Pancreatic Hormones and Metabolism in Ectotherm Vertebrates: Current Views

Plisetskaya, Erika M.; Duguay, Stephen J.

doi:10.1016/b978-0-12-629055-4.50015-5

Cited by 25 publications

(13 citation statements)

References 127 publications

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“…Lately, glucagon (Staub et al 1953), and presprosomatostatin (Hobart et al 1980) were discovered in fish BB. Since then numerous studies have been focussed on the characterization of the effect of these pancreatic peptides on fish metabolism, growth and reproduction (Mommsen and Busby 2006;Plisetskaya et al 1993;Sheridan and Hagemeister 2010;Sheridan and Kittilson 2004).…”

Section: Introductionmentioning

confidence: 99%

Glucose and lipid metabolism in the pancreas of rainbow trout is regulated at the molecular level by nutritional status and carbohydrate intake

Polakof¹,

Skiba‐Cassy²,

Kaushik³

et al. 2011

J Comp Physiol B

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Glucose and lipid metabolism in pancreatic islet organs is poorly characterized. In the present study, using as a model the carnivorous rainbow trout, a glucose-intolerant fish, we assessed mRNA expression levels of several genes involved in glucose and lipid metabolism (including ATP-citrate lyase; carnitine palmitoyltransferase-1 isoforms, CPT; the mitochondrial isoform of the phosphoenolpyrutave carboxykinase, mPEPCK and pyruvate kinase, PK) and glucosensing (glucose transporter type 2, Glut2; glucokinase, GK and the potassium channel, K(ATP)) in Brockmann bodies. We evaluated the response of these parameters to changes in feeding status (food deprived vs. fed fish) as well as to changes in the amount of carbohydrate (dextrin) in the diet. A general inhibition of the glycolytic (including the glucosensing marker GK) and β-oxidation pathways was found when comparing fed versus food-deprived fish. When comparing fish feeding on either low- or high-carbohydrate diets, we found that some genes related to lipid metabolism were more controlled by the feeding status than by the carbohydrate content (fatty acid synthase, CPTs). Findings are discussed in the context of pancreatic regulation of glucose and lipid metabolism in fish, and show that while trout pancreatic metabolism can partially adapt to a high-carbohydrate diet, some of the molecular actors studied seem to be poorly regulated (K(ATP)) and may contribute to the glucose intolerance observed in this species when fed high-carbohydrate diets.

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Section: Introductionmentioning

confidence: 99%

Glucose and lipid metabolism in the pancreas of rainbow trout is regulated at the molecular level by nutritional status and carbohydrate intake

Polakof¹,

Skiba‐Cassy²,

Kaushik³

et al. 2011

J Comp Physiol B

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“…Incubation of rainbow trout liver tissue in vitro revealed that sINS-and sGH-induced increases in steady-state mRNA levels are direct and rapid and occur at concentrations in the physiological range in the plasma of fish and other vertebrates (26,32). Additionally, these changes in steady-state SSTR mRNA levels were due to changes in rates of transcription, and not to alterations in SSTR mRNA stability.…”

Section: Discussionmentioning

confidence: 88%

“…The increased production of SS would then be able to bind to SSTRs, the surface expression of which was previously increased by the presence of INS and GH. Because of the physiological properties of INS and GH, it is not surprising that they differentially regulate SSTRs (26,29,32). For example, despite the involvement of both factors in growth, in some situations (e.g., fasting) their actions diverge (e.g., GH becomes catabolic) (32); differential interaction among INS, GH, SSTRs, and, ultimately, SSs may underlie such divergent conditions (via selective suppression of anabolic or growth-promoting pathways and/or selective activation of catabolic or growth-inhibiting pathways).…”

Section: Discussionmentioning

confidence: 99%

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Insulin and growth hormone stimulate somatostatin receptor (SSTR) expression by inducing transcription of SSTR mRNAs and by upregulating cell surface SSTRs

Nelson

Sheridan²

2006

American Journal of Physiology-Regulatory, Integrative and Comp

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This study examined the effects of insulin (INS) and growth hormone (GH) on mRNA and functional expression of somatostatin receptors (SSTRs). Rainbow trout liver was used as a model system to evaluate the direct effects of INS and GH on mRNA expression of three SSTR subtypes characterized previously from this species: SSTR1A, SSTR1B, and SSTR2. INS and GH directly stimulated steady-state levels of all SSTR mRNAs in a concentration- and time-dependent manner; however, the pattern of expression was hormone and SSTR subtype specific. INS stimulated SSTR2 expression to a greater extent than SSTR1A or SSTR1B expression, whereas GH stimulated SSTR2 and SSTR1B expression to a similar extent, with SSTR2 and SSTR1B expression being more responsive to GH than SSTR1A. Whether INS- or GH-stimulated SSTR expression resulted from altered rates of transcription and/or changes in mRNA stability also was investigated. Formation of nascent SSTR transcripts in nuclei isolated from rainbow trout hepatocytes was significantly stimulated by INS and GH. Neither INS nor GH, however, affected the stability of SSTR mRNAs. Functional expression of SSTRs was studied in Chinese hamster ovary (CHO-K1) cells stably transfected with SSTR1A or SSTR1B. Surface expression of functional SSTRs was stimulated by INS and GH. These findings indicate that INS and GH stimulate SSTR expression by regulating transcription of SSTR mRNAs and by increasing functional SSTRs on the cell surface, and they suggest that regulation of SSTRs may be important for the coordination of growth, development, and metabolism of vertebrates.

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“…In Geetrinidae the pancreas is between 3) islet of langerhanse (Gomori) (X320) oesophagus and large intestine (Sattari, 2002). Some teleost, for example Cyprinidae have hepatopancreas (Plisetskaya and Duguay, 1993). In lung fish protopetrous and many teleost as tuna, pancreas is an isolated organ.…”

Section: Resultsmentioning

confidence: 99%