In vitro effect of insulin on the uptake of glucose and α-aminoisobutyric acid in the thyroid gland of the turtle (Chrysemys dorbigni) (original) (raw)
Related papers
Journal of Experimental Zoology, 1993
Insulin stimulation of the glucose uptake by the thyroid gland of the turtle (Chrysemys dorbigni) has been previously reported. The aim of the present study was to examine the influence of different temperatures (6, 25, or 36°C) on this effect. Insulin-stimulated glucose uptake was evident when turtles were acclimated for 15 days at 25" or 36"C, and their glands studied at the respective temperatures. In glands from turtles acclimated at 6"C, this effect was only seen when the preincubation and incubation time was extended from 60 to 300 min. The findings show that in this ectotherm species (1) the insulin effect is temperature dependent, and (2) can be expressed at very low temperature.
Radioimmunoassay of insulin in fishes, experiments in Vivo and in Vitro
General and Comparative Endocrinology, 1971
This paper describes an adaptation of the radioimmunoassay of Hales and Randle for the determination of insulin levels in fish serum and in media used for the incubation of fish islets. Using codfish insulin as a reference standard, guinea pig anticod insulin serum, and "'I-labeled cod insulin, instead of the standard mammalian components, the average fasting serum insulin level (*SEM) was found to be 36 + 9 pU/ml in goldfish (Carassius auratus) and 19 * 6 pU/ml in toadfish (Opsanus tau). Serum insulin levels of fed goldfish were nearly double that of fasted fish. Glucose (40 or 100 mg/lOO ml) or leucine (1 mg/ml), stimulated the release of insulin by incubated islets of 0. tau. The leucine effect appeared to be enhanced b> the simultaneous addition of glucose (40 mg/lOO ml) to the incubation medium, Arginine (1 mg/ml) had no effect upon the release of insulin in vitro. The significance of the results is discussed. Marked chemical, biologic, and immunologic differences have been demonstrated between insulins of different animal species (Smith, 1966; Falkmer and Wilson, 1967). These differences result in poor affinity of fish insulin for antibody to mammalian insulin and make the measurement of insulin levels in fish, with commonly available antimammalian insulin sera and mammalian insulin standards difficult, if not impossible (Tashima and Cahill, 1968; Watkins et al., 1968; Dixit et al., 1969). This paper describes an adaptation of the insulin immunoassay of Hales and Randle (1963) in which cod fish insulin and guinea pig anticodfish-insulin serum (GPACIS) were substituted for the equivalent mammalian components. This sys-'Aided by Grants Nos. 5 ROl AM06034 and 5 SO1 FR05641.
In vivo" effects of insulin on carbohydrate metabolism of catfish (Ictalurus melas)
Comparative biochemistry and physiology. A, Comparative physiology, 1982
The effect of insulin was studied on blood glucose, and on the glycogen level of liver, muscles and heart in fed and in starved catfish (Ictalurus melas). Fish received intraperitoneally 60 iu/kg body weight of bovine insulin, or physiological saline and were sacrificed after 2, 4, 8, 24, 72 hr from injection. Insulin caused a decrease of blood glucose level, both in fed and in fasted animals, and the effect is more evident in fed animals. After insulin treatment, liver glycogen shows a decrease which is significant at the 8th and 24th hr in fasted and in fed animals respectively; after 72 hr the glycogen level in livers of fed and fasted animals is still very low. Insulin increases the glycogen level both in white and in dark muscle, both in fed and in fasted fish, although with different characteristics, but at the 72nd hr in all animals, the increases are significant. Hormone treatment does not change heart glycogen levels in fed catfish till the 24th hr, then there is a net decr...
