[Antidiuretic and oxytocic activity in the posterior lobe of the pituitary gland of sexually mature Wistar rats under the effect of continuous illumination and darkness].
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Animals↗
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Results for “OXYTOCICS”
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[Desamino-oxytocin, an oxytocic hormone not inactivated by serum from pregnant subjects].
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Animals↗
[The behavior of the serum oxytocin activity in uterine hypokinesia during oxytocic treatment].
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Female↗
The vasopressor and oxytocic activities of the hypothalamus and neurohypophysis influenced by stimulated alpha-adrenergic transmission during dehydration and subsequent rehydration in the white rat.
Under conditions of equilibrated water metabolism a single dose of methoxamine increased the content of vasopressin in the hypothalamus as well as that of oxytocin both in the hypothalamus and neurohypophysis. During dehydration the depletion of hypothalamic and neurohypophysial vasopressin was more marked in methoxamine-treated animals; this effect, however, was absent in the neurohypophysis on the 2nd day and in the hypothalamus on the 8th day of water deprivation. After two days of dehydration methoxamine inhibited the decrease of oxytocin content in the hypothalamus; simultaneously (2nd and 4th day of dehydration) it intensified this process in the neurohypophysis. During rehydration methoxamine impaired the renewal of vasopressin both in the hypothalamus and neurohypophysis; this effect was most marked on the 8th day of rehydration. On the contrary, it favoured somewhat the renewal of hypothalamic oxytocin in rehydrated rats (such an event was not found on the 8th day of rehydration). Moreover, methoxamine restrained initially (on the 2nd and 4th day of rehydration) the restoration of neurohypophysial oxytocin stores; following eight days of rehydration an opposite effect was here found. It is concluded that the response of the vasopressinergic and oxytocinergic neurons to alpha-adrenergic stimulation, brought about by using methoxamine as pharmacological tool, seems to be depended on the actual state of water metabolism. Impulses from the osmoreceptors may be therefore of some importance in modifying the change in vasopressin and oxytocin synthesis, transport and release resulting from stimulation of alpha-adrenergic transmission through neural chains including units susceptible to methoxamine.
Animals↗
Pharmacological evaluation of aqueous root extract of Selayak Hitam: lack of oxytocic activity.
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Abortifacient Agents↗
The adrenergic influences on the hypothalamic and neurohypophysial oxytocic activity in long-term dehydrated male white rats.
Rats dehydrated up to 12 days were given intraperitoneally phenoxybenzamine hydrochloride or amphetamine sulfate in daily doses of 0.2 mg/100 g or 0.5 mg/100 g, respectively. In not dehydrated animals, both drugs decreased significantly the hypothalamic and neurohypophysial oxytocin content. In dehydrated rats the oxytocin activity in the hypothalamo-neurohypophysial system diminished progressively; under such conditions, inhibition of alpha-adrenergic receptors (brought about by using phenoxybenzamine as pharmacological tool) as well as the stimulation of the alpha- and beta-adrenergic receptors (caused by amphetamine administration) potentiated the effects of osmoreceptor stimulation.
Amphetamine↗
The vasopressor and oxytocic activities of the hypothalamus and neurohypophysis are influenced by inhibited alpha-adrenergic transmission during dehydration and subsequent rehydration in the white rat.
During equilibrated water metabolism a single dose of dihydroergotamine (DHE) increased vasopressin release from the neurohypophysis; it had no effect on oxytocin content in the hypothalamus and neurohypophysis. After two days of dehydration DHE somewhat restrained the decrease of oxytocin in the hypothalamus; the release of vasopressin from the neurohypophysis was then increased. Under severe dehydration, i.e. under conditions of potent osmoreceptor stimulation, DHE influenced the vasopressin content neither in the hypothalamus nor in the neurohypophysis, but in some way it intensified oxytocin depletion in the neurohypophysis. Following two days of rehydration DHE somewhat restrained the renewal of vasopressin in the hypothalamus. No changes of oxytocin in the hypothalamus could be demonstrated at that time; in the neurohypophysis DHE intensified vasopressin repletion, but inhibited oxytocin repletion. Following four and eight days of rehydration DHE had no influence on vasopressin repletion rate in the hypothalamus and neurohypophysis. At that time oxytocin repletion in the neurohypophysis was increased; in the hypothalamus it was not affected by DHE. It is concluded that the response of the hypothalamo-neurohypophyseal system to alpha-adrenergic blockade-as brought about by dihydroergotamine treatment-seems to be dependent on the actual state of water metabolism. Impulses from the osmoreceptors may be therefore of some important in modifying the change in vasopressin and oxytocin release resulting from inhibition of alpha-adrenergic transmission through neural chains including units susceptible to dihydroergotamine.
