The Release of Antidiuretic Hormone From the Pituitary Stalk After Intravenous Calcium Chloride or Magnesium Chloride Infusion in Rats

Leśnik, H; Guzek, Jan W.; Traczyk, W

doi:10.1677/joe.0.0450083

Cited by 8 publications

(6 citation statements)

References 12 publications

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“…The outflow of VP from cut axons of the SOHT has been estimated to be 80 pg/h (Lesnik et al 1969) and this is clearly not sufficient to account for the present values of approximately 1 -25 ng VP/h in hypo¬ physial portal plasma. Thus, the high concentrations of VP and OT in hypophysial portal blood are due to the direct release of these nonapeptides into the hypo¬ physial portal vessels.…”

Section: Resultscontrasting

confidence: 62%

“…The plasma concentrations of OT were similar to those reported recently by Gibbs (1984) who collected portal blood by the method of Porter & Smith (1967). The high concentrations of VP in hypophysial portal plasma could be due to the direct release of VP into hypophysial portal blood, the presence of VP in blood arising from backflow from the posterior pituitary gland (Oliver et al 1977;Bergland & Page, 1978), the presence of VP in cerebrospinal fluid (CSF) (Dogterom, van Wimersma Greidanus & De Wied, 1978) or the leakage of VP from cut axons of the SOHT (Lesnik et al 1969). It is unlikely that a significant amount of either VP or OT in hypophysial portal plasma is due to backflow of blood from the posterior pituitary gland, since the present studies showed that there was no significant change in the concentration of either peptide in hypophysial portal plasma from animals in which the pituitary gland had been removed at the time of pituitary stalk section compared with concentrations in hypophysial portal plasma from animals in which the pituitary gland had been left in situ (Text- fig.…”

Section: Resultsmentioning

confidence: 84%

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Oxytocin and vasopressin in rat hypophysial portal blood: experimental studies in normal and Brattleboro rats

Horn¹,

Robinson²,

Fink³

1985

Journal of Endocrinology

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Oxytocin (OT) and vasopressin (VP) were measured by radioimmunoassay in hypophysial portal and peripheral blood from male Wistar rats and heterozygous and homozygous Brattleboro rats anaesthetized with urethane. In Wistar rats the concentrations of OT and VP were about 50 times greater than the concentrations in peripheral blood, whether or not the pituitary gland was left in situ during collection, and also considerably greater than the reported concentrations of the peptides in the cerebrospinal fluid. The release of both peptides was increased significantly by a lesion of the supraoptico-hypophysial tract that led to diabetes insipidus, but which left intact the external layer of the median eminence (ME). Concentrations of VP were undetectable in plasma from homozygous Brattleboro rats, but the portal plasma concentrations of VP in heterozygous Brattleboro rats were not significantly lower than in Wistar rats. The concentrations of OT in portal plasma from both types of Brattleboro rat were significantly higher than in Wistar rats. The output of VP and OT into hypophysial portal blood of Wistar rats was not significantly affected by electrical stimulation of the suprachiasmatic, supraoptic or paraventricular nuclei or the ME using two types of stimuli, one of which produced an increase in peripheral plasma concentrations of VP and OT in intact rats and a significant increase in the release of LH-releasing hormone into hypophysial portal blood. The output of VP and OT into portal blood was also not significantly affected by either adrenalectomy with or without injection of dexamethasone or the injection of either the 5-hydroxytryptamine (5-HT) synthesis blocker, parachlorophenylalanine, or the 5-HT uptake blockers, alaproclate or zimelidine. These results show that large amounts of OT as well as VP are released into hypophysial portal blood from fibres of the hypothalamo-neurohypophysial system that terminate in the external layer of the ME. Although distinct from the fibres that terminate in the pars nervosa (PN), the findings in Brattleboro rats show that the VP fibres of the ME system originate in neurones with a genomic mechanism for VP synthesis similar to that of the VP neurones that project to the PN. The lack of effect of adrenalectomy and the administration of 5-HT synthesis and uptake blockers must be interpreted with caution since the results obtained with electrical stimulation suggest that when the pituitary stalk is cut the release of OT and VP into portal blood approaches a maximum and may therefore be difficult to alter by experimental manipulation.(ABSTRACT TRUNCATED AT 400 WORDS)

