direct comparison of various tocolytic substances in the same experimental model showed the best effect for fenoterol. Furthermore, we could demonstrate that the swine uterus perfusion system is a suitable model to study the influence of various conditions like the administration of drugs or the induction of oxidative stress on the uterus function.

Regulation of uterine angiotensin II receptors by estrogen and progesterone.

The characteristics of uterine receptors for angiotensin II and their regulation during the estrous cycle and after gonadal steroid treatment were investigated in the rat and rabbit. Binding of [125I]iodoangiotensin II to rat uterine particles was temperature dependent and saturable, and Scatchard analysis showed a single population of binding sites with Ka of about 109m−1. The concentration of uterine angiotensin II receptors changed markedly during the estrous cycle of the rat and after treatment with gonadal steroids. During the ovarian cycle, the concentration of angiotensin II receptors was about 4 times higher at proestrus than at diestrus II. Similar changes were observed when estrous cycles were induced in immature rats by a single injection of PMS gonadotropin. Ovariectomy was followed by a progressive decrease in uterine angiotensin II receptors, reaching 50% of the control values 8 days after castration. Conversely, injection of 17β-estradiol caused a dose-dependent increase in angiotensin II receptors measured 24 h after steroid treatment. Similarly, short term infusion of 17β-estradiol caused a progressive increase in angiotensin II receptors, which reached a maximum of 4- to 6-fold above control values at 36 h. However, after long term infusion of estradiol for 5–8 days, angiotensin receptors returned to or below the control values. Progesterone infusion for 7 days caused uterine angiotensin II receptors decrease by 93%. When immature rabbits were primed with estrogen, a 4-fold increase in the concentration of uterine angiotensin II receptors was measured. In progesterone-primed uteri, angiotensin II receptor concentration was no longer augmented by estrogen. No effects of steroids upon the affinity of the receptors for angiotensin II were detected, all changes in binding being due to alterations in the tissue content of receptor sites. These studies have revealed marked changes in the concentration of angiotensin receptors during the estrous cycle and after steroid treatment. Thus, receptors for angiotensin II are regulated by estrogen in manner similar to the control of receptors for other oxytocic hormones. These findings may explain the increased contractile sensitivity of estrogen-primed uteri to angiotensin II and suggest a role for angiotensin II in the physiological control of myometrial activity. (Endocrinology106: 5, 1980)

THE PHYSIOLOGY OF LABOUR

The time of onset of labour is usually reasonably clear-cut and will be described by the patient as the onset of painful uterine contractions. The exact reason whereby the uterus changes from a retentive to an expulsive organ is not yet clearly understood. It probably is the summation of several factors: the drop in the hormone progesterone, either in absolute terms or relative to the level of oestrogen; attainment of a critical degree of distension and intrauterine pressure; a critical change in the consistency or sphincteric quality in the cervix; a critical build up of contractile protein in the uterine muscle cells and its increasing sensitivity to oxytocic hormone(s).

The effect on milk yield of three times a day milking and of increasing the level of residual milk

SummaryExperiments were made to determine the effects on yield and butterfat percentage of three times a day milking and of inefficient milking using cows whose milk secretion rates had been shown to be unaffected by the milk accumulation involved. The milking treatments were applied to half-udders of the same cow to ensure that there was no difference between each pair of experimental units in the amount of oxytocic hormone released by the pituitary gland.Milking three times a day compared with twice a day over a 39-day period resulted in an increase of 12% in both milk and butterfat yields. Increasing the residual milk by 1 lb in each half-udder for a 39-day period caused a 15% decrease in both milk and butterfat yields. It was concluded that since the cause of these findings could be neither the direct effect of differences in milk accumulation nor the effect of different amounts of oxytocic hormone, some local cell effect was involved, activated either by differences in the amount of residual milk or by long-term effects of differences in milk accumulation.

Some properties of an oxytocic substance found in blood extracts.

Some physico-chemical and pharmacological properties of an oxytocic substance (O.S.) in acid-alcohol extracts of human blood have been investigated. Thissubstance is not believed to be oxytocin, K+, acetylcholinc, H.T., histamine, hypertensin, substance P, pepsitocin, or P.P.S. It is probably a polypeptide and of the potypeptides which are known to stimulate smooth muscle, it most closely resembles bradykinin, kallidin, or substances U and Z. AN OXYTOCIC (uterine-stimulating) substance (O.S.) can be ex- XJL tracted from blood. It does not appear to be oxytocic hormone. This substance has been found in blood extracts of (a) non-pregnant women and women during normal pregnancy and parturition (1); (b) lactating and non-lactating women (2 and 3); lactating cows and goats (4); and in sheep and the human male. This material (or a substance closely resembling it) has been extracted from the hypothalamus of cats, rats, mice and cows (5), and was not found in extracts of other parts of the brain and spinal cord.

Hypothalamus and somatotrophic hormone release.