Animals↗
The routine use of oxytocic drugs in the third stage of labour.
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Ergonovine↗
[Oxytocic activity of desamino-oxytocin (Sandopart). Personal clinical experience].
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Administration, Oral↗
[Indices of the plasma oxytocic activity of parturients treated with dosaminooxytocin].
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Adult↗
The impact of induced labour on postpartum blood loss.
It is generally believed that postpartum blood loss is less in patients whose labour is induced with prostaglandins than in patients delivered without induction. However, postpartum blood loss is known to be greater with precipitate labour and labours induced with oxytocin and prostaglandins, unless an oxytocic agent is continued after delivery. A retrospective study was undertaken at the University Hospital of the West Indies to look at the outcome of induced labour during 3 months, October-December 1998. Misoprostol induction was compared to the outcome after oxytocin induction, misoprostol induction plus oxytocin augmentation and those patients who delivered without oxytocics during this same time period. During that period, 524 patients were delivered and 51 (9.7%) were induced with misoprostol, 174 (33.2%) with oxytocin, 21 (4%) misoprostol plus oxytocin and 271 (51.7%) without oxytocic. Seven patients were eliminated from further analysis, as we were unsure of their induction status. Results showed no significant differences between the groups for variables such as maternal age, parity and fetal birth weight. There was a significantly greater mean blood loss at delivery with all induced labour compared with those not induced. For misoprostol 162.5(SD 190) ml, oxytocin (150 (SD 100) ml and for oxytocin plus misoprostol 150 (SD 150) ml, while controls had the lowest mean blood loss 100 (SD 130) ml occurring where no predelivery oxytocic was needed (P<0.03). Postpartum haemorrhage was highest with misoprostol 5.8% versus 4.4% for no oxytocic, 1.1% for oxytocin and 0% for misoprostol plus oxytocin. However, none of these values reached statistical significance. The misoprostol group also had the shortest first stage, 333 minutes versus 557 minutes for oxytocin, 576 minutes when both misoprostol and oxytocin was used and 344 minutes with no oxytocic. Blood loss was also independently directly associated with placental weight (P=0.01) and fetal birth weight (P=0.03), as well as the length of the third stage of labour (P=0.01), but not the length of the first stage of labour. Induction of labour with oxytocic agents is associated with greater blood loss. However, increased blood loss is not due to precipitate labour alone.
Abortifacient Agents, Nonsteroidal↗
Management of the third stage of labor: a survey of practice among Texas obstetricians.
Available evidence shows that the benefits of routine oxytocic administration in the third stage of labor far outweigh the potential risks. In 1990, T.F. Baskett, MD, reviewed the routine use of oxytocic drugs by Canadian obstetricians in the management of the third stage of labor. With Dr Baskett's permission, we sent a similar questionnaire to 1500 obstetricians in Texas: 1000 practiced in urban areas and 500 practiced in rural areas of the state. Ninety-four percent of Texas obstetricians answering the survey used oxytocics routinely in managing the third stage of labor. However, only 14.9% administered the oxytocics before delivery of the placenta, in contrast to 92.1% who gave oxytocics after the delivery of the placenta. Oxytocin was the chosen oxytocic drug for routine third-stage management (95%) as well as for postpartum hemorrhage (73.3%). Of the physicians surveyed, 55.9% used 15-methyl prostaglandin F2a (Hemabate) to treat postpartum hemorrhage refractory to other drugs within the past year. Of the respondents, 14.3% had managed acute uterine inversion during the past year. Thus, Texas obstetricians use Oxytocin routinely in the management of the third stage of labor, but few are converted to active management.
Attitude of Health Personnel↗
Neonatal jaundice after labour induced or stimulated by prostaglandin E2 or oxytocin.
