Oxytocic Fraction Research Articles

Bioassay-directed isolation of oxytocic principles from the methanol extract of Monechma ciliatum.

The hot methanol extract (HME) of Monechma ciliatum which has been reported to have potent oxytocic activity was purified by fractionation in an attempt to isolate the oxytocic principle. Thin layer analysis indicated that the oxytocic fraction was very polar. A positive reaction with ninhydrin-spray suggested that it is an amino acid/protein. Repeated column chromatography (CC) on silica gel followed by sephadex LH-20 column, accompanied by bioassay of the fractions on the rat isolated uterus enabled partial isolation of the oxytocic principle (P3) to be achieved. Although the exact structure of P3 could not be identified from the present study, various spectral analyses suggest that it is a small peptide made up of tyrosine, leucine and a third component which is probably serine. It is interesting to note that the parent compound, oxytocin, is also a peptide with tyrosine and leucine in its structure.

Bioassay‐directed isolation of oxytocic principles from the methanol extract of Monechma ciliatum

The hot methanol extract (HME) of Monechma ciliatum which has been reported to have potent oxytocic activity was purified by fractionation in an attempt to isolate the oxytocic principle. Thin layer analysis indicated that the oxytocic fraction was very polar. A positive reaction with ninhydrin-spray suggested that it is an amino acid/protein. Repeated column chromatography (CC) on silica gel followed by sephadex LH-20 column, accompanied by bioassay of the fractions on the rat isolated uterus enabled partial isolation of the oxytocic principle (P3) to be achieved. Although the exact structure of P3 could not be identified from the present study, various spectral analyses suggest that it is a small peptide made up of tyrosine, leucine and a third component which is probably serine. It is interesting to note that the parent compound, oxytocin, is also a peptide with tyrosine and leucine in its structure. Copyright © 1999 John Wiley & Sons, Ltd.

Distribution of neurohypophyseal hormones in some elasmobranch species

Pituitary extracts from species representing subgroups of the cartilaginous fishes were investigated for the presence of neurohypophyseal principles. Paper chromatography of pituitary extracts from Raia clavata and Scyliorhinus caniculus yielded two major oxytocic fractions. The pharmacological characteristics of the two components were determined by multiple bioassay, which showed differences between them. The presence of a trace of a vasotocin-like principle in Scyliorhinus extracts was also indicated by chromatography. Pituitary extracts of Squatina squatina and Rhinobatis rhinobatis also yielded two fractions. The fast-moving components of both S. squatina and R. rhinobatis extracts had similar Mg 2+ potentiation ratios. The slow-moving fraction of Rhinobatis was similar to that of Scyliorhinus. Bioassays of the slow-moving fraction of Squatina indicated the presence of vasotocin. Pituitary extracts of Carcharinus leucas and Negaprion brevirostris were chromatographically resolved into two fractions. The fast-moving principles of these two species showed similar pharmacological properties as those of other selachians; no definite conclusion could be reached as to the nature of these active fractions. Chromatography of Hexanchus griseus pituitaries yielded one major oxytocic region. The active principle was not potentiated by magnesium. Paper chromatograms of holocephalian ( Chimaera monstrosa, Hydrolagus collei, and Callorhynchus sp.) pituitary extracts showed two oxytocic regions. Neither of the two fractions was potentiated by magnesius.

Characterization of a principle resembling oxytocin in the pituitary of the holocephalian ratfish ( Hydrolagus colliei) by partition chromatography on Sephadex columns

An oxytocic fraction has been isolated from pituitaries of the ratfish ( Hydrolagus colliei) with pharmacological properties that differ from those of all known naturally occurring neurohypophysial principles except oxytocin. When subjected to partition column chromatography on Sephadex the Hydrolagus fraction appears to be a single peptide. Its mobilities on such columns are the same as those of oxytocin. If this principle is oxytocin its presence in the ratfish raises new questions concerning the manner in which neurohypophysial peptides have changed during the course of vertebrate evolution.

