The pancreatic insulin content and its relationship to plasma glucose and free fatty acid concentrations in the embryo and neonatal chick

Abstract

1. An inverse relationship was found between the plasma glucose and FFA concentrations of embryos aged between 14 and 20 d. 2. Both the plasma glucose and FFA concentrations were constant during hatching. 3. The insulin content of the pancreas increased between 14 and 20 d but fell during hatching.

Morphogenesis and differentiation of the avian endocrine pancreas, with particular reference to experimental studies on the chick embryo

“…There is evidence that responsiveness to glucose for release of insulin occurs much earlier in chick embryos (Foltzer et al, 1982;Leibson et al, 1976; see also Epple and Brinn, 1987) than in rat foetuses (Hellerström and Swenne, 1991;Kervran and Randon, 1980). There is at present no information as to when chick insulin cells first respond to glucose by replicating but our data would suggest that this could occur during embryonic life when blood glucose levels are rising (Benzo and Green, 1974;Langslow, 1975;Simon and Leclercq, 1982). This is in contrast to the situation in the rat where glucose fails to provoke insulin cell replication in islets from younger foetuses, although such cells are stimulated to divide by a raised level of amino acids.…”

“…Based in part on experiments performed on cultured mammalian islet cells (de Gasparo et al, 1978;, and taking account of plasma glucose levels in the chick embryo (Langslow, 1975;Simon and Leclercq, 1982), we (1) raised the glucose level in F12.ITS from 10 to 20 mM and (2) raised the level of essential amino acids approximately 5-fold from 503 to 2,285 mg/l (see Rawdon and Andrew, 1997). These nutrient levels are known to stimulate replication of rodent insulin cells (de Gasparo et al, 1978;.…”

Development of embryonic chick insulin cells in culture: Beneficial effects of serum-free medium, raised nutrients, and biomatrix

“…Furthermore, our material was responsive to glucose at a significantly earlier stage of embryonic development than were the rat islets. It is known that in chick embryos, plasma glucose increases from Day 5 to levels that, at hatching, are not far short of adult levels (7,24,43). We are unaware of the age at which chick insulin cells can first respond to glucose by replicating but there is evidence that responsiveness to glucose for the release of insulin occurs much earlier in chick embryos (11,12) than in rat fetuses (44).…”

“…insulin at 5 p_g/ml, transferrin at 5 p.g/ml, and selenium at 10 lo M. In an effort to improve the yield of insulin cells, we modified the standard medium. On the basis of information gleaned partly from literature on cultured mammalian endocrine cells (see 10,46) and taking account of plasma glucose levels in chick embryos (24,43), we (a) raised the glucose level from 1.8 mg/ml (10 n~¢) to 3.6 mg/ml (20 ~, (b) raised the level of essential amino acids by increasing glutamine fourfold to 584.6 mg/ 1 and the others approximately fivefold to 1700 mg/1. and (c) combined (a) and (b).…”

Effect of in ovo ghrelin administration on subsequent serum insulin and glucose levels in newly-hatched chicks

“…Insulin content of the embryonic pancreas rises to peak during days 14-20 of incubation with subsequent falling at hatching time, but the blood glucose level of chickens is constant in pre-hatching, hatching or post-hatching period (Langslow, 1975). Glucose was found to readily enter the cells of the heart of 5-6 day chicken embryo, in which the uptake of 2-deoxyglucose was stimulated by physiological levels of insulin as early as 5-6 days (Kutchai et al, 1977).…”