Decreased Insulin Secretion in Islets from Rats Fed a Low Protein Diet Is Associated with a Reduced PKAα Expression

Abstract

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 alpha catalytic subunit of protein kinase A (PKAalpha) was 35% lower in islets from LP rats than in islets from NP rats (P<0.05). Moreover, PKAalpha 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 PKAalpha expression. These alterations in PKAalpha may be responsible in part for the decreased insulin secretion by islets from rats fed a low protein diet.

Diabetes-related changes in cAMP-dependent protein kinase activity and decrease in relaxation response in rat mesenteric artery

“…In rats fed a low-protein diet, insulin secretion by the islets was decreased, and this impairment was associated with reduced PKA Cat-␣ subunit expression (14). Moreover, the expression of the gene that encodes the regulatory subunit of PKA was increased in this model (14).…”

“…In rats fed a low-protein diet, insulin secretion by the islets was decreased, and this impairment was associated with reduced PKA Cat-␣ subunit expression (14). Moreover, the expression of the gene that encodes the regulatory subunit of PKA was increased in this model (14). Furthermore, PKA RII-␤ subunit knockout mice have been noted both to be leaner and to be protected against diet-induced obesity, insulin resistance, and dyslipidemia (2, 9, 51).…”

Differential activations of PKC/PKA related to microvasculopathy in diabetic GK rats

“…And the releases of glucagon and adrenocorticotropic hormone became markedly heightened under diabetic conditions (1,7). A lowered secretion might contribute to a reduced expression of PKA Cat-␣ subunit (15).…”

RetractedDecreased FKBP12.6 expression and enhanced endothelin receptor signaling associated with arrhymogenesis in myocardial infarction rats

“…To ensure there was a fixed amount of initial mRNA in parallel with β-actin, amplification was performed using the following oligonucleotides: Sense: 5′-GGT ATG GGT CAG AAG GAC TCC-3′, Antisense: 5′-TGA TCT TCA TGG TGC TGC TAG GAG CC-3′. Specific oligonucleotide primers for RyR2, FKBP12.6, PKA, ECE (endothelin converting enzyme) and preproET-1 (prepro-endothelin-1) were used and processed as described in previous work (He et al, 2007;Wang et al, 2004;Ferreira et al, 2004).…”