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Cambridge University Press, British Journal of Nutrition, 8(104), p. 1148-1155, 2010

DOI: 10.1017/s0007114510001820

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Taurine supplementation: involvement of cholinergic/phospholipase C and protein kinase A pathways in potentiation of insulin secretion and Ca2+handling in mouse pancreatic islets

This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

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Abstract

Taurine (TAU) supplementation increases insulin secretion in response to high glucose concentrations in rodent islets. This effect is probably due to an increase in Ca2+handling by the islet cells. Here, we investigated the possible involvement of the cholinergic/phospholipase C (PLC) and protein kinase (PK) A pathways in this process. Adult mice were fed with 2 % TAU in drinking water for 30 d. The mice were killed and pancreatic islets isolated by the collagenase method. Islets from TAU-supplemented mice showed higher insulin secretion in the presence of 8·3 mm-glucose, 100 μm-carbachol (Cch) and 1 mm-3-isobutyl-1-methyl-xanthine (IBMX), respectively. The increase in insulin secretion in response to Cch in TAU islets was accompanied by a higher intracellular Ca2+mobilisation and PLCβ2protein expression. The Ca2+uptake was higher in TAU islets in the presence of 8·3 mm-glucose, but similar when the islets were challenged by glucose plus IBMX. TAU islets also showed an increase in the expression of PKAα protein. This protein may play a role in cation accumulation, since the amount of Ca2+in these islets was significantly reduced by the PKA inhibitors:N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinoline sulfonamide (H89) and PK inhibitor-(6–22)-amide (PKI). In conclusion, TAU supplementation increases insulin secretion in response to glucose, favouring both influx and internal mobilisation of Ca2+, and these effects seem to involve the activation of both PLC–inositol-1,4,5-trisphosphate and cAMP–PKA pathways.