Partial restoration of impaired alpha1-adrenergic responsiveness in parotid cells of aged rats by S-adenosylmethionine treatment |
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Authors: | Mary Ann Kowatch Jeremiah F. Kelly Natalia A. Denisova George S. Roth |
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Affiliation: | (1) Molecular Physiology and Genetics Section, Laboratory of Cellular and Molecular Biology, Gerontology Research Center, National Institute on Aging, 4940 Eastern Avenue, 21224 Baltimore, Maryland, USA |
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Abstract: | The age related decrease in alpha1-adrenergic stimulated inositol 1,4,5 trisphosphate (IP3) production in parotid cells of aged rats can be partially restored by treatment with S-adenosylmethionine (SAM). This effect is completely blocked by S-adenosyl homocysteine (SAH) and occurs in association with an increase in the conversion of phosphatidylethanolamine to phosphatidylcholine and a decrease in membrane viscosity. In contrast, SAM treatment actually inhibits stimulated IP3 production in cells of young rats. The membrane viscosity of these cells is lower than that of those from aged rats. Although conversion of phosphatidylethanolamine to phosphatidylcholine is enhanced, no further decrease in membrane viscosity is elicited in young cell preparations. These findings suggest that age changes in the membrane environment may result in impaired alpha1-adrenergic signal transduction and that such alterations may be at least partially reversible by SAM treatment. |
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Keywords: | aging parotid cells alpha1-adrenergic s-adenosylmethionine |
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