Action of antidiuretic hormone on gastric secretion.

THE FIRST animal experiments involving the action of posterior pituitary extracts on the stomach were reported in 1916. Rogers and co-workers observed that pituitary extracts reduced the flow of gastric secretion in Pavlov pouch dogs. 1 Dodds found that single large subcutaneous injections of the posterior pituitary extract produced temporary collapse, bloody diarrhea, and decreased food intake in rabbits. If these animals were examined in the early stages of the reaction, acute gastritis was found, confined to the acid secreting portion of the mucosa. 2,3 Repeated oral or subcutaneous administration of the posterior pituitary extracts was found to cause single punched-out ulcers in the acid-bearing area of the rabbit's stomach, 4 blanching of the stomach and duodenum in rabbits, 5 and multiple hemorrhages, erosions, and small ulcers in the dog's stomach. 6 This gastrotoxic factor was found to be associated with the pressor and not the oxytocic fraction of the

The formation of peptides with uterine activity from ovine, human and bovine growth hormones and from bovine and ovine lactogenic hormones.

1. Both starch gel and disk electrophoresis demonstrated stepwise degradation of acidic preparations of human and bovine growth hormones and of ovine and bovine lactogenic hormones in solution at pH 9.0-10.0. This developed in 1-3 weeks in refrigerated solutions and in 5-16 hr on incubation at 37 degrees C. Increasing acidity accompanied degradation.2. Oxytocic activity, initially absent, developed in these same solutions of hormones during stepwise degradation and appeared to be associated with a single phase of degradation.3. Storage in solution at pH 9.5 generated oxytocic activity in an initially basic preparation of ovine growth hormone. The uterine action was attributable to a small amount of acidic material with electrophoretic properties very similar to those of the oxytocic fractions formed during stepwise degradation of the acidic preparations of growth and lactogenic hormones.4. Prolonged storage of all these hormones at pH 9.0-10.0 resulted in the formation of acidic substances of low molecular weight which ran close to the buffer front and were dialysable (14 hr) through membranes which permitted the passage of nonapeptides in 6-8 hr.5. alpha-Chymotrypsin very rapidly generated uterine stimulant action in freshly prepared solutions of human growth and bovine lactogenic hormones at pH 9.5.6. All the hormone samples used proved capable of hydrolysing purified ox haemoglobin, urea-denatured, at pH 9.5.

THE EXTRACTION OF HUMAN URINARY KININ (SUBSTANCE Z) AND ITS RELATION TO THE PLASMA KININS

Human urinary kinin (substance Z) has been extracted by modifications of the methods previously described by Gomes (1955) and Jensen (1958). The separation of two oxytocic fractions from such extracts by paper pulp chromatography (Walaszek, 1957; Jensen, 1958) could not be confirmed. Substance Z could not be distinguished from kallidin, bradykinin or glass-activated kinin by parallel quantitative assays, thus confirming that these four substances are very closely related.

Some effects of pressor-antidiuretic and oxytocic fractions of posterior pituitary extract on sodium, chloride, potassium and ammonium excretion in the dog.

Some effects of pressor-antidiuretic and oxytocic fractions of posterior pituitary extract on sodium, chloride, potassium and ammonium excretion in the dog.

The effect of posteriorpituitary hormone on the release of ACTH.

1) Exogenous posterior-pituitary hormone has an inhibitory effect on the release of ACTH provoked by epinephrine, histamine and cold.2) Vasopressor fraction in the posterior-pituitary hormone has this effect, but oxytocic fraction has not.3) Exogenous pitressin can not inhibit depletion of adrenal ascorbic acid following the administration of ACTH.4) 5mu. of pitressin per 100g. body weight has no inhibitory effect on the release of ACTH.5) A large amount of pitressin, more than 60mu. per 100g. body weight, causes a decrease in adrenal ascorbic acid. However, 0.02mg. of epinephrine per 100g. body weight of rats successively administered does not produce further depletion of adrenal ascorbic acid.6) Even a large dose of pitressin can not cause any reduction of adrenal ascorbic acid concentration in hypophysectomized rats.

