Insulin modifies aging-related inhibition of 1-stearoyl, 2-arachidonoylglycerol phosphorylation in rat synaptic terminals.
Neurochem Int
; 58(3): 330-6, 2011 Feb.
Article
em En
| MEDLINE
| ID: mdl-21167245
The purpose of the present study was to analyze diacylglycerol kinase (DAGK) activity in synaptic terminals from cerebral cortex (CC) and hippocampus (Hp) from adult (3-4 month-old) and aged (26-28 month-old) rats. The effect of insulin through DAGK activity on synaptosomes from adult and aged rats was also analyzed under conditions favoring saturated or unsaturated phosphatidic acid (PA) formation, using exogenous di-palmitoil glycerol (DPG) or 1-stearoyl-2-arachidonoylglycerol (SAG) as substrates. Results showed that the enzymatic activity preferentially uses SAG as substrate, thus indicating the presence of É-type DAGK. A significant decrease in DAGK activity transforming SAG into PA was also observed in both tissues from aged rats. Western blot detection of DAGKÉ showed that enzyme content undergoes no changes with aging. [3H] inositol incorporation into phosphoinosites was also analyzed to evaluate the role of DAGKÉ in their synthesis. Data obtained from 3H-inositol incorporation into phosphoinositides revealed that in synaptosomes from aged rats phosphatidylinositol (PI) synthesis is lower than in adult animals. Interestingly, in the presence of SAG, PI synthesis was restored to adult values. DAGK activity over SAG was more highly stimulated by insulin in CC and Hp synaptosomes of aged rats with respect to adult rats. On the other hand, insulin exerted a stimulatory effect on PI and phosphatidylinositol 4 phosphate (PI(4)P) synthesis in synaptosomal CC from aged rats. Taken together, our findings indicate that in aged rats insulin triggers a stimulatory mechanism that reverts the diminished synaptosomal ability to synthesize arachidonoyl phosphatidic acid (20:4 PA). The recovery of this PA species indicates that insulin positively regulates phosphoinositide synthesis.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fosfatidilinositóis
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Envelhecimento
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Terminações Pré-Sinápticas
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Diacilglicerol Quinase
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Diglicerídeos
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Insulina
Limite:
Animals
Idioma:
En
Revista:
Neurochem Int
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Argentina
País de publicação:
Reino Unido