In a prospective study of neonatal jaundice 739 infants, delivered vaginally, in the vertex presentation, and without major complications, were examined. Labour was induced or stimulated after random allocation of the mothers to one of three oxytocics (prostaglandin E2 orally, oxytocin intravenously, or demoxytocin buccally). Oxytocics were unnecessary after primary amniotomy in 91 women. A linear logistic statistical analysis showed that gestational age has a highly significant influence on the risk of jaundice (defined by maximum serum level of bilirubin greater than or equal to 205 mumol/l). An apparent influence of birthweight could be explained by the correlation between birthweight and gestational age. The influence of the three oxytocic agents was not significant, although they may have had a slight effect; however, any such effect could be a consequence of the infants of mothers given oxytocics being less mature than those whom mothers did not receive oxytocics. The duration of labour and the mother's age also had no effect on risk of jaundice. Thus, neonatal jaundice after induced and stimulated labour seems to be primarily associated with fetal maturity; the pharmacological side-effect, if any, of oxytocics is of no importance.
Birth Weight↗
The metabolic effects of oxytocin are mediated by a uterine type of receptor and are inhibited by oxytocin antagonist and by arginine vasopressin in the dog.
Infusion of oxytocin (OT) into normal dogs, in doses which produced plasma levels of OT in the physiological range, has been shown to increase plasma levels of glucose, insulin and glucagon and increase rates of glucose production and uptake. This study sought to determine whether there was a correlation between these metabolic effects and the oxytocic potency of four less potent oxytocic analogues when infused into normal dogs. The rank order of oxytocic potency of all 4 correlated well with the rise in plasma glucose levels, and in 3 of the 4 with the rise in plasma insulin levels. An antagonist of the oxytocic effect of OT suppressed the usual OT-induced rise in plasma glucose, insulin and glucagon as well as the increased glucose production and uptake. Arginine vasopressin (AVP) infusion, which by itself did not produce any metabolic effects, blocked completely the effects of OT infusion to raise plasma glucose and insulin levels and increase glucose production and uptake. The data suggest that the metabolic effects of OT in the dog are mediated by OT receptors that are similar to those producing the oxytocic effects. Whether the inhibition by AVP of the metabolic and hormonal effects of OT occurs at the receptor or post receptor level or via other mechanisms remains to be determined.
Animals↗
The misoprostol third stage of labour study: a randomised controlled comparison between orally administered misoprostol and standard management.
OBJECTIVE: To compare misoprostol with standard oxytocic regimens in the prevention of postpartum haemorrhage. DESIGN: Randomised controlled trial. SETTING: Obstetric unit in a large teaching hospital. METHODS: One thousand women randomised to 500 microg misoprostol given orally or to standard oxytocic regimens of oxytocin, oxytocin with ergometrine, or ergometrine. MAIN OUTCOME MEASURES: Incidence of postpartum haemorrhage and the incidence and severity of side effects. RESULTS: Postpartum haemorrhage occurred in 12% of women given misoprostol and in 11% of women given standard oxytocic drugs (relative risk (RR) 1.10, 95% confidence interval (CI) 0.79, 1.55). Blood loss of 1000 mL or more occurred in 2% of women in each group. Nausea, headache, dizziness and tiredness were less frequent with misoprostol (RR (95% CI) 0.71 (0.59, 0.84); 0.53 (0.38, 0.74); 0.73 (0.61, 0.87) and 0.88 (0.83, 0.94) respectively). The main side effects of misoprostol were shivering (RR 1.95, 95% CI 1.69, 2.25) and a rise in temperature (difference in mean rise 0.34 degrees C, 95% CI 0.26, 0.42). CONCLUSION: Oral misoprostol for the prevention of postpartum haemorrhage was comparable to standard oxytocics. Many side effects were less common with misoprostol but shivering and pyrexia were more common. Larger randomised trials are needed before establishing the equivalence between misoprostol and standard oxytocic drugs in the prevention of postpartum haemorrhage.
Administration, Oral↗
Some pharmacological actions of four synthetic analogues of oxytocin.