Reflex stimulation of the neurohypophysis (posterior pituitary gland) and the nature of posterior pituitary hormone (s).

THE sensory stimulus of suckling evokes nervous reflex release of the oxytocic substance from the neurohypophysis, which in turn stimulates the contractile tissue of the breast and causes a rise of milk pressure in the mammary ducts1. Electrical stimulation of the nerve supply (the supraopticohypophysial tract) of the neurohypophysis, or injection of posterior pituitary extracts (especially the oxytocic fraction)2, elicits similar effects on the breast. Rise in intra-mammary duct pressure produced by injection of the oxytocic substance, or by excitation of the milk ejection reflex alone, does not usually result in free flow of milk to the exterior, possibly because of some sphincter-like mechanism at the nipple. In some cases, however, excitation of the milk ejection reflex results in dribbling of milk from a nipple that is not being suckled or milked ; for example, the flow that may occur from the unsuckled breast of a nursing woman or from the udder of a cow subjected to routine procedures preceding milking.

Influence of the adenohypophysis on the frog water-balance response.

IN THE intact frog the injection of posterior pituitary extract causes a marked increase in the rate of water uptake. This water-balance response is the result of an increase in the permeability of the skin to water and is produced by the oxytocic fraction. Adenohypophyseal function appears to be necessary for a normal water-balance response. Jones and Steggerda (1935) reported a complete loss of the response in frogs hypophysectomized more than one week. Chen et al. (1943) noted that the response declines to 25 per cent of normal ten days after removal of the adenohypophysis but does not disappear completely. This paper concerns the changes in water balance that occur in the frog following hypophysectomy. Alterations in permeability of the skin as well as in the response to pitocin have been observed. The response has also been restored to normal by means of appropriate hormone replacement in the hypophysectomized frog.

The role of the neurohypophysis in the milk-ejection reflex.

1. Nursing and suckling behaviour of rabbits is described, and evidence given that an active process of milk ejection ('let-down') occurs in this as in other species. 2. Intravenous injection of posterior pituitary extracts in anaesthetized rabbits resulted in ejection of milk from a cannulated teat duct. The threshold dose was about 5 mU. and maximal responses were produced by 200 mU. of extract. Whole posterior pituitary extract was more effective than the oxytocic fraction, which was in turn more effective than the vasopressor fraction. 3. Stimulation of the supraopticohypophysial (s.o.h.) tract in anaesthetized rabbits also resulted in ejection of milk from a cannulated duct. Kymographic records of this response were similar to those obtained after injection of appropriate doses of posterior pituitary extract. 4. Lesions in the s.o.h. tract in lactating rabbits caused a marked diminution in the quantity of milk obtained by their litters in standard suckling tests, and incomplete evacuation of the mammary glands. Intravenous injection of posterior pituitary extract (30–200 mU.) into the does immediately before nursing gave a marked increase in the amount of milk obtained by the young and complete evacuation of the mammary glands. Stimulation of the region of the s.o.h. tract in these animals failed to elicit milk ejection from cannulated teat ducts. 5. Rabbits with hypothalamic lesions that did not involve the s.o.h. tract showed a normal milk-ejection reflex when suckled by their young, and a milk-ejection response after electrical stimulation of the s.o.h. tract.

The Water-Balance Principle of Crustacean Eye-Stalk Extracts

ABSTRACT Eye-stalks of the brackish water-crab, Carcinus moenas, and of the fresh-water crayfish, Potamobius fluviatilis, were extracted according to the pharmacopoeia! method for the extraction of posterior pituitary glands. Injection of such eye-stalk extracts resulted in a temporary increase in the body water of frogs. The increase produced by the extract of one eye-stalk of Carcinus was approximately equal to that produced by the injection of 20 milliunits pitocin ( = oxytocic fraction of mammalian posterior pituitary extract). The crustacean eye-stalk extracts had no significant oxytocic, chloruretic, or antidiuretic effect.

