Decreased insulin secretion in islets from rats fed a low protein diet is associated with a reduced PKAalpha expression
2004
Ferreira, F. | Barbosa, H.C.L. | Stoppiglia, L.F. | Delghingaro-Augusto, V. | Pereira, E.A. | Boschero, A.C. | Carneiro, E.M.
A low protein diet has been shown to affect the amount and activity of several enzymes and to decrease insulin secretion by islets isolated from rats fed such a diet. To understand the mechanisms involved in this phenomenon, we investigated the effects of forskolin, a stimulator of adenylyl cyclase, on insulin secretion by pancreatic islets from rats fed a normal (17%; NP) or low (6%; LP) protein diet for 8 wk. Isolated islets were incubated for 1 h in Krebs-bicarbonate solution containing 8.3 mmol glucose/L, with or without 10 micromol forskolin/L. The forskolin-induced insulin secretion was higher in islets from NP rats than in those from LP rats (P < 0.05). Western blotting revealed that the amount of the catalytic subunit of protein kinase A (PKA) was 35% lower in islets from LP rats than in islets from NP rats (P < 0.05). Moreover, PKA mRNA expression was reduced by 30% in islets from LP rats (P < 0.05). Our results indicated a possible relationship between a low protein diet and a reduction in PKA expression. These alterations in PKA may be responsible in part for the decreased insulin secretion by islets from rats fed a low protein diet.
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