Four structural analogues of oxytocin were investigated with regard to their oxytocic, milk-ejecting, pressor and diuretic/antidiuretic effects. In three of them the isoleucyl group of oxytocin was replaced by a phenylalanyl, leucyl, or valyl residue; in the fourth the asparaginyl group was replaced by a glutaminyl residue. Synthetic oxytocin and the international standard pituitary (posterior lobe) powder were used for comparison. Although the analogues showed marked differences in their oxytocic effects, there was a fairly good agreement between the results obtained on the isolated rat uterus and the blood pressure of the chicken for each polypeptide. The milk-ejection pressure test gave much higher values throughout. The pressor and antidiuretic activities of the four analogues showed no obvious correlation with the values obtained in the other tests. The valyl and the leucyl analogues also had a diuretic effect. The phenylalanyl analogue was remarkable for the close correspondence between its oxytocic and antidiuretic effects: practically identical values were obtained for the potency, whether measured on the rat uterus in vitro, the blood pressure in the chicken, the cat uterus in situ or water diuresis in the rat. The leucyl analogue showed an oxytocic activity on the cat uterus in situ or the rabbit mammary gland roughly 7 to 9 times as high as that measured by means of the conventional bioassay methods, such as the blood pressure of the chicken or the rat uterus in vitro. The glutaminyl analogue, the weakest of the whole series, had only a modest effect on the mammary gland. The valyl analogue was the most interesting of the new polypeptides. Its oxytocic action on the cat uterus in situ and its milk-ejecting effect were greater than that of synthetic oxytocin, whereas its antidiuretic and pressor effects were less. In cats and rats, the uterine effect was stronger in situ than in vitro. There were also distinct species differences between cats, rabbits, and rats in their sensitivity to valyl-oxytocin.
Animals↗
Characterization of Gaddum's substance R.
1. When the isolated small intestine of the rat is perfused via the mesenteric artery, an oxytocic principle (Gaddum's substance R) is released which is detectable in the perfusate after 30 min and is present in samples collected 8 h later. 2. The oxytocic activity of substance R is lost after boiling but is unaffected by treatment with thioglycolate. Furthermore, atropine, methysergide and indomethacin failed to antagonize uterine contractions to substance R. 3. Neither substance R nor urinary kallikrein alone induce a contraction of the guinea-pig isolated ileum. However, in the presence of kininogen both substance R and urinary kallikrein produce a slow and prolonged contraction of the guinea-pig ileum. 4. The oxytocic and kininogenase properties of both substance R and urinary kallikrein are inhibited by Trasylol. 5. Soy bean trypsin inhibitor (SBTI) selectively inhibited both the oxytocic and the kininogenase activities of substance R but not those of urinary kallikrein. 6. Gel filtration of substance R resolved a single peak of oxytocic activity with an estimated molecular weight of 40 kDa. 7. We conclude that substance R is a kininogenase enzyme which may be distinguished from plasma kallikrein by its molecular weight and from urinary kallikrein by its susceptibility to SBTI. The exact nature of this enzyme remains to be elucidated.
Animals↗
The pharmacological basis for the use of dried sheep placenta in traditional obstetric practice in Nigeria.
Dried sheep placenta is sometimes used in traditional medicine to facilitate labour. The effects of an extract of powdered dried sheep placenta with normal saline on guinea-pig uterus, ileum, spontaneously beating atrium and Langendorff heart, rat uterus and hindquarters, and cat blood pressure were therefore examined. It was found that 1 g of dried sheep placenta had, on the guinea-pig uterus, an oxytocic activity equipotent with 0.075-0.32 i.u. of oxytocin. The oxytocic activity was unaffected at pHs between 4 and 10 or by boiling for 30 min or autoclaving for 15 min. Neither atropine nor promethazine inhibited the oxytocic action, but promethazine inhibited, to the same degree, contractions induced in the ileum by equipotent doses of the infusion and histamine. Atropine, however, had no effect on infusion-induced contractions in the ileum. The vasoconstriction induced in the rat hindquarters was antagonized by promethazine and phentolamine. Cat blood pressure was reduced, but it had positive inotropic and chronotropic effects on the spontaneously beating guinea-pig atrium and on the guinea-pig Langendorff heart. It was concluded that the dried placenta contains a chorionic oxytocic substance the action of which is independent of stimulation of H1 receptors or of muscarinic receptors.
Animals↗