Insulin Secretion and Content in Isolated Rat Pancreatic Islets Following Treatment with Gestational Hormones

Hager, Diana; Georg, Ralph H.; Leitner, J. Wayne; Beck, Paul

doi:10.1210/endo-91-4-977

Cited by 28 publications

(15 citation statements)

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“…The enhanced insulin response to a glucose stimulus and the slightly impaired glucose tole¬ rance observed in this study are consistent with those observed in humans treated with progeste¬ rone (Costrini & Kalkhoff 1971 ;Hager et al 1972) or MPA (Gershberg et al 1969;Tuttle & Turkington 1974;Spellacy et al 1970). From our study it appears that MPA administration, without causing GH elevation, induces increased insulin levels in dogs (Fig.…”

Section: Discussionsupporting

confidence: 90%

Influence of medroxyprogesterone acetate (Provera) on plasma growth hormone levels and on carbohydrate metabolism

Eigenmann¹,

Rijnberk²

1981

Acta Endocrinologica

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Section: Discussionsupporting

confidence: 90%

Influence of medroxyprogesterone acetate (Provera) on plasma growth hormone levels and on carbohydrate metabolism

Eigenmann¹,

Rijnberk²

1981

Acta Endocrinologica

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“…The nuclear events which lead to subse-Administration of certain steroids to rats will induce hyperinsulinism and islet hypertrophy [1], and combination of progesterone and estradiol will effect changes somewhat similar to that observed in late pregancy [2][3][4][5]. It has not been possible to observe short term direct effects of progesterone and estradiol on insulin secretion in vitro from isolated islets [2,4].…”

Section: Discussionmentioning

confidence: 99%

Binding of3H-progesterone by isolated rat islets of Langerhans

et al. 1978

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Summary.Islets of Langerhans isolated from normal female rats have been used in studies of 3H-progesterone uptake by intact islet cells. The intracellular sites which are involved in binding of the hormones have been determined by subcellular fractionation and autoradiography. Uptake of 3H-progesterone into islets occurred in a temperature and concentration dependent manner. The uptake increased rapidly in the first 30 min, and could be partially displaced by addition of excess unlabelled progesterone. 3H-progesterone uptake was lowered by incubation of the islets in the absence of Ca ++, at 0 ° compared to 37 ° C, or to a much lesser extent when islet cycilic AMP levels were raised by addition of 3-isobutyl-1-methylxanthine. However, uptake was unaffected by prior treatment of the islets with neuraminidase or phydroxymercuribenzoate. Differential centrifugation of islets which had previously been incubated with 3H-progesterone showed the highest specific activity of binding in the nuclei and debris fraction. Isolation of a purified nuclear fraction by sedimentation through sucrose solutions confirmed that binding was present in the nuclear component of this heterogeneous fraction, while autoradiographic studies suggested both nuclear and cytosolic localisation of 3H-progesterone. In a separate series of experiments, evidence was obtained for the existence of saturable cytosolic binding of progesterone, and for movement of labelled hormone from the cytosol to the nuclear fraction.It is suggested that, in the islets of Langerhans as in other target tissues, the action of progesterone involves penetration into the cells, binding to a cytosolic receptor protein, and subsequent transfer to the nucleus. The nuclear events which lead to subse-

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“…The hormones of pregnancy may be responsible for this effect. Ample evidence is available that pregnancy hormones stimulate insulin secretion in the rat (3,6,42,55), and early data in human subjects suggests a reciprocal inhibitory effect on glucagon secretion (56).…”

Section: Discussionmentioning

confidence: 99%

Plasma glucagon and insulin in rat pregnancy. Roles in glucose homeostasis.

Saudek¹,

Finkowski²,

Knopp³

1975

J. Clin. Invest.

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A B S T R A C T To determine if pancreatic glucoregulatory hqrmones can be implicated in the glucose fall of pregnancy, we have measured plasma immunoreactive insulin and glucagon (IRI and IRG) in rats. Fed rats in midgestation show a rise in IRI without a corresponding increase in IRG. In late gestation, IRG rises significantly, but only enough to keep pace with a further rise in IRI. On a molar basis, IRI remains the predominant hormone despite a marked fall in blood glucose. After a 48-h fast IRI falls to comparably low levels in pregnant and virgin rats. A small rise in IRG is seen in virgin but not in pregnant rats despite frank hypoglycemia in the latter. Thus, IRG secretion in pregnancy is diminished relative to IRI in the fed state and fails to increase in the fasted state despite the stimulus of a lower glucose in both instances.To evaluate IRG secretory reserve, the IRG response to i.v. alanine was assessed in late gestation. In fed rats a greater IRG increase is seen in pregnancy; after fasting no difference is seen between pregnant and virgin rats. These results preclude an absolute deficiency in glucagon secretion. Pancreas hormone stores were also measured in an effort to explain the altered secretory state. We find reciprocal changes in IRI and IRG content favoring IRG in midgestation and IRI in late gestation. Thus, pancreas hormone storage is altered in pregnancy but does not account for the changes in hormone secretion. Rather, pregnancy exerts

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Insulin Secretion and Content in Isolated Rat Pancreatic Islets Following Treatment with Gestational Hormones

Cited by 28 publications

References 0 publications

Influence of medroxyprogesterone acetate (Provera) on plasma growth hormone levels and on carbohydrate metabolism

Influence of medroxyprogesterone acetate (Provera) on plasma growth hormone levels and on carbohydrate metabolism

Binding of3H-progesterone by isolated rat islets of Langerhans

Plasma glucagon and insulin in rat pregnancy. Roles in glucose homeostasis.

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