Localization of insulin to gastroenteropancreatic cells in the turtle gastrointestinal tract
General and Comparative Endocrinology, 1990
Insulin has been localized immunocytochemically to open-type gastroenteropancreatic endocrine cells in sections of Bouin's-fmed upper, middle, and lower intestine from Chrysemys picta, Pseudemys scripta scripta, P. scripta elegans, P. floridama, Sternotherus odoratus, and Trionyx spinifer asper. Radioimmunoassay of extracts of mucosal scrapings from Chrysemys intestine indicates differential amounts of insulin-like immunoreactivity within the intestine (higher amounts in the lower intestine) and in concentrations approximately one-tenth to one-fifth that found in extracts of Chrysemys pancreas. The presence of insulin in the gastrointestinal tract of chelonians represents a major departure from the typical vertebrate condition which is characterized by an absence of insulin from the spectrum of regulatory peptides in the gut. Q 1990 Academic MS, IW.
Insulin binding and biological activities in the FRTL-5 rat thyroid cell line
Metabolism, 1987
A cloned rat thyroid cell line was examined for both insulin binding and responsiveness. The characteristics of insulin binding to thyroid cells were similar to those observed in typical insulin target cells. The '261-insulin binding was time and temperature dependent and Scatchard analysis suggested the presence of two major binding sites with high and low affinity constant (Kd = 1.4 x lo-" mol/L and 1.5 x lo-' mol/L, respectively). '261-insulin was also internalized and degraded in a temperature-dependent manner. IGF, was weakly effective in completing '261-insulin binding to FRTL-5 cells 157% inhibition at 333 nmol/L), whereas noninsulin-related peptide hormones were ineffective. Exposure of FRTL-5 cells to insulin stimulated both methyl-aminoisobutyric acid (M-AIB) and 2deoxy-D-glucose (2DG) transport. These effects were evident at lo-' mol/L and maximal at TO-' mol/L insulin. Maximal stimulation was three-to four-fold over basal value for both M-AIB and 2DG transport. These data suggest that insulin specifically binds to FRTL-5 cells and regulates different biological functions of this thyroid cell line.
Insulin-like peptides in the lobster Homarus americanus I. Insulin immunoreactivity
General and Comparative Endocrinology, 1983
Experiments were conducted to determine if insulin-like peptides are present in the lobster Homarus americanus. Peptides were found that bind specifically to bovine insulin antibodies in a modified vertebrate radioimmunoassay. Extracts of whole hepatopancreas, gut, and hemolymph contained insulin immunoreactivity (IRI) concentrations of 67.5, 14.0, and 11.0 ng, respectively, per 700-g lobster. No insulin immunoreactivity was detected in neurosecretory cells of the eyestalk. The highest immunoreactivity was measured in the hepatopancreas, in the same fractions of eluate which contained the highest immunoreactivity when a bovine insulin standard was passed through the same chromatographic column.
Fator de crescimento ligado à insulina na reprodução animal
Pubvet
O desenvolvimento da produção de gametas femininos (gametogênese) ocorre de forma interessante, pois seu processo depende de diversos fatores combinados. Esta revisão abordará esses mecanismos morfofuncionais do ovário e a foliculogênese, correlacionando a função dos fatores de crescimento ligados à Insulina (IGFs) que irão influenciar na produção de hormônios esteroides, na manutenção da maturação folicular, e ainda elucidar como a dieta alimentar auxilia melhor nessas fases. Além disso, com as novas pesquisas em reprodução animal, é importante enfatizar o papel e auxiliar os Fatores de Crescimento Insulínicos durante este processo fisiológico, mostrando todo o seu potencial para uma dinâmica folicular mais eficiente em qualquer espécie.
Isolation, purification, and primary structure of insulin from the turtle Chrysemys dorbigni
General and Comparative Endocrinology, 1991
Insulin A and B chains from pancreas of the turtle Chrysemys dorbigni have been purified to homogeneity, and their primary structures have been determined. The sequence of the A chain is G-I-V-E-Q-C-C-H-N-T-C-S-L-Y-Q-L-E-N-Y-C-N, and that of the B chain is A-A-N-Q-H-L-C-G-S-H-L-V-E-A-L-Y-L-V-C-G-E-R-G-F-F-Y-S-P-K-A. The amino acid sequence of Chrysemys insulin is identical to that of another turtle (Pseudemys scripta), the chicken, and turkey. When compared with alligator insulin, it has three conservative substitutions in the B chain. However, there are seven substitutions when compared with the insulin of the rattlesnake.