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Section: Resultscontrasting

confidence: 62%

Section: Resultsmentioning

confidence: 84%

Oxytocin and vasopressin in rat hypophysial portal blood: experimental studies in normal and Brattleboro rats

Horn¹,

Robinson²,

Fink³

1985

Journal of Endocrinology

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“…injection of 1 ml Locke solution containing additionally 60 /iM-CaCl2, induces an enhanced release of antidiuretic activity from the hypothalamic end of the cut rat pituitary stalk (Lesnik, Guzek & Traczyk, 1969). The same amount of CaCl2 was injected i.v.…”

Section: Discussionmentioning

confidence: 99%

Effect of Intravenous and Intracarotid Injections of Hypertonic Fluids on the Release of Melanocyte-Stimulating Hormone From the Rat Posterior Pituitary Lobe Incubated in Situ

Cyrkowicz¹,

Traczyk²

1975

Journal of Endocrinology

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The posterior pituitary lobe of male rats under urethane anaesthesia was incubated in situ. The pituitary gland was exposed by thr transpharyngeal apprach. The posterior lobe remained in neural and partial vascular connexion with the hypothalamus, whereas the anterior lobe was entirely remobed. Incubation fluid was collected and its melanophore-stimulating activity was assayed in hypophysectomized frogs. No effect was observed after the i.v. injection of 1 ml 120 muM-NaC1 with 60 muM-CaC12 or isotonic NcC1 solution. Hypertonic solutions of 5% NaC1 and 25% glucose injected intravenously to the limit of 0-5% of the body weight, transiently enhanced the release of MSH from the posterior pituitary lobe by 66% (significant) and 15% (not significant) respectively. Intracarotid injection of 0-3 ml 5% NaC1 solution resulted in the highest increase (95%) of MSH release.

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“…T OM as/T raczyk/G uzek in a variety of situations [LeSnik et al, 1969]. The present study deals with the influence of hippocampal stimulation on the release of ADS from the cut pituitary stalk and on the rate of urine flow.…”

mentioning

confidence: 98%

ADH Release from Cut Pituitary Stalk and Intact Pituitary Gland during Hippocampal Stimulation of Various Frequencies in Rats

Tomas¹,

Traczyk²,

Guzek³

1973

Neuroendocrinology

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Release of antidiuretic substance (vasopressin) from the central end of the cut pituitary stalk and the urine flow rate were estimated during electrical stimulation of the CA₁ field of the left hippocampus in rats. Frequencies of 4, 12, or 36 c/sec were used for hippocampal stimulation during the collection of the antidiuretic substance released from the cut infundibular axons, and frequences of 4 or 36 c/sec were used for hippocampal stimulation during urine flow determination. In all experiments, the current and voltage were adjusted to obtain approximately the same energy per train of pulses (2,160 nanowatt seconds). The antidiuretic activity of the fluid washing the cut pituitary stalk decreased during 4 c/sec hippocampal stimulation, showed no significant change during 12 c/sec stimulation, and increased considerably during 36 c/sec stimulation. The rate of urine flow did not alter during hippocampal stimulation at 4 c/sec, but decreased markedly during 36 c/sec stimulation. It is assumed that the hippocampus is able to trigger an increase or decrease in the rate of axoplasmic flow of antidiuretic substance and in the release of antidiuretic hormone from the pituitary gland. The frequency of hippocampal stimulation determines the response when the energy per train of electrical pulses remains constant.

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The Release of Antidiuretic Hormone From the Pituitary Stalk After Intravenous Calcium Chloride or Magnesium Chloride Infusion in Rats

Cited by 8 publications

References 12 publications

Oxytocin and vasopressin in rat hypophysial portal blood: experimental studies in normal and Brattleboro rats

Oxytocin and vasopressin in rat hypophysial portal blood: experimental studies in normal and Brattleboro rats

Effect of Intravenous and Intracarotid Injections of Hypertonic Fluids on the Release of Melanocyte-Stimulating Hormone From the Rat Posterior Pituitary Lobe Incubated in Situ

ADH Release from Cut Pituitary Stalk and Intact Pituitary Gland during Hippocampal Stimulation of Various Frequencies in Rats

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