Bioassay Procedures for Neurohypophysial Hormones and Similar Polypeptides

Stürmer, E.

doi:10.1007/978-3-642-46127-9_4

Cited by 14 publications

(9 citation statements)

References 146 publications

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“…To our knowledge the role of the sympatheticadrenomedullary system on ductal tone has not yet been addressed under non-stressed conditions. The presence of a tonic sympathetic influence on the mammary glands has been proposed by Stürmer (1968) and observed in anaesthetized lactating rats by Grosvenor et al (1972). It is attractive to postulate that in the present study the intensity of such influence represents the background activity of the sympathetic-adrenomedullary regulation which may decrease as lactation progresses.…”

Section: Discussionmentioning

confidence: 88%

Mammary resistance: a possible controlling factor in milk ejection

Lau

Henning

1987

Journal of Endocrinology

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At 8 and 13 days post partum, rats have the same total milk availability; yet, in response to suckling they release a greater amount of milk on day 13 than on day 8. Increased sensitivity to suckling in the more advanced lactators may result from a greater release of oxytocin or from changes in the mammary glands as lactation advances. The present study explores this latter possibility in anaesthetized dams at 8-9 and 13-15 days of lactation. Milk release and intramammary pressure were measured in anaesthetized dams in response to various doses of oxytoxin. Milk release was determined from the body weight gain of pups which had been fasted for 5 h before suckling on dams which had been isolated for 5 h. This parameter was significantly greater in 13- to 15-day lactators than in 8- to 9-day lactators over the range of oxytocin doses examined. In contrast, intramammary peak pressure and its dissipation time were significantly larger in the 8- to 9-day lactators than in the 13- to 15-day lactators. The compliance of the mammary glands was indirectly assessed at the two stages of lactation. When a constant pressure pulse was introduced into a cannulated gland, the resulting pressure peak was significantly greater in 8-day than in 13-day lactators, indicating a greater resistance in the former. Taken together, these results indicate that when endogenous oxytocin is inhibited (by anaesthesia) the greater milk release observed at the later stage of lactation in response to various doses of oxytocin may be due to a decline in mammary resistance as lactation progresses.

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Section: Discussionmentioning

confidence: 88%

Mammary resistance: a possible controlling factor in milk ejection

Lau

Henning

1987

Journal of Endocrinology

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“…The gland cubes were stored in Tyrode's medium until used for assay. They were placed in the solution to be tested and the milk-ejection phenomenon was observed under stereomicroscope at an environmental temperature of about + 22 ~ As recommended by Stiirmer (1968) fifteen mammary cubes were tested for each solution and the mean milk-ejection time was considered to be a quantitative response index of the oxytocic activity. Unknown extracts were assayed against synthetic oxytocin (Richter, Budapest, batch No.…”

Section: Bioassay Of Oxytocinmentioning

confidence: 99%

The hypothalamic and neurohypophysial oxytocin content as influenced by desmethylimipramine in normal and pinealectomized white male rats

Guzek

Juszczak

1985

J. Neural Transmission

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Pinealectomized, sham-operated and non operated control rats were injected intracerebroventricularly (i.c.v.) with a single dose of desmethylimipramine hydrochloride (DMI; 20 micrograms, dissolved in 10 microliters of normal saline); after 4 hours they were decapitated and the hypothalamic and neurohypophysial oxytocin content was bioassayed using the milk-ejection effect in vitro. DMI decreased oxytocin content of the hypothalamus and neurointermediate lobe in non operated and sham-operated animals. In pinealectomized rats the oxytocin content of the hypothalamus and neurointermediate lobe diminished and could be further reduced by an i.c.v. DMI injection. As shown in animals pretreated with phenoxybenzamine, these events might be only partially related to an increase of alpha-adrenergic transmission.

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“…The ability of oxytocin to lower chicken blood pressure is the basis for a bioassay method for this peptide. 23 …”

Section: Oxytocinmentioning

confidence: 99%

Vasoactive peptides. State-of-the-art review.

Said¹

1983

Hypertension

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SUMMARY At least 16 naturally occurring peptides either constrict or dilate blood vessels. Many of these peptides are present in nerve cells and nerve terminals supplying systemic and pulmonary blood vessels and the heart. Such neuropeptides are released locally as neurotransmitters, and can influence vascular tone, local and regional blood flow, arterial blood pressure, and cardiac function. There is evidence for the participation of at least some vasoactive peptides in the regulation of these functions and in the mediation or modulation of systemic shock and arterial hypertension. The investigation of vasoactive peptides in relation to cardiovascular function and dysfunction is at a promising threshold. There is a growing conviction that these peptides participate in the regulation of many organ functions. Neuroscientists, endocrinologists, and gastroenterologists have led other groups in recognizing the likely physiological and clinical significance of these peptides, most of which are found in the brain and gut.1 " 1 Since many biologically active peptides are capable of influencing vascular smooth muscle, and thus blood flow and blood pressure, peptides with these vasoactive properties are reviewed here. Emphasis is placed on the cardiovascular effects of the more recently identified peptides, with special reference to their possible roles in the regulation of blood pressure in normal and abnormal states. Bradykinin and angiotensins, which are extensively reviewed elsewhere, are only briefly mentioned here. Biological Activity of PeptidesWhich Peptides are Vasoactive?Peptides with vasoactive properties are given in the accompanying list (see box), which is not meant to be complete. For some of these peptides (e.g., angiotensin II, bradykinin), vasoactivity is a dominant feature of their biological actions; for others (e.g., prolactin, parathyroid hormone), the pressor or vasodepressor activity has generally been overshadowed by other actions of the peptide.As will become apparent in the following para : graphs, the ability to induce either vasodilation or vasoconstriction is shared by a variety of apparently unrelated peptides. It is possible in some instances, however, t o ' recognize certain structural features among these peptides that correlate with their vasodilator or vasoconstrictor activity. Such features will be noted. AngiotensinsAngiotensin II (table 1) is one of the most potent systemic vasopressors known. Its formation from angiotensin I through the action of angiotensin-converting enzyme, the localization and properties of this enzyme, and the physiology, pathophysiology, and pharmacology of the renin-angiotensin systems in the body are topics of recent comprehensive reviews.5 "" Bombesin A 14-residue peptide (table 1) isolated from the skin of the frog Bombina bombina, bombesin has spasmogenic activity on a variety of vascular and non-vascular smooth muscle structures.12 It induces vasoconstriction and systemic hypertension in most animal species, hypotension in monkeys, but neither in humans...

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Bioassay Procedures for Neurohypophysial Hormones and Similar Polypeptides

Cited by 14 publications

References 146 publications

Mammary resistance: a possible controlling factor in milk ejection

Mammary resistance: a possible controlling factor in milk ejection

The hypothalamic and neurohypophysial oxytocin content as influenced by desmethylimipramine in normal and pinealectomized white male rats

Vasoactive peptides. State-of-the-art review.

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