The Regulation of Insulin Secretion by the Ovine Foetus in Utero

Bassett, J. M.; Thorburn, G. D.

doi:10.1677/joe.0.0500059

Cited by 63 publications

(50 citation statements)

References 30 publications

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“…These factors may help t o explain some of the earlier conflicting data regarding insulin secretion responses in several species. Reported insulin responses to glucose injections in both the monkey (1 8), rat (1 5), and man (21) were minimal, whereas, in the fetal sheep, a response t o acute glucose o r fructose injection has been observed by some authors (4,5,9) and not by others (25). The present results suggest that some of this variation may relate t o the degree and duration of the stimulus.…”

Section: Discussionmentioning

confidence: 51%

“…Immunoreactive insulin was measured load in several species are conflicting; insulin levels have been by a modification of the double antibody technique of Morgan described as either increasing in sheep (4,5,9) and man (17,and Lazarow (19). Glucagon was assayed using a double 21) or remaining unchanged in man (2), monkeys (18), and antibody radioimmunoassay developed in our laboratory (23);…”

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confidence: 99%

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Insulin-Glucagon Substrate Interrelations in the Fetal Sheep

et al. 1974

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Extract METHODS AND MATERIALSTwenty-four studies were conducted in 14 sheep fetuses to Fourteen healthy date-bred pregnant ewes with gestational investigate the pancreatic islet a! and /3 cell responses to ages ranging from 100-145 days were studied. The chronic substrate infusions. The studies were conducted between 100 indwelling catheter preparation was utilized and has been days gestation and near term, using indwelling vascular described previously (14). Briefly, a laparotomy through a left catheters for infusions and blood sampling. constant glucose flank incision was performed using spinal anesthesia and infusions (6 mg/kg/min) produced a significant rise in the aseptic technique. Either a jugular vein and carotid artery or a mean concentration of insulin in plasma by 105 min, but no femoral vein and artery were isolated and catheterized, change in glucagon in plasma was observed. Near term (>I35 depending on whether the fetal head or hind limb was most days) the mean plasma insulin increment with constant glucose conveniently exposed. Following catheter placement, the fetus infusion was significantly greater and occurred sooner than in was returned to the uterine cavity and the laparotomy closed.fetuses early in gestation (

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Section: Discussionmentioning

confidence: 51%

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confidence: 99%

Insulin-Glucagon Substrate Interrelations in the Fetal Sheep

et al. 1974

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“…Immunoreactive insulin can be localized in the islets utilizing the fluorescent antibody technique by 80 days gestation, a week after the first histologic evidence of islet formation (76). Van (85) or by combined theophylline and glucose infusions (94 (95)(96)(97)(98)(99)(100).' Similar findings have been observed in mice with congenital pituitary dwarfism (101) and after hypophysectomy of fetal rats (102), rabbits (102), sheep (103,104), and monkeys (105).…”

Section: Introductionmentioning

confidence: 54%

The Ontogenesis of Human Fetal Hormones

Kaplan¹,

Grumbach²,

Shepard³

1972

J. Clin. Invest.

204

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A B S T R A CThere was a significant positive correlationi betweeni growth hormone content of the l)ituitary and gestational age, crown-rump length., and the weiglht of the l)ituitary gland.The content and concentration (nmicrogranis/niflligrani) of human growth hormone (HGEI) in the fetal pituitary showed significant incremenits (P < 0.001) for each 4 wk period of gestation until 35 wk. Furtlher increases in the HGH content were noted in l)ituitaries of children aged 1-9 yr (range of 832 to 11,211g).Immunoreactive GH was detected in fetal serumii at a concentration of 14.5 ng/ml as early as 70 (lays gestation, the youngest fetus assayed. The increment in content and concentration of pituitary GH bore a significant relationship to gestational age, crown-rump length, and to the weight of the pituitary gland (Table II and Figs. 2 and 3).The concentration and content of GH in the pituitaries of children less than 1 yr of age was comparable to the levels detected in fetal pituitaries at 32-40 wk of gestation with a mean content of 1202±252 Ag and a meani concentration of 10.1 + 1.4 Ag/mg (Fig. 1 ) (Fig. 4).Further evidence for the similarity of the GH in the pituitary gland of the fetus and adult was the comparable physicochemical properties observed after disc electrophoresis (Fig. 5). The position of the major band for the pituitary homogenates is similar, but the major band of the purified HGH was slightly more anodal. Similar observations were made after immunoelectrophoresis. The crest of the precipitin arc for the fetal pituitary homogenate when reacted with antiserum to HGH was located in slightly cathodal position and was similar to that observed for homogenates of pituitary glands of the children and adults (Fig. 6) (Fig. 7). The mean concentration at 10-14 wk was 65.2±9.6 ng/ml; at 15-19 wk mean concentration was 114.9±12.5 ng/ml; at 20-24 wk mean concentration was 119.3±19.8 ng/ml; at 25-29 wk the mean concentration was 72.0±6.5 ng/ml; and at 30-40 wk the mean 2Deamidation and other structural alterations of pituitary HGH during purification procedures affect its electrophoretic mobility (34). concentration was 26.5±11.5 ng/ml. The mean concentration in umbilical venous serum specimens obtained at delivery was 33.5±4.2 ng/ml.The concentration of serum HGH showed a significant negative correlation with gestational age (P < 0.001) (Table II).A significant difference was demonstrated in the mean concentration of serum HGH at 10-14 wk compared with all other gestational periods (P > 0.05) (Table I). No significant difference was demonstrated between the mean concentration at 15-19 wk, 20-24 wk, or 25-29 wk. The mean concentration of serum GH at 25-29 wk was significantly greater than at 30-40 wk (P < 0.02).In 17 fetuses from which matched serum and pituitary specimens were obtained, there was no significant correlation of the concentration of serum HGH to the pituitary content of HGH (P > 0.5) (Table II, Fig. 8).Serum HCS. HCS was detected in all 48 fetal sera tested in concentrations of 2-240 ng/ml. The lev...

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“…It is clear therefore that this early insulin release in an important component of the anticipatory reflex cardiovascular and endocrine changes which occur on ingestion of a meal and evidently comes into play shortly after birth when intermittent oral ingestion of nutrients first becomes of significance. Indeed it is possible that this anticipatory reflex release of insulin may be of greater significance for glucose homeostatic regulation in the newborn than the increased responsiveness of the fi-cell to glucose demonstrated in newborns of several species after initiation of feeding [10,[21][22][23]. Clearly the oral stimulus should be preserved wherever possible in feeding regimes for sick newborn infants.…”

Section: Discussionmentioning

confidence: 99%

“…Plasma concentrations of glucose and insulin were determined as described previously [10]. The radioimmunoassay for insulin utilized a disequilibrium system with talc as adsorbent to separate free from bound insulin.…”

Section: Analyticalmentioning

confidence: 99%