Summary1) Chronic treatment with posterior pituitary preparations containing ADH induces significant enlargement of tibia cartilage width in normal male and female rats; oxytocic hormone is ineffective in normal animals. 2) In hypophysectomized animals posterior pituitary hormones do not produce modification of the epiphyseal cartilages.

ARE THERE TWO OXYTOCIC HORMONES?

Medical Journal of AustraliaVolume 1, Issue 20 p. 671-672 Original Article ARE THERE TWO OXYTOCIC HORMONES? R. W. Hawker M.D., B.S. (Sydney), M.D. (Queensland), M.R.A.C.P., R. W. Hawker M.D., B.S. (Sydney), M.D. (Queensland), M.R.A.C.P. Department of Physiology, University of Queensland, BrisbaneSearch for more papers by this authorP. A. Robertson Ph.D. (London), P. A. Robertson Ph.D. (London) Department of Pharmacology, University of Sydney, SydneySearch for more papers by this author R. W. Hawker M.D., B.S. (Sydney), M.D. (Queensland), M.R.A.C.P., R. W. Hawker M.D., B.S. (Sydney), M.D. (Queensland), M.R.A.C.P. Department of Physiology, University of Queensland, BrisbaneSearch for more papers by this authorP. A. Robertson Ph.D. (London), P. A. Robertson Ph.D. (London) Department of Pharmacology, University of Sydney, SydneySearch for more papers by this author First published: 01 May 1958 https://doi.org/10.5694/j.1326-5377.1958.tb86672.xCitations: 4AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume1, Issue20May 1958Pages 671-672 RelatedInformation

Quantitative comparison of substances related to oxytocin: a new test.

A quantitative method of biological standardisation can be regarded as satisfactory when it is simple, rapid and accurate (Burn et al., 1950). It may be of secondary importance whether a) the function studied is the same as that influenced by the drug in man, and b) the conditions of the experiment are »physiological«. For instance, both the United States Pharmacopoeia (1955) and the British Pharmacopoeia (1953) recommend a method for standardising the oxytocic hormone of pituitary (posterior lobe) preparations which is based on the depression of the blood pressure in a chicken (Coon, 1939) although in clinical practice only the action on uterine muscle is important. In another widely employed method for the standardisation of oxytocin which is also recommended in the British Pharmacopoeia, the contractions of the isolated rat uterus are measured (Holton, 1948) but at a temperature of 32°C. or less, i. e. well below the body temperature.

The effects of nicotine, hexamethonium and ethanol on the secretion of the antidiuretic and oxytocic hormones of the rat.

The actions of nicotine, hexamethonium, and ethanol on the hypothalamo-hypophysial system have been investigated in the rat. The antidiuretic action of nicotine was not inhibited by ethanol, nor by doses of hexamethonium which were sufficient to block both its pressor and convulsant actions. Hexamethonium itself had an antidiuretic action the mechanism of which has been investigated. Nicotine caused a release of oxytocin into the blood which was not blocked by ethanol nor significantly reduced by hexamethonium. The results suggest that any synapse which exists at the supraoptic nuclei is dissimilar in its pharmacological properties to synapses at autonomic ganglia.

The neurosecretory substance in the hypothalamic-hypophysial system of the horse.

A good deal of hypothetical evidence has been presented for the view that the antidiuretic and oxytocic hormones are not produced in the posterior lobe of the hypophysis. These hormones appear to originate from a neurosecretory process in the neurosecretory nerve cells of the supraoptic and paraventricular nuclei in the hypothalamus and to migrate within the nerve fibers of the supraoptico-hypophysial tract and into the neurohypophysis (Hild, 1951, 1954 a, b and Hild & Zetler, 1951, 1952, 1953 a, b). Here they are stored and if necessary released. Neurosecretory neurons are described in many species of the animal kingdom from invertebrates to man. The product of the neurosecretory cells contains a stainable carrier substance in addition to the above mentioned hormones (Scharrer & Scharrer, 1954, and Scharrer, 1956). The product of the hypothalamic neurosecretory cells can be demonstrated histologically by certain methods. The chrome-alum-hematoxylin-phloxin-method (Gomori, 1941), first used to stain

AN IMPROVED METHOD FOR EXTRACTING OXYTOCIC AND ANTIDIURETIC HORMONES FROM BLOOD

AN IMPROVED METHOD FOR EXTRACTING OXYTOCIC AND ANTIDIURETIC HORMONES FROM BLOOD

Diabetes insipidus in pregnancy.