THE EFFECT OF NEUROHYPOPHYSIAL EXTRACTS ON THE WATER BALANCE OF LOWER VERTEBRATES

Summary(i) An injection of neurohypophysial extracts into frogs kept in water produces a temporary increase of body weight. This rise of weight (the ‘water‐balance effect’ or ‘Brunn reaction’) has beēn shown to be due to an increase of the body water. (2) The water‐balance effect has been clearly demonstrated in various species of amphibians only. It does not occur in teleost fishes or in mammals. Its occurrence in reptiles is doubtful and requires reinvestigation. It has not been investigated in cyclostomes or birds. (3) Evidence concerning the mechanism of the amphibian water‐balance effect may be summarized as follows, (a) The evidence for an increased water uptake through the skin following an injection of neurohypophysial extract appears satisfactory. However, further analysis of this extrarenal effect seems desirable. (b) Evidence for a renal inhibitory effect is suggestive but not unequivocal, (c) Evidence for a direct effect on the tissue imbibition is lacking. (4) The specificity of the neurohypophysial water‐balance effect with particular reference to the effect of other endocrine glands has been discussed: certain steroid hormones have been reported to produce slight increases of body weight in amphibians, but the mechanism of these increases has not been investigated. (5) Data referring to the influence of other hormones on the water‐balance effect of neurohypophysial extracts have been considered: it is pointed out (a) that in most of the experiments concerned the endocrine preparations were not “homologous, and (b) that the majority of the experiments were of very short duration. However, it has been shown that treatment with thyroxin for several days enhances the neurohypophysial water‐balance effect in winter frogs. (6) Subtotal hypophysectomy has been observed to produce polyuria in frogs and toads kept in water; the body weight of hypophysectomized animals is not significantly affected. Hypophysectomized frogs kept in dry surroundings do not seem to lose water more readily than normal controls. However, the probably unavoidable hypothalamic lesion and the removal of the adenohypophysis in the course of the operation obscures the issue. (7) There are not sufficient data to permit the formation of a theory regarding the physiological significance of the neurohypophysial water‐balance effect in amphibians. However, the fact that frogs in dry surroundings are less liable to lose water when injected with the oxytocic fraction of mammalian posterior pituitary extracts may be considered as supporting the suggestion that the response to the neurohypophysial water‐balance principle is an adaptation to an amphibious life. The absence of a water‐balance effect in wholly aquatic animals (fishes) and wholly terrestrial animals (mammals) may be noted in this connexion. (8) The principle producing a temporary increase of body water in amphibians (water‐balance principle) has been found in the neurohypophysis of all vertebrate classes investigated. The content of water‐balance principle has been quantitatively determined in the pituitary glands of elasmobranchs, marine and freshwater teleosts, amphibians, reptiles, birds and mammals. Cyclostomes have not been examined. (9) The water‐balance principle has been shown to be not identical with the mammalian posterior pituitary antidiuretic hormone and to be mainly contained in the oxytocic fraction. Its identity with the oxytocic hormone is doubtful.

Pituitary control of alimentary blood flow and secretion - Changes in the stomach produced by the administration of posterior pituitary extract

A preliminary report on the gastric lesion associated with the injection of a posterior lobe pituitary extract has been given (Dodds, Noble and Smith 1934; Dodds, Hills, Noble and Williams 1935). To assist in determining the mechanism of this reaction, careful histological studies have been made of the changes in the stomach mucosa. It has been found that the gastric lesion may be produced by the subcutaneous, intravenous or intracisternal injection of any posterior pituitary extract containing the pressor fraction. Control extracts of many tissues including anterior and intermediate lobes of the pituitary have been shown to be inactive. Similarly, the oxytocic fraction of the posterior lobe is without effect. For the extract to be effective when given by mouth, it is essential that the solution be in dilute acetic acid, similar to standard B.P. pituitary extract.