DIABETES insipidus is a rare complication of pregnancy. When this disease does happen to be associated with the pregnant state, however, considerable interest attaches to the combination, since there are implications both from the obstetrical and from the endocrine standpoint. To the obstetrician it is of importance to know whether an insufficient production of oxytocic hormone coincides with the inadequate elaboration of antidiuretic hormone, with the resultant possibility of dystocia. The obstetrician is interested also in the possibility that posterior pituitary extract administration, necessary for the treatment of the diabetes insipidus, might be responsible for the induction of premature labor. From an endocrine standpoint, further information is needed concerning the effect various normal hormonal shifts during pregnancy might have upon the function of the posterior lobe of the pituitary gland. That such shifts might well have an important effect is suggested by the well-known fact that in diabetes insipidus the

Estimation of the antidiuretic, vasopressor and oxytocic hormones in the pituitary gland of dogs and puppies.

The Journal of PhysiologyVolume 120, Issue 1-2 p. 141-145 ArticleFree Access Estimation of the antidiuretic, vasopressor and oxytocic hormones in the pituitary gland of dogs and puppies S. E. Dicker, S. E. DickerSearch for more papers by this authorChristine Tyler, Christine TylerSearch for more papers by this author S. E. Dicker, S. E. DickerSearch for more papers by this authorChristine Tyler, Christine TylerSearch for more papers by this author First published: 28 April 1953 https://doi.org/10.1113/jphysiol.1953.sp004880Citations: 35AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume120, Issue1-2April 28, 1953Pages 141-145 RelatedInformation

494. The milk-ejection response of the sow to standard doses of oxytocic hormone

The milk-ejecting activity of the hormones of the posterior-pituitary gland is well known and has been adequately reviewed (1). Most of the published information deals with the lactating dairy cow. In the course of work at this Station involving the lactating sow as a basis for assay of the milk-ejecting hormones (2, 3), data have been collected on the effect of a standard dose of oxytocin. Our normal assay procedure (2) involves giving the animal a preliminary dose of 0·5 unit of oxytocin. Thus over one lactation we have been able to record the time between injection into the ear vein and the onset of milk let-down, and the period during which milk may be obtained by simple hand-milking, for a number of sows. Braude & Mitchell (4) have published figures for the milk let-down effects of doses of oxytocin ranging from 1 to 10 units. The following results were obtained with &5 unit. All sows used were of the Berkshire breed.

Further Distribution Studies on the Oxytocic Hormone of the Posterior Lobe of the Pituitary Gland and the Preparation of an Active Crystalline Flavianate

Further Distribution Studies on the Oxytocic Hormone of the Posterior Lobe of the Pituitary Gland and the Preparation of an Active Crystalline Flavianate

Pressor and Oxytocic Hormones of the Pituitary Gland

Pressor and Oxytocic Hormones of the Pituitary Gland

Pressor and Oxytocic Hormones of the Pituitary Gland

Pressor and Oxytocic Hormones of the Pituitary Gland

Pressor and Oxytocic Hormones of the Pituitary Gland

Pressor and Oxytocic Hormones of the Pituitary Gland

An Examination of Factors Affecting the Precision of the Assay of the Oxytocic Hormone in Posterior Pituitary Lobe Preparations

Summary Work has been described which shows the errors which may be encountered under different experimental conditions of the uterine assay of oxytocin, or commercial posterior pituitary extracts where the ratio of oxytocin to vasopressin is not unity. By increasing the concentration of magnesium chloride in the British Pharmacopoeia 1948 Ringer’s solution, the response of the guinea-pig uterus to pitocin is increased. The response of the guinea-pig uterus to pitressin is also potentiated by increasing the concentration of magnesium chloride, but to a different extent than is pitocin. Different concentrations of calcium chloride in the Ringer’s solution produce potentiation to both pitocin and pitressin, but to different extents. The pressor principle does not produce any oxytocic effect on the uterus suspended in Ringer’s solution from which calcium chloride is absent. The absence of glucose from the Ringer’s solution produces rapid fatiguing of the uterine strip. Temperature regulation of the Ringer’s solution is very important. The sensitivity of uteri from guinea-pigs treated with stilbæstrol is greater than the uteri of progesterone-treated guinea-pigs to both pitocin and pitressin. The ratio of the sensitivity of uteri from progesterone-treated guinea-pigs to pitressin and pitocin is almost unity, whilst the ratio of sensitivity for the uteri of guinea-pigs treated with stilbæstrol indicates that the uteri are more sensitive to pitocin than to pitressin. Seasonal variation in the number of virgin albino guinea-pigs used per assay was not found to be significant. The ratio of oxytocin to vasopressin in the test samples must be the same as the ratio which is stated for the standard. The type of uterus and the physiological salt solution should be stated. It is recommended that the modification of Ringer’s solution proposed by the British Pharmacopoeia 1948 should be used for the guinea-pig assay, and that the uterus of the guinea-pig should be that of a virgin in diæstrus. The chicken blood depressor method offers many advantages over the isolated guinea-pig uterine method. It is cheaper and quicker to perform, and is more accurate in that narrow fiducial limits can be obtained. Until the chicken blood depressor method has been studied exhaustively in many laboratories engaged on the assay of the oxytocic principle, the guinea-pig uterine assay should be run in parallel with the former.